Q80: Tm of duplex DNA increases by __ °C for every... - Cellular and Molecular Biology - Fish Biotechnology- ICAR JRF/SRF 2024 | Agrigyan

• Thermal Denaturation of Double-Stranded DNA:
• The melting temperature ($T_m$) of duplex DNA is defined as the temperature at which $50\%$ of the double helix denatures into single strands.
• Because guanine-cytosine ($G\equiv C$) base pairs are stabilized by three hydrogen bonds and strong base-stacking interactions compared to two bonds in adenine-thymine ($A=T$) pairs:
• According to the classical empirical relationship established by Marmur, Doty, and Frank-Kamenetskii:

• Thus, $T_m$ increases by approximately $0.41^\circ\text{C}$ (or $0.4^\circ\text{C}$) for every $1\%$ increase in GC content.
• nalysis:
• (0.4; GC): Correct.

Correct option: (4) 0.4; GC