form 4 biology chapter 3

1. MOVEMENT OF SUBTANCES ACROSS PLASMA
MEMBRANE

2. What is isotonic solution?
An isotonic solution is a solution in
which the concentration of solutes
in the solution is the same to the
concentration of solutes within the
cell,

3. What is hypotonic solution?
A hypotonic solution is a solution in
which the concentration of solutes
in the solution is less than the
concentration of solutes within the
cell.

4. What is hypertonic solution?
A hypertonic solution is a solution in
which the concentration of solutes
in the solution is higher than the
concentration of solutes within the
cell.

5. Effect of hypertonic
solution in plant cell
Water diffuses
out from the vacuole
by osmosis
Plasmolysed plant
become turgid again
by immersing
the plant in
hypotonic solution
Both of the vacuole
cytoplasm shrink &
the plasma membrane
pulls away from the cell wall,
process called plasmolysis
Water is taken up by osmosis
and the flaccid cell
becomes turgid again –
deplasmolysis
1
2
3
4

6. Effect of hypotonic
solution in plant cell
Water diffuses
into the large central
vacuole by osmosis
Vacuole gains water,
the plasma membrane
pushes against
the rigid cell wall
This causes the large
central vacuole
to expand and swell up
The cell is said
to be turgid

7. Effect of hypertonic solution
on animal cell
Water diffuses
out from the cell
by osmosis
The cell shrink
and being crenation

8. Effect of hypotonic
solution in animal cell
Water enter the cell
causing It to swell up
and eventually burst.
The plasma membrane
is too thin & delicate to
withstand the
osmotic pressure.
The bursting of
red blood cell
is known as haemolysis.

9. Hypertonic solution Isotonic solution Hypotonic solution

10. Movement of Substances Across the
Plasma Membrane
Page 20 & 21
(Practical Book)

11. OBJECTIVE
To investigate the movement of substances
across a semi-permeable membrane

12. PROBLEM STATEMENT
What is the size of molecules that can move
across a semi-permeable?

13. HYPOTHESIS
A small size molecule (…………) can move
across through semi-permeable membrane
but big size molecule (……………) cannot move
across through semi-permeable membrane.

14. VARIABLES
1. MANIPULATED :
- Size of the molecules.
2. RESPONDING :
- Colour changes of the solutions.
1. FIXED/CONTROLLED :
- Volume of glucose solution.

15. TECHNIQUE
 Carry out food test for the presence of
glucose and starch using Benedict’s solution
and iodine solution and record the result.

16. PROCEDURE
1. Soak the visking tubing
2. Tie one end of visking tubing with thread
tightly.
3. Record the colour of solutions.
4. Fill …….ml glucose solution and …….ml starch
solution into the visking tubing.
5. Tie the other end of the visking tubing tightly.

17. 5. Immerse the visking tubing into a beaker
containing …….ml distilled water and …..ml
iodine solution.
6. After 40 minutes, take out the visking tubing
from the beaker and put it in a dry beaker.
Record the colour of the solutions.
7. Carry out the Benedict’s test for both solution
(solution inside the visking tubing and inside
the beaker)
8. Record all the results in the table.

18. COMPARING AND CONTRASTING PASSIVE
AND ACTIVE TRANSPORT
PASSIVE TRANSPORT ACTIVE TRANSPORT
1. - Molecules / ions more
from a region of higher
concentration to a
region of lower
concentration.
2. - Does not energy
3. - Follow the
concentration gradient
1. - Molecules / ions more
from a region of lower
concentration to a
region of higher
concentration.
2. - Needs energy
3. - Against the
concentration gradient.

19. RESULTS
Contents Original
colour
Final
colour
Benedict’s
test
Visking
tubing
Beaker

20. Applications of osmosis in everyday life.
A) Plant cell
If plant are given to much fertilizer which
hypertonic to the cell sap of the root water
diffuses from the cell sap into the soil by
osmosis and the cell are plasmolysed
A wilting plant eventually dies if the plant is not
watered immediately

21. B) Animal cell
Fish can be preserved longer in the
hypertonic solution (salt solution) because
water diffuses out by osmosis and the fish
becomes dehydrated.
Without water microorganism cannot live.

22. Appreciating the movement of substances
across the plasma membrane
• The movement of substances across the
plasma membrane occurs in a continuous
and controlled manner
• To maintain proper function of the plasma
membrane and the cell as a whole, it is
essential for us to take care of our food and
water intake

23. CHAPTER 3

24. The permeability of the plasma membrane
Plasma membrane is a semi permeable membrane
Some substance can move across the membrane freely
while others cannot.
The movement of the substance through the plasma
membrane occurs through
- lipid bilayer
- pore protein
- carried by carrier protein

25. Factors that influence the permeability of the
plasma membrane depends on
• The size of the molecules
• The polarity of the molecules

26. There are molecules that can easily pass through the
plasma membrane
1. Lipid-soluble molecules
such as
-Glycerol
-Fatty acid
-Vitamin A, D, E, K
-Steroid type hormones
2. Non-polar molecules such
as
Water
Carbon dioxide
Oxygen

27. Substance that has large water-soluble molecules and ions can pass
through the membrane with the help of the pore proteins and carrier
proteins
Pore protein
Carrier protein
Carrier proteins have sites that can bind to specific molecules such as
glucose

28. The movement of substances across the
plasma membrane : PASSIVE
TRANSPORT
Page 44

29. PASSIVE TRANSPORT
 Definition :
- Movement of some substances across the plasma
membrane without any input of energy by the cell.
 Types of passive transport
1. Simple diffusion
2. Osmosis
3. Facilitated diffusion

30. 1. SIMPLE DIFFUSION
Net movement of molecules/ions
from a region of higher conc. to a lower
concentration /going down a conc. gradient
until an equilibrium is achieved.

31. 1.SIMPLE DIFFUSION
Example : Gaseous exchange between the
alveoli and blood capillaries.
Higher Oxygen
Concentration
Lower Oxygen
concentration
Movement of Oxygen
Structure of alveolus
Alveolus
Blood capillaries

32. 2. OSMOSIS
Net movement of freely moving water
molecules from a region of low solute conc. to
a high solute conc. through a semi-permeable
membrane until an equilibrium is achieved.

33. 2. OSMOSIS
High water concentration refers to a solution
with a low concentration of solute in the
water
Low water concentration refers to a high
concentration of solute in the water
The semi-permeable membrane is permeable
to water but impermeable to contain solutes
such as sucrose molecules

34. Examples: Absorption of water by root hairs of a plant
High water concentration
/ Low solute
concentration
Low water concentration / High solute
concentration
root hairs of
a plant

35. 3. FACILITATED DIFFUSION
• Movement of molecules or ions from a region of higher
concentration to a region of lower concentration with the
aid of carrier proteins and pores.
• Does not require energy.
• Carrier proteins are spesific as each can only combine
with a certain type of molecule.
• Pore proteins form pores or channels through which small
dissolved particles, especially ion can diffuse across the
plasma membrane.
• Example – Absorption of digested food in the villus

36. ACTIVE TRANSPORT
• Movement of molecules or ions against the concentration
gradient across the plasma membranes with the aid of carrier
proteins.
• The energy from ATP that is generated during respiration in the
mitochondria.
• The carrier protein changes shape when the phosphate group
from the ATP molecule binds to it. Then, the solute is moved
across the membrane.
• Example – ion intake by root hairs of a plant.

37. CHAPTER 4:
CHEMICAL COMPOSITION
OF THE CELL

38. The elements in the cell
Chief elements of
organic
compounds
Ions Trace elements
H Hydrogen
C Carbon
N Nitrogen
O Oxygen
P Phosphorus
S Sulphur
Na2+ Sodium
Mg2+ Magnesium
Cl- Chlorine
K+ Potassium
Ca2+ Calcium
Mn Manganese
Fe Iron
Co Cobalt
Cu Copper
Zn Zinc

39. The chemical compounds
in the cell
• Water
• Proteins
• Lipids
• Carbohydrates
• Nucleic acids
• Mineral salts
• Vitamins

40. Cell composition
Organic compounds
• Chemical compounds that
contain the carbon
element.
• Examples:
Carbohydrates
Proteins
Lipids
Nucleic acids
Vitamin
Inorganic compounds
• Chemical compounds that
do not contain carbon.
• Examples:
Water
Mineral salts

41. The importance of
organic compounds in the cell
1. Carbohydrates - major source of
energy in the cell.
2. Proteins - growth.
3. Lipids - constituent of protoplasm.
4. Nucleic acids - store genetic information
in the form of a code.
5. Vitamins – maintain health.

42. The importance of water
in the cell
 Main constituent of protoplasm
 Regulate body temperature
 As a shock-absorber to protect body organs
 Medium for biochemical reactions
 Helps in lubrication
 Transport medium in blood, lymphatic, excretory and
digestive systems and in the vascular tissues of plants
 The maintenance of a stable internal environment
within a living organism

43. 4.2 UNDERSTANDING
CARBOHYDRATES
Page 62

44. THE ELEMENTS OF
CARBOHYDRATE
CARBON
HYDROGEN
OXYGEN

46. TYPES OF CARBOHYDRATES
i) MONOSACCHARIDES
ii) DISACCHARIDES
iii) POLYSACCHARIDE

47. (i) MONOSACCHARIDES
• THE SIMPLEST TYPE OF CARBOHYDRATES
• EXAMPLES - GLUCOSE, FRUCTOSE AND
GALACTOSE

48. (ii) DISACCHARIDES
• FORMED WHEN TWO MONO-
SACCHARIDES COMBINE BY MEANS OF
CONDENSATION
• BROKEN INTO THEIR CONSTITUENT
MONOSACCHARIDES BY HYDROLYSIS

49. EXAMPLES OF DISACCHARIDES
• MALTOSE (glucose + glucose)
• LACTOSE (glucose + galactose)
• SUCROSE (glucose + fructose)
(MaLaS)

50. EXAMPLES OF POLYSACCHARIDES
• STARCH
• GLYCOGEN
• CELLULOSE

51. WHAT ARE PROTEINS?
• Large complex macromolecules made up of
carbon, hydrogen, oxygen and nitrogen atoms
• Some proteins also contain sulphur and
phosphorus.

52. STRUCTURES OF PROTEINS
PRIMARY STRUCTURE
- linear sequence of amino acids in
polypeptide chain
SECONDARY STRUCTURE
- polypeptide chain is coiled to form an
alpha-helix or folded into beta-pleated
sheets

53. TERTIARY STRUCTURE
- the helix chain or beta-pleated sheets folded into
a three-dimensional shape
QUARTENARY STRUCTURE
- the combination of two or more tertiary
structure polypeptide chains to form one large
and complex protein molecule.
STRUCTURES OF PROTEINS

54. MONOMER OF PROTEIN
AMINO ACIDS
TWO MOLECULES OF AMINO ACIDS
FORM A DIPEPTIDE

55. THE FORMATION & BREAKDOWN OF
PEPTIDES & POLYPEPTIDES
condensation
Amino acid + amino acid dipeptide + water
hydrolysis
hydrolysis
Polypeptides + water dipeptides or amino acids

56. TYPES OF AMINO ACIDS
ESSENTIAL AMINO ACIDS
* Cannot be synthesised by the body
* obtained from diet
* source : animal protein
NON-ESSENTIAL AMINO ACIDS
* Can be synthesised by the body
TYPES OF AMINO ACIDS

57. WHAT ARE LIPIDS?
• Energy rich compounds made of
Carbon, Hydrogen and Oxygen. Some
lipid also contain Phosphorus and
Nitrogen
• Insoluble in water
• Soluble in organic solvents

58. Types of Lipid
• Fats and oils (triglycerides), waxes,
phospholipids and steroids
• Waxes: the cuticle epidermis of leaves, fruits
and seed of some plants (waterproof)
• Sebum: excreted from oil gland to softened
our skin
• Phospholipid: plasma membrane

59. Types of Lipid
• Steroids: organic compounds
: eg. Cholesterol, Hormone
(Testosterone, oesterogen, progesterone)

60. The Formation of Triglycerides
• 3 molecules of fatty acid + 1 molecule of
Glycerol
Condensation
3Fatty acid + glycerol triglycerides + water
Hydrolysis

61. The Differences between saturated fats
and unsaturated fats
Saturated
fats
Item Unsaturate
d fats
no The presence of double bonds
between carbon atoms in fatty
acid
yes
no Ability to react with an
additional hydrogen atom
yes
Solid Conditions at room
temperature
Liquid
higher Cholesterol level lower
butter Examples Corn oil

62. 4.6 The Importance of Chemical Composition in Cells
Chemical
substances
Main Function Consequence of
deficiency
Carbohydrates Supply energy.
Form part of the cell
nucleus.
Become very weak
Proteins Make new cell.
Repair & replace
damaged & worn-out
tissues.
Make enzymes &
hormones.
Muscles are poorly
developed.
Become very weak.
Kwasyiokor.

63. Chemical
substances
Main Function Consequence of
deficiency
Lipids Supply energy.
Form part of cell
membrane.
Help absorb
certain vitamins.
Cell membrane will
not be formed.
Certain vitamins
will not be absorbed.
Enzymes Biological
catalysts.
All the biological
reactions will
proceed too slowly.

64. What would happen
if our bodies lack
a particular compound
such as proteins?

65. Enzymes cannot
be synthesised
New cell cannot
be produced
Without proteins
All biochemical reaction
will proceed too
slowly
Inhibit our
body
SUSTAIN
LIFE

66. UNIT 4.5
UNDERSTANDING ENZYMES
PAGE 70

67. ENZYMES
The role of enzymes in organisms
• Cells carries out thousands of biochemical
reactions [metabolism]
• Metabolism reaction starts with the substrate
molecules undergo the reaction
• Ends with a product or products
• Enzymes are biological catalysts that speed up
biochemical reaction in the cells

68. The general characteristics of enzymes
1. Enzymes are proteins which are synthesised
by living organism
• Enzymes reaction:
substrate products
2. Enzymes unchanged or undestroyed at the
end of the reactions
3. Enzymes have specific site called active site
- bind to specific substrates
enzyme

69. 3. Enzymes are highly specific
- each enzyme can catalyse one kind of
substrate
• example:
- strach molecules can fit into the active site of
amylase but not sucrase
4. Enzymes are needed in the small quantities
5. Enzyme-catalysed reaction are reversible

70. Enzymes Inhibitors
• Slow down or completely stop the enzyme
activity
• example:
- heavy metals such as lead and mercury

71. Cofactors
• Helper molecules for enzymes to function well
• There are inorganic and organic cofactors
• Example:
- inorganic: ferum and copper
- organic: vitamin B

72. Naming of Enzymes
• According to the name of substrate it catalyses
• Adding the suffix –ase at the end of the name of
substrate
• Example:
Enzymes Substrates
Lactase Lactose
Sucrase Sucrose
Lipase Lipid

73. • Example:
sucrose + water glucose + fructose
• Other enzyme that were named before a
systematic way of naming enzmes was
formed.
• Example:
- pepsin, trypsin and rennin
sucrase

74. The sites of enzyme synthesis
• Ribosomes are the site of enzyme synthesis.
• The synthesis information of enzymes is
carried by the DNA.
• DNA are codes to make different enzymes.
• Messenger RNA is formed to translate the
codes into a sequence of amino acids.
• Amino acids are bonded together to form
specific enzymes.

75. Intracellular and
extracellular enzymes
• Intracellular enzymes- synthesised and retained in
the producer cell.
• Are found in the cytoplasm, nucleus , mitochondria
and chloroplast
• Example:
 oxidoreductase catalyses biological oxidation -
reduction in the mitochondria

76. • Extracellular enzyme- synthesised in the cell
but secreted from the cell to work externally.
• Example:
- digestive enzymes produced by the pancreas
are not used by cells in the pancreas

77. Production of extracellular enzymes
• Synthesised in the ribosomes .
• Transported through the spaces between the rough
endoplasmic reticulum [ER]
• Protein depart from the rough ER wrapped in
vesicles that bud of from the side of the rough ER
• These transport vesicles fuse with the membrane of
the Golgi apparatus.

78. • Vesicles empty their contents into the membranous space
• These protein are then modified during their transport in
the Golgi apparatus
• Example:
- sugar + protein glycoproteins
• Secretory vesicles containing these modified proteins bud
off from the Golgi membrane travel to the plasma
membrane
• These vesicles will then fuse with the plasma membrane
before releasing the protein outside the cell as enzyme

79. Extracellular enzymes
nucleus
Transport
vesicle
ribosome
Rough
endoplasmic
reticulum
Golgi
apparatus Secretory
vesicle

80. Mechanism of Enzyme Action
• Enzyme action is a very specific reaction.
• Cause of the unique 3-dimensional (3D) shape
of an enzyme (active site)
• This specificity is due to the active site of the
enzyme (specific in shaped so that only a
certain substrate molecule will fit into it)

81. • The substrate molecules bind to the enzyme at these
active sites, forming an enzyme-substrate complex.
• In these complex, the substrate molecules was
changed into products.
• After that, the active sites will release the products.
• Then, the enzyme is ready to bind another substrate
molecule and run through the catalytic cycle once
again.
• This mechanism is known as lock-and-key
hypothesis.

82. Lock-And-Key Hypothesis
• Substrate bind to the enzyme same as a key open
the lock.
• The substrate molecules represent as the key and
enzyme represent as the lock.
• It can explain why enzymes are very sensitive to
the temperature and pH changing.

83. The catalytic cycle of an enzyme

84. Factors Affecting Enzyme Activity
• Every enzyme has different structure and reaction
mechanisms.
• Generally, all enzyme activities are affected by 4
factors:
i. Temperature
ii. pH
iii. Enzyme concentration
iv: Substrate concentration
p.E.S.T.

85. 1. Temperature
• The rate of enzyme-catalyses reaction increases with
the increase of temperature, until a point called the
optimum temperature.
• Most human enzymes have the optimum
temperature range between 37ºC - 40ºC.
• Below this temperature , enzyme is not active.
• Above this temperature, the enzyme start to
denature.
• After 60ºC the enzyme reaction will be stop.

86. Relation the mechanism of enzyme
action with temperature
• When the temperature increase above the
optimum temperature, the bonds are too weak to
maintain the enzyme’s shape against the
increased random movement of the atoms in the
enzyme.
• Chemical bond in the enzyme molecules are
changed followed by the 3-D structure of active
sites.
• So, the enzyme cannot bind with the substrate
molecule again.

87. Effect of temperature
to enzyme activity
10 20 30 40 50 60
Optimum Temperature
Reaction rate
Temperature (ºC)

88. 2. pH
• Enzyme is sensitive to changes in pH.
• Generally, most enzymes are active at pH 6-8.
• However, pepsin only active at the acidic pH
(pH 1- pH 2) while trypsin only active at the
alkali pH (pH 7- pH 9).

89. Relation the mechanism of
enzyme action with pH
• Ionic interactions between oppositely charged
(+) and (-) are hold enzymes together.
• A change in pH can alter the charges on the
active sites of the enzymes and the substrates
surfaces.
• This can reduce the ability of both molecules
to bind each other.

90. Effect of pH to enzyme activity
Reaction rate
pH
1 2 3 8
6
4 5 7 9 10 11
Pepsin
Amylase Trypsin
Copy Figure 4.13
Page 74

91. 3. Substrate concentration
• Rate of reaction will increase if the substrate
concentration was increase.
• Many substrates can combine with active site
of the enzyme molecules in one time.
• The rate of reaction is directly proportional to
the substrate concentration until at maximum
rate.

92. • After maximum rate, reaction rate cannot
increase although substrate concentration is
increasing.
• This because of the limited number of
enzyme.
• So the CONCENTRATION OF ENZYME become
a limiting factor.

93. Affected of substrate
concentration to substrate activity
Reaction rate
Maximum rate
Substrate
concentration
Copy Figure 4.14
Page 74

94. 4. Enzyme concentration
• Rate of reaction will increase if the substrate
concentration was increase.
• More active sites of enzyme are available for
the substrates molecules in one time.
• The rate of reaction is directly proportional to
the enzyme concentration until at maximum
rate.

95. • After maximum rate, reaction rate cannot
increase although enzyme concentration is
increasing.
• This because of the limited number of
substrate.
• So the CONCENTRATION OF SUBSTRATE
become a limiting factor.

96. Affected of enzyme
concentration to enzyme activity
Reaction rate
Maximum rate
Enzyme concentration

97. The uses of enzyme
• Enzyme technology
• Used in the manufactories such as:
- food, leather and textile industries
- manufacturing of detergents
• Example:
- protease is used to tenderise meat
- biological enzymes are used in washing powder

98. BIOLOGY
FORM 4
CHAPTER 5
CELL DIVISION

99. Cell division can be divided into two stage….
a) nuclear division
b) cytoplasmic division
mitosis
meiosis
cytokinesis

100. MITOSIS