Question

If DNA is subjected to high temperature of about 90 - 100${}^o$C, the following changes occur

• A. Hydrogen bonds of the bases break down.
• B. Phosphate changes to phosphoric acid.
• C. Bonds between only thymine and adenine break down.
• D. Bonds between only cytosine and guanine break down.

Answer 1

The correct option is A Hydrogen bonds of the bases break down.

If DNA is subjected to high temperature, the hydrogen bonds between the nitrogenous bases break down and the two strands separate. This process is called as melting of DNA. More the content of guanine (G) and cytosine (C) in the DNA, higher will be the melting temperature because G forms three hydrogen bonds with C as against adenine (A) and thymine (T) which form two hydrogen bonds.
So, the correct answer is option A.