Final answer:
DNA with a high proportion of Guanine-Cytosine (GC) base pairs has the highest melting temperature (TM) due to the three hydrogen bonds that stabilize the GC pairing.
Step-by-step explanation:
The DNA with a high proportion of Guanine-Cytosine (GC) base pairs has the highest melting temperature (TM). This is due to the three hydrogen bonds that form between guanine and cytosine, compared to the two hydrogen bonds that form between adenine and thymine. The DNA base pairing of adenine-thymine (AT) and guanine-cytosine (GC) are examples of complementary base pairs, in which the purines (adenine and guanine) pair with their corresponding pyrimidines (thymine and cytosine, respectively).
The DNA rich in Guanine-Cytosine (GC) base pairs has the highest melting temperature (TM). Guanine and Cytosine form three hydrogen bonds between them, making this base pair more stable and requiring more heat to break the bonds.