MCB 3020 Exam Review Questions with Correct Answers
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Course
MCB 3020
Institution
MCB 3020
Transcription of the lac operon is very high. - Answer-What is the phenotype of an E. Coli strain with a mutation in the lac operator that prevents the lac repressor from binding? Assume glucose is absent and lactose is present.
Attenuation is a common regulatory strategy used to control the tra...
MCB 3020 Exam Review Questions with
Correct Answers
Transcription of the lac operon is very high. - Answer-What is the phenotype of an E.
Coli strain with a mutation in the lac operator that prevents the lac repressor from
binding? Assume glucose is absent and lactose is present.
Attenuation is a common regulatory strategy used to control the transcription of operons
that code for: - Answer-Amino acid biosynthesis
Phase variation of flagellar proteins in Salmonella enterica involves... - Answer-DNA
rearrangements
A quorum-sensing gene system requires the accumulation of a secreted small molecule
called... - Answer-An Autoinducer
What can be used to control sigma factors? - Answer-Proteolysis
Anti-Sigma factors
Transcriptional regulation
The sigma factor is directly required for... - Answer-Transcription initiation
All of the following are true of transcription initiation EXCEPT:
a) The RNA polymerase holoenzyme binds.
b) GTP hydrolysis catalyzes bubble formation.
c) The closed complex becomes the open complex.
d) The first rNTP is usually a purine.
e) Position +1 marks the start of a gene. - Answer-B) GTP Hydrolysis catalyzes bubble
formation.
The termination of transcription can be caused by which of the following? - Answer-
NusA factor
Rho factor
Peptidyl transferase catalyzes the movement of the peptide from the tRNA in the
(BLANK) to the tRNA in the (BLANK). - Answer-P-site
A-site
The bonding of amino acids by the ribosomes (creating a petide bond) is done by a
protein called peptidyltransferase. - Answer-FALSE
If the first codon in an mRNA is AUG, then the first amino acid in the final, functional
protein is always methionine. - Answer-FALSE
, Mutations in the promoter sequences (-35, -10) of a gene usually affect the strength of
binding for the sigma factor. - Answer-TRUE
Conjugation differs from reproduction because conjugation - Answer-Transfers DNA
horizontally, to cells in the same generation.
Which of the following is not a product of transcription?
a) mRNA
b) A new strand of DNA
c) tRNA
d) rRNA
e) None of the above - Answer-b) A new strand of DNA
Sets of genes in operons are coordinately regulated by all of the following EXCEPT:
a) sigma factors
b) activators
c) small RNAs
d) irreversible changes in the DNA sequence - Answer-d) irreversible changes in the
DNA sequence
(BLANK) genes always occur in intergenic regions. - Answer-sRNA
When (BLANK) interacts with RNA polymerase, it increases the rate of transcription
initiation of the lac operon. - Answer-cAMP receptor protein
What occurs when an inducer is added to a medium containing an organism with a
metabolic pathway controlled by a repressor? - Answer-The inducer combines with the
repressor and inactivates the repressor.
The RNA Holoenzyme is composed of what? - Answer-Core Polymerase- contains
proteins required to elongate the RNA chain.
Sigma Factor- protein needed for initiation of RNA synthesis.
The role of the sigma factor is... - Answer-to recognize the consensus sequences in the
promoter.
Consensus Sequence - Answer-Consists of the most likely base/s at each position of
the predicted promoter. Some positions are highly conserved, while others are less
conserved.
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