Deck 12: Transcription

Question 1

RNA differs from DNA in that RNA possesses a hydroxyl group on the 2'-carbon atom of its sugar, contains uracil instead of thymine, and is normally single stranded. Several classes of RNA exist within bacterial and eukaryotic cells.

-Which class of RNA is correctly paired with its function?

A) Small nuclear RNA (snRNA): processes rRNA
B) Transfer RNA (tRNA): attaches to an amino acid
C) MicroRNA (miRNA): carries information for the amino acid sequence of a protein
D) Ribosomal RNA (rRNA): carries out RNA interference

Answer 1

Transfer RNA (tRNA): attaches to an amino acid

Question 2

Within a single gene, only one of the two DNA strands, the template strand, is usually transcribed into RNA.
-What is the difference between the template strand and the nontemplate strand?

Answer 2

The template strand is the DNA strand that is copied into an RNA molecule, whereas the nontemplate strand is not copied.

Question 3

A transcription unit is a piece of DNA that encodes an RNA molecule and the sequences necessary for its proper transcription. Each transcription unit includes a promoter, an RNA-coding region, and a terminator.

-Which of the following phrases does not describe a function of the promoter?

A) Serves as sequence to which transcription apparatus binds
B) Determines the first nucleotide that is transcribed into RNA
C) Determines which DNA strand is template
D) Signals where transcription ends

Answer 3

Signals where transcription ends

Question 4

A promoter is a DNA sequence that is adjacent to a gene and required for transcription. Promoters contain short consensus sequences that are important in the initiation of transcription.

-What binds to the -10 consensus sequence found in most bacterial promoters?

A) The holoenzyme (core enzyme + sigma)
B) The sigma factor alone
C) The core enzyme alone
D) mRNA

Question 5

Transcription ends after RNA polymerase transcribes a terminator. Bacterial cells possess two types of terminator: a rho-independent terminator, which RNA polymerase can recognize by itself; and a rho-dependent terminator, which RNA polymerase can recognize only with the help of the rho protein.
-What characteristics are most commonly found in rho-independent terminators?

Question 6

General transcription factors and RNA polymerase assemble into the basal transcription apparatus, which binds to DNA near the start site and is necessary for transcription to take place at minimal levels. Additional proteins called transcriptional activators bind to other consensus sequences in promoters and enhancers and affect the rate of transcription.

-What is the difference between the core promoter and the regulatory promoter?

A) Only the core promoter has consensus sequences.
B) The regulatory promoter is farther upstream of the gene.
C) Transcription factors bind to the core promoter; transcriptional activator proteins bind to the regulatory promoter.
D) Both b and c.

Question 7

Transcription is initiated when the basal transcription apparatus, consisting of RNA polymerase and transcription factors, assembles on the core promoter and becomes an open complex.
-What is the role of TFIID in transcription initiation?

Question 8

The different eukaryotic RNA polymerases use different mechanisms of termination. Transcription at genes transcribed by RNA polymerase II is terminated when an exonuclease enzyme attaches to the cleaved 5' end of the RNA, moves down the RNA, and reaches the polymerase enzyme.

-How are the processes of RNA polymerase II termination and rhodependent termination in bacteria similar and how are they different?