Question

Which one of the following statements about RNA and DNA is false?

A. DNA is generally more stable than RNA
B. Rarely, an RNA duplex can form and is generally more stable than DNA
C. A-T base pairs have fewer hydrogen bonds, therefore A.T rich DNA melts at a lower temperature than G-C rich DNA
D. Annealing is the process of bringing DNA strands back together below the melting temperature
E. A-U base pairs have substantially stronger hydrogen bonds than in A-T base pairs

Answer 1

The false statement among those given is E. A-U base pairs have substantially stronger hydrogen bonds than in A-T base pairs. Actually, A-U and A-T pairs both involve two hydrogen bonds, indicating no substantial difference in their bond strength.

Step-by-step explanation:

Among the statements regarding RNA and DNA, the false statement is: E. A-U base pairs have substantially stronger hydrogen bonds than in A-T base pairs. While adenine (A) pairs with thymine (T) in DNA and with uracil (U) in RNA, A-T base pairs in DNA have two hydrogen bonds just as A-U base pairs in RNA do. Therefore, A-U and A-T base pairs do not differ substantially in the strength of their hydrogen bonds.

DNA's double helix structure consists of two complementary strands linked by hydrogen bonds between paired bases. Hydrogen bonding also plays a key role in the structure of RNA, although RNA is typically single-stranded. Certain regions within an RNA molecule can form complementary base pairs with each other, enabling RNA to fold into complex structures. In the context of stability and melting temperatures, G-C rich DNA has a higher melting temperature than A-T rich DNA because G-C base pairs form three hydrogen bonds, compared to the two bonds of A-T base pairs, making G-C associations more thermally stable.

The process of separating DNA strands is known as denaturation, and the rejoining of strands is called annealing. Contrary to the false statement, having fewer hydrogen bonds typically means weaker interactions, not stronger.