Genetics Exam 3

I wish the professor taught this class better idk.

A silent mutation is most likely the result of which of the following (hint: look at the genetic code):

 

Transition

 

Transversion

Transition

Which of the following would likely result in a frameshift mutation?

 

Depurination

 

Trinucleotide repeat expansion

 

Base modifier

 

Intercalating agent

Intercalating agent

Which of the following recognizes a mismatch?

 

Uvr Complex

 

MutL

 

MutH

 

MutS

MutS

The Uvr complex can distinguish between the parent strand and the daughter strand when repairing DNA mutations.

 

True

 

False

False

UV radiation is a physical mutagen that most commonly causes:

 

Thymine dimers

 

Base modifications

 

Frameshift

 

Depurinations

Thymine dimers

Of the following mutations, which would lead to a 50% chance of a point mutation when the mutation is identified by DNA repair mechanisms before DNA replication?

 

Depurination

 

Cytosine deamination

 

5-methylcytosine deamination

 

Trinucleotide repeat expansion

5-methylcytosine deamination

Which of the following would repair a depurination?

 

Mismatch repair system

 

Nucleotide excision repair

 

Photolyase

 

Non-homologous end joining

Nucleotide excision repair

The disorder Xeroderma Pigmentosum results in the absence of:

 

Photolyase

 

Uvr proteins

 

MutL

 

BRCA2

Uvr proteins

The sequence below is the TEMPLATE strand of DNA.  Following transcription, which of the following would be the sequence of the RNA?

5’ – A T C G G T A T C G T A – 3’

 

5’ – TAGCCATAGCAT – 3’

 

5’ – UAGCCAUAGCAU – 3’

 

5’ – UACGAUACCGAU – 3’

 

5’ – TACGATACCGAT – 3’

 

5’ – AUCGGTAUCGUA – 3’

5’ – UACGAUACCGAU – 3’

The role of the sigma factor is to:

 

Bind to the TATA box and recruit RNA polymerase

 

Facilitate hairpin formation during termination

 

Recruit RNA polymerase for transcription

 

Recognize the intron/exon boundaries during splicing

Recruit RNA polymerase for transcription

A gene that is transcribed at low amounts, but is incapable of increasing the rate of transcription would most likely be the result of what?

 

A mutation in the promoter

 

A mutation in the regulatory sequence

 

A mutation in the start site

 

An absence of general transcription factors

A mutation in the regulatory sequence

What do both the rho-dependent and rho-independent mechanisms of termination have in common? 

 

Terminate transcription immediately after the stop codon

 

A sequence rich with A-U base pairs

 

Both require a helicase to separate the DNA-RNA complex

 

The formation of a hairpin structure

The formation of a hairpin structure

The polyA tail is responsible for:

 

Alternative splicing

 

Transport of the mRNA out of the nucleus

 

Initiation of translation

 

Preventing degradation

 

All of the above are functions of the polyA tail

Preventing degradation

snRNPs are involved in which of the following?

 

Splicing

 

Transcription

 

Translation

 

Coupling

Splicing

Alternative splicing allows an organism to ___________. 

 

Carry fewer genes

 

Carry more genes

 

Produce fewer gene products

Carry fewer genes

Which of the following is translated into protein?

 

Introns

 

Promoter

 

Exons

 

Terminator

 

All of the above are translated into protein

Exons

Which of the following is NOT used during TRANSLATION?

 

mRNA

 

tRNA

 

Ribosome

 

Terminator

Terminator

The peptidyl transferase is the enzymatic function of the:

 

Splicesome

 

Large ribosome subunit

 

Small ribosome subunit

 

Polymerase

Large ribosome subunit

The role of the small ribosomal subunit is to:

 

Bind the release factor

 

Recognize the start codon

 

Recognize the mRNA

 

Attach ATP to the acceptor stem

Recongize the mRNA

Which of the following will bind to the release factor?

 

UAA

 

AUA

 

GUU

 

AUG

UAA

Which of the following contains a CODON?

 

tRNA

 

mRNA

 

Intron

 

rRNA

 

Both answers A and B contain codons

mRNA

Molecule X interacts with a DNA binding protein, causing the protein to bind to DNA and down-regulate gene expression.  Molecule X is a:

 

Activator

 

Repressor

 

Inducer

 

Co-repressor

 

Inhibitor

Co-repressor

The lac operon contains how many promoters?

 

0

 

1

 

3

 

4

1

Which of the following sites would be a target of a TRANSLATIONAL REPRESSOR?

 

Shine-Delgarno sequence

 

Stop codon

 

Enhancer

 

Silencer

Shine-Delgarno sequence

The inducer molecule for the lac activator protein is:

 

TPP

 

Tryptophan

 

cAMP

 

Glucose

cAMP

What would be the result if the trp codons in region 1 of the trp leader sequence were missing?

 

Transcription would always occur

 

Transcription would always attenuate

Transcription would always attenuate

Which of the following circumstances would favor binding of CAP protein and the lac repressor to DNA?

 

High glucose, low lactose

 

Low glucose, low lactose

 

High glucose, high lactose

 

Low glucose, high lactose

Low glucose, low lactose

A protein that covers and hides the intron/exon boundary site is:

 

Translational regulator

 

Splicing repressor

 

Splicing enhancer

 

RISC

Splicing repressor

Which of the following protects turtles from apoxia (absence of oxygen)?

 

ß-Galactosidase

 

INS

 

APOLD1

 

trpL

APOLD1

Which of the following would NOT occur if an insulator were removed from DNA?

 

Heterochromatin would spread to a region that would otherwise be euchromatin

 

An enhancer or silencer would interact with an inappropriate gene

 

Regulatory transcription factors would bind to the wrong enhancer or silence

 

All of the above are possible if an insulator were removed from DNA

Regulatory transcription factors would bind to the wrong enhancer or silence

Regulatory transcription factors would NOT bind to which of the following?

 

TATA Box

 

Enhancer sequence

 

Glucocorticoid Response Element

 

Silencer

 

Operator

TATA Box

Which transcription factor is the most likely to bind to the following sequence (the underlined nucleotides are binding sites for the alpha-helix of the transcription factor(s))

 

ATCGAATTAGCGTATGATTATACGA

 

Zinc finger

 

Leucine zipper homodimer

 

Helix-loop-helix heterodimer

Leucine zipper homodimer

DNA undergoes a mutation in a region adjacent to a housekeeping gene.  The mutation causes the entire housekeeping gene to undergo chromatin remodeling to a heterochromatin state.  The mutation event likely altered a ______________.

 

Regulatory element

 

Silencer

 

Enhancer

 

Insulator

Insulator

Downregulation of the glucocorticoid receptor leads to:

 

A greater response to the glucocorticoid hormone

 

Individuals who are less tolerant to stress

 

Imprinting of the glucocorticoid hormone

 

Fewer glucocorticoid response elements

Individuals who are less tolerant to stress

Which of the following would have the highest levels of gene expression?

 

A promoter that is methylated

 

A mutation that has rendered an enhancer inactive

 

HDAC activity on an enhancer

 

HAT activity on a promoter

HAT activity on a promoter

The inactive X chromosome would contain which histone variant?

 

H2AX

 

MacroH2A

 

H3.3

 

cenH3

MacroH2A

Which DNA Polymerase is responsible for most DNA replication?

DNA Pol III

What DNA Polymerase is responsible for removing and filling in primers?

DNA Pol I

A transition mutation results in:

A. A purine being replaced by a pyrimidine

B. A pyrimidine being replaced by a purine

C. A purine replaced by another purine

D. An insertion or deletion of one base

C

Which of the following describes a transversion?

A. G → A

B. A → G

C. T → G

D. C → T

C

A germ-line mutation differs from a somatic mutation because it:

A. Occurs in body tissues only

B. Cannot be passed to offspring

C. Occurs in gametes and is heritable

D. Always produces cancer

C

Huntington disease is caused by:

A. A deletion in exon 3 of the huntingtin gene

B. Expansion of a CAG trinucleotide repeat

C. A point mutation in the promoter

D. Loss of a start codon

B

Which of the following is a mutagen that inserts itself between base pairs?

A. Base analog

B. Deaminating agent

C. Intercalating agent

D. Alkylating agent

C

Photolyase repairs DNA damage caused by:

A. Oxidative stress

B. Ultraviolet light–induced thymine dimers

C. Depurination

D. Intercalating agents

B

Which of the following is a spontaneous mutation?

A. Deamination of cytosine to uracil

B. Incorporation of 5-bromouracil

C. Alkylation by EMS

D. Intercalation of ethidium bromide

A

A reactive oxygen species (ROS) can cause:

A. Base oxidation leading to mispairing

B. Insertion mutations

C. Frameshift suppression

D. Ribosomal stalling

A

A  trinucleotide repeat expansion leads to:

A. Gene deletion

B. Frameshift mutation

C. Hairpin formation and repeat instability

D. Chromosomal inversion

C

Photoreactivation directly reverses thymine dimers using:

A. ATP hydrolysis

B. Photolyase and visible light

C. Nucleotide excision repair

D. Homologous recombination

B

The mismatch repair system differs from nucleotide excision repair because it:

A. Removes bulky adducts

B. Recognizes distortions in the double helix

C. Detects incorrect base pairing after replication

D. Uses photolyase

C

Non-homologous end joining (NHEJ) differs from homologous recombination repair

(HRR) because:

A. NHEJ uses a homologous chromosome as a template

B. NHEJ is error-prone and can lead to indels

C. HRR joins blunt ends without loss

D. HRR acts only in G1 phase

B

The Pribnow box is located:

A. In prokaryotes

B. In eukaryotes

C. Upstream of the terminator

D. In the Shine-Dalgarno sequence

A

The transcription bubble forms when:

A. Ribosomes begin translation

B. RNA polymerase unwinds a small DNA region

C. DNA ligase seals Okazaki fragments

D. The rho protein binds to RNA

B

Which statement about the template strand is correct?

A. It has the same sequence as the RNA (except U for T)

B. It is read 5′ → 3′ by RNA polymerase

C. It is complementary to the mRNA

D. It always contains the start codon

C

Rho-independent termination involves:

A. Rho binding and ATP hydrolysis

B. Formation of a hairpin

C. The sigma factor

D. rho gene mutations

B

The TATA box is most similar in function to which bacterial element?

A. Operator

B. Pribnow box

C. Shine-Dalgarno sequence

D. Terminator

B

Enhancers function by:

A. Binding RNA polymerase II directly

B. Increasing transcription from distant sites via activator proteins

C. Repressing translation

D. Splicing introns

B

Which of the following is not a modification of pre-mRNA?

A. 5′ capping

B. Poly-A tail addition

C. RNA editing

D. DNA methylation

D

Introns are:

A. Coding sequences retained in mRNA

B. Noncoding regions removed during splicing

C. Sequences promoting transcription

D. Regions bound by repressors

Alternative splicing increases protein diversity by:

A. Changing promoter sequences

B. Producing multiple mRNAs from one gene

C. Modifying tRNA molecules

D. Altering ribosomal RNA

B

The sequence hypothesis proposes that:

A. DNA directly converts to protein

B. RNA sequence determines amino-acid sequence

C. Protein dictates mRNA structure

D. Ribosomes control gene expression

B

The start codon in most mRNAs is:

A. UAA

B. UAG

C. AUG

D. UGA

C

The anticodon of a tRNA pairs with:

A. The ribosome E site

B. The codon in mRNA

C. The Shine-Dalgarno sequence

D. The 3′ poly-A tail

B

The E, P, and A sites of the ribosome function respectively in:

A. Entry of tRNA, peptide bond formation, exit of empty tRNA

B. Exit, peptide-bond formation, aminoacyl-tRNA entry

C. Peptide bond formation, translocation, exit

D. Release, attachment, elongation

B

Ochratoxin A inhibits translation by:

A. Blocking the ribosomal A site

B. Degrading mRNA

C. Inhibiting RNA polymerase II

D. Causing tRNA mischarging

A

The lacZ gene encodes:

A. Lactose permease

B. β-galactosidase

C. CAP protein

D. Repressor

B

When lactose is present and glucose is absent:

A. The lac repressor binds the operator

B. cAMP–CAP activates transcription

C. The operon is repressed

D. No allolactose is formed

B

An effector molecule such as allolactose functions by:

A. Binding to RNA polymerase II

B. Changing the shape of a regulatory protein

C. Repressing CAP binding

D. Blocking the Shine-Dalgarno sequence

B

Housekeeping genes differ from regulated genes because they:

A. Are only expressed in response to signals

B. Encode proteins needed under all conditions

C. Are repressed by glucose

D. Lack promoters

B

The trp repressor binds to the operator when:

A. Tryptophan levels are high

B. Tryptophan levels are low

C. Attenuation occurs

D. Ribosomes stall at leader peptides

A

Attenuation in the trp operon depends on:

A. Repressor binding only

B. Formation of alternative hairpins in the leader mRNA

C. The CAP–cAMP complex

D. RNA polymerase pausing at the promoter

B

Riboswitches regulate gene expression by:

A. Changing mRNA structure upon ligand binding

B. Binding to DNA directly

C. Degrading RNA polymerase

D. Recruiting ribosomes

A

Combinatorial control refers to:

A. Genes controlled by a single activator

B. Integration of multiple transcription factors to regulate one gene

C. Translation control through ribosomes

D. Chromosomal deletions

B

General transcription factors (GTFs):

A. Bind enhancer regions only

B. Are required for RNA polymerase II to initiate transcription

C. Are unique to repressors

D. Mediate RNA splicing

B

The glucocorticoid receptor activates transcription when:

A. Bound by cortisol and dimerized

B. Unbound and cytoplasmic

C. Phosphorylated without ligand

D. Degraded by proteasomes

A

Upregulation of a gene results in:

A. Decreased mRNA transcription

B. Increased mRNA transcription

C. Loss of enhancer activity

D. Histone deacetylation

B