Ch. 12 Concept Check & Comprehension Questions Flashcards
Which of the following base sequences is used during transcription?
Promoter and terminator
The three stages of transcription are..
Initiation, elongation, and termination
Which of the following statements is false?
All genes encode polypeptides that function as units within proteins
With regard to a promoter, a transcriptional state site is..
Located at the +1 position and is where the first base is used as a template for transcription
For the following five sequences, what is the consensus sequence? 5'-GGGAGCG-3' 5'-GAGAGCG-3' 5'-GAGTGCG-3' 5'-GAGAACG-3' 5'-GAGAGCA-3'
5’-GAGAGCG-3’
Sigma factor is needed during which stage of transcription?
Initiation
A uracil-rich sequence occurs at the end of the RNA in..
p-independent termination
Which RNA polymerase in eukaryotes is responsible for the transcription of genes that encode proteins?
RNA polymerase II
An enhancer is a ___ that ___ the rate of transcription.
cis-acting element, increases
The basal transcription apparatus is composed of..
- five general transcription factors
- RNA polymerase II
- a DNA sequence containing a TATA box and transcriptional start site
With regard to transcriptional termination in eukaryotes, which model suggests that RNA polymerase is physically removed from the DNA?
Torpedo model
Which of the following are examples of RNA modification?
- splicing
- 7-Methylguanosine cap
- PolyA tail
A ribozyme is..
An RNA molecule with catalytic function
Which of the following statements about the spliceosome is false?
A spliceosome removes exons from RNA molecules
What are functions of the 7-methylguanosine cap?
- exit of mRNA from the nucleus
- efficient splicing of pre-mRNA
- initiation of translation
What are key differences between bacteria and eukaryotes?
- initiation of transcription requires more proteins in eukaryotes
- a 7-methylguanosine cap is added only to eukaryotic mRNAs
- splicing is common in complex eukaryotes but not in bacteria
Organization of sequences of a bacterial gene and it’s mRNA transcript.
If a mutation changed the start codon into a stop codon, would this mutation affect the length of the RNA? Explain.
The mutation would not affect the length of the RNA, because it would not terminate transcription. However, the encoded polypeptide would be shorter.
What does the term consensus sequence mean?
When comparing a group of related sequences, the consensus sequence is the most common base found at each location within that sequence.
The binding of sigma-factor protein to the promoter region.
Why is it necessary for portions of sigma-factor protein to fit into the major groove?
Parts of sigma-factor must fit into the major groove so it can recognize a base sequence of a promoter.
The initiation stage of transcription in bacteria.
What feature of the –10 sequence makes it easy to unwind?
The –10 is AT rich, which has fewer hydrogen bonds compared to a region with a lot of GC base pairs.
p-dependent termination.
What would be the consequences if a mutation removed the rut site from this RNA molecule?
The mutation would prevent p-dependent termination of transcription.
p-independent or intrinsic termination.
Why is NusA important for this process?
NusA helps RNA polymerase to pause, which facilitates transcriptional termination.
A common pattern for the promoter of protein-encoding genes recognized by RNA polymerase II.
What is the functional role of the TATA box?
The TATA box provides a precise starting point for the transcription of eukaryotic protein-encoding genes
Steps leading to the formation of the open complex.
Why is carboxyl terminal domain (CTD) phosphorylation functionally important?
The phosphorylation of CTD allows RNA polymerase to proceed to the elongation phase of transcription
The processing of a precursor tRNA molecule in E. coli.
What is the difference between an endonuclease and an exonuclease?
Ah endonuclease can cleave within a strand, whereas an exonuclease digests a strand, one nucleotide at a time, starting at one end.
Mechanisms of RNA splicing.
Which of these three mechanisms is very common in eukaryotes?
Splicing via a spliceosome is very common in eukaryotes.
Splicing of pre-mRNA via a spliceosome.
Describe the roles of snRNPs in the splicing process.
snRNPs are involved in recognizing the intron boundaries, cutting out the intron, and connecting the two adjacent exons together.
Attachment of a 7-methylguanosine cap to the 5’ end of mRNA.
What are three functional roles of the 7-methylguanosine cap?
- proper splicing of pre-mRNA
- the exit of mRNA from the nucleus
- the binding of mRNA to a ribosome
RNA editing by deamination.
What is a functional consequence of RNA editing?
That the amino acid sequence of an encoded polypeptide may be changed, which can affect its function
