15. Gene Expression

Transcription in eukaryotes requires which of the following molecules in addition to RNA polymerase?

During transcription of DNA to RNA:

What happens during the initiation step of DNA transcription?

Which of the following properties is NOT shared by RNA polymerase and DNA polymerase?

In eukaryotic cells, transcription cannot begin until

a. The two DNA strands have completely separated and exposed the promoter.

b. Several transcription factors have bound to the promoter.

c. The 5′ caps are removed from the mRNA.

d. The DNA introns are removed from the template.

The RNA polymerase enzyme binds to ________, initiating transcription.

a. Amino acids

b. tRNA

c. The promoter sequence

d. The ribosome

In a particular bacterial species, temperature-sensitive conditional mutations cause expression of a wild-type phenotype at one growth temperature and a mutant phenotype at another—typically higher—temperature. Imagine that when a bacterial cell carrying such a mutation is shifted from low to high growth temperatures, RNA polymerases in the process of elongation complete transcription normally, but no new transcripts can be started. The mutation in this strain most likely affects:

a. The terminator sequence

b. The start codon

c. Sigma

d. One of the polypeptides of the core RNA polymerase