Question

Each sequence below indicates one of two strands of a DNA molecule. The two strands of which molecule would be held together most tightly?

a)5′-GGGGGGGGGG-3′
b)5′-ATATATATAT-3′
c)5′-AAAAAAAAAA-3′
d)5′-GAGAGAGAGA-3′
e)5′-GTGTGTGTGT-3′

Answer 1

The strand of DNA that would be held together most tightly is 5′-GGGGGGGGGG-3′.

Step-by-step explanation:

With DNA strands, the two strands are held together by hydrogen bonding between the nitrogenous bases. Adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G).

In option a), the sequence is 5′-GGGGGGGGGG-3′, which means it has a repeated sequence of guanine (G). Since guanine (G) pairs with cytosine (C), this strand will be held together tightly as each base can form three hydrogen bonds.

Therefore, the correct answer is a) 5′-GGGGGGGGGG-3′.