Question

question 18
gene regulation can involve a protein repressor that blocks ______ from initiating transcription.
a rna polymerase
b dna polymerase i
c rrna
d mrna
e dna polymerase iii

Explanation:

Gene regulation via repressors targets transcription initiation. RNA polymerase is the enzyme that starts transcription by binding to DNA promoters. Repressors block RNA polymerase access to promoters, halting transcription. DNA polymerases (I/III) function in DNA replication, not transcription; rRNA and mRNA are RNA types, not initiation enzymes.

Answer:

A. RNA polymerase