Question

Explain Watson and Crick's model of DNA.

Answer 1

The following points explain the model of DNA as proposed by Watson and Crick:

1. DNA is made up of double helix made up of polynucleotide chains that are coiled with each other in a right-handed fashion.

2. The two strands are anti-parallel to each other. One stand runs in 5'-3' polarity and other runs in 3' to 5' polarity.

3. The deoxyribose sugar and the phosphate group attached to it form the backbone of the polynucleotide strands.

4. The nitrogenous bases attached with deoxyribose sugar through glucosidic bonds form the inner core.

5. The nitrogenous bases of the two strands form hydrogen bonds as per their complementary, such that Adenine forms two H-bonds with Thymine and Guanine forms three H-bonds with cytosine.

6. The diameter of the DNA is 20nm and the bases are at 0.34 nm. There are 10 base pairs per turn and the length of the turn is 3.4 nm.

7. The helix shows a minor groove and a major groove.