Question

Sigma reduces the affinity of RNAP core for non-promoter sequences 10,000-fold and increases affinity for specific promoter DNA 1,000-fold.

A. 10,000; 1,000

B. 15,000; 800

C. 1,000; 10,000

D. 5,000; 500

Answer 1

The sigma factor alters the affinity of RNA polymerase for DNA sequences, decreasing affinity for non-promoter sequences by 10,000-fold and increasing affinity for promoter sequences by 1,000-fold, therefore the correct answer is A. 10,000; 1,000.

Step-by-step explanation:

The student's question revolves around the specificity of RNA polymerase (RNAP) core enzyme to promoter sequences in the presence of the sigma factor. Sigma factor is a protein that plays a crucial role in transcription initiation by increasing the affinity of RNAP for promoter sequences while decreasing its affinity for non-promoter DNA sequences. According to the student's question, the sigma factor reduces the affinity for non-promoter sequences 10,000-fold and increases the affinity for specific promoter DNA 1,000-fold. Therefore, the correct option is A. 10,000; 1,000.

The significant change in affinity due to the presence of the sigma factor ensures that RNAP binds to the appropriate promoter regions to initiate accurate transcription of genes. This selectivity is essential for the proper regulation of gene expression.