Question

In which of the following will DNA melt at the lowest temperature?

• A. 5 -AATAAAGC - 3'
  3' TTATTTCG 5'
• B. 5' - AATGCTGC - 3
  3' - TTACGACG 5'
• C. 5' - ATGCTGAT - 3'
  3' - TACGACTA 5'
• D. 5' - GCATAGCT 3'
  3' - CGTATCGA 5'

Answer 1

The correct option is A 5 -AATAAAGC - 3'

3' TTATTTCG 5'

The melting temperature of a DNA(T${}_m$) is that temperature at which 50% of double-stranded DNA changes to single-stranded DNA. The T${}_m$ depends on the guanine-cytosine(GC) content of the DNA. Thus, the DNA having least GC content will have least T${}_m$ while the DNA having maximum GC will melt at a higher temperature. Considering the options given option A has least GC content of all four options.

So, the correct answer to the question is '5'-AATAAAGC-3'

3'-TTATTTCG-5'