Biology · Biochemistry - Nucleic Acid Structure
Which of the following correctly describes the structural basis for the higher melting temperature (Tm) of poly(GC) compared to poly(AT) DNA, AND a second independent reason why GC-rich sequences are more thermostable?
Verified Solution4 OptionsUpdated: October 2026👁️1 View
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- 1G≡C pairs have a shorter glycosidic bond; AND GC pairs exclude water more effectively than AT pairs
- 2AT-rich sequences melt first because thymine is more hydrophilic; AND GC stacks are stabilized by additional covalent cross-links
- 3G≡C has 3 H-bonds vs A=T has 2 H-bonds; AND GC-rich sequences are more stable due to stronger ionic interactions with Mg2+
- 4G≡C has 3 H-bonds vs A=T has 2 H-bonds; AND G-C pairs have greater base stacking energy due to larger electron delocalization in the purine-pyrimidine stack✓
Correct answer
G≡C has 3 H-bonds vs A=T has 2 H-bonds; AND G-C pairs have greater base stacking energy due to larger electron delocalization in the purine-pyrimidine stack
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