Question

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 $\left(T_m\right)$ ?

• A. i
• B. ii
• C. iii
• D. iv

Answer 1

Answer: (D)

iv

In DNA molecule A pairs with T by two hydrogen bond and G pairs with C by three hydrogen bonds. Thus the template with more G and C nucleotide will have higher melting points as more energy is needed to break three bond. Thus the correct option is D.