What is a common function of RNA polymerases during transcription?

RNA polymerases play a crucial role in the process of transcription, which is the first step in gene expression. Their primary function is to synthesize a complementary strand of RNA from a DNA template. During transcription, RNA polymerase binds to a specific region of the DNA known as the promoter, unwinds the DNA strands, and begins synthesizing RNA by adding ribonucleotides that are complementary to the DNA template strand. This means that if the DNA has an adenine base, RNA polymerase will incorporate uracil in the RNA strand rather than thymine, which is present in DNA.

This synthesis occurs in the 5' to 3' direction, and the resulting RNA strand is a copy of one of the DNA strands (the coding strand) but is single-stranded and consists of ribonucleic acid. This newly synthesized RNA molecule will eventually undergo processing and serve various functions, including acting as a messenger RNA (mRNA) for protein synthesis.

Other options mentioned do not accurately represent the primary functions of RNA polymerases in transcription. For instance, RNA polymerases do not degrade RNA strands, form double-stranded RNA, or repair damaged RNA during transcription; these actions fall under different cellular processes or enzymes. Hence, the