What is the difference between G-C and A-T pairings in DNA structure?

[Roy Flint]

What is the difference between G-C and A-T pairings in terms of double helix formation in DNA structure?

 

[S. Khan]

One difference is that G pairs to C with 3 hydrogen bonds, whereas A pairs to T with 2 hydrogen bonds. This makes G-C pairing stronger than A-T pairing, and G-C-rich DNA more difficult to denature. Both types of pairing are important for stabilizing the double helical structure. This pairing is also important for replication of DNA.

[W. Norman]

Notice also that C at specific CpG sequences is the site of DNA methylation. This a type of epigenetic modification of the genome.

[Author]

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