Download the chemical constituents of cells constituents include

THE CHEMICAL CONSTITUENTS
OF CELLS
CONSTITUENTS INCLUDE
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Carbohydrates
Lipids
Proteins
Nucleotides and Nucleic acids
Inorganic components
Carbohydrates
• compounds of Carbon, Hydrogen and
Oxygen
• source of energy in respiration
• as structural materials in plants and insects
• as storage materials
Carbohydrates
Carbohydrates
Monosaccharides
Disaccharides
Polysaccharides
Monosaccharides
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cannot hydrolyzed into simpler unit
sweet
soluble in water
can be crystallized
all are reducing sugars
e.g. Hexose and Pentose
Hexose
• Hexose include
glucose, fructose and
galactose
• glucose can be found
in all living cells
• fructose can only be
found in fruit and
honey
Glucose
Galactose
Pentose
• Pentose such as ribose
found in nucleic acid
Disaccharides
• made up of 2 monosaccharides joining
together by glycosidic bond
• sweet
• soluble in water
• can be crystallized
• all are reducing sugars except sucrose
Sucrose
• found in sugar cane and
beet root
• formed by condensation
of glucose and fructose
• is non reducing as the
reducing groups are
involved in the
glycosidic bond
Sucrose
Maltose
• found in germination seeds
• formed by condensation of two glucose
compounds
Polysaccharides
• made up of more than 10 monosaccharides
from hydrolysis
• tasteless
• insoluble in water
• cannot be crystallized
• e.g. cellulose, starch and glycogen
Cellulose
• found in plant cell wall only
• formed by linear polymer of  glucose
• molecules are arranged in bundles of
parallel chains by hydrogen bonding
Starch
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carbohydrate stored in plants
formed by polymerization of  glucose
exist in helical chain form
helical chains are folded and packed to form
starch grain
Glycogen
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food stored in animal
formed by polymerization of  glucose
more highly branched than starch
exist as tiny granules in cytoplasm
Lipids
• compounds of Carbon, Hydrogen and
Oxygen with smaller proportion of Oxygen
than Carbohydrates
• insoluble in water
• soluble in non polar solvents
• esters of fatty acid and glycerol
Functions of Lipids
• for energy production which have higher
energy value than carbohydrate and protein
• as structural materials in cell membrane
• as stored energy in oils and fats
• as good heat insulator to reduce heat loss
• as constituent of vitamin D and hormones
• as solvent for fat soluble vitamins
Phospholipids
• found in cell membrane
• as structural components of membrane
Triglycerides
• As storage compounds
Proteins
• make up of amino acids
• 3-dimensional in shape
Properties of Proteins
• colloidal in nature which can affect osmotic
potential
• denature under high temperature, extreme
pH and presence of certain chemicals
• amphoteric, can combine with acids and
alkalis to stablize pH
Amino Acids
• 20 kinds of amino acids
• soluble in water
• insoluble in non polar solvent
Essential & Non-essential
Amino Acids
• man can only synthesize about 10 kinds of
amino acids
• non-essential amino acids are those amino
acids that can be synthesized by the body
• essential amino acids are those amino acids
that cannot be synthesized by the body and
must obtain from other sources
• plants can synthesize all amino acids
Nucleotides and Nucleic Acids
Nucleotides
Mononucleotides
Dinucleotides
Polynucleotides
ATP
as energy-rich compound
NAD
as a coenzyme
RNAs and DNAs
as carriers of genetic information
Nucleotides
• consist of phosphoric acid, sugar backbone
and nitrogenous base
• two types of nitrogenous bases:
pyrimidine base and purine base
Pyrimidine Bases
Cytosine (C)
Uracil (U)
Thymine (T)
Purine Bases
Adenine (A)
Guanine (G)
Nucleic Acids
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carry genetic information
determine the characteristics of an organism
are polymers of nucleotides
two types of nucleic acids: DNA and RNA
Deoxyribonucleic acid (DNA)
- A double helix structure of DNA
- The base A pairs with T
and base G pairs with C
Ribonucleic Acid (RNA)
- A Single strand RNA
Inorganic Components
• ions
• water
The Occurrence of Ions in Cells
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soluble and can effect osmotic potential
can affect pH of cytoplasm
act as metabolites in biochemical reactions
activate enzymes
be constituents of biomolecules
The Biological Significance of Water
• as the main constituent of protoplasm
• as medium and metabolite in many
biochemical reactions
• as universal solvent to dissolve substances
to aid absorption, excretion and
transportation