Biomolecules

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Flow of metabolites through the metabolic pathways has a definite rate

& direction like automobile traffic in a city. This metabolic flow is called

dynamic state of body constituents.

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The energy released through catabolism is stored in the form of chemical

bonds. When needed, this bond energy is utilized for biosynthetic,

osmotic and mechanical works.

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The most important energy currency in living system is the bond energy

in adenosine triphosphate (ATP).

(AIPMT 2000)

ËÑZÝMËS

Enzymes are biological

catalysts which

influence the speed of

biochemical reactions.

Ribozymes: Nucleic acids

(RNA) that behave like

enzymes. (NEET-II 2016)

Almost all enzymes

are proteins but

all proteins are not

enzymes.

Enzymes form tertiary

structure (3D) with

some crevices (pockets)

called ‘active site’ into

which the substrate fits.

Enzymes are specific.

i.e. each enzyme has its

own substrate.

Carbonic anhydrase is

the fastest enzyme. It

accelerates the following

reaction 10 million times.

Carbonic anhydrase

2

2

2

3

CO

H O

H CO

+





In a metabolic pathway, each step is catalysed by different

enzymes. E.g. In glycolysis [Glucose (C6H12O6)®2 Pyruvic acid

(C3H4O3)] ten different enzymes take part.

In the absence of enzyme, only 200 molecules of H2CO3 are

formed in an hour. In the presence of carbonic anhydrase

about 600,000 molecules are formed per second.

ÑÅTÜRË ØF ËÑZÝMË ÅÇTÏØÑ (ÇÅTÅLÝTÏÇ ÇÝÇLË)

It includes the following steps: