Biomolecules

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5'end

Hydrogen bond

3'end

T-Thymine

Purines

G-Guanine

Pyrimidines

Phosphate

Sugar

A-Adenine

C-Cytosine

5'end

3'end

ÏÑ

B-DÑÅ:

One full turn of helical strand has 10

steps (10 base pairs).

(AIPMT 2003)

Length of one full turn (pitch) = 34 Å

(i.e. 3.4 Å for each step).

At each step, the strand turns 36°.

(AIPMT 2007)

MËTÅBØLÏSM

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All the biochemical reactions taking place inside a living system together

constitute metabolism. Some of the examples are:

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Removal of CO2 from amino acids to form amine.

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Removal of amino group in a nucleotide base.

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Hydrolysis of a glycosidic bond etc.

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In metabolism, there is a series of linked multistep chemical reaction

called metabolic pathways. It is of 2 types: