1. Chapter 4: Chemical Composition of Cells
Carbohydrate
1. Consists of ____________, _____________ and ____________ in the ratio CnH2nOn.
2. Functions:
a) Provide _____________ during respiration
b) Stored food in animals’ liver ( _____________ ) and in plants’ cell ( _____________ )
c) Build _________ ___________ in plant cells
d) External skeleton of insects
3. Carbohydrate can be divided into 3 types:
a) ________________________ c) _______________________
b) ________________________
4. Monosaccharide
a) _____________ form of carbohydrate
b) Some examples are _________________ (most common monosaccharide),
______________ (found in fruits) and ________________ (found in milk).
c) Monosaccharides are _______________ sugar which turns ________ ___________ of
Benedict’s solution to _______________________ precipitate upon heating.
5. Disaccharide
a) ________________ + ________________  Disaccharide + ____________
b) The process of producing disaccharide is __________________
c) Some of the disaccharides are ________________ (malt sugar), _________________
(cane sugar) and _________________ (milk sugar).
d) Glucose + Glucose 
Glucose + Fructose 
Glucose + Galactose 
e) Maltose is used for _______________ beer while sucrose is used as ______________
in beverage and cooking. Lactose is present in mammal’s ________, including human.
f) Only ______________ is non-reducing sugar.
6. Polysaccharide
a) Many glucose undergo ________________ to form polysaccharide.
b) Polysaccharides are insoluble in __________, do not crystallize and do not taste sweet.
c) 3 types of polysaccharides are ______________, ____________ and ______________
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2. d) _________ is the main energy storage in plants and can be found in
_________________________________________.
e) ____________ is the main energy storage in animals and yeast. They are stored in
liver and muscle.
f) _____________ makes up the cell wall of plant cells, which provide support for plants.
g) Polysaccharide can be broken down via __________________ process.
Protein
1. Consists of ____________, ____________, _____________ and _____________. Some
may have sulphur and phosphorus.
2. The building block of protein is _____________ ____________.
3. Amino acids are joined by _____________ _____________ to form protein via
_________________ process.
4. Many amino acids bind together to form _____________________.
5. Breaking of polypeptide is known as ________________.
6. Amino acids can be grouped into 2 types:
a) _____________ amino acids (can’t be synthesized by body cells. Obtained from food.)
b) _________________ amino acids (can be synthesized by body cells)
7. Structure of protein can be classified into 4 levels:
a) ______________ ______________ (arranged in sequence forming long linear chain
of polypeptide)
b) ______________ _______________ (coiled to form ______________ or
_______________ sheet)
c) ______________ _______________ (folded in various way to form globular protein)
d) ______________ ________________ (folded polypeptide chains joined together
forming a large complex protein molecule)
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3. 8. Importance of protein:
a) __________ of new cells and replace dead cells
b) Synthesis of ____________, _________________ and some hormones
c) Form keratin (skin) and collagen (bone)
d) Synthesis of haemoglobin ( _______________ structure)
Lipids
1. Consists of ____________, ______________ and ______________.
2. Building blocks are __________ ____________ and __________________.
3. Triglycerides (a type of lipid) are made up of 1 ___________ and 3 ____________
___________.
4. Triglycerides is formed when ______________ bind with _____________ ____________
via _________________ process. Triglycerides can be broken down by _______________
5. Fats and oils are triglycerides. Fats and oils can be divided into saturated and unsaturated
fat.
Aspect Saturated fats Unsaturated fats
Presence of double bond
at fatty acid
Reaction with additional
hydrogen bonds (give
reason for your answer)
Cholesterol level
State at room temperature
Example
6. Importance of lipids:
a) Source of ________________ (twice of carbohydrate)
b) ____________ insulator (keep organisms warm)
c) _____________ major organs
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4. Nucleic acids
1. Basic unit structure is _______________ which consists of ___________ sugar,
_______________ base and __________________ group.
2. Two types of nucleic acid:
a) DNA (deoxyribonucleic acid) which consists of ____ strands of polynucleotides,
twisted into ___________ ____________ structure.
b) RNA (ribonucleic acid) which consists of ____ strand of polynucleotide.
3. Importance of nucleic acids in cells:
a) Carry __________ _________________ in all cells
b) Regulate in ________________ synthesis
c) Determine the traits inherited from parents
Water
1. Importance of water:
a) As a _____________ to dissolve substances such as gases (O2 & CO2) for respiration
b) As a _____________ for biochemical reaction
c) Maintain body _______________
d) As _____________ medium as blood plasma (90%) carries many biological molecules
e) Provide _____________ such as in respiratory tract to allow diffusion of gas
f) Provide ____________ such as in plants, especially when the cells are turgid
Enzymes
1. Enzymes are ____________ _______________ that increase the rate of biochemical
reactions.
2. Enzyme + Substrate  ____________________________  Enzyme + Product
3. Works by the ___________________________ Hypothesis
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5. 4. Characteristics:
a) __________ _____ biochemical reactions
b) Not _____________ or destroyed after reaction
c) Needed in very _____________ amount
d) ___________________ reaction
e) Work with narrow range of _______________ (350C – 400C) and sensitive to ____.
5. Enzyme synthesis is the same as protein synthesis because
________________________________________________________________________
DNA in nucleus carries _____________________ for protein synthesis
Information in DNA is ______________ into mRNA which carries information
to _______________
The information is __________________ and protein is formed in ribosome
6. Enzymes can be divided into two types, ie. ____________________ (use within the cell)
and _______________________ (to be secreted outside the cell).
7. For extracellular enzymes, after the enzyme is synthesized as shown in (5), it follows a
series of steps:
Proteins enter rough ER and packed as ____________ _____________
Transport vesicle carries protein into _________ ______________ where
protein is modified into enzymes
Enzymes are packed into ____________ ___________ and transported to
plasma membrane
Secretory vesicle is fuses with plasma membrane and enzyme is released
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6. Production of extracellular enzymes
8. Factors that affect enzyme activities are _____________, _____, ___________________
and ______________________
Temperature pH
Substrate Enzyme
concentration concentration
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