All chemical reaction in a cell
Nutrient – Carbohydrate ( Glycosidic Bond )
Protein (Peptide)
Lipid (Ester)
Removal of CO2 from amino acid to form amine
Removal of amino group in a nucleotide base
Hydrolysis of glycosidic bond
The organic compounds taking part in metabolism is called metabolites. They are of two types:Primary Metabolites
They have identifiable functions in psychological processes and necessary for life.
Example amino acids, nucleic acids, sugars, lipids, vitamins, etc.
Secondary Metabolites
They are not directly involved in the normal growth, development or reproduction of organism.
Example essential oils, toxins, pigments, lectins, drugs, etc.
Metabolic pathways are similar to the automobile traffic in a city. Flow of metabolites through the
metabolic pathways has a definite rate and direction like automobile traffic. This metabolic flow is
called the dynamic state of body constituents.
There are two types of metabolic pathways:
Anabolic (biosynthetic) pathways and Catabolic pathways
Anabolic (Biosynthetic) pathways
Catabolic pathways
Simpler molecules form complex structures
(constructive process)
Complex molecules become simple structures
(destructive process)
It consumes energy
It releases energy
Example: formation of acetic acid from
cholesterol, assembly of amino acids to protein,
photosynthesis
Example: formation of lactic acid from glycose
(glycolysis) respiration
The energy released through catabolism is stored in the form of chemical bond. When needed, this
bond energy is utilised for biosynthetic, osmotic & mechanical works.
The most important energy currency in the living system is the bond energy in adenosine triphosphate
(ATP)
Enzymes are biological catalysts which influence the speed of biochemical reactions OR They
are biological catalyst that speed up the rate of reaction without being involved
All enzymes are proteins but all proteins are not enzymes
The chemicals on which the enzyme acts are called substrate
Enzyme converts substrates into products
Enzymes are specific, i.e., each enzyme has its own substrate
Enzymes get damaged at high temperature
Enzymes lower the activation energy of the reaction
Enzymes isolated from thermophilic organism (live under high temperatures) are thermostable
Enzymes form tertiary structure (3D) with some crevices (pockets) called ‘active site’ into
which the substrate fits
Nucleic acids (RNA) that behave like enzymes are known as Ribozymes
Carbonic anhydrase is the fastest enzyme. It accelerates the following reaction 10 million times
In the absence of the enzyme, only 200 molecules of 𝐻2 𝐶𝑂3 are formed in an hour. In presence of
carbonic anhydrase, about 600,000 molecules are formed per second!
In a multistep chemical reaction (metabolic pathway), each step is catalysed by different enzymes
Example: In glycolysis {Glucose (𝐶6 𝐻12 𝑂6 ) → 2 pyruvic acid 𝐶3 𝐻4 𝑂3 )} 10 difference enzymes take
part
In a chemical reaction, there will be breaking of bonds.
𝐵𝑎(𝑂𝐻)2 + 𝐻2 𝑆𝑂4 → 𝐵𝑎𝑆𝑂4 + 2𝐻2 𝑂
(inorganic chemical reaction)
𝑆𝑡𝑟𝑎𝑐ℎ + 𝐻2 𝑂 → Glucose
(organic chemical reaction)
Rate of reaction = amount of product formed / unit time