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BIO SCORE
CHAPTER 2 : CELL STRUCTURE AND FUNCTIONS
SUBTOPIC : 2.1 Prokaryotic and eukaryotic cells
LEARNING OUTCOMES: a) State the three principles of cell theory.
b) Explain the structures of prokaryotic and eukaryotic cells.
c) Illustrate and compare the structures of prokaryotic and eukaryotic cells (plant
and animal cells).
.
MAIN IDEAS/
KEY POINT EXPLANATION NOTES
a) State the
three principles
of cell theory.
▪ All living things are composed of cells (All organisms are composed of one
or more cells).
▪ Cells are the structural and functional unit of life.
▪ All cells come from pre-existing cells by division.
b) Explain the
structures of
prokaryotic
and eukaryotic
cells.
▪ Pro : before, early, primitive, first
▪ Karyon : nucleus
▪ Prokaryotic cell : Cell that has genetic material that is not enclosed by
nuclear membrane.
▪ e.g. of prokaryotic cell: bacteria
Explanation
about structure
of bacteria
(Circular) DNA • Is found in a single and coiled chromosome.
• Not associate with histone protein.
• Not enclosed in a nucleus (lies freely in cytoplasm).
• Located in a nucleoid region.
Plasmid • Small, double-stranded circular DNA
• Containing extra genes / provide genetic
informations for certain activities of cell
Shape • Spherical (cocci)
• Rod-shaped (bacilli)
• Spiral
Glycocalyx /
Capsule • Outside of / external to cell wall
• Made up of polysaccharide and protein
• Protect against immune system of host cell
Cell membrane • Membrane and other structures that surround and
protect the cytoplasm
• Main components are phospholipid bilayer and
embedded proteins
• Control the flow of materials into and out of cell
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MAIN IDEAS/
KEY POINT EXPLANATION NOTES
Explanation
about structure
of bacteria
Cell wall • Made up of peptidoglycan
• Provide structural support and maintain shape of the
bacterial cell
Cytoplasm • Semifluid (water-based) solution
• Composed of water and organic molecules
• Enclosed by plasma membrane
Fimbria (sin.);
Fimbriae (pl.) • Fine, hair-like bristles that present in multiple
numbers
• Help bacterial cell in adhesion to host cell or other
bacterial cell
Pilus (sin.);
Pili (pl.) • Bristle-like structures that present single or in pairs
• Longer than fimbria
• Help in adhesion to another bacterial cell during the
transfer of DNA (sex / conjugation pilus)
Flagellum (sin.);
Flagella (pl.) • Long fibers / structures that protrude from the
surface of the bacteria cell
• Mainly for locomotion / movement / motility
Ribosome • Tiny particle compose of RNA and protein
• Site of protein synthesis
Mesosome • Irregular fold in plasma membrane
• Site of cellular respiration
Structure of bacterial cell
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MAIN IDEAS/
KEY POINT EXPLANATION NOTES
Different shape of bacterial cell
Structure of flagella, fimbriae and pilus
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MAIN IDEAS/
KEY POINT EXPLANATION NOTES
Eukaryotic cells
▪ Eu : true
▪ Karyon : nucleus
▪ Eukaryotic cell : Cell that has genetic material that is enclosed by nuclear
membrane.
▪ E.g. of eukaryotic cell : animal cell, plant cell
Explanation
about structures
of eukaryotic
cells
▪ Have membrane-bounded nucleus
▪ Nuclear envelope / membrane enclose the nucleus (separating its contents
from the cytoplasm)
▪ Genetic material is linear DNA that is associated with histone protein
▪ Has membrane-bounded organelles
▪ There are two classes of organelles :
1) Endomembrane system : organelles that communicate with one another via
small vesicles or membrane channels
2) Energy related organelles such as mitochondria, chloroplasts
DNA associate with histone protein
Structure of an animal cell
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MAIN IDEAS/
KEY POINT EXPLANATION NOTES
Structure of a plant cell
c) Illustrate and
compare the
structures of
prokaryotic
and eukaryotic
cells (plant
and animal
cells).
Illustration of
prokaryotic cell
(e.g. bacterial
cell)
Structure of a prokaryotic cell
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MAIN IDEAS/
KEY POINT EXPLANATION NOTES
Illustration of
eukaryotic cells
Structure of eukaryotic cells
Comparison
between
prokaryotic and
eukaryotic cells
***Refer to similarities and differences
Similarities :
- Both cells are surrounded by plasma membrane
- Both cells have DNA as genetic material
- Both cells have cytoplasm, ribosome, smooth and rough ER, mitochondria,
nucleus, nucleolus
Plant cell
Animal cell
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MAIN IDEAS/
KEY POINT EXPLANATION NOTES
Comparison
between
prokaryotic and
eukaryotic cells
Differences between prokaryotic and eukaryotic cells
Features /
characteristics
Prokaryotic cells Eukaryotic cells
Cell division
Binary fission with no
spindle formation
By mitosis or meiosis or
both with spindle fiber
formation
Cell walls
Composed of
peptidoglycan
Animal cell has no cell wall,
plant cell has cellulose cell
wall and cell wall of fungi
composed of chitin
Membrane-
bounded
organelles
Absent in prokaryotic
cells Present in eukaryotic cells
Ribosome
Has small size (70S)
ribosome
Has large size (80S)
ribosome; Small size (70S)
ribosome present in
organelles
Genetic
materials
Circular DNA lies freely
in cytoplasm.
DNA not associate with
histone protein.
Linear DNA located in
double membrane-bounded
nucleus.
DNA associate with histone
protein.
Flagella
Simple flagella lack of
'9+2' microtubule
arrangement
Complex flagella with '9+2'
microtubule arrangement
Plasmid Present in some bacteria Absent in eukaryotic cell
Cellular
respiration
Site of cellular respiration
is mesosome
Site of cellular respiration is
mitochondrion
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BIO SCORE
CHAPTER 2 : CELL STRUCTURES AND FUNCTIONS
SUBTOPIC : 2.2 Structures and functions: Cell membrane and organelles
LEARNING OUTCOMES:
a) Show the detailed structures of typical plant and animal cells and state the organelles present.
b) Explain the structures and 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
a) Show the detailed
structures of
typical plant and
animal cells and
state the
organelles
present.
Detailed structures
of typical plant and
animal cells
Animal cells seen under light compound microscope
Plant cells seen under light compound microscope
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MAIN IDEAS/
KEY POINT EXPLANATION NOTES
Detailed structures
of typical plant and
animal cells
Animal cells seen under electron microscope
Plant cells seen under electron microscope
Organelles present in
plant and animal
cells
Organelles in animal cell
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MAIN IDEAS/
KEY POINT EXPLANATION NOTES
Organelles present in
plant and animal
cells
Organelles in plant cell
b) Explain the
structures and
functions of the
following
organelles :
nucleus, rough
endoplasmic
reticulum,
smooth
endoplasmic
reticulum, Golgi
body, lysosome,
ribosome,
mitochondria,
chloroplast and
centriole.
Organelle :
▪ Structures that suspended within cytosol and perform specific
functions inside cell.
▪ Can be divided into membranous organelles and non-membranous
organelles
Membranous
organelles
Non-membranous
organelles
Nucleus
Chloroplast
Mitochondria
Rough ER
Smooth ER
Golgi apparatus
Lysosome
Ribosome
Centriole
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Explanation on the
structures and
functions of
organelles
Organelles Structures Functions
Nucleus ▪ Spherical or oval in shape
▪ Double membrane nuclear
envelope enclose the nucleus
and separate it from cytoplasm.
▪ Has outer membrane that is
continuous with endoplasmic
reticulum and also has inner
membrane
▪ Inner part of nucleus is
nucleoplasm which is semifluid
medium containing chromatin,
nucleotides, mineral ions,
enzymes and nucleolus
▪ Surface of nuclear membrane
has nuclear pore that regulate the
entry and exit of molecules e.g.
protein, RNA from nucleus.
▪ Nucleolus is small dense
spherical body within nucleus
that consist of RNA and protein
• Store genetic
information /
genes of a cell :
contain
chromatins /
chromosomes
in nucleoplasm
• Control
production of
RNA and
proteins in cell
• Control all
activities of cell
by regulating
synthesis of
proteins and
enzymes
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Explanation on the
structures and
functions of
organelles
Rough
endoplasmic
reticulum (ER)
▪ Consist of network of
membranous flattened
sacs called cisternae
▪ Membrane of ER
separate the ER
lumen @ cavity /
cisternal space from
the cytosol
▪ Membrane of rough
ER is continuous with
the outer membrane
of nucleus
▪ There are ribosomes
on outer surface of
the rough ER
membrane
⚫ Synthesis secretory
proteins (e.g.
hormone)
- polypeptides
synthesized by
ribosomes are
transported to
ER lumen
- inside ER
lumen, the
polypeptides
are modified by
enzymes (add
carbohydrate
chain to the
protein
forming
glycoprotein)
⚫ Involve in
intracellular
transport of
proteins (the
glycoprotein is
packaged inside
transport vesicle and
the vesicle is carried
to Golgi body)
Smooth ER ▪ Consist of network of
membranous tubules
called cisternae
▪ Membrane of ER
separate the ER
lumen @ cavity /
cisternal space from
the cytosol
▪ Lack of ribosomes on
outer surface of the
smooth ER membrane
⚫ Site of lipid
synthesis
⚫ Breakdown of
stored glycogen to
glucose in liver
⚫ Store calcium ions
in sarcoplasmic
reticulum of skeletal
muscle
⚫ Detoxify drugs and
poison in liver
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Explanation on the
structures and
functions of
organelles
Golgi
apparatus /
body
▪ Consist of a group of
flattened membranous sacs
called cisternae
▪ Each cisterna has lumen
▪ Has two sides : cis face and
trans face
▪ Cis face is usually located
near the ER and receive
transport vesicles from ER
▪ Trans face bud off transport
vesicles containing specific
products to be carried to
other locations inside cell or
to plasma membrane for
secretion
▪ Modify,
packaging and
sorting of
protein
• Cis face
receive
transport
vesicles
from ER
• Products of
ER are
modified
during
their transit
from cis face
to trans face
of Golgi body
• Trans face
package the
modified
products in
transport
vesicles and
sort the
vesicles
to be
transported
out of Golgi
body
▪ Form lysosome
▪ Form
polysaccharide
s e.g. pectin in
Golgi body of
plant cells
which then
incorporated
with cellulose
into cell walls
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MAIN IDEAS/
KEY POINT
EXPLANATION NOTES
Explanation on the
structures and
functions of
organelles
Lysosome ▪ Spherical in shape
▪ Single-membrane
bounded organelle
▪ Produced by Golgi
apparatus
▪ Contains hydrolytic
enzymes
3) Involve in
intracellular food
digestion
(phagocytosis)
4) Involve in
autophagy
(digestion of old
@ worn out
organelles)
5) Involve in
autolysis
(digestion of old
@ damaged cells
results in apoptosis
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Ribosome ▪ Not bounded by
membrane
▪ Are complexes made of
ribosomal RNA (rRNA)
and protein
▪ Consist of two subunits
: large subunit and
small subunit
▪ Can be found as free
ribosomes (suspended
in cytosol) and bound
ribosomes (attach to
rough ER)
⚫ Site of protein
synthesis
- most of the
proteins made by
free
ribosomes function
within cytosol
- bound ribosomes
make proteins
that
are inserted into
membranes, for
packaging within
organelle e.g.
lysosome or
secretory proteins
Mitochondria ▪ Rod-shaped
▪ Double membrane-
bounded organelle :
- smooth outer
membrane
- highly folded inner
membrane forming
cristae
▪ Cristae is highly folded to
increase the surface area
of inner membrane thus
increasing the efficiency
of energy / ATP
production
▪ Intermembrane space is
the narrow region between
outer and inner
⚫ Site of cellular
respiration /
energy @ ATP
production
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membranes
▪ Mitochondrial matrix
containing enzymes, DNA
and ribosomes is enclosed
by the inner membrane
Chloroplast ▪ Double membrane-bounded
organelle
▪ Outer and inner membrane is
separated by very narrow
intermembrane space
▪ Inside chloroplast is another
membranous system in the form
of flattened, interconnected sacs
called thylakoids
▪ Stack of thylakoids are called
granum
▪ Thylakoid membrane contain
photosynthetic pigments e.g.
chlorophyll
▪ Fluid outside thylakoid is
stroma which contain enzymes,
DNA and ribosomes
▪ Site of photo-
synthesis
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MAIN IDEAS/
KEY POINT EXPLANATION NOTES
Explanation on the
structures and
functions of
organelles
Endomembrane System:
• Components of endomembrane system includes the nuclear envelope,
endoplasmic reticulum, Golgi apparatus, lysosome, various kinds of
vesicles, vacuoles and plasma membrane.
• The system carries out variety of tasks in the cell, including synthesis of
proteins, transport of proteins into membranes and organelles or
out of the cell, metabolism and movement of lipids and
detoxification of poisons.
• The membranes of this system are related either through direct physical
continuity or by formation of vesicles (membranous sacs).
Centriole ▪ In animal cells,
microtubules grow out
from centrosome (region
that is located near the
nucleus)
▪ Within the centrosome of
animal cells, is a pair of
centrioles
▪ Each centriole is
composed of nine sets of
triplet microtubules
arrange in a ring
⚫ May help
to organize
the spindle
fibre
during
mitosis and
meiosis in
animal
cells
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c) Show the
structure of
plasma
membrane based
on Fluid Mosaic
Model.
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d) Explain the
structure of plasma
membrane and
functions of each of
its components
▪ Fluid Mosaic model is proposed by Singer and Nicolson
▪ 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
▪ Two main components of plasma membrane are phospholipids and
proteins
▪ Phospholipids are amphipathic molecules that means have both
hydrophobic and hydrophilic regions
- hydrophilic head
- hydrophobic tail
▪ Importance of hydrophobic regions in plasma membrane :
- allow the cell membrane to be selectively permeable
- allow movement of lipid soluble molecules
- reduce loss of water from inside cell
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MAIN IDEAS/
KEY POINT EXPLANATION NOTES
Explanation on the
structure of plasma
membrane and
functions of each of
its components
▪ 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
- reducing fluidity of membrane / membrane less fluid at warm
/higher temperature
- membrane more fluid at lower temperature
▪ Two types of membrane proteins :
- intrinsic @ integral protein (either fully or partially embedded
in phospholipids bilayer)
- peripheral @ extrinsic protein (attach to phospholipids
bilayer)
▪ Functions of membrane proteins :
- as transport protein
- as enzymes
Channel
protein
Carrier protein
(for passive
transport)
Carrier protein
(for active
transport)
Has specific active site that binds with specific substrate during enzymatic reactions
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Explanation on the
structure of plasma
membrane and
functions of each of its
components
- involve in signal transduction / as cell surface receptor
- as intercellular joining / involve in cell adhesion
- as cell surface identity marker or involve in cell
recognition
- provide attachment site for cytoskeleton and
extracellular matrix
Act as receptor that has
specific binding site for
signaling molecule e.g.
hormone
Membrane proteins of neighboring cells are joined together forming tissue e.g. epithelial cells
Helps to maintain cell
shape and
to stabilize location of
certain membrane
proteins
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MAIN IDEAS/
KEY POINT EXPLANATION NOTES
Explanation on the
structure of plasma
membrane and
functions of each of
its components
▪ 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)
▪ Carbohydrate chains attach to lipid forming glycolipid
▪ 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 (e.g. MHC marker)
- enable cell recognize other cell by binding to molecules
containing carbohydrates on extracellular surface of plasma
membrane
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BIOLOGY SCORE
CHAPTER 2: CELL STRUCTURE AND FUNCTIONS SUBTOPIC : 2.3 Cells are grouped into tissues (animal tissues)
LEARNING OUTCOMES : (a) Describe the types of animal cells & tissues.
(b) Explain the following types of animal cells and tissues:
(i) Epithelial cells, nerve cell, muscle cells and connective tissue.
MAIN IDEAS/
KEY POINT EXPLANATION NOTES
a) Describe the
types of animal
cells & tissues.
▪ A group of similar cells and their intercellular substance joined together to
perform a specific function.
Four basic types according to their function and structure:
▪ Epithelial tissues
▪ Nervous tissues
▪ Muscle tissues
▪ Connective tissues
b) Explain the
types of animal
cells and
tissues:
A. Epithelial
tissues
▪ Characteristics:
- Consists of cells arranged in continuous sheets, in single or multiple layer.
- Closely packed and held tightly together by many cell junction.
- Has little intercellular space.
- Avascular (without blood vessels).
- Has a free surface.
- Has microvilli (intestine) and cilia (trachea).
- Rest on basement membrane.
- Covers a body surface (epidermis).
- Line inner body cavity, tubes and blood vessels.
- Cover the thoracic and abdominal organ.
- Also found in gland.
▪ General functions:
- Secretion
- Absorption
- Protect external and internal body surfaces from microbes, chemical,
dehydration and friction.
▪ Classification:
• Based on shape and number of cell layers.
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MAIN IDEAS/
KEY POINT EXPLANATION NOTES
Types of
Epithelium
Tissue
Types of Epithelial Tissue:
▪ Simple Squamous
▪ Simple Cuboidal
▪ Simple Columnar
▪ Stratified Squamous
Types Structure Distribution Function
Simple
squamous
• A single
layer of
flattened
cells with
disc-shaped.
• Central
nuclei.
• Air sacs of
lungs
• Glomerular
capsule of
Kidney
• Lines of heart
• Blood vessels
• Allow passage of materials
by diffusion and filtration
where protection is not
important.
Simple
cuboidal
• Single layer
of cube-
shaped
cells.
• Large &
spherical
central
nuclei.
• Thicker
than simple
squamous.
• Kidney tubule
• Ovary surface
& testes
• Ducts and
secretory
portions of
small gland
• Secretion of hormone or
saliva. (Salivary & Thyroid
gland.)
• Absorption (Reabsorption
of molecules by Proximal
Convoluted tubule in
kidney.)
Simple
columnar
• Single layer
of
rectangular/
tall cells.
• Nuclei
(round or
oval) near
base of
cells.
• Goblet cells
& cells with
microvilli &
cilia.
• Gallbladder
• Duct of gland
• Lines the
gastrointestinal
tract
• Uterine tube
• Bronchi.
• Secretion of enzymes,
mucus and other
substances.
• Ciliated type propels
mucus or reproductive cells
by ciliary action
• Absorbing nutrients.
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MAIN IDEAS/
KEY POINT EXPLANATION NOTES
Types Structure Distribution Function
Stratified
squamous
• Several
layers cells
&
regenerates
rapidly.
• Cuboidal to
columnar
shape in
deep layers.
• Squamous
cells form
the apical
layer.
• Outer skin
• Anus
• Vagina
• linings of the
mouth
• oesophagus.
• Protects underlying
tissues in areas subjected
to abrasion.
• New cells formed to
replace cell that are
sloughed off.
B. Nervous
tissues
▪ Made up of neuron and neuroglia (supporting cells).
▪ Neurons consist of:
- dendrite
- cell body
- axon
▪ Axon
- Single extension of cytoplasm.
- Function: conducts impulse away from the cell body.
▪ Dendrite
- Highly branched extensions.
- Function: conduct signals toward the cell body.
-
▪ Node of Ranvier
- Small uncovered parts of axon between the myelin
sheath.
- Function: Site for accelerating impulse transmission.
▪ Myelin sheath
- Layer of fatty material (surround the axons).
- Produce by Schwann cell.
- Function: Protects axons and provide
electrical insulation.
▪ Neuroglia
- Supports and nourish the neurons.
- Example: Schwann cell
▪ Distribution: Brain, spinal cord and nerves.
▪ Function: to transmit impulse.
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MAIN IDEAS/
KEY POINT EXPLANATION NOTES
C. Muscle
tissues
▪ Structures:
- Muscles are responsible for all types of body movement
- Composed of muscle fibers (cell)
▪ Types:
- Skeletal Muscle
- Smooth Muscle
- Cardiac Muscle
▪ Skeletal Muscle
- Consists of several bundles of muscle fibers (cell)
- Muscle fibers consist of myofibrils
- Most are attached by tendons to bone.
- Muscle Fibers (cell): Striated (banding), Cylindrical and long,
Multinucleate, Sarcolemma (plasma membrane)
- Myofibril: Bundle of myofilaments – Actin (Thin Filament) and Myosin
(Thick Filament)
▪ Smooth Muscle
- Lack striation
- Spindle-shaped cells
- Single nucleus
- Involuntary control
- Functions: Propel substances of objects (foodstuff) along internal
passageways
- Location: Wall of internal organs (digestive tract) or hollow organs
▪ Cardiac Muscle
- Has striations
- Single nucleus
- Branched and interconnected
- Joined to another muscle cell at an intercalated disc.
- Involuntary control
- Function: As it contracted, it propels blood into the circulation
- Location: the walls of heart
-
Skeletal Muscle Smooth Muscle Cardiac Muscle
Tubular shape Spindle shape Elongate shape
Striated Non-striated Striated
Multinucleated Uninucleated Uninucleated
No intercalated disc No intercalated disc Has intercalated disc
Voluntary control Involuntary control Involuntary control
No branch No branch Branched
Attached to tendons of
bone
Wall of digestive tract Wall of heart
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MAIN IDEAS/
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D. Connective
tissues
1. Compact
Bones
▪ Animal tissue that functions mainly to bind and support other tissues, having
a sparse population of cells scattered through an extracellular matrix.
▪ Functions:
- Provide support, strength and flexibility.
- Transport of material.
- Store energy.
- Defend body against pathogens.
▪ Compact Bones
- Consists of Haversian System or Osteon.
- Forms the external layer of all bones.
- Matrix:
- Hard and rigid with collagen fibres.
- Contains water and impregnated with calcium carbonate and calcium
phosphate.
- Each Havesian System consist of:
- Lamella: Irregular cylinder with layer of matrix.
- Havesian Canal: Contain artery, vein, lymph and nerve fibers.
- Lacunae: Contains osteocytes.
- Canaliculi: contain cytoplasmic strands.
- connect to lacunae to each other and to a central canal.
- transport material to and from blood vessels in the Havesian
Canal.
- Central canal/ Havesian Canal: serves as a passageway for blood
vessels and nerves.
- Volkman Canal: connect the Havesian canals to each other.
- Bones cell:
- Osteoblasts (Bone forming cell): Deposit a matrix of collagen.
- Osteocytes: Non-dividing and inactive bone cells.
- Osteoclasts: Reabsorb the matrix.
-
- Functions of compact bones:
- Skeleton give a body
shape and support.
- Protect internal
organs.
- Attached to
skeletal
muscles
for movement.
- Blood cell production
(bone marrow).
- Reservoir for
calcium
and phosphorus.
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MAIN IDEAS/
KEY POINT EXPLANATION NOTES
2. Hyaline
Cartilage
Structure of compact bone
Structure of hyaline cartilage
▪ Hyaline Cartilage
- Extracellular Matrix:
- Collagenous fiber embedded in chondroitin sulphate
- Hyaline Cartilage Cells:
- Chondroblast: immature cells
- Secrete matrix: chondroitin sulphate and collagen
- Chondrocytes: mature cells
- Maintaining the matrix
- Located in lacunae
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MAIN IDEAS/
KEY POINT EXPLANATION NOTES
3. Blood
- Distribution:
- Nose, ears and caps on the ends of some bones.
- Function of hyaline cartilage:
- Provides smooth surfaces for movement at joints, as well as flexibility
and support
- Supporting trachea and bronchial tube
- Acting as shock absorbers between vertebrates
▪ Blood
- Extracellular Matrix:
- Plasma (water, salts and dissolved proteins)
-
- Cells
- Erythrocytes
- Leukocytes
- Platelets
Erythrocytes: red blood cells
- Biconcave disc-shape
- Lack of nuclei
- Thinner in the center than at its edge
- Contain haemoglobin, enzyme and inorganic ions
- Function: Transport oxygen, carbon dioxide, nutrients and waste
Leukocytes: white blood cells
- Larger than erythrocytes
- Spherical in shape
- Have nucleus and organelles
- Two types:
- Granulocytes: Granular cytoplasm
and lobed nuclei
- Agranulocytes: Clear cytoplasm and
nuclei not lobed
- Function: Responsible for antibody
production and other specific defense against pathogens
- Lymphocyte B: Produce antibody
- Neutrophils and Monocytes: Engulf foreign substances
Platelets
- Fragments of cells broken off from large cells in the bone marrow
- No nuclei
- Function:
- Blood clotting
- Repair gaps in the wall of blood vessel
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Blood cells organization
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CHAPTER 2: CELL STRUCTURE AND FUNCTIONS SUBTOPIC : 2.3 Cells are grouped into tissues (plant tissues)
LEARNING OUTCOMES : (a) Describe the types of plants cells & tissues.
(b) Explain the following types of plants cells and tissues:
(ii) Meristem, Parenchyma, Collenchyma, Sclerenchyma, Xylem and Phloem.
MAIN IDEAS/
KEY POINT EXPLANATION NOTES
(a) Describe
the types of
plants cells &
tissues.
▪ Meristematic tissue
▪ Permanent tissue
- Ground tissue
- Vascular tissue
- Dermal tissue
(b) Explain the
following types
of plants cells
and tissues:
1. Meristem
tissues
▪ Meristem Tissue: Undifferentiated embryonic tissue in the active growth
regions of plants
▪ Location: Shoot tips and Root tips
▪ Structure:
- Cells are small and isodiametric
- Have large nucleus
- Have dense cytoplasm and few organelles
- Closely packed
- Have thin primary cell wall
- Cell actively divided
▪ Function: Differentiate to form specialized function
▪ Types and Function:
Types Function
Apical meristem
- Elongate shoots and roots.
- Produce primary plant body.
Lateral meristem
- Add thickness to woody plants (increase girth).
- Produce secondary plant body.
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Types of meristematic tissues
2. Ground
tissues
Types Parenchyma Collenchyma Sclerenchyma
Structure - shape: isodiametric
- thin primary wall
- thin and flexible
- contain cellulose,
hemicellulose and
pectin
- permeable to
water and permit
passage of solutes
- have large central
vacuole
- nucleus and
- shape: polygonal
- primary wall
- thicker than
parenchyma
- contain
cellulose,
hemicellulose
and pectin
- thickening occur
at the corners of
the walls
- pits are present in
- Dead at maturity
- Tough and thick
secondary cell
walls
impregnated
with lignin
- No intercellular
air spaces
- Pits are present in
the walls
- Lack living
protoplasts when
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cytoplasm pushed
to the periphery
- cell are loosely
packed together
- many large
intercellular air
space
- no secondary wall
- Perform most of
metabolic functions
of the plant
(photosynthesis)
- Synthesizing and
storing various
organic products
(starch and water)
- Intercellular air
spaces permit
gaseous exchange
the wall
they mature
- Various shape
and size
- Two types:
- Fiber
- Sclereids
- Structure of
Fiber:
- Long and
slender
- Group together
in strands
- Tapering ends
- Very tiny
cavity in the
center of the
cell
- Structure of
Sclereid:
- Shorter than
fiber
- Irregular in
shape
- Thick wall
- Lignified
secondary wall
Parenchyma Collenchyma Sclerenchyma
Distribution - Cortex of stem
- Cortex of roots
- Mesophyll
- Pulp of fruit
- Endosperm of
seed
- Outer regions of
cortex
- Below the
epidermis of
leaves, petioles
and soft stems of
dicot plant
- Leaf veins
- Young stem
Fiber:
- Below the
epidermis of
stem or roots
- Around
vascular bundle
Sclereid:
- Stem, leaves
and seeds
- Fruits (pears
and guava)
Function - Photosynthesis.
- Gaseous
Exchange and
buoyancy for
aquatic plants
(Intercellular air
spaces).
- Packing tissues
- Supporting tissue:
provide the
herbaceous plant
with mechanical
strength and
flexibility.
- Provide much of
support for stem
Fiber:
- Acts as
supporting
tissue.
Sclereid:
- Protective
tissue: gives
strength and
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(around vascular
tissues).
- Food storage
- Secretion (Sugary
nectar, hormones,
enzymes and
tannins).
in which
secondary
growth has not
taken place.
- Photosynthesis:
some
collenchyma
contain
chloroplast
support to the
plant structure
or organ.
3. Vascular
Tissue
▪ Involves in transport of materials around the plant body.
▪ Two types:
- Xylem: Vessel Elements and Tracheid
- Phloem: Sieve tube and Companion cell
Types Structure Function
Xylem
Vessel
element
- Secondary wall: lignin
- Ends open and connect to one
another to form long pipes
- Dead cells with hollow lumen
- More water can flow with less
friction
Transport water
and dissolved
minerals from
the roots to the
leaves
Tracheid
- Thick lignified
- Lumen: small and hollow when
mature
- Tapering end wall
- Lots of pits: allow water to move
to another tracheid also
surrounding living cells
Types Structure Function
Phloem
Sieve tube
- Consist of sieve elements (sieve
cells) joined together to form a
long tube.
- End walls are perforated forming
sieve plates with sieve pores.
- Cells are alive, with thin cellulose
walls and protoplasm.
Transport
organic material
(photosynthesis)
from one part of
the plant to
another.
Companion
cell
- Located beside the sieve tube.
- Have a nucleus, dense cytoplasm
with small vacuoles.
- Metabolically active (have
mitochondria and ribosomes).
- Linked to sieve elements by
numerous plasmodesmata.
Provide ATP for
active transport
during
transportation of
organic
material.
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Xylem
Vessel element Tracheid
Phloem
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CHAPTER 2: CELL STRUCTURE AND FUNCTION SUBTOPIC : 2.4 Cell Transport
LEARNING OUTCOMES : (a) Overview the various transport mechanisms across the membrane.
(b) Explain the various transport mechanism across the membrane
(i) Passive transport: Simple diffusion, facilitated diffusion and osmosis.
(ii) Active transport: Sodium-potassium pump and Bulk transport
(Endocytosis and Exocytosis)
MAIN IDEAS/
KEY POINT EXPLANATION NOTES
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.
▪ Plasma membrane is selectively permeable.
- Only allow some material to pass.
- Inhibits passage of other materials.
Passive
transport
▪ Diffusion of solute across membrane.
▪ From high concentration region to low concentration region.
▪ Does not require energy/ ATP.
▪ Down concentration gradient.
▪ Until equilibrium is achieved.
▪ 3 types:
- simple diffusion
- facilitated diffusion
- osmosis
Simple diffusion
▪ Diffusion of solute directly through phospholipid bilayer to move across a
plasma membrane.
▪ Example of solutes/molecules are lipid soluble molecule, oxygen gas, carbon
dioxide.
Facilitated
diffusion
▪ Carrier-assisted diffusion of molecules across a cell membrane through
specific channels from a region of higher concentration to lower
concentration.
▪ Help/aid by carrier protein and channel proteins
▪ The process is driven by concentration gradient
▪ Does not require energy/ ATP
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▪ Example of molecules are glucose, fructose, amino acids, some vitamins, urea
▪ Carrier protein:
- bind to molecule and change their shape to move specific molecules in or
out of the cell
- example: glucose
▪ Channel protein:
- have a tunnel that allow movement of ions or charge molecules to move
in or out of the cell
- example: sodium ion or chloride ion
Comparison
between
simple diffusion
and
facilitated
diffusion
Simple diffusion Facilitated diffusion
Through the phospholipid bilayer Through the transport protein (carrier
or channel protein)
Happens to the small and non-polar
particles
Happens to large and polar particles
Movement of molecules occur down the concentration gradient
Not require energy
Osmosis ▪ The movement / diffusion of water across a
selectively permeable membrane from area of higher water potential to area
of lower water potential.
▪ Water potential: ψ (psi)
▪ Water molecules move from hypotonic
solution to hypertonic solution until solution are isotonic.
Concept of
water potential
▪ Water potential is free energy / potential energy of water.
▪ The tendency of water molecules to enter or leave from the solution by
osmosis.
▪ Unit of water potential is kilopascal (kPa)
▪ Components of water potential:
- solute potential
- pressure potential
▪ Formula of water potential:
Ψ = Ψp + Ψs
Water potential = pressure potential + solute potential
▪ Solute potential:
- A measure of the change in water potential of the system due to the
presence of solute molecules.
- usually negative value.
▪ Pressure potential:
- The component of water potential due to the hydrostatic pressure that is
exerted on water in a cell.
- usually positive value.
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MAIN IDEAS/
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▪ What happen to animal cell and plant cell in different tonicity of solution?
Active transport ▪ The movement of molecules / ions from a region of lower concentration
region to a region of higher concentration region// against concentration
gradient
▪ Require energy in the form of ATP
▪ Require transport / carrier / pump protein
▪ Example is Sodium-potassium pump
Active transport
(Sodium-
potassium
pump)
▪ Concentration of sodium ions (Na+) is higher outside of the cell; meanwhile
concentration of potassium (K+) ions is higher inside of the cell.
▪ For each cycle, Sodium- potassium pump transport THREE intracellular Na+
out of the cell and TWO extracellular K+ into the cell.
▪ Involve phosphorylation; the addition of phosphate group; which cause the
changes in conformation of protein.
Mechanisms /
steps in sodium
potassium pump
▪ 3 intracellular Na+ bind to specific site on carrier / pump protein
▪ The binding stimulates phosphorylation of carrier protein by ATP
▪ The phosphorylation causes the protein to change its conformation
▪ Causing expel of Na+ to the outside of cell.
▪ 2 extracellular K+ bind to specific site on carrier protein
▪ The binding triggers release of phosphate group from carrier protein
▪ Loss of phosphate restore original conformation of carrier protein
▪ K+ is released into the cell
▪ The cycle is repeated.
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Sodium-Potassium Pump
Bulk transport
▪ Transport materials that are too large
▪ Materials are transported across membrane via vesicles
▪ Types:
1. Endocytosis: Cellular uptake of biological molecules and particulate
matter via formation of vesicles from the plasma membrane.
2. Exocytosis: The cellular secretion of biological molecules by the fusion
of vesicles containing them with the plasma membrane.
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Endocytosis:
▪ Types of Endocytosis: Phagocytosis and Pinocytosis
Phagocytosis Pinocytosis
Large solid particles, such as food ad
bacteria are brought inside the cell by
invagination (an infolding of the cell
membrane)
Liquids or dissolved materials are
taken in via a small vesicle
‘cell eating’ ‘cell drinking’
Uptake of large solid particle Uptake of small liquid droplet
Eg: Engulfing bacteria by the
macrophage
Eg: Taking in of dissolved solutes
by absorptive cells in kidney and
intestines
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