Question

Which of the DNA will have higher melting temperature with below mentioned base compositions:

• A. G-30%, C-30%, A-20%, T-20%
• B. G-20%, C-20%, A-30%, T-30%
• C. G-40%, C-40%, A-10%, T-10%
• D. G-10%, C-10%, A-40%, T-40%

Hint:

More G-C = More Bonds = More Heat needed to melt.

Answer 1

The Correct Option is C

Step 1: Concept
The melting temperature ($T_m$) of DNA is the temperature at which the double strands separate.

Step 2: Meaning
$T_m$ depends on the stability of hydrogen bonds between base pairs.

Step 3: Analysis
G-C pairs have 3 hydrogen bonds; A-T pairs have only 2. DNA with higher G-C content is more stable and requires higher temperature to melt.

Step 4: Conclusion
Option (3) has 80% G-C content, giving it the highest $T_m$.

Final Answer: (3)