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Class 11
>>Biology
>>Biomolecules
>>Nature of Bond Linking Monomers in a Polymer
>>Explain the double helix structure of DN
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Explain the double helix structure of DNA molecule.
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The characteristics of the double helical structure of DNA proposed by Watson and Crick are as follows
i) The structure of DNA molecule resembles a spirally twisted ladder.
ii) It is made of two polynucleotide chains which are made of nitrogen base (Adenine, Guanine, Cytosine, and Thymine), sugar (deoxyribose sugar), and a phosphate.
iii) The two polynucleotide chains are held together by the hydrogen bonds formed between the purines and the pyrimidines (nitrogen bases)
iv) The purine A (Adenine) forms two hydrogen bonds with the pyrimidine T (Thymine) and the other purine G (Guanine) pairs with the other pyrimidine C (cytosine) via three hydrogen bonds
v) Polynucleotide chains are helically coiled and are antiparallel to each other.
v) The nitrogen bases connect the two opposite strands like the rings of a ladder.