CHAPTER 2 : CELL STRUCTURES AND FUNCTIONS
SUBTOPIC 2.1 : Cell as a Unit of Life
LEARNING OUTCOMES:
b) Describe how cells are grouped into tissues and organs.
MAIN IDEAS/
Karyon means nucleus
Prokaryotic cell has genetic material that is not enclosed by nuclear
membrane.
Explanation
• Not associate with histone protein.
• Not enclosed in a nucleus (lies freely in
cytoplasm).
information for certain activities of cell
Shape • Spherical (cocci)
• Made up of polysaccharide and protein
• Protect against immune system of host cell
Cell
and protect the cytoplasm
and embedded proteins
cell
of the bacterial cell
MAIN IDEAS/
• Enclosed by plasma membrane
numbers
other bacterial cell
pairs
pilus)
Flagellum
(sin.);
surface of the bacteria cell
• Mainly for locomotion / movement / motility
Ribosome • Tiny particle compose of RNA and protein
• Site of protein synthesis
• Site of cellular respiration
Structure of bacterial cell
MAIN IDEAS/
Eukaryotic
cells
Eukaryotic cell has genetic material that is enclosed by nuclear
membrane.
Explanation
about
contents from the cytoplasm)
Genetic material is linear DNA that is associated with histone
protein
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MAIN IDEAS/
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MAIN IDEAS/
1. Cells are the simplest unit of life.
2. Individual cells are specialized to perform specific functions that help
to maintain homeostasis and benefit the body as a whole.
3. Groups of cells that are similar in structure and perform a common or
related function are called tissues.
4. There are four basic types of tissue in the human body:
• Epithelial tissues
• Muscle tissues
• Nerve tissues
• Connective tissues
5. Two or more tissues that come together to form a specific function
for the body.
• For example stomach
Is lining by epithelium tissues that produce digestive juices.
The wall is made up by muscle tissues to churns and mixes
stomach contents.
the muscle to contract more vigorously.
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CHAPTER 2 : CELL STRUCTURES AND FUNCTIONS
SUBTOPIC 2.2 : Structures and functions: plasma membrane and organelles
LEARNING OUTCOMES:
a) Show the structures of typical plant and animal cells and state the organelles present.
b) Identify the structures and state the functions of the following organelles : nucleus, rough
endoplasmic reticulum, smooth endoplasmic reticulum, Golgi body, lysosome, ribosome,
mitochondria, chloroplast and centriole.
c) Show the structure of plasma membrane based on Fluid Mosaic Model.
d) Explain the structure of the plasma membrane and the functions of each of its components.
MAIN IDEAS/
KEY POINT
EXPLANATION NOTES
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MAIN IDEAS/
32 BIOLOGY STUDENT’S COMPANION RESOURCES [SES DB014]
MAIN IDEAS/
functions inside cell.
organelles
Membranous
organelles
Non-membranous
organelles
Nucleus
Chloroplast
Mitochondria
Double membrane nuclear
envelope enclose the
nucleoplasm which is
protein, RNA from
Rough
endoplasmic
Golgi
apparatus /
body
flattened membranous
and trans face
receive transport
other locations inside
MAIN IDEAS/
KEY POINT
EXPLANATION NOTES
Ribosome Not bounded by
membrane thus
increasing the
intermembrane space
Centriole In animal cells,
nucleus)
centrioles
triplet microtubules
The structure
of plasma
Fluid because phospholipids and proteins are able to move laterally /
side by side in the phospholipids bilayer
Mosaic because arrangement of different proteins partially or fully
embedded or attached to the phospholipids bilayer
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Two main components of plasma membrane are phospholipids and
proteins
hydrophobic and hydrophilic regions
- allow the cell membrane to be selectively permeable
- allow movement of lipid soluble molecules
- reduce loss of water from inside cell
Cholesterol are found in plasma membrane of animal cells between
the tails of phospholipids
Function of cholesterol is to regulate fluidity of membrane under the
influence of temperature
higher temperature
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MAIN IDEAS/
- intrinsic @ integral protein (either fully or partially embedded
in phospholipids bilayer)
bilayer)
Channel
protein
transport)
Has specific active site that binds with specific substrate during enzymatic reactions
Act as receptor that has
specific binding site for
MAIN IDEAS/
- as cell surface identity marker or involve in cell recognition
Carbohydrate chains attach to protein forming glycoprotein
(e.g. variation in carbohydrate chain of glycoproteins on the surface
of RBC contribute to the 4 human blood types A, B, AB and O)
Importance of membrane carbohydrates in cell-cell recognition :
- sorting of cells into tissues and organs in animal embryo
- basis for rejection of foreign @ non-self tissue by immune
system
containing carbohydrates on extracellular surface of plasma
membrane
- provide attachment site for cytoskeleton and extracellular matrix
Membrane proteins of neighboring cells are joined together forming tissue e.g. epithelial cells
Helps to maintain cell
shape and to stabilize
CHAPTER 2 : CELL STRUCTURES AND FUNCTIONS
SUBTOPIC 2.3 : Cells are grouped into tissues (animal tissues)
LEARNING OUTCOMES :
(a) Describe animal tissues.
(b) State the types, structures, functions and distributions of the following tissues: Epithelial tissues
(simple squamous, simple cuboidal, simple columnar), nerve tissues (motor neuron), muscle
tissues (smooth muscle), connective tissues (blood).
MAIN IDEAS/
Animal tissues
Animal tissues are composed of groups of cells with a similar appearance
and a common function.
Epithelial tissues
Nerve tissues
Muscle tissues
Connective tissues
A. Epithelial tissues
Classification is based on cell shape and number of cell layers.
Structures:
- Consists of cells arranged in continuous sheets, in single or multiple
layer.
- Has little intercellular space.
- Avascular (without blood vessels).
- Has a free surface.
- Has microvilli (such as in intestine) and cilia (in trachea).
Functions:
- Secretion
- Absorption
dehydration and friction.
- Line inner body cavity, tubes and blood vessels.
- Cover the thoracic and abdominal organ.
- Also found in gland.
MAIN IDEAS/
MAIN IDEAS/
Structures:
Neurons consist of:
Dendrite
-
sheath.
Myelin sheath
- Produce by Schwann cell.
electrical insulation.
- Example: Schwann cell
Structures :
Distribution:
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MAIN IDEAS/
Structures:
Having a sparse population of cells scattered through an extracellular matrix.
Consist of extracellular matrix (plasma) and cells
Plasma contain water, salts, dissolved proteins
Plasma also contain platelets and cells (leukocytes / white blood cells and
erythrocytes / red blood cells)
Erythrocytes / red blood cells
- Agranulocytes: Clear cytoplasm and nuclei not lobed
Functions:
pathogens
• Neutrophils and Monocytes:
Engulf foreign substances
from large cells in the bone
marrow
CHAPTER 2 : CELL STRUCTURES AND FUNCTIONS
SUBTOPIC 2.3 : Cells are grouped into tissues (plant tissues)
LEARNING OUTCOMES :
(a) Describe plants tissues.
(b) State the types, structures, functions and distributions of the following tissues: Apical meristem,
ground tissues (parenchyma, collenchyma, sclerenchyma), vascular tissues (xylem and phloem).
MAIN IDEAS/
Plants tissues
All three basic vascular plant organs – roots, stems and leaves are composed
of three fundamental tissue types : dermal, vascular and ground tissues.
Each of these general types forms a tissue system that is continuous
throughout the plant, connecting all the organs.
Types of plant tissues are dermal tissues, vascular tissues and ground
tissues. The dermal tissue system serves as the outer protective covering of
the plant. The main functions of the vascular tissue system are to facilitate
the transport of materials through the plant and to provide mechanical
support. Ground tissue system is not just the filler. It includes cells
specialized for functions such as storage, photosynthesis and support.
The types,
2. Ground tissue – parenchyma, collenchyma and sclerenchyma
3. Vascular tissue – xylem and phloem
1. Meristem tissues
Plants can keep growing because they have undifferentiated tissues called
meristems containing cells that can divide, leading to new cells.
Apical meristems provide cells that enable primary growth (growth in
length)
Structures:
- Have large nucleus
- Closely packed
- Cell actively divided
2. Produce primary plant body (in herbaceous / nonwoody plants)
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MAIN IDEAS/
2. Ground tissues
MAIN IDEAS/
Cell wall • Thin and
walls
• Lack of living
MAIN IDEAS/
Two types of vascular tissue :
- Xylem : composed of vessel elements and tracheid
- Phloem : composed of sieve tube and companion cell
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MAIN IDEAS/
another to form long pipes
- Dead cells with hollow lumen
- More water can flow with less
friction
Transport
mature
to another tracheid also
cells) joined together to form a
long tube.
- Cells are alive, with thin cellulose
walls and protoplasm.
with small vacuoles.
- Metabolically active (have
mitochondria and ribosomes).
numerous plasmodesmata.
Provide ATP
for active
MAIN IDEAS/
CHAPTER 2 : CELL STRUCTURES AND FUNCTIONS
SUBTOPIC 2.4 : Cell Transport
osmosis) and active transport (sodium-potassium pump)
MAIN IDEAS/
Transport
Across
Membrane
Process to move substances across the cell membrane (plasma membrane) are
essential to the life of the cell.
- Example: Gaseous exchange
Plasma membrane regulates the passage of molecules into and out of the cell.
- Enable a cell to control substances and how much of each enters or leaves
the cell
- It allows the cell to maintain a difference between its internal
environment and extracellular fluid.
- It supplies the cell with nutrients, removes wastes and maintains volume
and pH.
- Only allow some material to pass.
- Inhibits passage of other materials.
Passive
transport
From high concentration region
to low concentration region.
- Simple diffusion
- facilitated diffusion
bilayer to move across a plasma membrane.
Example of solutes/molecules are lipid soluble
molecule, oxygen, carbon dioxide.
MAIN IDEAS/
concentration.
Does not require energy/ ATP
Example of molecules are glucose, fructose, amino acids, some
vitamins, urea
Carrier protein:
molecules in or out of the cell
- example: glucose
Channel protein:
out of the cell
- example: sodium ion or
The movement / diffusion of water across a selectively permeable
membrane from area of high water potential to area of low water
potential until achieve equilibrium
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MAIN IDEAS/
Active
transport
The movement of molecules / ions from a region of low concentration to a
region of high concentration (against concentration gradient)
Require energy in the form of ATP
Require transport / carrier / pump protein
Example is sodium-potassium pump
Concentration of sodium ions (Na+) is higher outside cell; meanwhile
concentration of potassium (K+) ions is higher inside cell.
The protein pump has three binding sites for Na+ and two binding sites
for K+
Sodium- potassium pump transport THREE Na+ out of the cell and
TWO extracellular K+ into the cell.