Question

The RNA polymerase assembles a complementary strand of RNA that adds nucleotides to the 3' end of the growing sequence.

a. True
b. False

Answer 1

The statement is true: RNA polymerase synthesizes RNA by adding nucleotides to the 3' end of the growing RNA sequence during transcription.

Step-by-step explanation:

The statement that RNA polymerase assembles a complementary strand of RNA by adding nucleotides to the 3' end of the growing sequence is true. During the process of transcription, the RNA polymerase enzyme binds to DNA at a sequence known as a promoter. This marks the beginning of the gene to be transcribed. The enzyme then unwinds a segment of the DNA, exposing the coding strand which acts as the template.

In stage 2, elongation, RNA polymerase slides along the template DNA strand and aligns ribonucleoside triphosphates (NTPs) with their complementary DNA bases (adenine with uracil, and cytosine with guanine). A phosphodiester bond is formed between the incoming NTP and the 3'-OH group of the RNA strand already synthesized. This process results in the synthesis of RNA in the 5' to 3' direction; additional nucleotides are always added to the 3' end of the growing RNA molecule.