BIO305 Exam 4, Practice Exam B
Indicate whether the following mutation is A) cis-acting or B) trans-acting.
1. Mutation of the UAS sites for GAL2. (2 pts)
Indicate whether the following mutation would be most likely A
...
BIO305 Exam 4, Practice Exam B
Indicate whether the following mutation is A) cis-acting or B) trans-acting.
1. Mutation of the UAS sites for GAL2. (2 pts)
Indicate whether the following mutation would be most likely A) recessive or B) dominantnegative.
2. Mutation of the GAL80 gene such that the Gal80 protein cannot bind Gal4. (2 pts)
3. Gal4 binds which of the following: (3 pts)
A) TBP
B) the Mediator complex
C) the SWI-SNF complex
D) A and B
E) A, B, and C
4. A region of DNA encompassing 500 bp upstream of yeast gene X has been mutated to
include two GAL UAS sites; in addition, this DNA region contains all typical promoter
elements, but lacks a binding site for Mig1. Transcription of gene X would now be: (4 pts)
A) increased under conditions with galactose present relative to conditions with galactose
and glucose present
B) decreased under conditions with galactose present relative to conditions with galactose
and glucose present
C) at identical levels under conditions with galactose present relative to conditions with
galactose and glucose present
5. What would be the effect of mutating the DNA region described in question 4 to contain four
GAL UAS sites? (3 pts)
A) increased transcription of gene X under conditions with galactose present and glucose
absent
B) no effect on transcription of gene X under conditions with galactose present and glucose
present
C) no effect on transcription of gene X under conditions with galactose present and glucose
absent
D) no effect on transcription of gene X under any condition
E) increased transcription of gene X under all conditions
6. What would be the likely phenotype upon deleting the a1 gene from one MAT locus in a
diploid (a/α) yeast cell? (4 pts)
A) haploid-specific genes would be transcriptionally active
B) haploid-specific genes would be transcriptionally repressed
C) a-specific genes would be transcriptionally repressed
D) A and C are correct
E) B and C are correct
BIO305 Exam 4, Practice Exam B
7. In an effort to identify regulatory sequences important for transcription, a collection of
mutants has been generated. Each mutant carries a single base mutation in a region of
DNA 400 bp immediately upstream of gene Y, such that, collectively, the full mutant
collection contains a mutation at each nucleotide position in the 400 bp region. Transcription
of gene Y is measured in each mutant relative to wild type, and the cumulative results are as
follows. “-1” indicates the nucleotide one base upstream of the transcriptional start site.
Coordinates Transcription level relative to wild type
Mutations in bp -1 to -30 1.0 (on average)
Mutations in bp -31 to -40 0.3 (on average)
Mutations in bp -41 to -150 1.0 (on average)
Mutations in bp -151 to -158 3.0 (on average)
Mutations in bp -159 to -200 1.0 (on average)
Mutations in bp -201 to -220 0.3 (on average)
Mutations in bp -221 to -400 1.0 (on average)
From these data, which of the following statements accurately identify regions that are
required for likely recognition by transcriptional activators or repressors? (3 pts)
A) The -31 to -40 and -201 to -220 DNA sequences are required for binding of a
transcriptional activator; the -151 to -158 sequence is required for binding of a
transcriptional repressor.
B) The -31 to -40 and -201 to -220 DNA sequences are required for binding of a
transcriptional repressor; the -151 to -158 sequence is required for binding of a
transcriptional activator.
C) The -1 to -30, -41 to -150, -151 to -158, -159 to -200, and -221 to -400 DNA sequences
bind transcriptional activators.
D) The -31 to -40 and -201 to -220 DNA sequences bind transcriptional repressors.
E) C and D are correct
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