Question

which action is one role of rna polymerase during transcription?

o to build a molecule of mrna

o to switch uracil with thymine on the exposed gene

o to break down an already existing protein

o to produce a start sequence

Explanation:

During transcription, RNA polymerase synthesizes mRNA by adding complementary RNA nucleotides to the DNA template strand. It does not switch uracil with thymine (RNA has uracil instead of thymine, and this is a natural process, not a "switching" by the enzyme in the way described). It also does not break down proteins (that's the role of proteases) or produce a start sequence (the start sequence is part of the DNA/RNA structure, and the enzyme's main role is polymerization to form mRNA).

Answer:

to build a molecule of mRNA