C INTRODUCTION: Cell is a basic unit of life considered as structural and fu of an organism. Robert H discovered cell. He first observe a piece of dead cork cells. He d in his book “Micrographia”. Leeuwenhoek (1674) first obse cell and used the term “Animalc The study of cell structure is ca The study of cell structure, reproduction is called Cell biolog Robert hooke is known as ‘father cytology’. Swanson is called the ‘Father of cytology’ CELL THEORY In 1838, Malthias Schleid botanist, examined a larg plants and observed tha are composed of differe cells which form the tis plant. At about the Theodore Schwann (18 Zoologist, studied differ animal cells and reporte had a thin outer layer w known as the ‘plasma me also concluded, based on on plant tissues, that the cell wall is a unique cha plant cells. Schwann proposed the that the bodies of anima are composed of cells a of cells. Schleiden and Schwan formulated the cell t theory however, did not how new cells were for Virchow (1855) first ex cells divided and new formed from pre-exi (Omnis cellula-e cellula). the hypothesis of Sc Schwann to give the c final shape. Cell understood today is (i) all living organ composed of cells and cells. (ii) all cells arise from cells. CELL THE UNIT OF LIFE e and It is unctional unit Hooke (1665) ed the cell in described cell erved animal cule” for it. alled cytology. function & gy. r of modern den, German ge number of at all plants ent kinds of ssues of the same time, 839), British ent types of ed that cells which is today embrane’. He n his studies e presence of aracter of the e hypothesis als and plants and products nn together theory. This explain as to rmed. Rudolf xplained that w cells are isting cells . He modified chleiden and cell theory a theory as nisms are products of pre-existing EXCEPTION OF CELL I. Virus/ Virion II. viroids III. prions SIZE AND SHAPE OF SIZE Cell differ greatl activites. Mycoplasma laid Only 0.3 m in le pneumonia like o of mycoplasma h 0.1 m)] Bacteria 3 to 5 Largest unicellul Acetabularia alg Largest isolated egg Human red bloo Longest animal c (Neurons) Longest plant ce (Boehmaria) EAGLE 1. Smallest cell ha to volume ratio 2. Virus is acellular between living an SHAPE The shape of the the funtion they They may be dis columnar, cuboid even irregular. T may vary with th perform. PROKARYOTIC CELL Cell that bears naked ge nucleus is without Nucl as prokaryotic cell. 1L THEORY n/ Bacteriophage, F CELL ly in size, shape and dlawii (Smallest cells) ength [PPLO (pleuro organisms) is a type having the size about 5 m lar Eukaryotic cell - ga - (10cm) single cell ostrich od cell 7.0 m cell nerve cell ell ramie E EYE as higher surface area r and connecting link and non living. e cell may vary with y perform. sc-like, polygonal, dal, thread like or The shape of the cell he function they LS enetic material i.e. lear envelop is known
Transcript
CELL
INTRODUCTION: Cell is a basic unit of life and It is considered as structural and functional unit of an organism. Robert Hooke (1665)discovered cell. He first observed the cell in a piece of dead cork cells. He described cell in his book “Micrographia”. Leeuwenhoek (1674) first observedcell and used the term “Animalcule”The study of cell structure is called The study of cell structure, function & reproduction is called Cell biology.Robert hooke is known as ‘father ofcytology’. Swanson is called the ‘Father of modern cytology’
CELL THEORY
In 1838, Malthias Schleiden, botanist, examined a large number of plants and observed that all plants are composed of different kinds of cells which form the tissues of the plant. At about the same time, Theodore Schwann (1839), Zoologist, studied different types of animal cells and reported that cells had a thin outer layer which is today known as the ‘plasma membrane’. He also concluded, based on his studies on plant tissues, that the presence of cell wall is a unique character of the plant cells.
Schwann proposed the hypoththat the bodies of animals and plants are composed of cells and products of cells.
Schleiden and Schwann formulated the cell theory. This theory however, did not explain as to how new cells were formed. Virchow (1855) first explained tcells divided and new cells are formed from pre-existing cells (Omnis cellula-e cellula). the hypothesis of Schleiden Schwann to give the cell theory a final shape. Cell theory as understood today is
(i) all living organisms are composed of cells and products of cells.
(ii) all cells arise from precells.
CELL THE UNIT OF LIFE
Cell is a basic unit of life and It is and functional unit
Robert Hooke (1665) bserved the cell in
dead cork cells. He described cell
observed animal “Animalcule” for it.
is called cytology. , function &
Cell biology. r of
‘Father of modern
Malthias Schleiden, German botanist, examined a large number of plants and observed that all plants are composed of different kinds of cells which form the tissues of the plant. At about the same time,
(1839), British Zoologist, studied different types of
ls and reported that cells had a thin outer layer which is today known as the ‘plasma membrane’. He also concluded, based on his studies on plant tissues, that the presence of cell wall is a unique character of the
proposed the hypothesis that the bodies of animals and plants are composed of cells and products
Schwann together formulated the cell theory. This theory however, did not explain as to how new cells were formed. Rudolf
(1855) first explained that cells divided and new cells are
existing cells e cellula). He modified
Schleiden and to give the cell theory a
l theory as
all living organisms are ed of cells and products of
all cells arise from pre-existing
EXCEPTION OF CELL THEORYI. Virus/ Virion/ II. viroids III. prions
SIZE AND SHAPE OF CE
SIZE Cell differ greatly in size, shape and
activites. Mycoplasma laidlawii (Smallest cells)
Only 0.3 m in length [PPLO (pleuro pneumonia like organisms) is a type of mycoplasma having the size about
0.1 m)]
Bacteria 3 to 5 Largest unicellular Eukaryotic cell
Acetabularia alga
Largest isolated single egg
Human red blood cell
Longest animal cell (Neurons)
Longest plant cell (Boehmaria)
EAGLE EYE
1. Smallest cell has higher surface area to volume ratio
2. Virus is acellular and connecting link between living and non living.
SHAPE The shape of the cell may vary with
the funtion they perform.
They may be disc
columnar, cuboid
even irregular. The shape of the cell
may vary with the function they
perform.
PROKARYOTIC CELLS
Cell that bears naked genetic material i.e.
nucleus is without Nuclear
as prokaryotic cell.
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XCEPTION OF CELL THEORY Virus/ Virion/ Bacteriophage,
SIZE AND SHAPE OF CELL
Cell differ greatly in size, shape and
sma laidlawii (Smallest cells)
m in length [PPLO (pleuro umonia like organisms) is a type
ma having the size about
3 to 5 m unicellular Eukaryotic cell -
Acetabularia alga - (10cm)
lated single cell ostrich
Human red blood cell 7.0 m
ongest animal cell nerve cell
Longest plant cell ramie
AGLE EYE
Smallest cell has higher surface area
Virus is acellular and connecting link between living and non living.
The shape of the cell may vary with
the funtion they perform.
They may be disc-like, polygonal,
columnar, cuboidal, thread like or
even irregular. The shape of the cell
vary with the function they
PROKARYOTIC CELLS
Cell that bears naked genetic material i.e.
Nuclear envelop is known
The prokaryotic cells are represented by
bacteria, blue-green algae, mycoplasma and
PPLO (Pleuro Pneumonia like Organisms)
They may vary greatly in shape and size. The
four basic shapes of bacteria are bacillus
(rod like), coccus (spherical), vibrio (comma
shaped) and spirillum (spiral).
They have following characters :
(i) Like eukaryotic cells, they are
different in shape and size but small
than eukaryotes & divide rapidly.
(ii) Naked genetic material
‘genophore’ and area in
present known as Nucleiod
(iii) Genomic DNA is circular & termed as
single chromosome.
(iv) Beside genomic DNA, small circular
DNA is also present in many bacteria
called plasmid. The plasmid DNA
confers certain unique phenotypic
characters to such bacteria,
make them antibiotic resistant & also
responsible for bacterial
transformation.
(v) Prokaryotic cell envelope consists of
three layers–outer glycocalyx, middle
EAGLE EYES
Periplasmic Space (Analogous to
lysosome) present between cell wall
and cell membrane in bacteria
The prokaryotic cells are represented by
green algae, mycoplasma and
Organisms).
They may vary greatly in shape and size. The
four basic shapes of bacteria are bacillus
(rod like), coccus (spherical), vibrio (comma
y have following characters :
Like eukaryotic cells, they are
different in shape and size but small
than eukaryotes & divide rapidly.
material is called
and area in which it is
Nucleiod.
is circular & termed as
Beside genomic DNA, small circular
DNA is also present in many bacteria
The plasmid DNA
confers certain unique phenotypic
characters to such bacteria, which
make them antibiotic resistant & also
responsible for bacterial
Prokaryotic cell envelope consists of
outer glycocalyx, middle
cell wall and innermost cell
membrane.
(vi) If these envelopes are stained by Gram
stain (Crystal violet
called Gram positive bacteria while
other those don’t have are called Gram
negative bacteria.
(vii) Glycocalyx, a polysacchride envelope
forms either loose sheath
or thick and tough structure
(viii) Plasma membrane extensions like
vesicles, tubules and lamellae not only
help in cell wall formation, DNA
replication, and distribution to
daughter cells, increase in surface area
but also form some specific structure
for specific function like
respiration (analogous to mitochondria)
and chromatophore
(analogous to chloroplast).
(ix) Cell wall form some filamentous
extensions called flagellum. It consists
of filament, hook & basal body and
helps in locomotion. Filamen
longest portion and extends from the
cell surface to the outside.
(x) Besides flagella, Pili and Fimbriae are
also surface structures of the bacteria
but do not play a role in motility. The
pili are elongated tubular structures
made of a special
fimbriae are small bristle like fibres
sprouting out of the cell
bacteria, they are known to help
attach the bacteria to rocks in streams
and also to the host tissues.
(Analogous to
between cell wall
and cell membrane in bacteria.
CELL ENVELOPE ITS MODIFICATIONS
Most prokaryotic cells, particularly
the bacterial cells, have a chemically
complex cell envelope. The cell
envelope consists of a tightly
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cell wall and innermost cell
If these envelopes are stained by Gram
Crystal violet) then they are
called Gram positive bacteria while
other those don’t have are called Gram
negative bacteria.
Glycocalyx, a polysacchride envelope
forms either loose sheath slime layer
or thick and tough structure capsule.
Plasma membrane extensions like
vesicles, tubules and lamellae not only
help in cell wall formation, DNA
replication, and distribution to
daughter cells, increase in surface area
but also form some specific structure
for specific function like mesosome for
(analogous to mitochondria)
chromatophore for photosynthesis
(analogous to chloroplast).
Cell wall form some filamentous
extensions called flagellum. It consists
of filament, hook & basal body and
helps in locomotion. Filament is
longest portion and extends from the
cell surface to the outside.
Besides flagella, Pili and Fimbriae are
also surface structures of the bacteria
but do not play a role in motility. The
are elongated tubular structures
made of a special pilin protein. The
are small bristle like fibres
sprouting out of the cell in some
bacteria, they are known to help
attach the bacteria to rocks in streams
and also to the host tissues.
NVELOPE ITS MODIFICATIONS
Most prokaryotic cells, particularly
the bacterial cells, have a chemically
complex cell envelope. The cell
envelope consists of a tightly bound
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three layered structure i.e., the
outermost glycocalyx followed by the
cell wall and then the plasma
membrane. Although each layer of
the envelope performs distinct
function, they act together as a
single protective unit. Bacteria can be
classified into two groups on the
basis of the differences in the cell
envelopes and the manner in which
they respond to the staining
procedure developed by Gram viz.,
those that take up the gram stain
(crystal violet) are Gram positive
(Purple Colour) and the others that
do not are called Gram negative
(Red/Pink) bacteria.
The cell wall determines the shape of
the cell and provides a strong
structural support to prevent the
bacterium from bursting or
collapsing.
Inclusion bodies: Reserve material in
prokaryotic cells are stored in the
cytoplasm in the form of inclusion
bodies. These are not bound by any
membrane system and lie free in the
cytoplasm, e.g., phosphate granules,
cyanophycean granules and glycogen
granules. Gas vacuoles are found in
blue green and purple and green
photosynthetic bacteria.
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Double Membranous
CELL STRUCTURE
Cytoplasm (PH =7.2) Cell Boundaries
Gycocalyx Cell wall Cell membrane
Nucleus
Main area of cellular activities & various chemical reactions occur in it to keep
the cell in living state
Hyaloplasm/ Cytosol / Intracellular fluid. It is a complex Substance that makes up the liquid portion of the Cytoplasm of cell
Trophoplasm/ Cytoplasmic inclusions
Cell organelles (metabolically Active content of the cell)
Ergastic bodies/ Non-living inclusion /Deutoplasm The cytoplasm also contain substances which are metabolically inactive)
Non Membranous
Single Membranous
ENDOMEMBRANE
SYSTEM
Nucleus E.R Ribosome
Plastid Golgi body Centriole Mitochondria Lysome Vacuole
MICROBODIES Glyoxisome peroxisome Sphaerosome
Carbohydrates
Nitrogenous
products
Reserve Products
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AN OVERVIEW OF CELL
The onion cell which is a typical plant
cell, has a distinct cell wall as its
outer boundary and just within it is
the cell membrane.
Cells that have membrane bound
nuclei are called eukaryotic whereas
cells that lack a membrane bound
nucleus are prokaryotic.
In both prokaryotic and eukaryotic
cells, a semi-fluid matrix called
cytoplasm occupies the volume of
the cell.
The cytoplasm is the main area of
cellular activities in both the plant
and animal cells. Various chemical
reactions occur in it to keep the cell
in the ‘living state’.
Besides the nucleus, the eukaryotic
cells have other membrane bound
distinct structures called organelles
like the endoplasmic reticulum (ER),
the golgi complex, lysosomes,
mitochondria, microbodies. The
prokaryotic cells lack such membrane
bound organelles.
Ribosomes are non-membrane bound
organelles found in all cells – both
eukaryotic as well as prokaryotic cell.
Within the cell, ribosomes are found
not only in the cytoplasm but also
within the two organelles –
chloroplasts (in plants) and
mitochondria and on rough ER.
Animal cells contain another non-
membrane bound organelle called
centriole which helps in cell division.
CELL WALL
A non-living rigid structure called the
cell wall forms an outer covering for
the plasma membrane of Bacteria
Fungi, Algae and Plants.
Algae have cell wall made up of
cellulose, galactans, mannans and
minerals like calcium carbonate.
In other plants it consists of
cellulose, hemicellulose, pectins and
proteins.
Bacterial cell wall mainly composed
of Peptidoglycans (Polysaccharide +
amino acid).
The cell wall of Fungi are composed
of Chitin and Polysaccharides.
Dinoflagellates cell wall has stiff
cellulose plate on the outer surface
(Plated cell wall)
Cell wall of diatoms is made up of
silica and known as FRUSTULE
EAGLE EYE
1. Archaebacteria differ from other
bacteria in having a different cell wall
structure and this feature is
responsible for their survival in
extreme condition.
2. In Euglenoids instead of a cell wall,
the have a protein rich layer called
pellicle which makes their body
flexible.
Lysosome
Rough endoplasmicreticulum
Nucleus
Nucleolus
Golgiapparatus
Nuclearenvelope
Plasmamembrane
Vacuole
Middle lamella
Mitochondrion
RibosomesChloroplastCytoplasm
Peroxisome
Microtubule
Plasmodesmata
Smoothendoplasmic
reticulum
Cell wall
Plant cell
Microvilli
Plasmamembrane
Centriole
Peroxiome
Lysosome
Ribosomes
Mitochondrion
Roughendoplasmic
reticulumCytoplasm
Nucleus
Nucleolus
Nuclearenvelope
Smoothendoplasmic
reticulum
Golgiapparatus
Animal cell
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MIDDLE LAMELLA
It is cementing layer for joining of
two adjacent plant cells.
It is composed of calcium/magnesium
pectate.
Retting of fibres and softerning of
fruits are due to dissolution of
calcium pectate in middle lamella by
“pectinase enzyme”
PRIMARY WALL
It is elastic, permeable, thin, single
layered outer most wall layer of plant
cell. Its diameteris 0.1–3μ m and
Cellulose, hemicellulose and pectin
contents are roughly in equal amount
in primary wall.
Root hairs, parenchymatous cells &
meristematiccells are formed of only
primary wall.
Its growth takes place by
intussuception (Addition of materials
with in the existing wall).
SECONDARY WALL
It lies inside the primary wall. Its diameter is
3–10μ m. Its growth takes place by Accretion
(deposition of materials over the surface of
existing structure). It consists of at least
three layers–S1, S2, S3, This wall is made up
of cellulose, hemicellulose & pectin. Number
of different materials may be deposited in
the wall.
(a) Lignin :The deposition of lignin on the
cell wall is called lignification that
provides strengthening to the cell
wall.
(b) Suberin :It is fatty substance that
makes the wall impermeable. It
reduces the transpiration rate in
plants. It is found in the cork and
casparian strips of endodermal cells.
The deposition of suberin is called
suberisation.
(c) Cutin :It lies as a distinct layer on the
outside of the epidermal cell wall. It
is fatty substance that reduces the
rate of transpiration.
PITS
They represent unthickened areas in
the secondary walls of plant cells
that occur as a depressions.
A pit contains pit chamber and a pit
membrane. The latter is composed of
primary wall and middle lamella.
Pits are two types
(a) Simple pits :It bears uniform width of
the pit chamber.
(b)Bordered pits :Its chamber is flask shaped
due to overarching of secondary wall on its
mouth. Its pit membrane has thickening of
S.
No.Primary Wall
S.
No.Secondary Wall
1 It is single layered formed in young
growing cell.
1 It is three or more layered formed when
the cell has stopped growing.
2 Cellulose microfibrils are shorter,
wavy and loosely arranged.
2 Cellulose microfibrils are longer, closely
arranged, straight and parallel.
3 Cellulose content is compartively low. 3 Cellulose content is compartively high.
4 Hemicellulose is upto 50%. 4 Hemicellulose is about 25%.
5 Pits are usually absent. 5 Pits are common.
6 It grows by intussusception. 6 It grows by accretion.
7 Lipid content is 5-10%, protein is 5%. 7 Lipid is absent, protein content is 1% or
less.
Differences Between Primary and Secondary Walls
7
suberin called Torus. These pits are found
abundantly in tracheids of gymnosperms
(have maximum number of bordered pits)
and in vessels of angiosperms.
TERTIARY WALL
Present only in tracheids of Gymnosperms &
composed of cellulose & xylan.
Functions of Cell wall : Cell wall not only
gives shape to the cell and protects the cell
from mechanical damage and infection , it
also helps in cell- to - cell interaction and
provides barrier to undesirable
macromolecules.
EAGLE EYES
1. EXPANSIN : A special protein called
expansin helps in growth of cell wall
by loosing the cellulose microfibril
and addition of new cell wall
material takes place in the space.
Thus expansin is called as "cell wall
loosening factor".
2. PLASMODESMATA : These are
cytoplasmic connections between
two adjacent plant cells.
Plasmodesmata are characteristic of
multi-cellular plants and they
maintain continuity of cytoplasm
between adjacent cells. E.R. tubules
(Desmotubules) help to maintain
continuity of cytoplasm.The cell wall
and middle lamellae may be
traversed by plasmodemata.
3. EXTENSIN : This protein connects
pectin and Cellulose.
4. Cell wall material (Cellulose,
hemicellulose, Pectin and lignin) are
synthesized in plant golgi body or
dictyosome.
5. Material of lipid nature (cutin &
Suberin) are synthesized in
sphaerosome.
CELL MEMBRANE
All the living cells are covered by a
thin, delicate, elastic, selectively–
permeable and living boundry, which
is called as – cell membrane (by
Nageli & Kramer) or plasmalemma (By
J.Q. plowe) or bio membrane or
plasma membrane.
The detailed structure of the
membrane was studied only after the
advent of the electron microscope in
the 1950s. Meanwhile, chemical
studies on the cell membrane,
especially in human red blood cells
(RBCs), enabled the scientists to
deduce the possible structure of
plasma membrane.
Biochemical investigation clearly
revealed that the cell membranes
possess lipid, protein and
carbohydrate. The ratio of protein
and lipid varies considerably in
different cell types. In human beings,
the membrane of the erythrocyte has
approximately 52 per cent protein and
40 per cent lipids
STRUCTURE OF BIOMEMBRANES
(1) Sandwitch or Trilamellar model :By
Davson &Danielli (1935).
According to this model, the plasma–
membrane is made up of three layers
in which a bimolecular layer of lipid
CHEMICAL COMPOSITION
Proteins Carbohydrates Lipids
58-60% 1–2% 20–40%
8
is sandwitched between two single
layers of proteins.
According to this model each protein
layer is 20Å thick and bilayer of
phospholipid is 35Å thick. Thus total
thickness is 75Å (PLLP – structure,
75–100Å average)
Phospholipid molecule called as
amphipathic molecule due to
presence of two type of parts
(hydrophillic head and hydrophobic
tail).
Hydrophilic head of the phospholipid
binds with protein layer by hydrogen
and ionic bonds.
Hydrophobic tail of phospholipid are
attached to each other by vanderwall
force.
(2) Fluid mosaic model :By Singer &
Nicolson (1972)
This is latest & most widely accepted
model for the structure of
plasmalemma.
According to fluid mosaic model
proteins are arranged in phospholipid
layer as mosaic pattern.
Thus membrane is termed as "protein
icebergh in a sea of phospholipid" or
"Gulab Jamun (protein) in a
concenterated solution (phospholipid)
of sugar".
(1) Phospholipids :
Phospholipid is the main component
of cell membrane because it forms
continous structural frame of cell
membrane. Main type of
phospholipids are phosphatidyl
serine, phosphatidyl choline
(Lecithin), phosphatidyl ethanolamine
(cephalin)
The studies showed that the cell
membrane is composed of lipids that
are arranged in a bilayer. Also, the
lipids are arranged within the
membrane with the polar head
towards the outer sides and the
hydrophobic tails towards the inner
part.This ensures that the nonpolar
tail of saturated hydrocarbons is
protected from the aqueous
environment. The lipid component of
the membrane mainly consists of
phosphoglycerides.
Phospholipid layer provides fluidity to
plasma membrane because
phospholipids are rich in unsaturated
fatty acid which are liquid in nature.
The Quasifluid nature of lipid enable
lateral movement of protein with in
the overall bilayer. This ability to
move within the membrane is
measured as its, fluidity.
The fluid nature of the membrance is
also important in various function
like cell growth, formation of
intercellular junction, endocytosis, cell
division etc.
Cholesterol is also present in plasma
membrane. Cholesterol are more rigid
than phospholipid. So it helps in
stability of membrane structure.
EAGLE EYE
Cholesterol is absent in prokaryotic
cell. Thus Hopanoids (Pentacyclic
sterol) provide stability to prokaryotic
cell membrane)
(2) Proteins :
Two types of protein are present in
plasma membrane. (On the basis of
ease of extraction)
(a) Integral or intrinsic protein
Protein layer (20 Å)
Bio
-mole
cula
r la
yer
of phospholip
ids (
35Å
)
Protein layer (20 Å)
Pores (0.35 nm)
Nonpolar hydrophobic tail
Polar hydrophilic head
9
These protein are tightly binds with
phospholipid. Thus, they can not
easily removed from membrane.
Integral proteins are of 2 types
Partially buried
Totally buried
Some integral proteins which are
totally buried through the complete
thickness of membrane. These type
of protein are called as tunnel /
Transmembrane/channel protein
which provide a passage for
movement of water soluble material
across the membrane.
(b) Peripheral or extrinsic protein
These are superficially arranged on
outer side and can be seperate easily.
These protein have enzymatic activity.
Spectrin are helical type of extrinsic
protein founds on cytosolic face
(towards cytoplasm) of membrane
and attached to intrinsic protein.
Spectrins are part of cytoskeleton.
Oligosaccharides of the glycolipids &
glycoproteins on the outer surface
of plasma membranes are involved
in cell to cell recognition
mechanism. Best example of cell
recognition is fertilisation, (where
sperm & egg recognize to each
other) and blood - Antigens.
Sugar Protein
Lipid bilayer
Cholesterol
Fluid mosalic model of plasma membrane
Integral
protein
Outside the cellGlycoprotein
(Oligosaccharides)
PhospholipidsPore formed by integral protein
Glycolipid(Oligosaccharides)
Peripheral protein(Extrinsic)
Non cytosolic half of bilayer
Cytosolic half of bilayer
Phospholipid bilayer
Cholesterol
Peripheral protein
Tunnel protein
Spectrin
Inside the cell
Fluid-mosaic molel of membrane
TRANSPORT THROUGH PL
One of the most important functions
of the plasma membrane is the
transport of the molecules across it.
The membrane is selectively
permeable to some molecules
present on either side of it. Many
molecules can move briefly across
the membrane without any
requirement of energy and this is
called the passive transport.
Neutral solutes may move across the
membrane by the process of simple
diffusion along the concentration
gradient, i.e., from higher
concentration to the lower. Water
may also move across this me
from higher to lower concentration.
Movement of water by diffusion is
called osmosis.
As the polar molecules cannot pass
through the nonpolar lipid bilayer,
they require a carrier protein of the
Passive transport(Energy is not utilized)
Diffusion
Diffusion is a movement of molecules from higher concentration to lower concentration through a lipid bi
TRANSPORT THROUGH PLASMA MEMBRANE
One of the most important functions
of the plasma membrane is the
transport of the molecules across it.
The membrane is selectively
permeable to some molecules
present on either side of it. Many
molecules can move briefly across
the membrane without any
quirement of energy and this is
passive transport.
Neutral solutes may move across the
membrane by the process of simple
diffusion along the concentration
gradient, i.e., from higher
concentration to the lower. Water
may also move across this membrane
from higher to lower concentration.
Movement of water by diffusion is
As the polar molecules cannot pass
through the nonpolar lipid bilayer,
hey require a carrier protein of the
membrane to facilitate their
transport across the me
A few ions or molecules are
transported across the membrane
against their concentration gradient,
i.e., from lower to the higher
concentration. Such a transport is an
energy dependent process, in which
ATP is utilised and is called
transport, e.g., Na
TRANSPORT
Passive transport (Energy is not utilized)
Active transport(Energy is
Movement of molecules occurs from lower concentration to higher concentration with
help of ATP
Facilitated Diffusion
Diffusion is a movement of molecules from higher concentration to lower concentration through a lipid bilayer
Movement of molecules from high concentration to lower concentration with the help of specific protein.
10
MEMBRANE
membrane to facilitate their
transport across the membrane.
A few ions or molecules are
transported across the membrane
against their concentration gradient,
i.e., from lower to the higher
concentration. Such a transport is an
energy dependent process, in which
ATP is utilised and is called active
Na+/K+ Pump.
Active transport (Energy is utilized)
Movement of molecules occurs from lower concentration to higher concentration with
help of ATP
Movement of molecules from high concentration to lower concentration with the help
11
FUNCTIONS OF PLASMA MEMBRANE
(i) Endocytosis
(a) Pinocytosis or Cell Drinking :
Ingestion of liquid material by
plasmalemma in the form of vesicles
(Pinosome) is called pinocytosis.
(b) Phagocytosis or Cell eating :
Ingestion of solid complex materials
by membranes in the form of
vesicles (Phagosome) is called
Phagocytosis.
(ii) Exocytosis/Emiocytosis/Cell vomiting :
Egestion of waste materials from cell
through plasma membrane.
EAGLE EYES
1. However phospholipid bilayer
has fluid property but no
evidence of flip flop mechanism
for protein molecule (Flip Flop
means exchange of molecules
from one monolayer with those
in the monolayer on the other
side).
2. Rotational diffusion and lateral
diffusion of protein and lipids is
possible in membrane.
3. Plasma membrane is an asymmetrical
structure because carbohydrate is
presents on outer surface and
spectrin protein is present only on
inner surface of plasma membrane.
Examples
1. Which of the following is the smallest
cell-
(A) Human nerve cells
(B) Chlamydomonas
(C) Virus
(D) PPLO
Ans. (D)
Solution
Mycoplasma laidlawii (PPLO-
Pleuropneumonia like organisms) is
smallest cell.
2. All cells are derived from pre-existing
cells" is the famous generalization of-
(A) Schultz
(B) Schleiden
(C) Lamarck
(D) Virchow
Ans. (D)
Solution
All cells are derived from pre-existing
cells (omnis cellula–e cellula) given
by Rudolf virchow.
3. Cell wall is the secretory product of-
(A) Lysosomes
(B) Cytoplasm
(C) Plasmodesmata
(D) Middle lamella
Ans. (B)
Solution
cell- wall is the secretory product of
Cytoplasm.
Educatalyzer
1. Amphipathic molecule in pasma
membrane is -
(A) Protein
(B) Carbohydrates
(C) Phospholipids
(D) All the above
2. Cell membrane is composed of -
(A) Proteins and cellulose
(B) Proteins and phospholipids
(C) Proteins and carbohydrates (D) Proteins, phospholipids and some
carbohydrates 3. Carbohydrates which present in the
cell membrane take part in:-
(A) Transport of substance
(B) Cell recognition
(C) Attachment to microfilament
(D) Attachment to microtubules
4. According to Singer and Nicolson
which of the following are present in
plasma membrane
(A) Chitin and phospholipid
(B) Phospholipid, extrinsic and
intrinsic protein
(C) Carbohydrates and protein
(D) Hemi cellulose and cellulose
12
CELL ORGANELLES
Metabolically active and living
structures of cytoplasm are called
organelles.
ENDOMEMBRANE SYSTEM
While each of the membranous
organelles is distinct in terms of its
structure and function, many of
these are considered together as an
endomembrane system because their
functions are coordinated.
The endomembrance system include
endoplasmic reticulum (ER), golgi
complex, lysosomes and vacuoles.
Since the functions of the
mitochondria, choroplast and
peroxisomes are not coordinated
with the above components, these
are not considered as part of the
endomembrane system.
ENDOPLASMIC RETICULUM
Electron microscopic studies of
eukaryotic cells reveal the presence
of a network of reticulum of tiny
tubular structures scattered in the
cytoplasm that is called the
endoplasmic reticulum (ER)
Components of E.R.
(1) Cisternae- These are long
flattened and unbranched units
arranged in stacks.
(2) Vesicles - These are oval
membrane bound structures.
(3) Tubules - These are irregular,
often branched tubes bounded by
membrane. Tubules may free or
associated with cisternae.
ER divide the intracellular
space into two distinct
compartment i.e. Luminal
(inside ER) and extra luminal
(cytoplasm) compartments.
TYPES OF ENDOPLASMIC
RETICULUM
On the basis of nature of its
membranes, endoplasmic reticulum
is of two types.
(i) RER – Rough Endoplasmic
Reticulum
(ii) SER – Smooth Endoplasmic
Reticulum
Rough E.R.
(Granular)
Smooth E.R.
(Agranular)
1. It bears ribosomes
attached to its
membranes
Ribosomes
absent on the
outer surface of
membrane
2. It consists of
cisternae and few
tubules
It consists of
tubules and
vesicles
3. It takes part in
the synthesis of
proteins and
enzymes Ex:-
pancreas, liver,
Goblet cells
It performs
synthesis of
glycogen, lipids
and steroids. Ex:-
Interstitial cells,
Adipose tissue,
adrenal cortex,
Muscles,
Glycogen storing
liver cells
4. RER bears
ribophorin- I &
ribophorin-II for
the attachment
of ribosomes
Ribophorins are
absent
5. It may develop
from nuclear
envelope
It may develop
from RER.
13
FUNCTIONS OF E.R.
(1) Mechanical support : Microfilaments,
Microtubules and E.R. forms
endoskeleton of cell. (2) Intracellular exchange : E.R. forms
intracellular conducting system. Transport of materials in cytoplasm from one place to another may occurs through the E.R.
At some places E.R. is also connected to P.M. So E.R. can secrete the materials outside the cell.
(3) Rough E.R. : Provides site for the protein synthesis, because rough E.R., has ribosomes on its surface.
(4) Lipid Synthesis : Lipids (cholesterol &
phospholipids) synthesized by the
agranular portion of E.R. (Smooth
E.R.). The major lipids synthesized by
S.E.R. are phospholipids and
cholesterol.
(5) Cellular metabolism: The membranes
of the reticulum provides an
increased surface for metabolic
activities within the cytoplasm.
(6) Detoxification : Smooth ER concerned
with detoxification of drugs,
pollutants and steroids.
Cytochrome P450 in E.R. act as enzyme
which function in detoxification of
drugs and other toxins
EAGLES EYES
(1) Sarcoplasmic Reticulum (S.R.): These
smooth S.E.R. occurs in skeletal and
cardiac muscles. S.R. Stores Ca+2
and energy rich compounds required
for muscle contraction.
(2) Myeloid Bodies :–
Myeloid bodies are the specialised
smooth E.R. which found in
pigmented epithelial cells of the
retina. Myeloid body is light sensitive
structure and may be involved in
pigment migration. (3) Microsomes - These are pieces of
E.R. with associated ribosomal particles. These can be obtained by
fragementation and high speed centrifugation of cell. They do not exist as such in the living cell. Scientist used microsome for invitro protein synthesis study.
(4) R.E.R. of nerve cell are called nissl's bodies.
(5) Protein synthesized on ribosomes
attached to the R.E.R are targeted for
the E.R., GB, lysosome, plasma
membrane and outside the cell.
(6) Free Ribosomes create proteins that
are released directly into the
cytoplsam for use by the cell.
GOLGI COMPLEX Camillo Golgi (1898) first observed
densely stained reticular structure near the nucleus. These were later named Gogi bodies after him.
Golgi body also named as Golgi body
Dalton complex
Golgi complex
Lipochondria ( rich in lipids)
Baker's body
Idiosome
Dictyosome (plant golgi body)
The cytoplasm surrounding Golgi
body have fewer or no other
organelles. It is called Golgi ground
substance or zone of exclusion.
STRUCTURE
Golgi complex is made up of three
parts –
(1) Cisternae : These are flat disc
shaped, sacs like structure. Many
cisternae are arranged in a stack
(parallel to each other). Diameter 0.5
μm to 1.0 μm .
Varied number of cisternae are
present in Golgi complex.
Golgi body show definite polarity.
Convex surface of cisternae which is
towards the nucleus is called cis face
or forming face.
14
Concave surface of cisternae which is
towards the membrane is called
Transface or maturing face.
(2) Tubules : These are branched and
irregular tube like structures
associated with cisternae.
(3) Vesicles : Spherical structures arise
by budding from tubules. Vesicles are
filled with secretory materials.
FUNCTIONS OF GOLGI BODY
(1) Packaging and Secretion : Chief
function of golgi body is secretion
(export) of macromolecules.
Secretion involve three steps :
(a) Golgi body recieves the materials
from E.R. through it's cis face.
(b) These materials are chemically
modified by golgi body. For e.g.
glycosylation of proteins and
glycosidation of lipids takes
place in golgi body and it yields
glycoprotiens and glycolipids.
(c) After chemical modifications
materials are packed in vesicles.
These vesicles are pinched off
from trans face of golgi body and
discharged outside the cell.
The golgi apparatus principally
performs the function of packaging
materials, to be delivered either to
the intra-cellular targets or secreted
outside the cell. Materials to be
packaged in the form of vesicles
from the ER fuse with the cis face of
the golgi apparatus and move
towards the maturing face. This
explains, why the golgi apparatus
remains in close association with the
endoplasmic reticulum. A number of
proteins synthesised by ribosomes on
the endoplasmic reticulum are
modified in the cisternae of the golgi
apparatus before they are released
from its trans face. Golgi apparatus is
the important site of formation of
glycoproteins and glycolipids.
All the macromolecules which are to
be sent outside the cell, move
through the golgi body. So golgi body
is termed as “Director of
macromolecular traffic in cell” or
middle men of cell.
(2) Cell plate formation(Phragmoplast)
during cell formation.
(3) Formation of acrosome during
spermiogenesis.
(4) Formation of Lysosome It is collective
function of golgi body and E.R.
(5) Synthesis of cell wall Material
(Polysaccharide synthesis)
(6) Vitelline membrane of egg is secreted
by golgi body.
ROUTE OF THE SECRETORY
PRODUCT
E.R. transport vesicles Cis region of GB
Trans region of GB secretory vesicle
Plasma membrane.
LYSOSOME
These are membrane bound vesicular
structures formed by the process of
packaging in the golgi apparatus. The
isolated lysosomal vesicles have been
found to be very rich in almost all
types of hydrolytic enzymes
(hydrolases – lipases, proteases,
carbohydrases) optimally active at
the acidic pH (pH 5). These enzymes
are capable of digesting
Cisternae
Golgi apparatus
Discharged vesicles
Vesicles
Fusing with cis face
Tubules
Transition vesicles
Cisternae
Trans or Maturing face
Cis or Forming face
Golgi Apparatus
15
carbohydrates, proteins, lipids and
nucleic acids.
With the exception of mammalian
RBC they were reported from all
cells.
In plant cells large central vacuole
functions as Lysosome. So in higher
plants lysosomes are less frequent.
But number of lysosomes is high in
fungi (Example Neurospora)
Lysosomes are filled with 50
different type of digestive enzymes
termed as Acid hydrolases .
These acid hydrolases function in
acidic medium (pH 5). Membrane of
lysosome has an H+ pump
mechanism which produce acidic pH
in lumen of lysosome.
Lysosomes are highly polymorphic
cell organelle. Because during
functioning, lysosomes have different
morphological and physiological
states.
Types of lysosomes and their functions
TYPES OF LYSOSOMES
Lysosomes show pleomorphism and
are of four types.
(i) Primary lysosomes : These are newly
synthesized lysosomes from Golgi
complex by GERL system. They
contain inactive enzymes.
(ii) Secondary lysosomes
(hetorophagosomes or
phagolysosomes) : It is formed by the
union of primary lysosome with food
vacuole (Phagosome).
(iii) Tertiary lysosomes (residual bodies or
telolysosomes) : After digestion the
products are
absorbed in to the cytoplasm. The
undigested remains are left in the
lysosome. It is called residual body.
This moves to the surface and
throws the contents by exocytosis.
(iv) Autophagic Lysosomes or
Cytolysosomes or autophagosomes:
Lysosomes containing cell organelles
to be digested are known as
Autophagosomes.
FUNCTIONS
(1) Intracellular digestion:
(a) Heterophagy: This is digestion of
foreign materials received in cell by
phagocytosis and pinocytosis.
(b) Autophagy: Digestion of old or
dead cell organelles. Autophagy also
takes place during starvation of cell.
(2) Crinophagy:
Excessive secretory granules of
hormone in endocrine gland may be
digested by lysosomes. This event is
called crinophagy. Thyroglobulin
stores in thyroid gland with its
follicles and after crinophagy by
proteases it produces thyroxine.
Cellular digestion (Autolysis) :
Sometimes all lysosomes of a cell
burst to dissolve the cell completely
16
(so Lysosome called as suicidal bags
of cell). Old cells are removed by
autolysis. Unwanted organs of
embryo are destroyed by autolysis
Cathepsin of lysosome digests the
tail of tadpole of frog during
metamorphosis.
EAGLES EYES
Membrane stabilizers are substances,
which stabilize the lysosome
membrane and stop its rupture, thus
prevents autolysis. e.g. cholesterol,
chloroquine, cortisone etc.
Membrane labilizers are substances
which make the lysosome membrane
fragile and increase the chance of
autolysis e.g. Progesterone,
testosterone, Vitamin A, D, E, K, U.V.
radiations, bile salts etc.
Biogenesis of Lysosome Lyosomes
originates from G E R L - (Golgi
associated Endoplasmic Reticulum
from which Lysosomes arise).
VACUOLES
The vacuole is the membrane-bound
space found in the cytoplasm. It
contains water, sap, excretory
product and other materials not
useful for the cell.
The vacuole is bound by a single
membrane called tonoplast. In plant
cells the vacuoles can occupy up to
90 per cent of the volume of the cell.
In plants, the tonoplast facilitates the
transport of a number of ions and
other materials against concentration
gradients into the vacuole, hence
their concentration is significantly
higher in the vacuole than in the
cytoplasm.
The non living content of vacuoles is
known as cell sap which is rich in K+
and acetic acid.
In Amoeba the contractile vacuole is
important for excretion. In many
cells, as in protists, food vacuoles are
formed by engulfing the food
particles.
EAGLES EYES
Gas vacuoles (Pseudovacuoles): These
are found in some prokaryotes like
blue grean algae where they perform
buoyancy regulation and they also
protect the cell from UV radiation.
Food vacuoles: These vacuoles
contain digestive enzymes.
Example
1. In which of the following cells the
endoplasmic reticulum is absent-
(A) Kidney cells
(B) Liver cells
(C) Mammalian mature erythrocytes
(D) Mammalian eye cells
Ans. (c)
Solution
Mature mammalian erythrocyte
(R.B.C.) lacks cell organelles.
2. Surface of Golgi cisternae towards
nucleus is ………….. face and towards
plasma membrane is …… face.
(A) trans, cis
(B) maturing, forming
(C) maturing, trans
(D) cis, maturing
Ans. (D)
Solution
The Golgi cisternae are concentrically
arranged near the nucleus with
distinct convex cis or forming face
and concave or trans or the maturing
face.
17
3. Which of the following statement is
not correct for the vacuoles?
(A) Contractile vacuoles are helpful in
excretion
(B) Sap vacuole is bound by a single
membrane
(C) Food vacuoles are formed by
engulfing the food particles
(D) Tonoplast facilitates the
transport of ions against eh
concentration gradient into the
cytoplasm
Ans. (D)
Solution
Tonoplast facilitate the transport of
ions against the concentration
gradient into the cell sap.
Educatalyzwer 1. ER divides the intracellular space into
two distinct compartments, luminal ………… and extra luminal ……… compartments.
(A) Cytoplasm, inside ER (B) Inside ER, cytoplasm (C) Nucleus, cytoplasm (D) Inside ER, nucleus
Diagrammatic representation of internal structure of Cilia or Flagella
Peripheral microtubules(doublets)
Interdoublet bridge(B-A linker)
Central microtubuleRadial spoke
(Nexin)
Central sheath
Plasma membrane
Bridge
AB
A
B
A
InnerInner Dynein arms
(AT Pase activity)
24
(b) Kinetosome or basal granule or
Blepheroplast or Basal body : It is
membraneless structure, lies
immediately below the plasma
membrane. Basal body exhibit cart
wheel structure similar to centriole.
(9 triplet fibriles connected to a
central hub in basal body).
(c) Rootlet or Rhizoplast : This is a
conical bundle of protein fibers
which arises from basal body to
different directions. Rootlet have
dark bands composed of ATPase.
TYPES OF FLAGELLA
(1) Whiplash – When the laterel hair
like structures absent.
(2) Tinsel – When the flagella bears
lateral hairs like structure
(flimmers)
Cilia and Flagella are similar
in structure but some
differences may observed
Cilia Flagella
1. The cilia are
small in size
(5–10 m)
1. Flagella are
long (up to
150 m)
2. Number of
cilia per cell is
very large.
2. Few in
number
3. Cilia beat in a
coordinated
3. Flagella
beats
manner
independently
(Non
coordinated
manner)
4. They take part
in locomotion,
attachment,
feeding and
sensation.
4. Flagella
involved
only in
locomotion.
EAGLE EYES 1. Prokaryotic and Eukaryotic flagella
are made up of flagellin and tubulin
protein respectively.
2. Prokaryotic flagella do not show 9 + 2
arrangement of microtubules.
3. Cilia or flagella are absent in Red
algae, Blue green algae or
cyanobacteria.
CENTROSOME & CENTRIOLES
Centrosome was discovered by
Benden. Boveri named as centrosome.
Centrosome is absent in almost all
plant cell.
Two centrioles (diplosome) located
just outside the nucleus and lie at
right angle (90°) to each other.
Cytoplasm which surrounds
centrioles called as " Centrosphere".
Centrioles and centrosphere
collectively called centrosome or
Microcentrum. Each centriole is
surrounded by amorphous
pericentriolar mass, which is called
as massules or crown or satellite.
Centrioles are membraneless
elongated structure which exhibit
cart wheel structure (Just like Basal
body of cilia). Basal body is also a
type of centriole.
Centrioles are absent in higher
plants.
Each centriole is composed of 9
peripheral triple fibrils of
Whiplash
Tinsel
Flimmer
(Naked/smooth)
microtubules but in the central part
these are absent. Thus centribole has
9 + 0 arrangement of tubules.
Each peripheral triplet fibril is
consists of three subfibrils
from outside towards innerside. A is
spherical or tubular shaped whereas
B & C are C–shaped. A consists of 13
protofilaments.
A linker connects two peripheral
triplet fibrils in such a way that A
subfibril of a peripheral triplet fibril is
connected with C sub fibril of
adjacent peripheral triplet fibril. This
linker is called C–A linker
In the central part a proteina
Hub is present.Nine radial spokes
arise from Hub. The tip of e
has a thickening ‘X’ before
attachment on ‘A’ subfibril of a
periphral triplet fibril. ‘Y’ thickening
connects two ‘X’ thickenings the
former is also connect at C
by a connective.
FUNCTION OF CENTRIOLE
The main function of centriole is
locomotion and the role of centriole
in cell division is secondary function.
Centrioles take parts in synthesis of
Basal bodies, cilia, flagella, spindle
poles.
Distal centriole of sperm synthesizes
Axial filament of sperm.
microtubules but in the central part
these are absent. Thus centribole has
arrangement of tubules.
ach peripheral triplet fibril is
subfibrils–C,B, A
from outside towards innerside. A is
spherical or tubular shaped whereas
shaped. A consists of 13
A linker connects two peripheral
a way that A
subfibril of a peripheral triplet fibril is
connected with C sub fibril of
adjacent peripheral triplet fibril. This
A linker.
In the central part a proteinacious
Nine radial spokes
arise from Hub. The tip of each spoke
has a thickening ‘X’ before
attachment on ‘A’ subfibril of a
periphral triplet fibril. ‘Y’ thickening
connects two ‘X’ thickenings the
former is also connect at C–A linker
The main function of centriole is
and the role of centriole
in cell division is secondary function.
Centrioles take parts in synthesis of
Basal bodies, cilia, flagella, spindle
Distal centriole of sperm synthesizes
Proximal centriole of sperm
cleavage in fertilized egg after
fertilization.
EAGLE EYES
1. Formation of new centriole
S-phase but completes in
of Interphase.
MICROBODIES
These are membrane bounded spherical
bodies filled with enzymes are called as
‘‘Micro–Bodies’’.
On the basis of functions microbodies are of
following types –
1. Sphaerosomes
Sphaerosomes occur only in plant
cells. They are major site of lipid
storage and synthesis in plants.
Sphaerosomes also have lysosome
like activity so they
plant lysosomes
2. Peroxisomes or Uricosomes
In animal cells
concerned with peroxide (
metabolism. Catalase
H2O2 into water and oxygen.
In plants, peroxisomes
with photorespiration
pathway).
Peroxisomes involved in
of fatty acids.
3. Glyoxysomes
Occurs in oil containing seeds, yeast
cells, guard cells
Glyoxysomes occurs only in plants
especially in fatty seeds
seed, ground nut seed etc.)
EAGLE EYES
Glyoxysomes are considered as a
highly specialised peroxisomes
Glyoxylate acid cycle
25
Proximal centriole of sperm stimulate
cleavage in fertilized egg after
EAGLE EYES
Formation of new centriole starts in
but completes in G2-Phase
BODIES
These are membrane bounded spherical
bodies filled with enzymes are called as
On the basis of functions microbodies are of
Sphaerosomes occur only in plant
cells. They are major site of lipid
storage and synthesis in plants.
Sphaerosomes also have lysosome
like activity so they also termed as
plant lysosomes.
Peroxisomes or Uricosomes
In animal cells peroxisomes
concerned with peroxide (H2O2)
Catalase degrade the
into water and oxygen.
peroxisomes concerned
photorespiration (glycolate
Peroxisomes involved in -oxidation
Occurs in oil containing seeds, yeast
guard cells etc.
Glyoxysomes occurs only in plants
fatty seeds (castor
seed, ground nut seed etc.).
EAGLE EYES
Glyoxysomes are considered as a
highly specialised peroxisomes.
Glyoxylate acid cycle takes place in
26
glyoxysomes. This cycle convert fats
into carbohydrats.
Glyoxylate cycle is modified TCA
cycle.
Example
1. Arrangement of microtubules in
centriole is-
(A) 9 + 2
(B) 2 + 9
(C) 11 + 0
(D) 9 + 0
Ans. (D)
Solution
Centriole (membrane less cell
organelle) show 9+0 arrangement of
microtubules.
2. The Ribosomes are made up of
(A) DNA + Protein
(B) RNA + Protein
(C) DNA + RNA
(D) None of these
Ans. (B)
Solution
Ribosomes (membrane less cell
organelle) are made up of rRNA
+proteins (Ribnucleoprotein particles)
3. 70s type of ribosomes found in :-
(A) Prokaryotic cells
(B) Prokaryotic cells, chloroplasts and
mitochondria
(C) Mitochondria
(D) Nucleus, mitochondria
Ans. (B)
Solution
Ribosomes are made up of rRNA &
protein and are of two types–70 and
80s. 70s ribosomes are found in
prokaryotic cell, mitochondria and
plastids.
Educatalyzer 1. Polysome is formed by
(A) A ribosome with several subunits
(B) Ribosomes attached to each other
in a linear arrangement
(C) Several ribosomes attached to a
single mRNA
(D) Many ribosomes attached to a
strand of endoplasmic reticulum
2. Conversion of H2O2 into H2O and O2
occurs in ……… by the enzyme………
(A) Glyoxysome, Catalase
(B) Peroxisome, Urease
(C) Sphaerosome, Lipase
(D) Uricosome, Catalase
3. An elaborate network of filamentous......
structure present in the cytoplasm is
collectively referred to as the ...........
(A) Cytoskeleton, proteinaceous
(B) Proteinaceous, Cytoskeleton
(C) Lipoidal, Mitochondria
(D) Lipoidal, plasma membrane
4. In which of the following tubulin
protein is not present?
(A) Plasma membrane
(B) Cilia
(C) Flagella
(D) Microtubules
NUCLEUS
INTRODUCTION
Nucleus as a cell organelle was first
described by Robert Brown as early as
1831. Later the material of the
nucleus stained by the basic dyes
(Acetocarmine) was given the name
chromatin by Flemming.
"Nucleus is double membrane bound
dense protoplasmic body, which
controls all cellular metabolism and
encloses the genetic information of
cell".
Nucleus is consider as controller or
director of cell. Importance of
nucleus in control of heredity, growth
and metabolism was experimentally
proved by Hammerling. (Experiment
was on Acetabulariaa single cell
largest alga).
If the nucleus of a cell is,
experimentally removed, then
unicellular organism will die after
27
some time. Thus nucleus is very
important.
Strasburgar stated that "Nucleus
arises from divison of pre-existing
nucleus only. The study of nucleus is
known as Karyology.
Generally eukaryotic cell contain at
least one nucleus but nucleus is
absents in mature phloem sieve tube
elements and mature RBCs of
mammals (exceptionaly nucleus is
present in RBCs of camel & lamma).
The size of Nucleus is 5–25
The size of the nucleus depends on
the volume of cell, amount of DNA
protein and metabolic activity of cell.
In a cell there is a definite nucleo
cytoplasmicm ratio (given by Hertwig).
Nucleocytoplasmic
index = n
c n
(V )
(V ) (V )
Vn = Volume of nucleus
Vc = Volume of cell
STRUCTURE OF NUCLEUS
Interphase nucleus : Nucleus of cell
when it is not dividing .
(i) Nuclear membrane or nuclear
envelope or karyotheca.
(ii) Nuclear matrix / Nucleoplasm /
Karyolymph / Karyolasm.
(iii) Nucleolus / little nucleus / Ribosome
(i) NUCLEAR MEMBRANE
Electron microscopy has revealed
that the nuclear envelope, which
consists of two parallel membranes
with a space between (10 to 50 nm)
called the perinuclear space.
These membrane forms a barrier
between the materials present inside
the nucleus and that of the
cytoplasm.
The outer membrane usually remains
continuous with the endoplasmic
reticulum and also bears ribosomes
on it. At a number of places the
nuclear envelope is interrupted by
minute pores, which are formed by
the fusion of its two membranes.
These nuclear pores are the passages
through which movement of RNA and
protein molecules takes place in both
directions between the nucleus and
the cytoplasm.
Each nuclear pore is guarded by a
octagonal discoid structure of
nucleoplasmin protein this structure
is called as annulus or Bleb. (Annulus
+ Pore = Nuclear Pore complex).
The inner side of inner nuclear
membrane is lined by nuclear lamina.
This structure is formed by filaments
of lamin protein.
Pore complex provides the main
channel, between nucleoplsm and
cytoplam, while nucleoplasmin
regulates nucleocytoplasmic traffic.
(ii) NUCLEOPLASM OR
KARYOLYMPH
It is jelly like fluid, Its pH is 7·4 ± 0·2
and it is reservoir of number of
chemicals like nucleotides,
28
nucleosides, ATPs, proteins &
enzymes of RNA & DNA polymerases,
endonucleases, minerals, (Ca++,
Mg++) etc.
Nucleoplasm contain high
concentration of Nucleotides in the
form of triphosphate. (ATP, GTP, TTP,
CTP, UTP)
Chromatin net and nucleolus are
embedded in nucleoplasm.
EAGLE EYES
Nucleoplasm provides site for process of
transcription.
(iii) CHROMATIN NET
Chromatin Tern given by Flemming
Interphase nucles has a loose and
indistinct network of nucleoprotein
fibers called chromatin, which
embeded in nucleoplasm. Chromatin
net is mainly formed of DNA and
histone protein complexes.
Chromatin fibres contain genetic
information and condensed to form
constant number of chromosomes
during cell division.
Chemically chromatin consists of
DNA (31%), RNA (2-5%), Histone
protein (basic proteins) (36%) and
non histone proteins (Acidic proteins)
(28%).
On the basis of relative (H2A, H2B, H3,
H4, H1) amount of arginine and lysin
there are five type of Histone protein.
Amino acid Type of histone
Lysin rich H1
Slightly lysin rich H2A, H2B
Arginine rich H3, H4
Chromatin net has two type of
chromatins. (a) Euchromatin : This is lightly
stained and diffused part of chromatin. Which is transcriptionally or genetically more active. Generally
euchromatin lies at central part of nucleus.
(b) Heterochromatin : This is dark stained, thick and condensed part of chromatin this part has more histone and less acidic protein. Heterochromatin is genetically less active chromatin. Heterochromatin occurs near nuclear membrane.
Difference between Euchromatin and
Heterochromatin.
Eu-
chromatin
Hetero-
chromatin
(i) Consist of
thin,
extended,
lightstained
part of
chromatin.
(i) Consist of
thick,
condensed
part of
Chromatin and
dark stained.
(ii) Genetically
more active
chromatin
(ii) Less active or
inactive
chromatin.
(iii) Less
histone
protein
(iii) More histone
protein
(iv) Replicate in
early s
phase
(iv) Replicate in
late s phase
(iv) NUCLEOLUS
The nucleoplasm also contain
nucleous.
The nucleoli are spherical and
membraneless structure so that the
content of nucleous is continous with
the rest of the nucleoplasm.
It is a site for active ribosomal RNA
synthesis.
Nucleolus usually attached to
chromatin (or chromosomes) at
specific site called Nucleolar
organiser region/NOR. Number of nucleolus in a nucleus is
one. Onion cell has 4, and in oocytes
of amphibian has 2000 nucleoli.
Human cell has 5 nucleoli.
29
Nucleolus disappears during
prophase and reappears in telophase.
FUNCTIONS OF NUCLEOLUS
Ribosome formation is the chief role
of nucleolus, thus its called as
Ribosme factory of cell, the proteins
of ribosomes are synthesised in
cytoplasm but it diffused in to
nucleus and reach at nucleolus. Here
r-RNA and ribosomal proteins are
assembled to form ribosomes which
move to cytoplasm through nuclear
pores.
Larger and more numerus nucleoli are
present in cells actively carrying out
protein synthesis.
FUNCTIONS OF NUCLEOLUS
(i) Genetic information: Nucleus
contains genetic information in its
chromatin (store house of genetic
material) (ii) Transmission of genetic information:
Nucleus takes part in transmission of
genetical information from parent
cell to daughter cell or the one
generation to next.
(iii) In cell-division: Division of nucleus is
pre-requisite to cell division.
(iv) Control of metabolism: Nucleus
controls metabolism of cell by
sending m-RNA in cytosol (Basically
biomolecule DNA controls cellular
activities through directing synthesis
of enzyme).
(v) Variations : Variation develops due to
change in genetic material of
nucleus. (Evolutionary role).
CHROMOSOMES
INTRODUCTION
At the time of cell division the
chromatin material get condensed to
form chromosomes, thus
chromosome is highly condensed
form of the chromatin. Chromosomes
are not visible during interphase
stage.
First of all, chromosomes was
observed by Hofmeister (1818) and
Karl Nageli in pollen mother cells
(PMC) of Tradescantia.
Strasburger (1875) described
chromosome structure appeared in
nucleus during cell division. (Credit of
discovery of chromosomes goes to
Strasburger)
Term "Chromosome" was proposed
by Waldeyer. (Term 'Chromatin, was
suggested by Flemming)
SIZE
Size–Chromosomes are 0.5 –30m in
length and 0.2–3m diameter. Trillium
plant has longest chromosome)
Plants generally have larger
chromsomes than animals and
amongst plants, monocots have
bigger chromosomes than dicots.
During cell division, Dehydration &
condensation of chromatin network
take place as a result chromatin is
converted into chromosomes.
Chromosomes can be best studied at
metaphase stage because size of
chromosomes is the shortest during
metaphase (Shape of chromosome is
studied at Anaphase stage)
CHROMOSOME NUMBER IN SOME ORGANISMS
Plants 2n n
Mucor hemelis (Fungi) 2 1
Haplopappus gracilis (Family compositae) 4 2
Pisum sativum (Pea) 14 7
Zeamays (Maize)
Wheat (Triticum)
Ophioglossum reticulatum
Animals
Ascaris megalocephala (Round worm)
Drosophila melanogaster
Chimpanzee/Gorilla
Homo sapiens
Aulocantha (a protozoan)
2n = number of chromosome in
diploid cell. n = number of
chromosome in haploid cell.
The number of chromosome is
definite for each species. For
example every normal human being
has 46 chromosomes in each body
cell.
Gametes of all organisms contain
only one of each chromosome. The
number of chromosomes in a gamete
is called "Genome" or haploid
chromosome (Human 23) ‘‘A
complete set (n) of chromosomes (all
genes) inherited as a unit from one
parent is known as genome,,
A single human cell has
approximately 2.2 meter long thread
of DNA distributed among its
(23 pairs) chromosomes.
TYPES OF CHROMOSOMES ON THE
BASIS OF POSITION OF
CENTROMERE
(i) Telocentric : When centromere is
terminal or located at the tip of
chromosome.
(ii) Acrocentric : When the centromere is
sub-terminal or located near the tip.
(iii) Metacentric : When the centromere is
located at mid of the chromosome.
20
42
Ophioglossum reticulatum (Pteridophyta) 1260
2n
(Round worm) 2
(Fruit fly) 8
48
46
(a protozoan) 1600
2n = number of chromosome in
diploid cell. n = number of
chromosome in haploid cell.
omosome is
te for each species. For
example every normal human being
has 46 chromosomes in each body
Gametes of all organisms contain
only one of each chromosome. The
number of chromosomes in a gamete
or haploid
(Human 23) ‘‘A
complete set (n) of chromosomes (all
genes) inherited as a unit from one
parent is known as genome,,.
approximately 2.2 meter long thread
of DNA distributed among its forty six
ON THE
When centromere is
or located at the tip of
When the centromere is
or located near the tip.
When the centromere is
of the chromosome.
(iv) Sub metacentric
centromere located
mid point of chromosome.
The ratio of length of the long arm to
the short arm of a chromosome is
called arm ratio
maximum in acrocenteric
chromosome.
STRUCTURE OF CHROMOS
which appears in
metaphasechromosome
1. Pellicle– This is
proteinaceous covering or sheath of
chromosome.
2. Matrix – This is a liquid nongenetic
achromatic ground substance of
chromosome, which has different type
of enzymes, minerals, water, proteins.
3. Chromatid – At metaphase
chromosome is consist
cylindrical structures
chromatids. Both sister chromatids
are joined together by a common
30
10
21
630
n
1
4
24
23
800
Sub metacentric : When the
centromere located near centre or
mid point of chromosome.
The ratio of length of the long arm to
the short arm of a chromosome is
arm ratio. Arm ratio is
maximum in acrocenteric
STRUCTURE OF CHROMOSOME (Parts
which appears in
metaphasechromosome)
This isoutermost, thin
proteinaceous covering or sheath of
This is a liquid nongenetic
achromatic ground substance of
chromosome, which has different type
of enzymes, minerals, water, proteins.
At metaphase stage each
chromosome is consist of two
cylindrical structures - called
. Both sister chromatids
are joined together by a common
31
centromere. A chromosome, may have
single chromatid (in Anaphase or
Telophase) or two chromatid. (as in
prophase metaphase)
Each chromatid is consist of a single
long thread of DNA associated with
histone. Non histone proteins and
RNA are also present.
4. Centromere/Kinetochore (Primary
constriction) - Each chromosome (at
metaphase) is consist of two
chromatids. Both the chromatids of a
chromosome are joined or connected
by a structure called Centromere. At
this point or centromere two protein
discs are present which is called
Kinetochore.
Kinetochores - constitute the actual
site of attachement of spindles to
chromosomes during cell division.
At the region of centromere the
chromosome is comparatively
narrower than remaining part of
chromosome, thus it is termed as
Primary constriction.
5. Secondary constriction - Besides
primary constrictions, other
constriction may also occurs on
some chromosome, which are known
as secondary constriction. These
constriction are non staining and
found at a constant location.
Secondary constriction-I is also
known as NOR (Nucleolar organizer
region) (13,14,15,21,22 chromosomes in
human)
Secondary constriction-II is found in
the chromosome number 1, 10, 13, 17
& Y chromosomes of human.
6. Satellite - part of chromosome
remains after the NOR is known as
chromosomes satellite/ Trabent.
Chromosomes with satellite part are
called as SAT chromosome (SAT -
Sine Acid Thymonucleinico)
7. Telomere - Chromosomes have
polarity and polar ends of
chromosomes are known as
Telomeres.Telomere prevents fusion
of one chromosomes to other
chromosome. Telomere rich in
Guanine base (5'-TTAGGG-3'). Enzyme
Telomerase presents in telomere part
of chromosome, which is a
Ribonucleoprotein.
EAGLE EYE
According to Richard kathan (2003)
telomeres of chromosomes becomes
shorter during ageing process.
Karyotype: is external morphology of
all Chromosomes of a cell which is
specific for each species of living
organisms. Karyotype can be studied
in metaphase of mitosis.
Karyotype includes the number of
chromosomes, relative size, position
of centromere, length of the arms,
secondary constrictions and banding
patterns.
Chromosome with
kinetochore
kin
etoc
hore
Chromonema
Second constriction II
Telomeric DNA (Synth. by Telomerase or RNP)
Telomere
MatrixKinetochore(Protein dics)
Primary constriction(Centromere)
Pellicle
Secondary constriction-INOR (r-RNA synthesis)
Satellite (Trabent)SAT
Chromomere
A schematic diagrammatic representation of chromosome
32
Idiogram: Diagrammatic representation of
Karyotype. In idiogram chromosomes are
arranged in decreasing order of size. Sex
chromosomes are placed in last Idiogram
is specific for every species.
SPECIAL CHROMOSOMES
POLYTENE CHROMOSOMES
(SALIVARY GLAND
CHROMOSOMES)
This type of chromosome was
discovered by Balbiani in salivary
glands of chironomous larva of
dipteran insect. These are also found
in salivary glands of drosophila.
In polytene chromosomes, number of
chromatids are very high due to
repeted division of chromosome
without centromeric and nuclear
division such division is called
endomitosis or endoreduplication
[repeated replication of DNA] Large
swellings are found on some places
that are called puffs (Balbiani rings).
In puffs DNA is uncoild for rapid
transcription of RNA and Synthesis of
proteins.
LAMP BRUSH CHROMOSOME
Found in oocytes of vertebrates
(Amphibia) during diplotene stage of
cell division. These chromosomes
look like lamp brush, thus called as
lamp brush chromosomes.
Axis of lamp brush chromosome is
consist of DNA, while matrix is
consist of RNA & proteins.
Lamp brush chromosome is
concerned with “Vitellogenesis” (Yolk
formation.)
Example
1. Hetero-chromatin is :-
(A) Darkly stained part of chromatin
(B) Lightly stained part of cristae
(C) Lightly stained part of grana
(D) Scattered Lobes in cytoplasm
Ans. (A)
Solution
Heterochromatin is darkly stained,
thick and condensed part of
chromatin.Heterochromatin is
genetically less active.
2. Genome is-
(A) Diploid set of chromosomes
(B) Haploid set of chromosomes
(C) A single chromosome
(D) None of the above
Ans. (B)
Solution
The number of chromosome in a
gametes or haploid chromosome is
called genome
3. The non-sticky chromosomal ends are
knwon as -
(A) Chromatids
(B) Centromere
(C) Chromomere
(D) Telomere
Ans. (C)
Solution
33
Chromosome have polarity and polar
ends of chromosomes are knownas
telomeres. Telomere prevent fusion
of one chromosome to other
chromosome. Telomere rich in
guanine bases (5’-TTAGGG-3’)
Educatalyze
1. The protein nucleoplasmin occurs in -
(A) Nuclear pore complex
(B) Sieve cells
(C) Nucleolus
(D) Heterochromatin
2. In bacterial cell DNA is extensively
looped and coiled with help of
(A) Acid proteins
(B) Histones
(C) Basic nucleopid protein called as
polyamines
(D) Actin
3. Who coined the term chromatin to
describe the thread like material of
the nucleus?
(A) W. Flemming
(B) W. Roux
(C) E. Strasburger
(D) Boveri
4. The telomeres of eukaryotic
chromosomes consists of short
sequence of
(A) Cytosine rich repeats
(B) Adenine rich repeats
(C) Guanine rich repeats
(D) Thymine rich repeats
34
Exercise-1 Cytoplasm, Size of Cell, Cell Wall
1. What type of material is the
cytoplasm?
(A) Water soluble material
(B) Fat soluble material
(C) Colloidal material
(D) Permeable material
2. Cell wall was first studied by
(A) Bonner
(B) Flemming
(C) Strasburger
(D) Robert Hooke
3. Which of the following is the smallest
cell
(A) Virus
(B) Chlamydomonas
(C) PPLO
(D) Human nerve cells
4. All cell are derived from pre-existing
cells” is the famous generalization of
-
(A) Schultz
(B) Virchow
(C) Lamarck
(D) Schleiden
5. One of the following is an exception
to cell theory
(A) Bacteria
(B) Prokaryotes
(C) Blue green algae
(D) Bacteriophage
6. Small cell are metabolically active as
they have
(A) Higher surface area to volume
ratio
(B) higher nucleocytoplasmic ratio
(C) Lower nucleocytoplasmic ratio
(D) both (1) & (2)
7. Cell wall is
(A) Dead and impermeable
(B) Dead and permeable
(C) Living and impermeable
(D) Living and selective
8. The intercellular structure separating
the walls of two adjacent cells is
(A) Primary wall
(B) Middle lamella
(C) Plasma membrane
(D) Secondary wall
9. The most abundant substance of
middle lamella is-
(A) Pectin
(B) Suberin
(C) Cutin
(D) Lignin
10. Ripening fruit becomes soft due to
(A) Incorporation of pectin in middle
lamella
(B) Conversion of strach into sugar
(C) Dissolution of pectate of middle
lamella
(D) Jelly formation at acidic pH
11. Which is the thickest wall layer
(A) Primary wall
(B) Tertiary wall
(C) Secondary wall
(D) Middle lamella
12. Plasmodesmata are:-
(A) Protoplasmic connections
(B) Pores in cell membrane
(C) Pores in cell wall
(D) 1 and 2 both
CELL MEMBRANE
13. Plasma membrane is :
(A) Permeable
(B) Impermeable
(C) Selectively permeable
(D) Semipermeable
14. Correct sequence of protein (P) and
lipid (L) in cell membrane is
(A) L-P-P-L
35
(B) P-P-L-L
(C) P-L-L-P
(D) L-P-L-P
15. According to fluidmosaic model
(proposed by Singer & Nicolson)
plasma membrane is composed of:-
(A) cellulose, hemicellulose
(B) Phospholipid and integrated
protein
(C) Phospholipid, extrinsic protein,
intrinsic protein
(D) Phospholipid and hemicellulose
16. Plasma membrane is fluid structure
due to presence of:
(A) Carbohydrate
(B) Lipid
(C) Glycoprotein
(D) Polysaccharide
17. Cell recognition and adhesion occurs
due to the following component of
the plasma membrane
(A) Protein
(B) Lipids
(C) Proteins and lipids
(D) Glycoproteins & glycolipids
18. Plasma membrane is asymmetric
because
(A) Lipids present in the outer and
inner side of the bilayer are
different
(B) Extrinsic proteins are more
abundant on the inner surface
than on the outer surface
(C) Oligosaccharides are attached
only to the external surface of
lipids and proteins of a
biomembrane
(D) All of these
19. According to widely accepted “fluid
mosaic model” cell membranes are
semi-fluid,where lipids and integral
proteins can diffuse randomly. In
recent years, this model has been
modified in several respects. In this
regard, which of the following
statements is incorrect?
(A) Proteins in cell membranes can
travel within the lipid bilayer
(B) Proteins can also undergo flip-
flop movements in the liplid
bilayer
(C) Proteins can remain confined
within certain domains of the
membranes
(D) Many proteins remain completely
embedded within the lipid bilayer
20. Fluid mosaic model of cell membrane
proposes that
(A) A lipid bilayer with embedded
proteins only
(B) A lipid bilayer with proteins on
the outer surface only
(C) A lipid bilayer coated with
proteins on both the surfaces
(D) A lipid bilayer with proteins of
two types, embedded (intrinsic)
and superficial (extrinsic)
21. Carrier molecules facilitating
transport across cell membrane are
(A) Proteinaceous
(B) Fatty acids
(C) Starch
(D) Alkaloids
22. Plasma membrane particularly in
animal cell is elastic due to
(A) Lipids
(B) Proteins
(C) Carbohydrates
(D) None of these
ENDOPLASMIC RETICULUM
23. Endoplasmic reticulum often bears
(A) Centrioles
(B) Lysosomes
36
(C) Ribosomes
(D) Plastids
24. Which organelle help in the synthesis
of lipids
(A) Golgi complex
(B) RER
(C) SER
(D) none of these
25. Which of the following is associated
with detoxification of drugs and
muscle contraction by the release and
uptake of Ca2+ ions
(A) Golgi complex
(B) RER
(C) SER
(D) Free ribosomes
26. The site of detoxification reaction in
liver is
(A) SER
(B) Free ribosomes
(C) RER
(D) hydrophobic interaction
27. In GERL system ER is -
(A) RER
(B) SER
(C) Both (1) and (2)
(D) None of these
28. ER is involved in all of the following
except-
(A) Production of ribosomes
(B) Synthesis of lipids
(C) Synthesis of proteins
(D) Transportation of molecules to
the cell membrane for export.
29. Which organelle help in the synthesis
of lipids, cholesterol, steroids and
visual pigments in epithelial cells of
retina.
(A) RER
(B) SER
(C) Golgi bodies
(D) All of these
30. Myeloid bodies, sarcoplasm of
muscles and nissl granules are rich
in-
(A) Fats
(B) Golgi bodies
(C) Lipids
(D) ER
31. The close functional relationship
between ER, Golgi, Lysosome are
represent as-
(A) GERL system
(B) Vacuolar system
(C) Annulated lamellae
(D) None of the above
32. Microsomes are related to
(A) Endoplasmic reticulum
(B) Spherosomes
(C) Lysosomes
(D) Plasmalemma
GOLGI COMPLEX
33. Cell organelles associated with
secretion are -
(A) Mitochondria
(B) Ribosomes
(C) Chloroplasts
(D) Golgi complex
34. Besides giving out secretory vesicles,
Golgi apparatus is also concerned
with formation of
(A) Grana of chloroplasts
(B) Plastids
(C) Cell plates after cells division in
plants
(D) Lysosomes
35. The Golgi complex is specialized for
(A) Glycosylation of lipids and
proteins
(B) Conversion of light energy into
chemical energy
(C) Generation of ATP
(D) Intracellular digestion
37
36. Which one takes part in acrosome
synthesis
(A) Golgi apparatus
(B) Lysosome
(C) Nucleus
(D) Mitochondria
37. The organelle that moves materials
out of the cell is-
(A) ER
(B) Lysosomes
(C) Golgi bodies
(D) Ribosomes bound on ER
38. Which organelle is located near the
nucleus and contains stack of
flattened cisternae structures?
(A) Centrosome
(B) Chloroplast
(C) Golgi bodies
(D) Centriole
39. Secretory vesicles are pinched off
from _____ side of dictyosomes-
(A) Plain
(B) Convex
(C) Concave
(D) All sides
LYSOSOME
40. Lysosomes are celled "suicide bags”
because they have
(A) Catabolic enzymes
(B) Food vacuole
(C) Hydrolytic enzymes
(D) Parasitic activity.
41. Most of hydrolytic enzymes of
lysosomes function at-
(A) Basic pH
(B) Any pH
(C) Neutral pH
(D) Acidic pH
42. The mitochondria serves as a marker
for cytochrome oxidase and the
Lysosomes serve for ........
(A) Succinic dehydrogenase
(B) Catalse
(C) Galactosidase
(D) Acid phosphatase
43. Which of the following organelle show
polymorphism
(A) Golgi apparatus
(B) lysosome
(C) Mitochondria
(D) Chloroplast
44. Which types of lysosomes contribute
to the ageing process
(A) Primary lysosomes
(B) Secondary lysosomes
(C) Autophagic vacuoles
(D) Residual bodies
45. Pri. lysosome + phagosome forms
(A) Residual body
(B) Secondary lysosome
(C) Autophagic vacuole
(D) None
46. In plant cell lysosome is absent but a
plant cell with lysosome exceptionally
is-
(A) Spirogyra
(B) Neurospora
(C) Acetabularia
(D) Riccia
47. Autophagic vacuoles digest.
(A) Cell organelles
(B) Solid particles of Phagosomes
(C) Fluid droplets of pinosomes
(D) None of the above
VACUOLES
48. Vacuole is surrounded by a single
membrane called
(A) Plasmalemma
(B) Vacuole wall
(C) Tonoplast
(D) Tono membranous
49. A large and mature plant cell has
(A) Many Vacuoles
(B) A large vacuole
38
(C) No vacuole
(D) Many small vacuoles and a large
vacuole
50. In a plant cell vacuole contains-
(A) Water
(B) Dissolved salts
(C) Gases
(D) All of these
51. Cell sap is-
(A) Non living part of cytoplasm
(B) Living part of cytoplasm
(C) Living matter of cell
(D) Non living part of vacuole
52. Vacuolar cell sap has pH-
(A) Alkaline and hypotonic
(B) Neutral and isotonic
(C) Acidic and hypertonic
(D) Equal to cytoplasm and isotonic
53. Organic acid and most common
element in sap vacuole-
(A) Ca++, acitic acid
(B) K+, oxaloacetic acid
(C) Ca++, citric acid
(D) K+, acetic acid
54. Vacuoles help in-
(A) Making cell light
(B) Storing wastes and food particles
(C) Separating water from cytoplasm
(D) All of the above
MITOCHONDRIA
55. Mitochondria are the site of
(A) ATP formation
(B) Cellular respiration
(C) Electron transport
(D) All of these
56. Which of the following structure is
present in mitochondria.
(A) Oxysome
(B) Polysome
(C) Dictyosome
(D) Quantasome
57. Oxidative phosphorylation takes place
in
(A) Chloroplasts
(B) Vacuoles
(C) Mitochondria
(D) Ribosome
58. Cytochrome oxidases are found
(A) On outer wall of mitochondria
(B) In the matrix of mitochondria
(C) In the lysosomes
(D) On cristae of mitochondria
59. In living cells mitochondria can be
stained with
(A) Neutral red
(B) Janus green
(C) Crystal violet
(D) Aceto-orcein
60. Mtiochondria are not found in
(A) Liver cells
(B) Proteins
(C) Mature RBCs
(D) Immature RBCs
61. Mitochondria and chloroplast contain
(A) DNA
(B) DNA + RNA
(C) DNA + RNA + ribosomes
(D) Proteins
62. Synthesis of ATP in mitochondria
takes place
(A) In the matrix
(B) In the intracristal space
(C) At the cristae
(D) At the outer membrane
63. The mitochondrial DNA differs from
the nuclear DNA in
(A) Lacking association with histone
(B) Being circular in nature
(C) Having higher C–G ratio
(D) All of these
64. Mitochondria are absent in-
(A) Blue green algae
(B) W.B.C. of mammals
(C) Red algae
(D) Green algae
39
65. The inner membrane of mitochondria
bears foldings called cristae these
cristae
(A) Increase ATP supply
(B) Keep external substances away
(C) Increase the thickness of wall
(D) Increase surface area
66. Oxysomes or elementary particles are
centre of oxidative phosphorylation
are found in-
(A) Inner membrane of chloroplast
(B) Outer membrane of mitochondria
(C) Perimitochondrial space
(D) Inner membrane of mitochondria
67. Mitochondrial DNA is naked without
histone, double stranded and circular,
discovered by Nass and Nass It is rich
in
(A) C–A ratio
(B) A–G ratio
(C) A–T ratio
(D) G–C ratio
68. Enzyme ATPase is found in head of
oxysome that is called–
(A) F0
(B) F1–F0
(C) F1
(D) None of these
69. If a cell is placed under anaerobic
condition–
(A) ER will disappear
(B) Mitochondria will multiply
(C) Mitochondria will disappear
(D) Mitochondria and ribosomes will
multiply speedly.
70. Outer and inner membrane of
motochondria are–
(A) Structurally similar but
functionally different
(B) Functionally similar but
structurally different.
(C) Structurally and functionally
similar
(D) Structurally and functionally
dissimilar
71. Most of the biological energy is
supplied by mitochondria through–
(A) Breaking of sugars
(B) Oxidising TCA substrate
(C) Reduction of NADP+
(D) Breaking of Proteins
72. Inner membrane of mitochondria–
(A) Cytochrome oxidase
(B) Succinic dehydrogenase
(C) Malic dehydrogenase
(D) Both (1) and (2)
73. Mitoplast is–
(A) Mitochondria without inner
membrane
(B) Mitochondria without outer
membrane
(C) Membraneless mitochondria
(D) Another name of mitochondria
PLASTIDS
74. Which of the plastid stores protein
(A) Elaioplast
(B) Chloroplast
(C) Amyloplast
(D) Aleuroplast
75. The pigment which is not found in
chloroplast is-
(A) carotene
(B) chlorophyll
(C) xanthophyll
(D) anthocyanin
76. The most abundant protein in the
plant world is found in
(A) Root hairs
(B) Mitochondria
(C) Chloroplasts
(D) Viruses
77. The endosymbiotic theory explains-
(A) The origin of the nucleus
(B) The origin of mitochondria and
chloroplasts
(C) Why prokaryotic cells are
40
different from eukaryotic cells
(C) Where the endomembrane
system came
78. Chloroplasts are called semi-
autonomous structures due to
presence of-
(A) RNA only
(B) DNA only
(C) Both RNA and DNA
(D) Pigment and proteins
79. The process in which excess molecule
of glycolate passes out of the
chloroplast and enter in peroxisome
and oxidised, is called-
(A) Respiration
(B) Photosynthesis
(C) Photorespiration
(D) All of the above
80. Which one is universal photosynthetic
pigment in green plants
(A) chl a
(B) chl c
(C) chl d
(D) chl e
81. Dimorphic chloroplasts are found is
(A) C3 Plants
(B) C4 Plants
(C) Aquatic plants
(D) Xerophytic plants
82. Fret channels are characteristics of–
(A) Mitochondria
(B) Dictyosomes
(C) ER
(D) Chloroplast
83. The complex liquid matrix of
chloroplast is called–
(A) Cytoplasm
(B) Cytosol
(C) Hyaloplasm
(D) Stroma
84. Cup shaped and star shaped
chloroplasts are found in–
(A) Spirogyra and Cladophora
(B) Ulothrix and Chara
(C) Chlamydomonas and Zygnaema
(D) Vaucheria and Fritschiella
85. Larger thylakoids in chloroplast are
called–
(A) Grana lamellae
(B) Stroma lamellae
(C) Grana
(D) Loculus
86. A piece of corrot and a flower is put
in water separatly. The water
becomes purple in case of carrot but
remain colourless in flower case . It is
due to–
(A) In flowers, carotenoid pigments
are fat soluble and found in
chromoplast and not come out in
water.
(B) In carrot, Anthocyoxin pigments
are found in cell sap which are
water soluble.
(C) In flowers pigments are found in
cytoplasm while in carrot,
pigments are localized in
vacuoles.
(D) Both (1) and (2) are correct.
87. In chloroplast proteinaceous granule
surrounded by starch forms a
compact body called–
(A) Paramylum
(B) Dictyosome
(C) Microsome
(D) Pyrenoid
88. Agranal chloroplasts are found in –
(A) Mesophyll of maize leaves
(B) Bundle sheath of mango leaves
(C) Bundle sheath of sugarcane
leaves
(D) Mesophyll of pea plants
RIBOSOME
89. Engine of the cell is
(A) Ribosome
(B) Lysosome
41
(C) Vacuole
(D) Mitochondria.
90. Ribosomes are attached to
endoplasmic reticulum through
(A) r-RNA
(B) Hydrophobic interaction
(C) t-RNA
(D) Ribophorins
91. The smallest organelles in the cell are
(A) Dictyosomes
(B) Lysosomes
(C) Microsomes
(D) Ribosomes
92. The larger sub-unit of 80 S ribosomes
contain the following RNA molecule
(A) 23 S, 5.8 S. 5.0 S
(B) 28 S, 5.8 S. 5.0 S
(C) 25 S, 5.8 S. 5.0 S
(D) 25 S, 5.8 S. 5.0 S
93. Protein synthesis in an animal cell
occurs
(A) Only on the ribosomes present in
the cytosol
(B) Only on ribosomes attached to
the nuclear envelope and ER
(C) On ribosomes present in the
cytoplasm as well as in
mitochondria
(D) On ribosomes present in the
nucleolus as wall as in cytoplasm
94. Ribosomes are
(A) Amphoteric
(B) Positively charged
(C) Negatively charged
(D) None
95. Peptidyl transferase is found on-
(A) A-site of smaller unit of ribosome
(B) P-site of larger unit of ribosome
(C) Entire ribosome
(D) mRNA
96. Site of formation of ribosomal
precursor in cell is-
(A) Stroma
(B) Nucleus
(C) Nucleolus
(D) Golgi body
97. In ribosomes two subunits are -
(A) Joins only at the time of protein
synthesis
(B) Lie freely in cytoplasm
(C) Dissociates at the end of protein
synthesis
(D) All of the above
98. Ergasomes are formed by-
(A) 5 ribosomes
(B) More than 4 ribosomes attached
to ER
(C) more than 5 ribosomes attached
to a mRNA
(D) Cluster of ribosomes
99. 70 S type of ribosomes are found in-
(A) Eukaryotic cells
(B) Mitochondria
(C) Prokaryotic cells
(D) All of these
100. Organelle within organelle is
(A) Ribosome
(B) Lysosome
(C) Vacuole
(D) Mitochondria
CILIA & FLAGELLA& CENTRIOLES
101. Adenosine triphosphate (ATP) powers
the movement of cilia and flagella,
adenosine triphosphatase activity is
present in
(A) Nexin protein
(B) Dynein protein
(C) Massule
(D) Both (1) & (2)
102. Basal bodies are associated with the
development of-
(A) Cilia and flagella
(B) Cell plate
(C) Phragmoplast
(D) Kinetochore
103. Cilia and flagella have-
(A) Dissimilar internal structure and
42
are of similar size
(B) Dissmilar internal structure and
are of unequal size
(C) Similar internal structure and are
of dissimilar size
(D) Similar internal structure and are
of equal size
104. 9 + 0 microtubular structure is found
in-
(A) Centriole
(B) Basal body
(C) Blepharoplast
(D) All of these
105. Protein tubulin does not occur in-
(A) Flagella
(B) Plasma membrane
(C) Cilia
(D) Microtubule
106. Centrosome is
(A) Cytoplasmic structure of animal
cells
(B) A nuclear structure of animal
cells
(C) Cytoplasmic structure of plant
cells
(D) Cytoplasmic structure of animal
cells and some lower plants
107. Centrosome is rich in
(A) RNA
(B) DNA
(C) ATP
(D) Enzymes
108. Basal body could be another name of
centriole in view of internal structure
when
(A) It gives rise to spindle
(B) It divides during mitosis
(C) It gives basic reactions
(D) It gives rise to cilia and flagella.
109. Centriole and centrosome are found
in the cell of
(A) Animals
(B) Green plants
(C) Bacteria
(D) Cyanobacteria.
MICROBODIES
110. Glyoxylate cycle occuring in
glyoxysomes is a modified form of-
(A) Calvin cycle
(B) Glycolysis
(C) Kreb’s cycle
(D) Glycolate cycle
111. Plant lysosomes rich in fats and
taking part in -oxidation of fattyacids
are-
(A) Lysosomes
(B) microsomes
(C) Sphaerosomes
(D) Glyoxysomes
112. Catalase is found in-
(A) Cell membrane
(B) Lomasomes
(C) Mitochondria
(D) Peroxisome
113. From endosperm of germinating
castor bean extruded cell organelles
are-
(A) Peroxisomes
(B) Glyoxisomes
(C) Transosomes
(D) None
114. Glyoxylate cycle plays an important
role in conversion of-
(A) Glycerol into carbohydrate
(B) Fatty acids into carbohydrates
(C) Proteins into carbohydrates
(D) Simple carbohydrates into
complex carbohydrat
115. Which of the following organelle takes
part in photorespiration
(A) Glyoxisome
(B) Peroxisome
(C) Dictyosome
(D) ER
NUCLEUS
116. The cell nucleus was discovered by
(A) De Duve
43
(B) Robert Brown
(C) Robert Hooke
(D) Virchow
117. Nuclear material without nuclear
membrane is found in
(A) Mycoplasma and green algae
(B) Bacteria and green algae
(C) Bacteria and cyanobacteria
(D) Cyanobacteria and red algae
118. Genome is
(1) Diploid set of chromosomes
(2) Haploid set of chromosomes
(3) A single chromosome
(4) None of the above
119. A constriction on the chromosomes is
called
(A) Centromere
(B) Centrosome
(C) Centriole
(D) Chromomeres
120. Nucleolus takes part in the synthesis
of
(A) rRNA
(B) tRNA
(C) mRNA
(D) None of these
121. The genetic material of the bacterial
cell is localised within a discrete
region, called as
(A) Nucleus
(B) Nucleolus
(C) Plasmid
(D) Nucleoid
122. Nucleolus is produced from
(A) 1st constriction
(B) Nucleolar organising region of
certain chromosomes
(C) Nuclear envelope
(D) ER
123. Nucleolar organizer is a :-
(A) Primary constriction
(B) Secondary constriction
(C) Tertiary constriction
(D) Centriole
124. Chromosomes composed of :-
(A) DNA, RNA, Histones, Non histones
(B) DNA and Histones
(C) DNA and RNA
(D) DNA, RNA and Histones
125. Which part of chromosome is concern
with ageing of organism and cancer.
(A) Centromere
(B) Telomere
(C) Kinetochore
(D) Satellite
126. The non–sticky chromosomal ends
are known as –
(A) Chromatids
(B) Centromere
(C) Chromomere
(D) Telomere
127. Highest arm ratio occur in which
chromosome :–
(A) Telocentric
(B) Metacentric
(C) Submetacentric
(D) Acrocentric
128. The protein nucleoplasmin occurs in
(A) Nuclear pore complex
(B) Sieve cells
(C) Nucleolus
(D) Hetero chromatin
129. If the centromere is sub–median the
two arms are unequal then the
chromosome is called as
(A) Metacentric
(B) Submetacentric
(C) Acrocentric
(D) Telocentric
44
EXERCISE-2 1. Protein synthesis in an animal cell
occurs [2005]
(A) On ribosomes presents in
cytoplasm as well as in
mitochondria
(B) On ribosomes present in the
nucleolus as well as in
cytoplasm
(C) Only on ribosomes attached to
the nuclear envelope and
endoplasmic reticulum
(D) Only on the ribosomes present
in cytosol
2. Centromere is required for [2005]
(A) Movement of chromosomes
towards poles
(B) Cytoplasmic cleavage
(C) Crossing over
(D) Transcription
3. According to widely accepted “fluid
mosaic model” cell membranes are
semifluid, where lipids and integral
proteins can diffuse randomly. In
recent years, this model has been
modified in several respects. In this
regard, which of the following
statements are incorrect [2005]
(A) Proteins can also undergo flip-
flop
movements in the lipid bilayer
(B) Many proteins remain completely
embedded within the lipid bilayer
(C) Proteins in cell membranes can
travel within the lipid bilayer
(D) Proteins can remain confined
within certain domains of the
membranes
4. The main organelle involved in
modification and routing of newly
synthesized proteins to their
destinations is [2005]
(A) Endoplasmic Reticulum
(B) Lysosome
(C) Mitochondria
(D) Chloroplast
5. Which of the following statements
regarding mitochondrial membrane is
not correct? [2006]
(A) The outer membrane is
Permeable to all kinds of
molecules
(B) The enzymes of the electron
transfer chain are embedded in
the outer membrane
(C) The inner membrane is highly
convoluted forming a series of
infoldings
(D) The outer membrane resembles
asieve
6. Which one of the following is not a
constituent of cell membrane?
[2007]
(A) Phospholipids (B) Cholesterol
(C) Glycolipids (D) Proline
7. Select the wrong statement from the
following [2007]
(A)The chloroplasts are generally
much larger than mitochondria
(B) Both chloroplasts and
mitochondria contain an inner
and an outer membrane
(c) Both chloroplasts and
mitochondria have an internal
compartment, the thylakoid
space bounded by the thylakoid
membrane
(d) Both chloroplasts and
mitochondria contain DNA
8. Vacuole in a plant cell [2008]
(A) lacks membrane and contains air
(B) Lacks membrane and contains
water and excretory substances
(C) is membrane-bound and contains
storage proteins and lipids
(D) is membrane-bound and contains
water and excretory substances
9. The two subunits of ribosome remain
united at a critical ion level of
[2008]
(A) magnesium (B) calcium
(C) copper (D) manganese
10. Cellulose is the major component of
cell walls of: [2008]
(A) Pseudomonas
(B) Saccharomyces
(C) Pythium
(D) Xanthomonas
11. Polysome is formed by [2008]
(A) a ribosome with several subunits
45
(B) ribosomes attached to each other
in a linear arrangement
(C) several ribosomes attached to a
single mRNA
(D) many ribosomes attached to a
strand of endoplasmic reticulum
12. Keeping in view the “fluid mosaic
model” for the structure of cell
membrane, which one of the following
statements is correct with respect to
the movement of lipids and proteins
from one lipid monolayer to the other
(described as flipflop movement)?
[2008]
(A) While proteins can flip-flop, lipids
cannot
(B) neither lipids, nor proteins can
flip-flop
(C) Both lipids and proteins can flip-
flop
(D) While lipids can rarely flip-flop
proteins Cannot
13. Middle lamella is composed mainly of
[2009]
(A) Phosphoglycerides
(B) Hemicellulose
(C) Muramic acid
(D) Calcium pectate
14. Stroma in the chloroplast of higher
plant contains [2009]
(A) Chlorophyll
(B) Light-independent reaction
enzymes
(C) Light-dependent reaction
enzymes
(D) Ribosomes
15. Cytoskeleton is made up of [2009]
(A) Proteinaceous filaments
(B) Calcium carbonate granules
(C) Callose deposits
(D) Cellulose microfibrils
16. Plasmodesmata are [2009]
(A) Connection between adjacent
cells
(B) Lignified cemented layers
between cells
(C) Locomotory structures
(D) Membranes connecting the
nucleus with plasmalemma
17. The plasma membrane consists
mainly of [2010]
(A) phospholipids embedded in a
protein bilayer
(B) proteins embedded in a
phospholipid bilayer
(C) proteins embedded in a polymer of
glucose molecules
(D) proteins embedded in a
carbohydrate bilayer
18. The main arena of variuos types of
activites of a cell is [2010]
(A) Plasma membrane
(B) Mitochondrian
(C) Cytoplasm
(D) Nucleus
19. Which one of the following has its
own DNA? [2010]
(A) Mitochondria (B) Dictyosome
(C) Lysosome (D) Peroxisome
20. Which one of the following structures
between two adjacent cells is an
effective transport pathway?
[2010]
(A) Plasmodesmata
(B) Plastoquinones
(C) Endoplasmic reticulum
(D) Plasmalemma
21. What are those structures that appear
as ‘beads-on-string’ in the
chromosomes when viewed under
electron microscope? [2011]
(A) Genes (B) Nucleotides
(C) Nucleosomes (D) Base pairs
22. Peptide synthesis inside a cell takes
place in [2011]
(A) Ribosomes
(B) Chloroplast
(C) Mitochondria
(D) Chromoplast
23. Important site for formation of
glycoproteins and glycolipids is
[2011]
(A) Lysosome (B) Vacuole
(C) Golgi apparatus (D) Plastid
24. Select the the correct statement from
the following regarding cell membrane
[2012]
(A) Lipids are arranged in bilayer with
polar heads towards the inner
part
46
(B) Fluid mosaic model of cell
membrane was proposed by
singer and Nicolson
(C) Na+ and K+ ions move across cell
membrane by passive transport
(D) Proteins make up 60 to 70% of
the cell membrane
25. What is true about ribosomes
[2012]
(A) These are found only in eukaryotic cells
(B) These are self - splicing introns of
some RNAs.
(C) The prokaryotic ribosomes are 80
S, where ‘S’ stands for
sedimentation coefficient.
(D) There are composed of
ribonucleic acid and proteins
26. Which one of the following does not
differ in E.coli and Chlamydomonas
[2012]
(A) Cell wall
(B) Cell membrane
(C) Ribosomes
(D) Chromosomal Organization
27. Ribosomal RNA is actively synthesized
in [2012]
(A) Nucleoplasm (B) Ribosomes
(C) Lysosomes (D) Nucleolus
28. A major site for synthesis of lipids is:
[2013]
(A) RER
(B) SER
(C) Symplast
(D) Nucleoplasm
29. Which one of the following organelle
in the figure correctly matches with
its function? [2013]
(A) Rough endopolasmic reticulum,
formation of glycoproteins
(B) Golgi apparatus, protein synthesis
(C) Golgi apparatus, formation of
lipids
(D) Rough endoplasmic reticulum,
protein synthesis
30. Match the following and select the
correct answer [2014] A Centriole (i) lnfoldings in
mitochondria B Chlorophyll (ii) Thylakoids C Cristae (iii) Nucleic acids D Ribozymes (iv) Basal body
cilia or flagella
A B C D
(A) (iv) (ii) (i) (iii) (B) (i) (ii) (iv) (iii) (C) (i) (iii) (ii) (iv) (D) (iv) (iii) (i) (ii)
