Question

What do you understand by the double helical structure of DNA? Who proposed this structure?
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Answer 1

Double helix is the description of the structure of a DNA molecule. A DNA molecule consists of two strands that wind around each other like a twisted ladder. Each strand has a backbone made of alternating groups of sugar (deoxyribose) and phosphate groups.

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Answer 2

Explanation:

James Watson and Francis Crick proposed the double helical structure of the DNA. According to this structure,

• DNA molecule consists of two polynucleotide strands forming a double helix. Each helical turn has a length of 3.4nm in which ten nucleotides are present.

•Each polynucleotide strand has a backbone of sugar and phosphate. The nitrogenous base is attached to the sugar.

•The nitrogenous bases of the two strands of a double helix form a pair with the help of hydrogen bonds. Adenine pairs with thymine by two hydrogen bonds, whereas guanine pairs with cytosine by three hydrogen bonds.

• The hydrogen bonds hold the two strands of the helix together.

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