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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Chapter 6
A Tour of the Cell
PowerPoint lectures are originally from Campbell / Reece Media Manager
and Instructor Resources for BIOLOGY, 7th & 8th Edition by N. A.
Campbell & J. B. Reece Copyright 2005 & 2008 Pearson Education,
Inc. Publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
In the Late 1600s.
• The English scientist
Robert Hooke first
observed plant cells
with a crude
microscope.
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Robert Hooke
• Observed thin slices of
cork
• Reminded him about
the cells of the monks
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In the 1830s
• All living things are
composed of cells.
Matthais Schleiden
Theodor Schwann
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In the 1800s
• The cells arise only
from other cells.
• All disease conditions
of the organism can
be attributed to
diseased changes of
the body cells.
Rudolf Virchow
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Overview: The Importance of Cells
• All organisms are made of cells
• The cell is the simplest collection of matter
that can live.
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The Cell Theory
• The cell is an organism’s basic unit of
structure and function.
• All cells come from preexisting cells.
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Cell Diversity
• The human body has:
– 50 to 100 trillion cells.
– Over 200 different
types of cells
• Types of cells differ in
size, shape, subcellular
components, and
functions
LE 6-2
Measurements
1 centimeter (cm) = 10–2 meter (m) = 0.4 inch
1 millimeter (mm) = 10–3 m
1 micrometer (µm) = 10–3 mm = 10–6 m
1 nanometer (nm) = 10–3 µm = 10–9 m
10 m
1 m
Human height
Length of some
nerve and
muscle cells
Chicken egg
0.1 m
1 cm
Frog egg
1 mm
100 µm
Most plant and
animal cells
10 µm Nucleus
1 µm
Most bacteria
Mitochondrion
Smallest bacteria
Viruses 100 nm
10 nm
Ribosomes
Proteins
Lipids
1 nm
Small molecules
Atoms 0.1 nm
Un
aid
ed
eye
Lig
ht m
icro
sco
pe
Ele
ctr
on
mic
rosco
pe
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Concept 6.1: To study cells, biologists use microscopes and the tools of biochemistry
• Though usually too small to be seen by the
unaided eye, cells can be complex
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Microscopy
• Scientists use microscopes to visualize cells too
small to see with the naked eye
• In a light microscope (LM), visible light passes
through a specimen and then through glass
lenses, which magnify the image
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The Path of Light in the Light Microscope
• http://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab2/IMAGES/BRIGHTFIELD
%20SCOPE%20DIAGRAM.JPG
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Microscopy
• The quality of an image depends on:
– Magnification, the ratio of an object’s image size to its real size
– Resolution, the measure of the clarity of the image, or the minimum distance of two distinguishable points
– Contrast, visible differences in parts of the sample
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Microscopy / Magnification
Magnification, the ratio of an object’s image size to its real size.
LMs can magnify effectively to about 1,000 times the size of the actual specimen
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Microscopy / Resolution
Resolution, the measure of the clarity of the image, or the minimum distance of two distinguishable points
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Microscopy / Resolution
• The minimum resolution of a LM is about 200 nanometers (nm), the size of a small bacterium.
• The practical resolution limit of the electron microscope is closer to about 2 nm
• Most subcellular structures, or organelles, are too small to be resolved by a LM
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Microscopy / Contrast
- Contrast, visible differences in parts of the sample
- Various techniques enhance contrast and enable
cell components to be stained or labeled
Brightfield (unstained
specimen)
50 µm
Brightfield (stained
specimen)
Phase-contrast Fluorescence
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Electron Microscopes
• Electrons are used instead of light.
• Two basic types of electron microscopes (EMs)
are used to study subcellular structures
1. Transmission electron microscopes (TEMs)
focus a beam of electrons through a specimen
• TEMs are used mainly to study the internal
ultrastructure of cells
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Transmission Electron Microscope (TEM)
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Scanning Electron Microscope (SEM)
2. Scanning electron microscopes (SEMs) focus a
beam of electrons onto the surface of a specimen,
providing images that look 3D
LE 6-4 1 µm
1 µm
Scanning electron microscopy (SEM) Cilia
Longitudinal section of cilium
Transmission electron microscopy (TEM)
Cross section of cilium
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Isolating Organelles by Cell Fractionation
• Cell fractionation takes cells apart and separates
the major organelles from one another
• Cell fractionation enables scientists to determine
the functions of organelles
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Pellet rich in nuclei and cellular debris
Pellet rich in mitochondria (and chloro- plasts if cells are from a plant)
Pellet rich in “microsomes” (pieces of plasma membranes and cells’ internal membranes)
Pellet rich in
ribosomes
150,000 g 3 hr
80,000 g 60 min
20,000 g 20 min
1000 g (1000 times the force of gravity)
10 min
Supernatant poured into next tube
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Concept 6.2: Eukaryotic cells have internal membranes that compartmentalize their functions
• Every organism has one of two types of cells:
– prokaryotic or
– eukaryotic
• Only organisms of the domains Bacteria and
Archaea consist of prokaryotic cells
• Protists, fungi, animals, and plants all consist of
eukaryotic cells
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Basic features of all cells
• All cells have the following features in common:
– Plasma membrane
– Cytoplasm
– Chromosomes (carry genes in the form of
DNA)
– Ribosomes (make proteins according to
instructions from the genes)
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Comparing Prokaryotic and Eukaryotic Cells
• Prokaryotic cells are characterized by having
– No nucleus
– DNA in an unbound region called the nucleoid
– No membrane-bound organelles
– Cytoplasm bound by the plasma membrane
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Prokaryotic Cells
Fimbriae
Nucleoid
Ribosomes
Plasma membrane
Cell wall
Capsule
Flagella
Bacterial chromosome
(a) A typical rod-shaped bacterium
(b) A thin section through the bacterium Bacillus coagulans (TEM)
0.5 µm
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Eukaryotic cells
• Eukaryotic cells are characterized by having
– DNA in a nucleus that is bounded
by a membranous nuclear envelope
– Membrane-bound organelles
– Cytoplasm in the region between the plasma
membrane and nucleus
• Eukaryotic cells are generally much larger than
prokaryotic cells
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Cytoplasm’s Components of Eukaryotic Cells
The cytoplasm consists of:
– Organelles
– Cytosol
Organelles:
• Specific entities, each carries out a specific function for the cell.
Cytosol:
• The viscous, semitransparent fluid in which other cytoplasmic elements are suspended.
• Largely water with dissolved protein, salts, sugars, and other solutes.
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Why Cells are Small?
• A smaller cell has a higher surface area to
volume ratio, which facilitates the exchange of
materials into and out of the cell.
• Larger organisms do NOT generally have
larger cells than smaller organisms – simply
more cells
LE 6-7
Total surface area
(height x width x
number of sides x
number of boxes)
6
125 125
150 750
1
1
1
5
1.2 6 6
Total volume
(height x width x length
X number of boxes)
Surface-to-volume
ratio
(surface area volume)
Surface area increases while
Total volume remains constant
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A Panoramic View of the Eukaryotic Cell
• Every cell is surrounded by a plasma
membrane.
• The plasma membrane is a selective barrier that
allows sufficient passage of oxygen, nutrients,
and waste to service the volume of the cell
• Eukaryotic cells have internal membranes that
partition the cell into organelles
• Plant and animal cells have most of the same
organelles
LE 6-9a
Flagellum
Centrosome
CYTOSKELETON
Microfilaments
Intermediate filaments
Microtubules
Peroxisome
Microvilli
ENDOPLASMIC RETICULUM (ER
Rough ER Smooth ER
Mitochondrion Lysosome
Golgi apparatus
Ribosomes:
Plasma membrane
Nuclear envelope
NUCLEUS
In animal cells but not plant cells: Lysosomes Centrioles Flagella (in some plant sperm)
Nucleolus
Chromatin
LE 6-9b
Rough endoplasmic reticulum
In plant cells but not animal cells: Chloroplasts Central vacuole and tonoplast Cell wall Plasmodesmata
Smooth endoplasmic reticulum
Ribosomes (small brown dots)
Central vacuole
Microfilaments
Intermediate filaments
Microtubules
CYTOSKELETON
Chloroplast
Plasmodesmata
Wall of adjacent cell
Cell wall
Nuclear envelope
Nucleolus
Chromatin
NUCLEUS
Centrosome
Golgi apparatus
Mitochondrion
Peroxisome
Plasma membrane
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Concept 6.3: The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes
• The nucleus contains most of the genes (DNA) in
a eukaryotic cell.
Functions of the nucleus:
1. The nucleus controls cellular activities by making
proteins.
2. In the nucleus, DNA replication takes place to
transmit information from parents to offspring.
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The Nucleus: Genetic Library of the Cell
The nucleus is made of
the following parts:
1. The nuclear envelope: a double
membrane with pores enclosing the
nucleus,.
2. The nucleolus: Where components
of ribosomes are synthesized and
assembled to form ribosomal
subunits.
3. The chromatin: the fibrous material
in the nucleus of a nondividing cell,
made of DNA and associated
proteins.
LE 6-10
Close-up of nuclear envelope
Nucleus
Nucleolus
Chromatin
Nuclear envelope:
Inner membrane
Outer membrane
Nuclear pore
Pore
complex
Ribosome
Pore complexes (TEM) Nuclear lamina (TEM)
1 µm
Rough ER
Nucleus
1 µm
0.25 µm
Surface of nuclear envelope
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Ribosomes: Protein Factories in the Cell
• Ribosomes are particles made of ribosomal RNA and
protein
• Ribosomes carry out protein synthesis in two locations:
– In the cytosol. Free ribosomes synthesize proteins
that function within the cytosol.
– On the outside of the endoplasmic reticulum (ER) or
the nuclear envelope. Bound ribosomes synthesize
proteins that:
a. Build membranes
b. Are to be exported from the cell.
LE 6-11
Ribosomes
0.5 µm
ER Cytosol
Endoplasmic
reticulum (ER)
Free ribosomes
Bound ribosomes
Large
subunit
Small
subunit
Diagram of
a ribosome
TEM showing ER
and ribosomes
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Concept 6.4: The endomembrane system regulates protein traffic and performs metabolic functions in the cell
• In the cell, the endomembrane system is the membranous components that are either in direct contact or connected via transfer by vesicles.
• These components make up the endomembrane system that includes the:
– Nuclear envelope
– Endoplasmic reticulum
– Golgi apparatus
– Lysosomes
– Vacuoles
– Plasma membrane
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The Endomembrane System
Nuclear envelope
Nucleus
Rough ER
Smooth ER
Transport vesicle
cis Golgi
trans Golgi
Plasma
membrane
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The Endoplasmic Reticulum: Biosynthetic Factory
• The endoplasmic reticulum (ER) accounts for
more than half of the total membrane in many
eukaryotic cells
• The ER membrane is continuous with the nuclear
envelope
• There are two distinct regions of ER:
– Smooth ER, which lacks ribosomes
– Rough ER, with ribosomes studding its surface
LE 6-12
Ribosomes
Smooth ER
Rough ER
ER lumen
Cisternae
Transport vesicle
Smooth ER Rough ER
Transitional ER
200 nm
Nuclear
envelope
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Functions of Smooth ER
• The smooth ER
– Synthesizes lipids
– Metabolizes carbohydrates
– Stores calcium ions necessary for muscle
contraction.
– Detoxifies poisons and drugs
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Functions of Rough ER
• The rough ER
– Has bound ribosomes
– Is a membrane factory for the cell
– Produces proteins that:
a.Build membranes
b.Are to be exported from the cell.
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• The Golgi apparatus consists of flattened
membranous sacs called cisternae
The Golgi Apparatus: Shipping and Receiving Center
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The Golgi Apparatus: Shipping and Receiving Center
• Functions of the Golgi apparatus:
– Modifies products of the ER
– Manufactures certain macromolecules,
including some polysaccharides.
– Sorts and packages materials into transport
vesicles
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.20
Protein- containing
vesicles pinch off rough ER
and migrate to fuse with
membranes of Golgi
apparatus.
Proteins are modified within
the Golgi compartments.
Proteins are then packaged within different vesicle types, depending on their ultimate
destination.
Plasma mem- brane
Secretion by exocytosis
Vesicle becomes lysosome
Golgi apparatus
Rough ER ER membrane
Phagosome
Proteins in cisterna
Pathway B:
Vesicle membrane to be incorporated
into plasma membrane Pathway A:
Vesicle contents destined for exocytosis Extracellular fluid
Secretory vesicle
Pathway C:
Lysosome containing acid hydrolase
enzymes
1
3
2
The Golgi Apparatus: Shipping and Receiving Center
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Lysosomes: Digestive Compartments
• Lysosomes are membranous sacs of hydrolytic enzymes
that digest macromolecules such as proteins, fats,
polysaccharides, and nucleic acids.
• Functions of lysosomes:
• Intracellular digestion: Lysosomes can fuse with food vacuoles containing food items brought into the cell by phagocytosis.
• Recycle cell’s own organic material: Lysosomes use enzymes to recycle organelles and macromolecules, a process called autophagy.
• Programmed cell destruction in multicellular organisms or apoptosis
LE 6-14a
Phagocytosis: lysosome digesting food
1 µm
Plasma
membrane
Food vacuole
Lysosome
Nucleus
Digestive
enzymes
Digestion
Lysosome
Lysosome contains active hydrolytic enzymes
Food vacuole fuses with lysosome
Hydrolytic enzymes digest food particles
LE 6-14b
Autophagy: lysosome breaking down damaged organelle
1 µm
Vesicle containing damaged mitochondrion
Mitochondrion fragment
Lysosome containing two damaged organelles
Digestion
Lysosome
Lysosome fuses with vesicle containing damaged organelle
Peroxisome fragment
Hydrolytic enzymes digest organelle components
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Vacuoles: Diverse Maintenance Compartments
• Vesicles and vacuoles (larger versions of vesicles) are membrane-bound sacs with varied functions
• A plant cell or fungal cell may have one or several
vacuoles
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Types of vacuoles in various cells:
• Food vacuoles are formed by phagocytosis
• Contractile vacuoles, found in many freshwater
protists, pump excess water out of cells
• Central vacuoles, found in many mature plant
cells. The membrane surrounding the central
vacuole is called the tonoplast.
LE 6-15
5 µm
Central vacuole
Cytosol
Tonoplast
Central
vacuole Nucleus
Cell wall
Chloroplast
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Functions of the Central Vacuole:
• Stockpiling proteins and inorganic ions.
• Storing pigments.
• Storing defensive compounds against
herbivores.
• Increasing the surface area to volume ratio for
the whole cell.
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The Endomembrane System: A Review
• The endomembrane system regulates protein
traffic and performs metabolic functions in the
cell
LE 6-16-1
Nuclear envelope
Nucleus
Rough ER
Smooth ER
The Endomembrane System: A Review
The endomembrane system:
- regulates protein traffic within the cell
- performs metabolic functions in the cell
LE 6-16-2
Nuclear envelope
Nucleus
Rough ER
Smooth ER
Transport vesicle
cis Golgi
trans Golgi
The Endomembrane System: A Review
LE 6-16-3
Nuclear envelope
Nucleus
Rough ER
Smooth ER
Transport vesicle
cis Golgi
trans Golgi
Plasma
membrane
The Endomembrane System: A Review
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Concept 6.5: Mitochondria and chloroplasts change energy from one form to another
• Mitochondria and chloroplasts are not part of the endomembrane system.
• Both organelles have:
1- Small quantities of DNA
2- Their own ribosomes
3- Double membranes.
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Mitochondria: Structure
• Mitochondria are in nearly all eukaryotic cells
• They have a smooth outer membrane and an inner membrane folded into cristae
• The inner membrane creates two compartments: intermembrane space and mitochondrial matrix
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Mitochondria: Make ATP
• Mitochondria are the sites of cellular respiration , generating energy for the cell in the form of ATP.
• Cristae present a large surface area for enzymes that synthesize ATP
LE 6-17
Mitochondrion
Intermembrane space
Outer
membrane
Inner
membrane
Cristae
Matrix
100 nm Mitochondrial
DNA
Free
ribosomes
in the
mitochondrial
matrix
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Chloroplasts: Capture of Light Energy
• Chloroplasts contain the green pigment
chlorophyll, as well as enzymes and other
molecules that function in photosynthesis.
• In photosynthesis, the plants make sugar by
using light energy, carbon dioxide and
water.
• Chloroplasts are found in the leaves and
other green organs of plants and in algae
LE 6-18
Chloroplast
Chloroplast
DNA
Ribosomes
Stroma
Inner and outer
membranes
Granum
Thylakoid 1 µm
Chloroplast structure includes:
-Thylakoid membranes:
membranous sacs that are stacked
in some regions like poker chips into
grana (singular is granum)
- Stroma, the internal fluid
surrounding the thylakoid
membanes.
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Peroxisomes
• Peroxisomes are specialized metabolic
compartments bounded by a single membrane
• Peroxisomes produce hydrogen peroxide and
convert it to water.
• Peroxisomes in the liver detoxify alcohol and other
harmful compounds.
Peroxisome
1 µm
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Concept 6.6: The cytoskeleton is a network of fibers that organizes structures and activities in the cell
• The cytoskeleton is a network of fibers extending
throughout the cytoplasm
• It helps to support the cell and maintain its shape
• It interacts with motor proteins to produce motility
• Inside the cell, vesicles can travel along “monorails” provided by the cytoskeleton
• It is composed of three types of molecular structures:
– Microtubules
– Microfilaments
– Intermediate filaments
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Microtubules
• Microtubules are the thickest of the three components of
the cytoskeleton
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Microtubules / Maintenance of Cell Shape
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Microtubules / Chromosome Movement in Cell Division
Vesicle
Receptor for
motor protein
Microtubule
of cytoskeleton
Motor protein
(ATP powered)
ATP
Microtubules / Organelle Movements
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Microtubules / Organelle Movements
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Microtubules in Cellular Structures
• The following cellular structures have
microtubules as a basic component:
– Centrioles
– Cilia and flagella
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Centrosomes and Centrioles
• In many cells, microtubules grow
out from a centrosome near the
nucleus
• The centrosome is a “microtubule-
organizing center”
• In animal cells, the centrosome has a pair of centrioles, each with nine triplets of microtubules arranged in a ring. Centrioles have (9 + 0) arrangement of microtubules.
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Centrosomes
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Microtubules / Centrioles
0.25 µm
Microtubule
Centrosome
Centrioles
Longitudinal section of one centriole
Microtubules Cross section of the other centriole
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Microtubules / Centrioles
Figure 3.25a
Centrosome matrix
(a)
Centrioles
Microtubules
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Microtubules / Cilia and Flagella
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Microtubules / Cilia and Flagella
Cilia and flagella are extensions of the plasma
membrane that share a common ultrastructure:
– A core of microtubules sheathed by the plasma
membrane. Cilia and flagella have (9 + 2)
arrangement of microtubules.
– A basal body that anchors the cilium or
flagellum with a (9 + 0) arrangement of
microtubules.
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Microtubules / Cilia and Flagella
0.5 µm
Microtubules
Plasma
membrane Basal body
Plasma
membrane
0.1 µm
Cross section of basal body
Triplet
Outer microtubule
doublet 0.1 µm
Dynein arms
Central
microtubule
Cross-linking
proteins inside
outer doublets
Radial
spoke
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.27
(a) Phases of ciliary motion.
(b) Traveling wave created by the activity of
many cilia acting together propels mucus
across cell surfaces.
Power, or propulsive, stroke
Layer of mucus
Cell surface
Recovery stroke, when cilium is returning to its initial position
1 2 3 4 5 6 7
Cilia and flagella differ in their beating patterns
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Components of the Cytoskeleton / Microfilament
• Microfilaments, also called actin filaments, are
the thinnest components
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Microfilaments (Actin Filaments)
Microfilaments are solid rods
built as a twisted double
chain of actin subunits
• The structural role of microfilaments is to bear tension, resisting pulling forces within the cell
• They form a 3D network just inside the plasma membrane to help support the cell’s shape
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Microfilaments in Microvilli
• Bundles of microfilaments make up the core of microvilli of intestinal cells
Microvillus
Actin
filaments
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Microfilaments / Changes in Cell Shape and Cell Motility (as in Pseudopodia)
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Microfilaments / Muscle Contraction
Muscle cell
Actin filament
Myosin filament
Myosin arm
Myosin motors in muscle cell contraction
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Microfilaments / Animal Cell Division (Cleavage Furrow Formation)
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Microfilaments / Cytoplasmic Streaming
http://www.youtube.com/watch?v=n841Ab2c83Q
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Intermediate Filaments
• Intermediate filaments are fibers with diameters
in a middle range between microtubules and
microfilaments.
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Intermediate Filaments / Anchorage of cell organelles
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Intermediate Filaments / Formation of Nuclear Lamina
Nuclear lamina (TEM)
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Label The Cellular Organelles and Structures
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Label The Cellular Organelles and Structures
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Concept 6.7: Extracellular components and connections between cells help coordinate cellular activities
• Most cells synthesize and secrete materials that
are external to the plasma membrane
• These extracellular structures include:
– Cell walls of plants
– The extracellular matrix (ECM) of animal cells
– Intercellular junctions
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Cell Walls of Plants
• The cell wall is an extracellular structure that
distinguishes plant cells from animal cells
• The cell wall:
– protects the plant cell
– maintains the plant cell shape
– prevents excessive uptake of water by the cell
• Plant cell walls are made of cellulose fibers
embedded in other polysaccharides and protein
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Cell Walls of Plants
• Plant cell walls may have multiple layers:
– Primary cell wall: relatively thin and flexible
– Middle lamella: thin layer between primary walls of adjacent cells
– Secondary cell wall (in some cells): added between the plasma membrane and the primary cell wall
LE 6-28
Central
vacuole
of cell
Plasma
membrane
Secondary
cell wall
Primary
cell wall
Middle
lamella
1 µm
Central
vacuole
of cell
Central vacuole
Cytosol
Plasma membrane
Plant cell walls
Plasmodesmata
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Intercellular Junctions in Plants
Plasmodesmata are channels between adjacent plant
cells
• Through plasmodesmata, water and small solutes (and
sometimes proteins and RNA) can pass from cell to cell
Interior
of cell
Interior
of cell
0.5 µm Plasmodesmata Plasma membranes
Cell walls
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The Extracellular Matrix (ECM) of Animal Cells
• Animal cells lack cell walls but are covered by an
elaborate extracellular matrix (ECM)
• The ECM is made up of glycoproteins and other
macromolecules
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Intercellular Junctions in Animals
• Neighboring cells in tissues, organs, or organ systems often adhere, interact, and communicate through direct physical contact
• Intercellular junctions facilitate this contact.
• Animals have 3 main types of intercellular junctions:
– Tight junctions.
– Desmosomes (anchoring junctions).
– Gap (Communicating) junctions.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.5a
Interlocking
junctional proteins
Intercellular
space
Plasma membranes
of adjacent cells
Microvilli
Intercellular
space
Basement membrane
(a) Tight junctions: Impermeable junctions prevent molecules
from passing through the intercellular space.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.5b
Intercellular space
Plasma membranes
of adjacent cells
Microvilli
Intercellular
space
Plaque
Linker glycoproteins
(cadherins)
Intermediate
filament (keratin)
(b) Desmosomes: Anchoring junctions bind adjacent cells together
and help form an internal tension-reducing network of fibers.
Basement membrane
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.5c
Plasma membranes
of adjacent cells Microvilli
Intercellular
space
Intercellular
space
Channel
between cells
(connexon)
(c) Gap junctions: Communicating junctions allow ions and small mole-
cules to pass from one cell to the next for intercellular communication.
Basement membrane
LE 6-31
Tight junctions prevent
fluid from moving
across a layer of cells
Tight junction
0.5 µm
1 µm
0.1 µm
Gap junction
Extracellular
matrix
Space
between
cells
Plasma membranes
of adjacent cells
Intermediate filaments
Tight junction
Desmosome
Gap junctions
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The Cell: A Living Unit Greater Than the Sum of Its Parts
• Cells rely on the integration of structures and
organelles in order to function
• For example, a macrophage’s ability to destroy
bacteria involves the whole cell, coordinating
components such as the cytoskeleton, lysosomes,
and plasma membrane
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
You should now be able to:
1. Distinguish between the following pairs of terms:
magnification and resolution; prokaryotic and
eukaryotic cell; free and bound ribosomes;
smooth and rough ER
2. Describe the structure and function of the
components of the endomembrane system
3. Briefly explain the role of mitochondria,
chloroplasts, and peroxisomes
4. Describe the functions of the cytoskeleton
5. Describe four different intercellular junctions