In: Biology
Make a line drawing of DNA in which you show the major and minor groove. Explain how base stacking and hydrogen bonding contribute to the double helix.
Ans. In base pairing and stacking in DNA, many forces are involved and play roles. Between the bases in the complementary strands of DNA there are hydrogen bonds; 3 hydrogen bonds between G and C, 2 hydrogen bonds between A and T. This hydrogen bonding contributes to the stability of structure. There is attraction between base pairs which are stacked one above the other through Van der waals forces of the range of 3 kJ/mole. Hydrophobic forces stack the bases one above the other. Besides these factors, the process of stacking is also contributed by the structural confirmation of sugar-phosphate backbone present in the DNA molecule. All these contribute to the three dimensional maintenance of structure and stability of DNA double helix.