TOP HAT EXAM 3 Flashcards by Anifowose Olasubomi

RNA is synthesized from the ______.
a
3’ end to 5’ end

b
5’ end to 3’ end

c
amino terminus to carboxyl terminus

d
carboxyl terminus to amino terminus

b
5’ end to 3’ end

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Q2. During transcription, RNA polymerase produces a transcript that is ______ relative to the DNA template strand.
a
complementary

b
the same strandedness

c
antiparallel

d
Both A and C

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What type of RNA polymerase uses sigma factor?
a
Plant

b
Animal

c
Bacterial

d
Viral

c
Bacterial

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

A. The holoenzyme (core enzyme + sigma factor)

B. The sigma factor alone

C. The core enzyme alone

D. mRNA

A. The holoenzyme (core enzyme + sigma factor)

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In bacteria, the elongation stage of transcription is carried out by ______.

A. the RNA polymerase holoenzyme enzyme

B. the RNA polymerase core enzyme

C. sigma factor

D. the omega subunit

B. the RNA polymerase core enzyme

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In rho-dependent transcription termination, the rho factor initially binds to ______.

A. mRNA

B. DNA (near the end of the transcribed region)

C. RNA polymerase

D. the sigma subunit

A. mRNA

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Which of the following is NOT one of the DNA sequences known to regulate eukaryotic gene transcription by RNA polymerase II?

A. Regulatory promoter

B. Core promoter

C. Basal transcription apparatus

D. Enhancer

C. Basal transcription apparatus

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In eukaryotes, what initially binds to the TATA box on the DNA template?

A. Sigma factor

B. RNA polymerase

C. TFIID

D. Mediator

C. TFIID

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When a eukaryotic mRNA is hybridized to the complementary DNA, loops of unhybridized DNA are seen. These loops ____.

A. correspond to noncoding regions of the gene

B. are not transcribed into mRNA

C. demonstrate that genes and proteins are not colinear

D. Both A and C

E. All of the above

D. Both A and C

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Which of the following is NOT one of the four major types of introns?

A. Group I introns, which are self-splicing

B. Group II introns, found in some nuclear encoded rRNA genes, which are self-splicing

C. Nuclear pre-mRNA gene introns, which splice via the spliceosome

D. tRNA introns, which are spliced enzymatically

E. Each of the above is major type of intron

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Which of the following is/are NOT part of a mature mRNA in eukaryotic cells?

A. 5ʹ UTR

B. 5ʹ cap

C. Introns

D. 3ʹ UTR

C. Introns

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Which mRNA processing event adds stability to the mRNA?

A. Addition of a 5ʹ cap

B. Addition of a poly(A) tail to the 3ʹ end

C. Addition of a poly(U) tail to the 3ʹ end

D. Both A and B add stability

E. Both A and C add stability

D. Both A and B add stability

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If the 3ʹ splice site of an pre-mRNA intron is changed from the consensus CAG to a CAA, it is expected that _____.

A. the first step of the splicing reaction will be blocked

B. the lariat intermediate will not form

C. joining of the two exons will not occur

D. Both A and B

E. None of the above because CAA can function as a 3ʹ splice site

c
joining of the two exons will not occur

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A single gene can yield multiple types of mRNA by all of the following mechanisms except by _____.

A. alternative splicing of the exons of the pre-mRNA

B. use of alternative 3ʹ cleavage and polyadenylation sites in the pre-mRNA

C. editing of the mRNA to add, delete, or change the bases at some positions

D. shuffling the order of the exons in the mRNA relative to their order in the DNA

E. Both A and C

D. shuffling the order of the exons in the mRNA relative to their order in the DNA

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tRNA is modified posttranscriptionally by _____.

A. modifying certain bases enzymatically

B. cleavage of a larger pre-tRNA

C. removing an intron in some cases

D. adding nucleotides at the 3ʹ end

E. all of the above

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Which of the following statements is not true of ribosomes?

A. They are one of the most abundant molecular complexes of both eukaryotic and prokaryotic cells

B. They are made up entirely of ribosomal RNA molecules

C. They contain a small subunit and a large subunit

D. rRNAs undergo extensive processing before assembly into the ribosome

E. All of the above

B. They are made up entirely of ribosomal RNA molecules

Q1. How many nucleotides are in a codon?
a. 2

b. 3

c. 4

d. 5

e. 6

b. 3

Any given single-stranded DNA sequence has _____ possible reading frames, and the correct one is set by a(n) _____.
a
2; termination codon

b
4; initiation codon

c
3; initiation codon

d
3; termination codon

e
2; initiation codon

c
3; initiation codon

During tRNA charging, the amino acid is attached to the _____ of the tRNA.
a
5’ end

b. 3’ end

c. Anticodon loop

d. None of the above

b. 3’ end

Q4. Translation begins by binding of the _____ to the mRNA.

a
Small subunit of the ribosome

b
Large subunit of the ribosome

c
Intact ribosome

d
2 intact ribosomes

a
Small subunit of the ribosome

Q5. The creation of peptide bonds between amino acids is catalyzed by _____.
a. tRNA

b. protein in the small subunit

c. protein in the large subunit

d. rRNA

Which elongation factor(s) hydrolyze GTP?
a
EF-Ts

b
EF-G

c
EF-Tu

d
Both B and C

Regulation of gene activity can occur at several points in the pathway of information flow. Which of the following types of regulation takes place primarily in eukaryotes?
a. Modification of chromatin

b. Transcriptional regulation

c. Translational regulation

d. All of the above

a. Modification of chromatin

Motifs, such as zinc fingers, play a role in _____.
a
proteins binding to DNA

b
regulation of gene expression

c
cytokinesis

d
alternative splicing

e
Both A and B

DNA-binding proteins interact _____ with DNA usually via _____. a dynamically; hydrogen bonds b dynamically; covalent bonds c permanently; hydrogen bonds d permanently; phosphodiester bonds e permanently; ionic bonds

a dynamically; hydrogen bonds

A typical operon contains several functional regions. In which region does a regulator protein bind? a Structural genes b Promoter c Operator d Splice site e None of the above

c Operator

Q5. To activate the transcription of permease (and the whole lac operon) lactose needs to be present in the cell. How can lactose get in the cell when the permease gene is not activated? a The repressed lac operon is never completely repressed. b There is a second permease in the genome that initially transports lactose. c Lactose freely moves across the plasma membrane. d Though the lac operon has been studied for many years, this mystery is unsolved. e All of the above.

a The repressed lac operon is never completely repressed.

Low levels of glucose lead to all of the following, except that _. a cAMP levels increase b permease levels increase c beta-galactosidase levels increase d lac operon is activated e CAP-cAMP loses its affinity to DNA

e CAP-cAMP loses its affinity to DNA

Chromatin remodeling is an important way of regulating gene expression in _____. archaea b bacteria c eukaryotes

c eukaryotes

Histone acetylation is usually associated with _____ gene expression in eukaryotes. a decreased b increaseD c no change in

b increaseD

High levels of cytosine methylation in DNA is associated with _____ gene expression in eukaryotes. a decreased b increased c no change in

a decreased

What is the role of insulators in controlling gene expression? a They stabilize nucleosome structures b They recruit transcriptional repressor proteins c They prevent binding of the basal transcription apparatus d They block the role of enhancers

d They block the role of enhancers

The T-antigen gene is found in the genome of _____ and undergoes _____ . a E. coli ; alternative splicing b plants; alternative splicing c E. coli; transcription by reverse transcriptase d mammalian virus SV40; alternative splicing e mammalian virus SV40; transcription by reverse transcriptase

d mammalian virus SV40; alternative splicing

_____ regulates sex determination in fruit flies. a Alternative splicing of pre-mRNA b RNA interference c inhibition of translation d histone acetylation

a Alternative splicing of pre-mRNA Your answer

A RISC targets an mRNA using a _____. a CRSPR RNA b siRNA c miRNA d Either B or C

d Either B or C