1. Tardigrade
  2. Question
  3. Biology
  4. The sequences of four DNA molecules are given below (i) TATATATATATATA ATATATATATATAT (ii) TTTCCCGGGAAA AAAGGGCCCTTT (iii) TTGCGTTGCGCC AACGCAACGCGG (iv) GCCGGATCCGGC CGGCCTAGGCCG Which one of these DNA molecules will have the highest melting temperature (Tm) ?

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Q. The sequences of four DNA molecules are given below
(i) TATATATATATATA
ATATATATATATAT
(ii) TTTCCCGGGAAA
AAAGGGCCCTTT
(iii) TTGCGTTGCGCC
AACGCAACGCGG
(iv) GCCGGATCCGGC
CGGCCTAGGCCG
Which one of these DNA molecules will have the highest melting temperature $(T_m)$ ?

KVPYKVPY 2013

Solution:

The melting temperature of DNA is directly proportional to the number of hydrogen bonds in the DNA.
We know, that there are two $H$-bonds between adenine and thymine and three $H$-bonds between guanine and cytosine.
Thus, the DNA molecule, ‘iv’, i.e.
GCCGGATCCGGC
CGGCCTAGGCCG has the highest melting temperature.