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Biology Notes
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:
CHAPTER 2:
CELL STRUCTURE & FUNCTIONS
(8 HRS)
2.0 Cell Structure & Functions (8 hrs)
2.1 Prokaryotic & Eukaryotic Cells ()
2.2 Structure and functions: cell membrane and
organelles (2)
2.3 Cells are grouped into tissues (3)
2.4 Cell Transport (2)
Learning outcomes
2.1 Prokaryotic & Eukaryotic Cells
a) State cell theory.
b) Describe the structures of prokaryotic & eukaryotic
cells.
c) Compare the structures of prokaryotic and eukaryotic
cells.
4
Robert Hooke observed cork sample
Composed of a lot of tiny, empty box structures ~ cell
Cell ~ basic unit of living things
What Is Cell?
Learning Outcomes : 2.1 (a) State cell theory
Cork tissue
5
Introduced by Schleiden (1838), Schwann (1839) & Rudolf Virchow (1855)
Their work ~ cell theory
Cell Theory
Learning Outcomes : 2.1 (a) State cell theory
1. Cell is the building block of structure in living things
2. New cells come from preexisting cells
Cells can divide to form new cells
All living things are made of 1 or more cells
6
Cell Theory
Learning Outcomes : 2.1 (a) State cell theory
3. Cells contain hereditary information (DNA) which
is passed from cell to cell during cell division
4. Cell is the functioning unit of life
Cell is the smallest unit that can conduct all activities of
life (metabolism)
Based on structural organisation
Types of Cell
Prokaryotic cell Eukaryotic cell
Types of Cell
Learning Outcomes : 2.1 (b) Describe the structures of prokaryotic & eukaryotic cells
8
Eg: bacteria, cyanobacteria (blue green algae)
Prokaryotic Cell
Main Features
Lack a membrane-bounded nucleus
Genetic material is not enclosed by a nuclear membrane
Lies freely in cytoplasm, in a region called nucleoid
Learning Outcomes : 2.1 (b) Describe the structures of prokaryotic & eukaryotic cells
9
Capsule
Cell Wall Plasma
membrane
Cytoplasm
Chromosomal DNA
Flagellum
Plasmid DNA
Pili
Structures of Prokaryotic Cell
Ribosome
Learning Outcomes : 2.1 (b) Describe & compare the structures of prokaryotic & eukaryotic cell
10
Structure Explanation
Chromosomal
DNA
Single, circular, double stranded DNA
Plasmid DNA
(if present)
Small, circular, double stranded extra DNA
Usually gives resistance to antibiotics in some bacteria
Flagella (if
present)
Long threadlike structure for locomotion
Pili Shorter & straighter than flagella (numerous)
Adhesion to surface or to each other
Capsule (if
present)
Gel-like layer outside cell wall
Adhesion to surface or to each other, provide protection
Structures of Prokaryotic Cell
Learning Outcomes : 2.1 (b) Describe the structures of prokaryotic & eukaryotic cells
11
Eg: protists, fungi, plants & animals
Eukaryotic Cell
Main Features
Has membrane-bounded nucleus
Genetic material is enclosed by a nuclear membrane
Has many membrane bounded organelles
Organelle is a small structure suspended in cytoplasm that conduct certain function
Learning Outcomes : 2.1 (b) Describe the structures of prokaryotic & eukaryotic cells
12
Structures of Eukaryotic Cell
Learning Outcomes : 2.1 (b) Describe the structures of prokaryotic & eukaryotic cells
13
Feature Prokaryotic Cells Eukaryotic Cells
Cell Size Smaller, diameter 1-10 m Larger, diameter 10-100 m
Nucleus No membrane-bounded
nucleus
Genetic material lies freely
in cytoplasm (nucleoid)
Has membrane-bounded
nucleus
Genetic material is enclosed
by nuclear membrane
Genetic
material
Circular DNA Linear DNA
DNA does not associate
with histone protein
DNA associates with histone
protein
Differences Between Prokaryotic & Eukaryotic Cell
Learning Outcomes : 2.1 (c) Compare the structures of prokaryotic & eukaryotic cells
Learning Outcomes : 2.1 (c) Compare the structures of prokaryotic & eukaryotic cells
Circular DNA Linear DNA
Learning Outcomes : 2.1 (c) Compare the structures of prokaryotic & eukaryotic cells
DNA associates with histone protein
16
Feature Prokaryotic Cells Eukaryotic Cells
Organelle No membrane bounded
organelle
Has many membrane-
bounded organelles
Ribosome Smaller, subunit 70S Larger, subunit 80S
Cell wall Composed mainly of
peptidoglycan & murein /
amino acids
Composed mainly of
cellulose (plant) & chitin
(fungi)
Structure of
flagella
Simple, lack of 9+2
microtubules
arrangement
Complex, has 9+2
microtubules arrangement
Differences Between Prokaryotic & Eukaryotic Cell
Learning Outcomes : 2.1 (c) Compare the structures of prokaryotic & eukaryotic cells
Structure of Flagella
Learning Outcomes : 2.1 (c) Compare the structures of prokaryotic & eukaryotic cells
Flagella 9+2 microtubules arrangement
18
Feature Prokaryotic Cells Eukaryotic Cells
Cell division Mitosis & meiosis does not
occur.
Mostly by binary fission
without spindle formation
By mitosis, meiosis or
both.
Spindle is formed
Type of
organism
Unicellular or filamentous
organisms
Unicellular, filamentous
or multicellular
organism
Differences Between Prokaryotic & Eukaryotic Cell
Learning Outcomes : 2.1 (c) Compare the structures of prokaryotic & eukaryotic cells
19
Both cells are bounded by a plasma membrane
Both cells contain genetic material
Both cells have cytoplasm
Both cells have ribosomes
Similarities Between Prokaryotic & Eukaryotic Cell
Learning Outcomes : 2.1 (c) Compare the structures of prokaryotic & eukaryotic cells
2.0 Cell Structure & Functions (8 hrs)
2.1 Prokaryotic & Eukaryotic Cells ()
2.2 Structure and functions: cell membrane and
organelles (2)
2.3 Cells are grouped into tissues (3)
2.4 Cell Transport (2)
Learning outcomes
2.2 Cell Membrane & Organelles
a) Illustrate the detailed structures of typical plant and animal
cells.
b) Describe the structure of the plasma membrane and the
functions of each of its components.
c) Describe the structure and functions of the following
organelles:
nucleus lysosome
rough endoplasmic reticulum ribosome
smooth endoplasmic reticulum mitochondria
Golgi body chloroplast
centriole
Based on structure, 2 types:-
Eukaryotic Cell
Animal cell Plant cell
Eukaryotic Cell
Learning Outcomes : 2.2 (a) Illustrate the detailed structures of typical plant & animal cells
Structure of Animal Cell (Electron Microscope)
Learning Outcomes : 2.2 (a) Illustrate the detailed structures of typical plant & animal cells
Structure of Plant Cell (Electron Microscope)
Learning Outcomes : 2.2 (a) Illustrate the detailed structures of typical plant & animal cells
Plant Cell (Light Microscope)
Learning Outcomes : 2.2 (a) Illustrate the detailed structures of typical plant & animal cells
Animal Cell (Light Microscope)
Learning Outcomes : 2.2 (a) Illustrate the detailed structures of typical plant & animal cells
Cell wall
Plasma membrane
Cytoplasm
Structures Seen Under Light Microscope
Chloroplast
Vacuole
Plasma membrane
Cytoplasm
Nucleus
Plant Cell Animal Cell
Nucleus
Learning Outcomes : 2.2 (a) Illustrate the detailed structures of typical plant & animal cells
Plasma membrane separates the living cell from its nonliving surroundings
Size ~ 7.5-8 nm thick
Plasma membrane that surround the cell & membrane that surround the organelles has the same structure
Structure of plasma membrane is proposed by Singer & Nicolson (1972) ~ Fluid-Mosaic model
Plasma Membrane
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
Globular protein Phospholipids Carbohydrate Cholesterol
Fluid Mosaic Model ~ Structure
Major Others
Components
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
Phospholipids
hydrophobic
tails
hydrophilic heads
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
Phospholipid bilayer (2 layers of phospholipids)
Phospholipid has 2 parts:
head ~ polar, hydrophilic region tail ~ non-polar, hydrophobic region
Phospholipids have both hydrophobic & hydrophilic regions
Amphipathic molecules
The polar, hydrophilic heads points outward into cytoplasm &
extracellular fluid (outside the cell)
The non-polar, hydrophobic tails face inwards (away from
water)
Creating a hydrophobic region in the middle
Phospholipids
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
Types of Protein
Integral / Intrinsic Peripheral / Extrinsic
Globular Protein
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
Phospholipid
bilayer
Extrinsic protein
Intrinsic protein
Globular Protein
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
Intrinsic protein ~ partially / fully embedded within the
phospholipid bilayer (firmly
bound)
Extrinsic proteins ~ attached loosely to the surface of
phospholipids or protein
Fully embedded protein that penetrates the entire phospholipid
bilayer transmembrane protein
Intrinsic protein amphipathic
Globular Protein
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
Embedded proteins within phospholipid bilayer
creates a mosaic pattern (when viewed from the above)
Why Mosaic Pattern?
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
Why Fluid?
Fluid ~ mosaic pattern is dynamic
Phospholipid & extrinsic proteins can move laterally along the membrane
Lateral movement
Time
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
Why Fluid?
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
Protein form glycoprotein
Phospholipid form glycolipids
Carbohydrate
Other Components ~ Carbohydrate
Location: on the outer surface of the membrane,
Carbohydrate chain may combine with:-
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
Function: act as identification tag (described later)
Other Components ~ Carbohydrate
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
Found between phospholipids molecules
Function: to regulate membrane fluidity by restricting the movement of phospholipids (stabilize membrane structure)
Cholesterol
Other Components ~ Cholesterol
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
1. Act as Transport Protein
6. Attachment site of cytoskeleton
& extracellular matrix
3. Act as Receptor Protein
2. Act as Enzyme
4. Intercellular Joining
5. Cell-cell Recognition
Roles of Cell Membrane Components
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
Hydrophilic
channel
Selective permeable
1. Act as Transport Protein
Transmembrane protein transport
molecules across membrane
Transport protein has hydrophilic
channels that allow polar
molecules / ion to pass through
Eg: channel protein, carrier
protein
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
Globular protein has active site which can bind to a specific substrate
Catalyze specific chemical reaction
A B C
2. Act as Enzyme
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
3. Act as Receptor Protein
Has a binding site with a specific shape for chemical messenger
Eg: hormone / neurotransmitter
Send information into the cell
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
4. Intercellular Joining
Membrane proteins of adjacent cell may join together
Eg: gap junction
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
Act as identification tag
Specifically recognized by other cells
Eg: antigen is recognized by human cells as foreign
GLYCOPROTEIN
5. Cell-cell Recognition
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
6. Attachment site of cytoskeleton & extracellular matrix
Outer surface ~ attach to extracellular matrix
Inner surface ~ attach to cytoskeleton
Maintain cell shape
Learning Outcomes : 2.2 (b) Describe the structure of the plasma membrane & the functions of each of its component
Learning outcomes
2.2 Cell Membrane & Organelles
a) Illustrate the detailed structures of typical plant and animal
cells.
b) Describe the structure of the plasma membrane and the
functions of each of its components.
c) Describe the structure and functions of the following
organelles:
nucleus lysosome
rough endoplasmic reticulum ribosome
smooth endoplasmic reticulum mitochondria
Golgi body chloroplast
centriole
Nucleus
Learning Outcomes : 2.2 (c) Describe the structures & functions of nucleus
Largest organelle
Spherical-shaped
Inner parts of nucleus contain nucleoplasm
Structure
Enclosed by 2 layers of nuclear membrane
Which fused at intervals to form nuclear pores
Nuclear pore regulate movement of molecules across
nuclear membrane
Nucleus
Structure
Learning Outcomes : 2.2 (c) Describe the structures & functions of nucleus
Nucleus
Learning Outcomes : 2.2 (c) Describe the structures & functions of nucleus
Outer membrane is continuous with
endoplasmic reticulum
(ER)
Structure
Nucleolus
Spherical-shaped Non-membranous Dense mass structures Contain DNA, RNA & proteins
Nucleoplasm
A jellylike fluid contain nucleolus & chromatin
Chromatin
Long thin strands of DNA & histone protein
Function (nucleolus)
Site of rRNA synthesis Combine protein with rRNA
to form ribosome (ribosome subunit assembly)
Nucleus
Learning Outcomes : 2.2 (c) Describe the structures & functions of nucleus
Nucleus
Function
Control cell activities & cell division
Store genetic material
Site of RNAs synthesis & ribosomes subunit assembly
Learning Outcomes : 2.2 (c) Describe the structures & functions of nucleus
Extensive network of membranous tubules ~
cisternae (interconnected)
Continuous with the outer nuclear membrane
Enclosed by a single membrane
Space within ER ~ cisternal space / lumen
Endoplasmic Reticulum (ER)
Structure
Learning Outcomes : 2.2 (c) Describe the structures & functions of endoplasmic reticulum
Consist of more tubular sacs
Lack of ribosomes on outer surface
~ appear smooth
Rough ER Smooth ER
Types of ER
Consist of flattened sacs
Has ribosomes; attached on the
outer surface ~ appear granular
Endoplasmic Reticulum
Learning Outcomes : 2.2 (c) Describe the structures & functions of endoplasmic reticulum
Rough Endoplasmic Reticulum
Function
Intracellular transport of protein (package & transport
protein to Golgi body within transport vesicle)
Learning Outcomes : 2.2 (c) Describe the structures & functions of endoplasmic reticulum
Smooth Endoplasmic Reticulum
Function
Site of lipid synthesis
Detoxification of toxic waste (drugs & poison)
Storage of calcium ions in skeletal muscle cells
Learning Outcomes : 2.2 (c) Describe the structures & functions of endoplasmic reticulum
Enclosed by a single membrane
Consist of stacked flattened membranous
sacs ~ cisternae
Golgi Body
Structure
Learning Outcomes : 2.2 (c) Describe the structures & functions of Golgi body
The sacs are not physically connected
Space within Golgi body ~ cisternal space / lumen
Each Golgi stack has cis face & trans face
Cis face is facing towards the ER /
nucleus
Trans face is facing towards the plasma
membrane
Golgi Body
Structure
Learning Outcomes : 2.2 (c) Describe the structures & functions of Golgi body
Golgi
body
Nucleus Rough
ER
Secretory
vesicle
Plasma
membrane
Glycoprotein
cis face
trans face
Golgi Body
Learning Outcomes : 2.2 (c) Describe the structures & functions of Golgi body
Secretory
vesicles
Transport
vesicles
ER pinches off to form transport vesicles
Which move towards Golgi body
It fuses with the cis-face
Contents (eg: protein/ carbohydrate/lipid) is released
into lumen
Golgi body modifies the substances as it moves from
cis-face to the trans-face
Golgi Body
Learning Outcomes : 2.2 (c) Describe the structures & functions of Golgi body
Secretory
vesicle
Transport
vesicle
The tips of trans-face cisternae
pinches off to form secretory
vesicles
Secretory vesicles may:-
Move towards plasma
membrane & fuse with it to
release substances by
exocytosis
Remain in the cell ~ become
lysosome
Golgi Body
Function
Process, modify,
sorting, package
& transport
protein
Form lysosomes
Learning Outcomes : 2.2 (c) Describe the structures & functions of Golgi body
Small, spherical-shaped
Enclosed by a special single membrane
Contain many hydrolytic/digestive enzymes
Lysosome
Structure
Learning Outcomes : 2.2 (c) Describe the structures & functions of lysosome
Lysosome
Intracellular digestion
Digest macromolecules which enter the cell by phagocytosis process
Recycle cells own organic material Digest old / damaged organelles to recycle organic
material by autophagy process
Programmed cell destruction
Digest the whole cell by autolysis process
Function
Learning Outcomes : 2.2 (c) Describe the structures & functions of lysosome
Plasma membrane engulfs large molecules & pinches off to form food vacuole / phagosome by phagocytosis process
Primary lysosome fuses with food vacuole secondary lysosome
Hydrolytic enzymes digest large molecules
Useful substances are absorbed into cytosol
1. Intracellular Digestion
Learning Outcomes : 2.2 (c) Describe the structures & functions of lysosome
1. Intracellular Digestion
Learning Outcomes : 2.2 (c) Describe the structures & functions of lysosome
Eg: Amoeba & macrophage (engulf bacteria & digest them for defense or protection)
Amoeba engulf red yeast for food Macrophage engulf bacteria for protection
Old or damaged organelle is enclosed by a single
membrane to form autophagic vacuole / autophagosome
Lysosome fuse with autophagic vacuole & digest the
organelle with hydrolytic enzymes by autophagy process
2. Recycle cells own organic material
Learning Outcomes : 2.2 (c) Describe the structures & functions of lysosome
3. Programmed Cell Destruction
In old / damaged cell, lysosome membrane ruptures
Hydrolytic enzymes are released into the cytoplasm
Digest the whole cell by autolysis process
Eg : destroy old / damaged cell
: destroy leukocyte that phagocytize pathogen
: during metamorphosis & development
Learning Outcomes : 2.2 (c) Describe the structures & functions of lysosome
Autolysis during human embryo development Autolysis in tadpole tails
Endomembrane System
The membrane of the organelles are related through
direct physical continuity or by transfer of membrane
segments as vesicles
Endomembrane system include:-
nuclear membrane
endoplasmic reticulum
Golgi body
lysosome
vesicle / vacuole
plasma membrane
Learning Outcomes : 2.2 (c) Describe the structures & functions of lysosome
Small granule
Spherical-shaped
Non-membranous
Made of rRNA & protein
Consist of 2 subunits (large & small)
Ribosome
Structure
Learning Outcomes : 2.2 (c) Describe the structures & functions of ribosome
attached to nuclear membrane or RER
synthesize proteins for export / cell
membrane / lysosome
Free ribosome Bound ribosome
Types of ribosome
lies freely in cytoplasm
synthesize proteins that function
in cytosol
Learning Outcomes : 2.2 (c) Describe the structures & functions of ribosome
Function
Site of protein synthesis
Act as enzyme (ribozyme) to catalyze the formation of peptide bond
Ribosome
Learning Outcomes : 2.2 (c) Describe the structures & functions of ribosome
Mitochondria
Structure
Learning Outcomes : 2.2(c) Describe the structures & functions of mitochondria
Shape ~ oblong / biconvex /
cylindrical
Enclosed by 2 layers of
membrane
Space between outer & inner
membrane ~ intermembrane
space
Outer membrane is smooth
& point towards cytoplasm
Mitochondria
Learning Outcomes : 2.2 (c) Describe the structures & functions of mitochondria
Inner membrane is folded inwards to form cristae
Cristae increase the surface area for attachment of
enzymes involved in Electron Transport Chain (ETC)
Structure
Mitochondria
Inner membrane enclosed a
fluid-filled space ~ matrix
Matrix contains :-
bacterial-like DNA &
ribosome to synthesize own
protein & enzymes
enzymes involved in Krebs
cycle
Structure
Learning Outcomes : 2.2 (c) Describe the structures & functions of mitochondria
Mitochondria
Site of ATP synthesis / cellular respiration
Krebs cycle occur in matrix
ETC occurs in cristae
Function
Learning Outcomes : 2.2 (c) Describe the structures & functions of mitochondria
Chloroplast
Learning Outcomes : 2.2 (c) Describe the structures & functions of chloroplast
Shape ~ oblong /
biconvex
Enclosed by 2 layers
of membrane
Space between
outer & inner
membrane ~
intermembrane
space
Structure
Outer membrane points towards cytoplasm
Inner membrane enclosed a fluid-filled space ~ stroma
Chloroplast
Learning Outcomes : 2.2 (c) Describe the structures & functions of chloroplast
Stroma contains :-
bacterial-like DNA & ribosome to synthesise own protein &
enzymes
enzymes involved in Calvin cycle
Structure
Chloroplast
Structure
Learning Outcomes : 2.2 (c) Describe the structures & functions of chloroplast
Grana are interconnected by intergrana membrane / lamella
Chlorophyll & photosynthetic pigments are embedded within
thylakoid membrane
Embedded within
stroma, are
membranous system
called thylakoids
Thylakoids ~ flat discs
which are stacked to
form grana
Chloroplast
Site of photosynthesis
Light dependent reaction occurs in grana /
thylakoid
Light independent reaction occurs in stroma
Store starch (in stroma)
Function
Learning Outcomes : 2.2 (c) Describe the structures & functions of chloroplast
Semiautonomous Organelle
Both mitochondria & chloroplast can duplicate &
reproduce independently within the cell
semiautonomous organelle
Learning Outcomes : 2.2 (c) Describe the structures & functions of organelle
Centriole
Exist in pair, orientated at
90 angle to another
Located in a region called
centrosome ~ near nucleus
of animal cell
Each centriole composed of
9 sets of triplet
microtubules, arranged in a
circle (9x3)
Structure
Learning Outcomes : 2.2 (c) Describe the structures & functions of centriole
Centriole
Function
Organize microtubules assembly during cell division
(microtubules organizing center ~ MTOC)
Form the bases of cilia & flagella
Learning Outcomes : 2.2 (c) Describe the structures & functions of centriole
2.0 Cell Structure & Functions (8 hrs)
2.1 Prokaryotic & Eukaryotic Cells ()
2.2 Structure and functions: cell membrane and
organelles (2)
2.3 Cells are grouped into tissues (3)
2.4 Cell Transport (2)
2.0 Cell Structure & Functions (8 hrs)
2.1 Prokaryotic & Eukaryotic Cells ()
2.2 Structure and functions: cell membrane and
organelles (2)
2.3 Cells are grouped into tissues (3)
Animal cells & tissues Plant cells & tissues
Epithelial cells Meristem
Nerve cells Parenchyma
Muscle cells Collenchyma
Connective tissues Sclerenchyma
Xylem & Phloem
2.4 Cell Transport (2)
Learning outcomes
2.3 Cells are grouped into tissues
Describe the following types of cells and tissues:
Animal cells & tissues
epithelial muscle
nerve connective
Plant cells & tissues
meristem sclerenchyma
parenchyma xylem
collenchyma phloem
Muscle Tissue
Most abundant tissue
Cytoplasm contain many :
mitochondria
glycogen
myoglobin
myofilament (actin & myosin) ~
specialised for contraction
Main function ~ movement
Learning Outcomes : 2.3 Describe the structures, function and distribution of muscle cells
Muscle Tissue
Types of Muscle Tissue
Skeletal / Striated Cardiac Smooth
Plasma membrane ~ sarcolemma
Cytoplasm ~ sarcoplasm
Endoplasmic reticulum ~ sarcoplasmic reticulum
Modified Terms
Learning Outcomes : 2.3 Describe the structures, function and distribution of muscle cells
Muscle Tissue
Learning Outcomes : 2.3 Describe the structures, function and distribution of muscle cells
(a) Skeletal muscle
Spindle-shaped, elongated, pointed ends
Unbranched fibre, cells are arranged in parallel
Uninucleated, centrally located
No striations (no sarcomere)
Smooth Muscle
Structure
Learning Outcomes : 2.3 Describe the structures, function and distribution of muscle cells ~ smooth muscle
Smooth Muscle
Action
Type of control : involuntary / autonomic
Speed of contraction : slowest
Resistance to fatigue : greatest (do not tired easily)
Learning Outcomes : 2.3 Describe the structures, function and distribution of muscle cells ~ smooth muscle
Walls of digestive tract (alimentary canal) / urinary bladder / uterus / urinogenital tract / respiratory tract / blood vessel
(endothelium)
Smooth Muscle
Location
Learning Outcomes : 2.3 Describe the structures, function and distribution of muscle cells ~ smooth muscle
Cylindrical-shaped, very long, blunt ends
Unbranched fibre
Multinucleated, peripherally located (beneath sarcolemma)
Obvious striations (has sarcomere)
Extensive sarcoplasmic reticulum
Skeletal Muscle
Structure
Learning Outcomes : 2.3 Describe the structures, function and distribution of muscle cells ~ skeletal muscle
Skeletal Muscle
Learning Outcomes : 2.3 Describe the structures, function and distribution of muscle cells ~ skeletal muscle
Skeletal Muscle
Striations ~ repeating series of light bands (I band) & dark
bands (A band)
Due to arrangement of myofilaments
Thin filament (mainly actin)
Thick filament (mainly myosin)
Learning Outcomes : 2.3 Describe the structures, function and distribution of muscle cells ~ skeletal muscle
Skeletal Muscle
Action
Type of control : voluntary / somatic
Speed of contraction : fastest
Resistant to fatigue : least (easily tired)
Location
Attached to the skeleton / bones by tendon
Learning Outcomes : 2.3 Describe the structures, function and distribution of muscle cells ~ skeletal muscle
Cardiac Muscle
Structure
Learning Outcomes : 2.3 Describe the structures, function and distribution of muscle cells ~ cardiac muscle
Cylindrical-shaped, elongated, blunt ends
Branched fibre
Joined together from end to end at intercalated disc
Uni / binucleated, centrally located
Striated
Cardiac Muscle
Location
Walls of heart (for contraction of heart)
Action
Type of control : involuntary / autonomic
Speed of contraction : intermediate
Resistant to fatigue : intermediate
Learning Outcomes : 2.3 Describe the structures, function and distribution of muscle cells ~ cardiac muscle
Cardiac Muscle
Intercalated disc has gap junction
Speed up impulse transmission throughout heart muscle
Contract as a single unit
Heart muscle is myogenic (can initiate own impulse for
contraction without the help of Central Nervous System)
Learning Outcomes : 2.3 Describe the structures, function and distribution of muscle cells ~ cardiac muscle
Features Smooth
muscle
Skeletal muscle Cardiac
muscle
Shape Spindle-shaped,
elongated,
pointed ends
Cylindrical-
shaped,
elongated, blunt
ends
Cylindrical-
shaped,
elongated, blunt
ends
Branching Unbranched fibre Unbranched fibre Branched fibre,
fused together
Number of
nucleus per
cell
One
(Uninucleated)
Many nucleus
(multinucleated)
One or two
Location of
nucleus
Central Peripheral Central
Striations Absent Present Present
Differences of Muscle Cells
Learning Outcomes : 2.3 Describe the structures, function and distribution of muscle cells
Features Smooth
muscle
Skeletal muscle Cardiac
muscle
Type of
control
Involuntary Voluntary Involuntary
Speed of
contraction
Slowest Most rapid Intermediate
(varies)
Resistance
to fatigue
Greatest Least Intermediate
Location
Wall of digestive
tract
Attached to the
bone / skeletal
Wall of heart
Differences of Muscle Cells
Learning Outcomes : 2.3 Describe the structures, function and distribution of muscle cells
Three types of connective tissues are:
Connective Tissue
Hyaline Cartilage
Blood
Compact Bone
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues
Composition
Matrix Fiber
Connective Tissue
Cell
Non-living substance
around cells
Provide support
(eg: collagen, elastin)
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues
All connective tissue has 3 features in common:-
Composition
Matrix Fiber
Compact Bone
Cell
Hard calcified matrix Collagen Osteocyte
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues -compact bone
105
Compact Bone ~ Structure
Bone cell ~ osteocyte
Has many tiny cytoplasmic extension ~ canaliculi
Osteocytes are found in a cavity ~ lacunae
Osteocytes are arranged in circles
They are interconnected by canaliculi which enable the transfer of nutrients & wastes from one osteocytes to another
They secrete hard matrix composed of collagen fiber & inorganic mineral salts (mainly calcium) / hydroxyapatites
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues-compact bone
canaliculi lacuna
osteocyte
106
Compact Bone ~ Structure
Matrix are arranged in a circular tube ~ lamella
Several layers of lamella are found around the same central Haversian canal
These structure is called osteon / Haversian system ~ structural unit of bone
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues-compact bone
lamella lamella
osteon Haversian canal
Haversian canal contains nerve, blood & lymph vessel
Haversian canals are interconnected by Volkmanns canal
A unit of bone is covered by periosteum membrane
Compact Bone ~ Structure
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues-compact bone
Blood vessel
Periosteum
membrane
Volkmanns canal
108
Compact Bone ~ Function
Cellular level (osteocyte) ~ secrete hard matrix & maintain the bone matrix
Tissue level
Hard bone matrix gives basic shape to the body
Provide a hard framework that support the body
Protect soft internal organs in vertebrates
Storage of calcium / mineral salt
Site of blood cell synthesis within the bone marrow
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues-compact bone
Composition
Matrix Fiber
Hyaline Cartilage
Cell
Soft & elastic matrix
(chondrin) Collagen Chondrocyte
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues-hyaline cartilage
110
Hyaline Cartilage ~ Structure
Protected by an outer perichondrium layer
Which produces chondrocyte
Chondrocyte near the outer layer are flattened in shape but the inner region are angular
Chondrocyte are found in lacunae
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues-hyaline cartilage
111
Hyaline Cartilage ~ Structure
Each lacuna contain 1, 2 or 4 chondrocytes
Chondrocyte secretes soft & elastic matrix ~ chondrin
Composed of chondroitin sulphate & collagen
No blood vessel within matrix (O2 & nutrients diffuse from perichondrium through the matrix)
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues-hyaline cartilage
112
Hyaline Cartilage ~ Function
Cellular level (chondrocyte)
Secrete chondrin
Tissue level
Tough & flexible support
Cushioning properties
Location
Tip of nose, trachea, larynx
End of long bones
Function
Connect the ribs to sternum
Inter-vertebral disc
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues-hyaline cartilage
Composition
Matrix Fiber
Blood
Cell
The only fluid tissue containing blood cells suspended in plasma
Erythrocyte Plasma Collagen Leukocyte Platelet
~45% ~55%
Blood
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues -blood
Erythrocyte
Biconcave shaped ~ increase surface area
Thin at the center, thicker at the edge
No nucleus & organelles at maturity
Contain hemoglobin (respiratory pigment)
Function
Transport O2 & CO2
(respiratory gases)
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues - blood
Structure
Leukocyte
Have nucleus & organelles (the only true cell)
Spherical or irregular shaped
Larger than erythrocyte
Function
Defense against disease
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues -blood
Structure
Blood Cell
Leukocyte Platelet
Granulocyte Agranulocyte
Neutrophil Eosinophil Basophil
Types of Leukocyte
Erythrocyte
Lymphocyte Monocyte
most abundant
Lack granule
Nucleus round
Many granules
Nucleus multi-lobed
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues -blood
118
Neutrophil
Nucleus : multi-lobed (3-6 lobes)
Granule : very small
Function : phagocytize microorganisms / dead cells
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues -blood
119
Eosinophil
Nucleus : bi-lobed (2 lobes)
Granule : large size
Function : reduce the effect of allergy reactions
: attack parasitic worms
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues -blood
120
Basophil
Nucleus : U or S-shaped lobed (2 or 3-lobed)
Granule : many large granule
Function : release histamine (inflammatory substance)
: contain heparin (anticoagulant ~ prevent blood clotting)
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues -blood
121
Lymphocyte
Nucleus : large, spherical-shaped
Location : mostly in lymphoid tissue
Types : 2 (B & T-lymphocyte)
Function : specific defense mechanism / immune response
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues -blood
122
Monocyte
Largest leukocyte
Nucleus : U or kidney-shaped
It can differentiates into active macrophage
Function : phagocytize microorganisms / pathogen
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues -blood
123
Platelets
Cytoplasmic fragments of a large cell, megakaryocyte
No nucleus & organelle
Function : promotes blood clotting
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues -blood
Matrix ~ Plasma
Consist mainly of water, inorganic mineral salts & dissolved protein
& small amount of collagen
Learning Outcomes : 2.3 Describe the structures, function and distribution of connective tissues-blood
Learning outcomes
2.3 Cells are grouped into tissues
Describe the following types of cells and tissues:
Animal cells & tissues
epithelial muscle
nerve connective
Plant cells & tissues
meristem sclerenchyma
parenchyma xylem
collenchyma phloem
Classification
Number of cell layers Cell shape
Simple Stratified Squamous Cuboidal Columnar
Epithelial Tissue
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ epithelial
127
Epithelial Tissue
Stratified epithelium Simple epithelium
1 layer of cells More than 1 layer of cells
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ epithelial
128
Epithelial Tissue
Lower layer of cells
attached to the basement membrane
Uppermost layer
free surface (face lumen/cavity)
Basement
membrane
Free surface
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ epithelial
129
Cell Shape
Cuboidal
Squamous
Columnar
Cells : thin, flat
Nucleus : disc-shaped, central
Cells : cube-shaped
Nucleus : spherical-shaped, central
Cells : elongated, column-shaped
Nucleus : oval-shaped, close to the cell base
Large cytoplasm
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ epithelial
130
1. Simple Squamous Epithelium
Single layer of flat cells
With disc-shaped central nuclei
Location
Structure
Function
Alveoli of lungs
Lining of blood vessel (endothelium)
Glomerulus & Bowman capsule (in kidney)
Facilitate diffusion & filtration of
substances (very thin & permeable)
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ epithelial
1. Simple Squamous Epithelium
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ epithelial
132
2. Simple Cuboidal Epithelium
Single layer of cube cells
With spherical-shaped central nuclei
Location
Structure
Function
Lining of kidney tubules
Small glands
Ovary surface
Facilitate absorption & secretion
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ epithelial
133
3. Simple Columnar Epithelium
Single layer of columnar cells
With oval-nuclei located near to the base
Location
Structure
Function
Lining of digestive tract, gallbladder &
some glands
Facilitate absorption & secretion
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ epithelial
134
Special Structures of Epithelium ~ Microvilli
Microvilli ~ small finger-like projections due to the folding of plasma
membrane
Function:
Increase surface area for absorption
May present in:-
Simple cuboidal epithelial
Location: kidney tubules
Function: to absorb useful substances before excreted out in urine
Simple columnar epithelial
Location: digestive tract lining
Function: to absorb nutrients before excreted out in feces
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ epithelial
Special Structures of Epithelium ~ Cilia
Cilia ~ small & short hairlike structure
Beating of cilia create motion to move materials
Eg: Simple ciliated columnar epithelial
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ epithelial
Location: fallopian tubes or
oviduct, uterine tubes
Function: to move fertilized egg
from oviduct to the uterus
Location: lining of bronchi
Function: to remove mucus dust
trapped within mucus in
respiratory tract
Goblet Cells
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ epithelial
Goblet cells is cup-shaped cells
Location: digestive tract & respiratory tract
Function: secrete mucus to lubricate movement of digested material &
to trap dust & particles which enter respiratory tract
137
Only lower layer is metabolically active
Divide & push older cells upward
Replace uppermost older cells
More durable
Common in high abrasion areas
Function ~ protection
Eg: skin surface
Stratified Epithelium
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ epithelial
138
4. Stratified Squamous Epithelium
Thick ~ composed of many layers of
cells & uppermost layer is flat squamous
cells
Location
Structure
Function
Skin (keratinized), mouth, esophagus & vaginal lining
Protection from mechanical injury or invading
microorganisms, prevent excessive water loss (keratinized)
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ epithelial
139
Nerve Cell (Neuron) ~ Structure
Neuron is the nerve cell that generate & conduct nerve impulses
Enable communications between the body & brain to response to stimulus
Cell body
Dendrites
Axon
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ nerve cell
All neurons have 3 things in common:-
140
Large nucleus
Have organelles (except centriole), numerous mitochondria
Extensive rough endoplasmic reticulum (Nissl granules)
Dendrites ~ short highly-branched cytoplasm arise from the cell body
Function ~ receive message from other cells & carry the message to the cell body
Cell body
Dendrites
Motor Neuron ~ Structure
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ nerve cell
141
Long cytoplasmic branch arising from the cell body
Site where axon joins the cell body ~ axon hillock
Axon
Motor Neuron ~ Structure
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ nerve cell
Axon endings (synaptic knob) send signals from the neuron to other cells by releasing neurotransmitters
Function ~ carry impulse away from cell body
At certain parts of the axon, some neurons are enclosed in a myelin sheath myelinated neuron
142
Myelin sheath is formed by Schwann cell
Roll around axon
Form overlapping layers of membranes (myelin sheath)
Outermost membrane of Schwann cell ~ neurilemma
Composed of lipid & protein
Myelin sheath act as electrical insulator to speed up impulse transmission
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ nerve cell
Motor Neuron ~ Structure
Adjacent Schwann cells do not touch one another create gaps (axon is not completely covered by myelin sheath)
Small, uncovered part of axon between the Schwann cells ~ nodes of Ranvier
Nerve impulse jump from node to node along the axon
Speed up impulse transmission along the axon
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ nerve cell
Motor Neuron ~ Structure
144
Motor Neuron
Function
Transmit impulse from central nervous system to effector or motor organs, eg: muscle & glands
Learning Outcomes : 2.3 Describe the structure, function & distribution of animal tissues ~ nerve cell
Location
Most cell bodies of motor neuron is found within CNS & few in ganglion & its axon is found throughout the motor organs
Learning outcomes
2.3 Cells are grouped into tissues
Describe the following types of cells and tissues:
Animal cells & tissues
epithelial muscle
nerve connective
Plant cells & tissues
meristem sclerenchyma
parenchyma xylem
collenchyma phloem
In multicellular organisms, most cells differentiates in structure specialised cells
New structure is suitable to carry out specific function
A group of cells which are similar in structure & conduct specific function tissue
What is Tissue ?
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ meristem
Meristem
PLANT TISSUE
Permanent
Dermal Vascular
i. Parenchyma
ii. Collenchyma
iii. sclerenchyma
Ground
Types of Plant Tissue
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ meristem
i. Epidermis
ii. Periderm
i. Xylem
ii. Phloem
i. Apical
ii. Lateral
Young cells Actively dividing cells Unspecialized
Types: Apical meristem Lateral meristem
Meristem Tissue
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ meristem
Small
Isodiametric / cube
Thin primary cell wall
Large, central nucleus
Dense cytoplasm
Small vacuoles
Closely packed / no intercellular air spaces
Meristem ~ Structure
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ meristem
Types of
meristem
Location
Function
Apical Shoot tips & root tips Increase the length of stems
& roots (primary growth)
Lateral Cylinders around the
stem & root (cambium)
Increase the diameter of
stems & roots (secondary
growth)
Meristem ~ Distribution & Function
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ meristem
Functions :
Retain the ability to divide continuously by mitosis to produce new cells
For growth, reproduction & replacement of old, damaged cells
Permanent Plant Tissue
Mature & specialised cells
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ dermal
Outermost layer of cells @ surface of plant body
Dermal Tissue
Distribution
Tightly packed forming a protective layer on the surface
Structure
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ dermal
Function
Defense against :-
mechanical damaged, pathogenic organisms / disease & water loss
Least specialised cells Living cells at maturity (maintain cytoplasm) Carry out most of the metabolic functions of plant
Parenchyma Tissue
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ parenchyma
Parenchyma Tissue ~ Structure
Has nucleus (living cells)
Isodiametric/spherical-shaped
Thin & flexible primary cell wall, consist of cellulose,
hemicellulose & pectin
Large central vacuole
Cells are loosely packed/ large intercellular air spaces
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ parenchyma
Store food / organic substances (large vacuole)
Carry out photosynthesis for cells containing chloroplast (eg: mesophyll cells)
Allow gaseous exchange as there are large intercellular spaces
In flowers & fruits, cell contain chromoplast to attract pollinating agents & help in dispersal of fruits & seeds
Parenchyma Tissue ~ Function
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ parenchyma
In dicot stem :-
Cortex
Pith
Scattered within vascular bundle
Parenchyma Tissue ~ Distribution
Dicotyledon stem
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ parenchyma
Tissue Modified Parenchyma
Mesophyll Endodermis Pericycle
Cell
shape
Palisade
mesophyll ~
column-shaped
Spongy mesophyll
~ spherical /
irregular-shaped
Flat & elongated
(deposited with
suberin)
As
parenchyma
Distribu-
tion
Between upper &
lower epidermis of
leaves
Around vascular
tissue of root
(innermost layer
of root cortex)
Between
vascular tissue
& endodermis
of root
Modified Parenchyma
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ parenchyma
Modified Parenchyma
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ parenchyma
Mesophyll Endodermis & pericycle
Collenchyma ~ Structure
Has nucleus (living cells)
Polygonal-shaped, elongated with tapered ends
Cell walls are unevenly thickened at their corners with deposits of cellulose, hemicellulose & pectin
Pits are present in the cell walls
Cells are closely packed / less intercellular space
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ collenchyma
As supporting tissue to herbaceous plants / young parts of the plant
Gives flexible mechanical support (allow cells to expand & stretched as young stems grow)
Collenchyma ~ Function
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ collenchyma
1. Below the epidermis of
herbaceous plants
Collenchyma ~ Distribution
2. Midrib of leaves
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ collenchyma
3. Leaf petioles / stalk of leaves (eg: celery)
Sclerenchyma ~ Structure
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ sclerenchyma
No nucleus at maturity (dead cells)
Has primary & secondary cell walls
Secondary cell wall is evenly thickened with lignin
Small lumen
Pits are present in cell walls
Cells are tightly packed / no intercellular space
Function:
Gives support to the tissue
Gives mechanical strength & rigidity to the plant
Protect from mechanical damage
Sclerenchyma ~ Function & Distribution
Distribution:
Leaf veins / vascular bundle
Wood, inner bark
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ sclerenchyma
Structure:
Polygonal-shaped Elongated with tapered ends Which overlap & interlock with
one another (increase strength)
Fewer pits than sclereids Eg: jute fibers for making rope
Sclerenchyma ~ Fibers
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ sclerenchyma
Structure:
Irregular-shaped
Shorter than fibers
Unevenly thickened with lignin
Pits maybe branched or not
Cells with unbranched pits ~ stone cells
Eg: in pears (cause gritty texture)
Distribution:
Hard shells of seeds & nuts in fruits
Sclerenchyma ~ Sclereids
Cherry pit
Pear stone cells
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ sclerenchyma
Complex tissue
Consist of 4 tissues ~ tracheid, vessel, fiber & parenchyma
Dead at functional maturity
Xylem
Structure:
No nucleus (dead cells) at maturity
Elongated, thin
Tapered ends which overlap & interlock with one another
Small empty lumen
Thick lignified secondary wall
Have pits in cell walls
Which allow water to flow from 1 tracheid to the other
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ xylem
No nucleus (dead cells) at maturity
Shorter & wider than tracheid
Tubular / less tapered than tracheid
Wide empty lumen
Thick lignified secondary wall
Both ends are highly perforated / open
Cells are stacked from end to end to form a continuous hollow tube
Pits are present to allow lateral movements of water
Vessels ~ Structure
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ xylem
Young mature vessel
Xylem ~ Vessels
i. Annular / ring
ii. Spiral / helix
iii. Scalariform
iv. Reticulate
v. Pitted
Uneven deposition of lignin creates different pattern in vessel:-
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ xylem
Function
Transport water & minerals from root to other parts of plant
Give mechanical support (lignified vessels & tracheid can resist compression & tension)
Distribution
Vascular bundle
Xylem ~ Function & Distribution
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ xylem
Complex tissue
Consist of 4 tissues ~ sieve tube cell, companion cell, fiber & parenchyma
Phloem
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ phloem
Living cells at maturity
But nucleus & most organelles degenerate
Thin layer of cytoplasm remains at the periphery of the cell
Has only primary cell wall (no lignin)
Long cylindrical structure
End walls are perforated forming sieve plate
Sieve plate has pores which allows cytoplasm to extend between sieve tube cells
Sieve tube cell are stacked end to end to form a long sieve tube
Phloem ~ Sieve tube cells structure
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ phloem
A modified parenchyma which is found next to sieve tube cell
Metabolically active
Phloem ~ Companion cell structure
Structure:
Have nucleus (living cells) at maturity
Dense cytoplasm
Small vacuoles
Many mitochondria & ribosomes
Thin primary cell wall
Interconnected to sieve tube cell by numerous plasmodesmata
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ phloem
Function
Transport organic substance from leaves to other parts of plant
Companion cell helps sieve tube elements to transport organic substances
Distribution
Vascular bundle
Phloem ~ Function & Distribution
Learning Outcomes : 2.3 Describe the structure, function & distribution of plant tissues ~ phloem
2.0 Cell Structure & Functions (8 hrs)
2.1 Prokaryotic & Eukaryotic Cells ()
2.2 Structure and functions: cell membrane and
organelles (2)
2.3 Cells are grouped into tissues (3)
2.4 Cell Transport (2)
2.4 Cell Transport
Explain the various transport mechanisms across the membrane
Passive transport - Simple diffusion - Facilitated diffusion - Osmosis
Active transport - Sodium potassium pump - Bulk Transport (endocytosis & exocytosis)
Learning outcomes
Types of Transport Across Membrane
Passive Transport
Endocytosis Exocytosis
Simple Diffusion
Facilitated Diffusion
Osmosis
Active Transport
Na-K Pump
Phagocytosis Pinocytosis
Learning Outcomes : 2.4 Explain the various transport mechanisms across the membrane
Bulk Transport
Characteristic of Cell Membrane
Cell membrane is selectively permeable
Allow some substances to pass through
But does not allow other substances to pass through
Cell membrane is permeable to lipid soluble molecule & small non-polar substance due to its hydrophobic region of phospholipid bilayer
Impermeable to polar molecules & ions
Enable cell to retain polar molecules & ions within the cell (mostly are important for the cell)
Learning Outcomes : 2.4 Explain passive transport across membrane
Passive Transport
Movement of a substance from higher concentration to lower concentration gradient
Or movement of a substance down a
concentration gradient
Across a selective permeable membrane
Without using energy
Learning Outcomes : 2.4 Explain passive transport across membrane
Simple Diffusion
(extracellular fluid)
(cytoplasm)
Some molecules diffuse freely across
phospholipid bilayer
Movement of a substance from higher concentration to lower concentration gradient across phospholipid bilayer
Without using energy
Without the help of transport protein
Learning Outcomes : 2.4 Explain passive transport across membrane ~ simple diffusion
Simple Diffusion
Molecules that can diffuse easily across phospholipid bilayer:-
Lipid soluble molecules (eg: cholesterol, steroid)
Small, non-polar/uncharged molecules (O2, CO2)
Small, polar molecules (eg: H2O, glycerol)
Learning Outcomes : 2.4 Explain passive transport across membrane ~ simple diffusion
Simple Diffusion
Although water are polar, they are small enough to pass through the space between the fluid fatty acids as they move
Rate of diffusion increase when:-
Temperature increase
Molecules involved is in gas state rather than liquid
Size of molecules reduce (faster for smaller molecules)
Large differences in concentration gradient between inside & outside the cell
Learning Outcomes : 2.4 Explain passive transport across membrane ~ simple diffusion
Simple Diffusion ~ Importance
Enable atoms & small molecules diffuse faster across membrane
Eg: O2, CO2 as respiratory gases, important in ATP synthesis
Eg: H2O, important to facilitate chemical reaction
Enable lipid soluble molecules to diffuse freely
Eg: steroid hormone (testosterone) for homeostatic regulation
Learning Outcomes : 2.4 Explain passive transport across membrane ~ simple diffusion
Facilitated Diffusion
Movement of a substance from higher concentration to lower concentration gradient across plasma membrane
With the help of transport protein
Without using energy
Involve ions & polar molecules (eg: Na+, Cl-, glucose, amino acids)
Learning Outcomes : 2.4 Explain passive transport across membrane ~ facilitated diffusion
Facilitated Diffusion
Learning Outcomes : 2.4 Explain passive transport across membrane ~ facilitated diffusion
1. Channel protein
2. Carrier protein
Transport protein:- 2 main types
Facilitated Diffusion ~ Importance
Transport ions & polar molecules or water soluble molecules across membrane
Eg: water, ions (Na+, Cl-), sugars (glucose) & amino acids
Learning Outcomes : 2.4 Explain passive transport across membrane ~ facilitated diffusion
Osmosis
Movement of water molecules
From higher water potential to lower water potential region
Across a selective permeable membrane
Without using energy
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
Water Potential
Definition:
Tendency of water molecules to move from 1 area to another area
Symbol ~
Pure water has the highest water potential, = 0 kPa
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
Solute Potential
A measure of the change in water potential of a solution due to the presence of solute molecules
When solute molecules is dissolved in pure water, it reduces its water potential, becoming negative (-ve)
Symbol, s (always has ve value)
A solution with less solute than the other has higher water potential
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
189
Types of Solution
Hypertonic
Hypotonic
Low concentration of solute relative to another solution
High concentration of solute relative to another solution
Isotonic
Same concentration of solute relative to another solution
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
Osmosis
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
Less solute More solute
Net movement of water molecules
Pressure applied to piston to resist upward movement
Water plus solute
Pure water
Water molecule
Molecule of solute
Selectively permeable membrane
When water diffuse into the plant cell, it enters vacuole
Vacuole enlarge & creates a pressure towards cytoplasm & cell wall turgor pressure
Also called as pressure potential, p
p always has +ve value
The point at which plasmolysis is just about to happen incipient plasmolysis, p = 0
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
192
Water potential inside & outside the cell is equal
Water moves into & out of the cell at the same rate by osmosis
Animal / plant cell does not change its shape
When a cell is put into an isotonic solution
No net movement of water into or out of the cell
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
193
The cell has higher water potential than outside the cell
Water moves out from the cell by osmosis
Animal cell becomes crenated / shrink
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
When a cell is put into a hypertonic solution
194
When a cell is put into a hypertonic solution
In plant cell, water moves out from vacuole vacuole shrinks
Plasma membrane detached & pulled away from the cell wall
Plant cell becomes plasmolysed / flaccid
The starting point of plasmolysis ~ incipient plasmolysis
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
Plasma membrane
Vacuole
Vacuolar membrane (tonoplast)
Cytoplasm Plasma membrane
Vacuole Nucleus
(a) (b) (c)
Turgid Plasmolyzed Plasmolyzed
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
196
Water potential outside the cell is higher than in the cell
Water from outside moves into the cell by osmosis
Plant cell becomes turgid
When a cell is put in a hypotonic solution
Animal cell swell (if too much water moves in, it may lysed / burst)
If erythrocyte burst ~ haemolysis
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
Outside cell
Outside cell
Outside cell
Inside cell
Inside cell
Inside cell
No net water movement
Net water movement out of the cell
Net water movement into the cell
Isotonic solution Hypertonic solution Hypotonic solution
(a)
(b)
(c)
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
198
Calculation of Water Potential in Plant Cell
Water potential = solute potential + pressure potential
Which cell has higher water potential?
A ~ = -200 kPa
B ~ = -400 kPa
C ~ = -500 kPa
D ~ = -600 kPa
= s + p
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
Cell A Cell B
s = -8 MPa p = 3 MPa
= -10 Mpa s = -10 Mpa
= ? p = ? -5 MPa 0 MPa
Example 1
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
Cell A
Sucrose solution, s = -1000 kPa
s = -500 kPa p = 200 kPa
Calculate the water potential of this cell.
State whether water will move in or out of the cell. Explain.
What happen to the volume of the cell?
= s + p = -500 + 200 kPa = -300 kPa
Water moves out from the cell by osmosis
Because cell A has higher water potential than surrounding solution
Decrease
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
Example 2
Cell A
Cell B
s = -2200 kPa p = 1000 kPa
s = -1600 kPa p = 800 kPa
Calculate the water potential of cell A & cell B
Example 3 (a)
Cell A, = s + s
= -2200 + 1000 kPa
= -1200 kPa
Cell B, = s + s
= -1600 + 800 kPa
= -800 kPa
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
Cell A
Cell B
s = -2200 kPa p = 1000 kPa
s = -1600 kPa p = 800 kPa
Exercise 3 (b)
State the direction of water flow between the 2 cells. Give reason.
Cell A, = -1200 kPa
Cell B, = -800 kPa
Water flows from cell B to cell A
Because cell B has higher water potential than cell A
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
Cell A
Cell B
s = -2200 kPa p = 1000 kPa
s = -1600 kPa p = 800 kPa
Exercise 3 (c)
Calculate the final values of water potential & pressure potential after equilibrium is reached. Assume that no changes occurs to s
Cell A, = -1200 kPa
Cell B, = -800 kPa
For cell A, at equilibrium,
= s + p
P = - s
= -1000 (-2200) kPa
= -1000 + 2200 kPa
= 1200 kPa
At equilibrium, A = B = cell A + cell B
= -1200 + (-800) kPa
= -1000 kPa
2
2
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
Cell A
Cell B
s = -2200 kPa p = 1000 kPa
s = -1600 kPa p = 800 kPa
Exercise 3 (c)
Calculate the final values of water potential & pressure potential after equilibrium is reached. Assume that no changes occurs to s
Cell A, = -1200 kPa
Cell B, = -800 kPa
At equilibrium, A = B = cell A + cell B
= -1200 + (-800) kPa
= -1000 kPa
2
2
Learning Outcomes : 2.4 Explain passive transport across membrane ~ osmosis
For cell B, at equilibrium,
= s + p
P = - s
= -1000 (-1600) kPa
= -1000 + 1600 kPa
= 600 kPa
Active Transport
Movement of a substances against concentration gradient or from lower concentration to higher concentration gradient
Across a selective permeable membrane
Which needs energy
Involve transport protein
Learning Outcomes : 2.4 Explain active transport across membrane ~ Na-K Pump
Endocytosis Exocytosis
Active Transport
Na-K Pump
Allow cell to maintain useful nutrients in the cell against concentration gradient
Na-K Pump
Outside the cell : [Na+] , [K+]
Inside the cell : [Na+] , [K+]
3 Na+ in the cell binds to a specific site of transport protein
The binding of Na+ stimulates the hydrolysis of ATP (in the cell) into ADP (adenosine diphosphate) + Pi (inorganic phosphate)
Pi binds to transport protein (phosphorylation) & change its conformation
Causes it to pump 3 Na+ to the outside
Increasing its concentration outside the cell
Learning Outcomes : 2.4 Explain active transport across membrane ~ Na-K Pump
Na-K Pump
Learning Outcomes : 2.4 Explain active transport across membrane ~ Na-K Pump
Na-K Pump
2 K+ outside the cell binds to a specific site of transport protein
Stimulates the release of phosphate group from the transport protein (dephosphorylation)
Causes transport protein to restore its original conformation
2 K+ is pumped into the cell
Increasing its concentration inside the cell
Na-K pump is important for transmission of nerve impulses
Learning Outcomes : 2.4 Explain active transport across membrane ~ Na-K Pump
Endocytosis
A process in which bulk substances are taken into the cell
Requires energy
Involves invagination (folding) of cell membrane (cannot occur in plant cell due to the presence of cell wall)
2 types of endocytosis:
Learning Outcomes : 2.4 Explain active transport across membrane ~ bulk transport (endocytosis)
Endocytosis
Phagocytosis Pinocytosis
Phagocytosis
A process in which large, solid particles is taken into the cell
Presence of large particles causes the cell membrane to invaginate
Forming cytoplasmic extension ~ pseudopodia which surround the large particle & trapped them
Pseudopodia fuse together to form food vacuole / phagocytic vacuole / phagosome
Learning Outcomes : 2.4 Explain active transport across membrane ~ endocytosis (phagocytosis)
2. The vacuole then pinches off inside the cell.
1. Folds of the plasma membrane surround the particle to be ingested, forming a small vacuole around it.
Phagocytosis
Primary lysosome will fuse with phagocytic vacuole & activates the enzyme inside lysosome
Secondary lysosome releases its enzyme to digest the particles
Useful substance is absorbed into cytoplasm
Waste substance is released by exocytosis outside the cell
Learning Outcomes : 2.4 Explain active transport across membrane ~ endocytosis (phagocytosis)
3. Lysosomes may fuse with the vacuole and digest the substance
Eg: macrophage engulf bacteria Eg: Amoeba engulf Paramecium / food
Pinocytosis
A process in which dissolved solutes are taken into the cell
Presence of dissolved solutes causes the cell membrane to invaginate
To form a tiny canals of cytoplasmic extension
Dissolved solutes are trapped within tiny canals / microvilli
Learning Outcomes : 2.4 Explain active transport across membrane ~ endocytosis (pinocytosis)
Cytosol
Pinocytosis
Learning Outcomes : 2.4 Explain active transport across membrane ~ endocytosis (pinocytosis)
At the end of tiny canals / cytoplasmic extensions, it pinches off to form pinocytic vesicles / pinosome
The dissolved solutes is directly absorbed into cytoplasm
Eg: uptake of dissolved solutes in kidney tubules & intestines
Microvilli Pinocytic vesicle
Phagocytosis & Pinocytosis
Learning Outcomes : 2.4 Explain active transport across membrane ~ endocytosis
Exocytosis
A process in which cells release substance out of the cell
Vesicle move towards cell membrane & fuse with it
Substance within vesicles are released outside the cell (during secretion)
1. A vesicle move towards the plasma membrane
2. fuses with it
3. release its contents outside the cell.
Learning Outcomes : 2.4 Explain active transport across membrane ~bulk transport (exocytosis)
Reference
Campbell N.A & Reece, J.B., Biology, 6th ed. (2002), Pearson Education, Inc.
Solomon E.P & Berg, L.R, Biology, 7th ed. (2005) Thomson Learning, Inc.
Mader, S.S Biology, 8th ed. (2004) McGraw-Hill Companies, Inc.