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CHAPTER 14
Concept check questions (in figure legends)
FIGURE 14.2
Concept check: If a mutation changed the start codon into a stop codon, would this
mutation affect the length of the RNA? Explain.
Answer: The mutation would not affect the length of the RNA, because it would not
terminate transcription. However, the encoded polypeptide would be shorter.
FIGURE 14.5
Concept check: What does the term “consensus sequence” mean?
Answer: When comparing a group of related sequences, the consensus sequence is the
most common base found at each location within that sequence.
FIGURE 14.6
Concept check: Why is it necessary for portions of the sigma () factor protein to fit into
the major groove?
Answer: Parts of sigma factor must fit into the major groove so it can recognize a base
sequence of a promoter.
FIGURE 14.7
Concept check: What feature of the -10 sequence makes it easy to unwind?
Answer: The -10 is AT rich, which has fewer hydrogen bonds compared to a region with
a lot of GC base pairs
FIGURE 14.10
Concept check: What would be the consequences if a mutation removed the rut site from
this RNA molecule?
Answer: The mutation would prevent -dependent termination of transcription.
FIGURE 14.11
Concept check: Why is NusA important for this process?
Answer: NusA helps RNA polymerase to pause, which facilitates transcriptional
termination.
FIGURE 14.13
Concept check: What is the functional role of the TATA box?
Answer: The TATA box provides a precise starting point for the transcription of
eukaryotic structural genes.
FIGURE 14.14
Concept check: Why is CTD phosphorylation functionally important?
Answer: The phosphorylation of CTD allows RNA polymerase to proceed to the
elongation phase of transcription.
FIGURE 14.17
Concept check: What is the difference between an endonuclease and an exonuclease?
Answer: An endonuclease can cleave within a strand, whereas an exonuclease digests a
strand, one nucleotide at a time, starting at one end.
FIGURE 14.18
Concept check: Which of these three mechanisms is very common in eukaryotes?
Answer: Splicing via a spliceosome is very common in eukaryotes.
FIGURE 14.20
Concept check: Describe the roles of snRNPs in the splicing process.
Answer: snRNPs are involved in recognizing the intron boundaries, cutting out the
intron, and connecting the two adjacent exons together.
FIGURE 14.21
Concept check: What are three functional roles of the 7-methlyguanosine cap?
Answer: The 7-methylguanosine cap is important for the proper splicing of pre-mRNA,
the exit of mRNA from the nucleus, and the binding of mRNA to a ribosome.
FIGURE 14.23
Concept check: What is a functional consequence of RNA editing?
Answer: The consequence of RNA editing is that the amino acid sequence of an encoded
polypeptide may be changed, which can affect its function.