Question

The 5' end of a DNA molecule can be chemically distinguished from the 3' end because there is a(n) ________ group at the 5' end and a(n) ________ group at the 3' end.

A) amine; carboxyl
B) phosphate; sulfate
C) hydroxyl; hydrogen
D) phosphate; hydroxyl
E) amine; hydroxyl

Answer 1

The 5' end of a DNA molecule is distinguished by a phosphate group, while the 3' end has a hydroxyl group, making the correct answer D) phosphate; hydroxyl.

Step-by-step explanation:

The 5' end of a DNA molecule can be chemically distinguished from the 3' end because there is a phosphate group at the 5' end and a hydroxyl (OH) group at the 3' end. The phosphate group of one nucleotide is covalently bonded to the 5' carbon of the sugar molecule, which starts the sequential linking of nucleotides. The hydroxyl group, on the other hand, is found attached to the 3' carbon on the sugar. This orientation is critical for processes such as DNA replication and RNA transcription.

Therefore, the correct answer to the question is D) phosphate; hydroxyl.