Deck 19: Regulation Of Gene Expression In Eukaryotes

Question 1

At which level is the gene expression of eukaryotes regulated?

A) Transcription
B) Post-transcriptional processing
C) Translation
D) Transcription and post-transcriptional processing
E) All of these are correct.

Answer 1

E

Question 2

If gene expression is regulated at the transcriptional level,where in a eukaryotic cell does this regulation take place?

A) Nucleus
B) Mitochondria
C) Rough ER
D) Ribosome
E) Cytoplasm

Answer 2

A

Question 3

In a gene with multiple introns present,what will happen if two successive introns,separated by one exon are removed together at the same time by a spliceosome?

A) The exon will be removed with the introns.
B) The exon will be removed but later reinserted in the same place.
C) The exon will be removed but later reinserted at the end of the gene.
D) The exon will remain in the sequence.
E) The exon will remain in the sequence but will be altered.

Answer 3

A

Question 4

Which component of a eukaryotic cell can serve as the location for regulation of gene expression?

A) Nucleus
B) Cytoplasm
C) Mitochondria
D) Nucleus and cytoplasm
E) All of these are correct.

Question 5

Positive and negative regulator proteins that bind to specific regions of the DNA and stimulate or inhibit transcription in eukaryotes are known as

A) transcription inhibitors.
B) transcription factors.
C) unit factors.
D) translation regulators.
E) None of these are correct.

Question 6

Which of the following would not induce eukaryotic gene expression?

A) Heat
B) Light
C) Hormones
D) siRNAs
E) Growth factors

Question 7

Hormone-induced gene expression is mediated by specific sequences in the DNA known as A)HREs.
B)HSPs.
C)ESTs.
D)STRs.
E)PCRs.

Question 8

How is it possible for a single gene to encode different polypeptides?
1)Post translational processing
2)Alternative splicing during post transcriptional processing
3)Abnormal spliceosome activity during post transcriptional processing

A) 1
B) 2
C) 3
D) 1 and 2 and 3
E) It is not possible.

Question 9

Which of the following can affect RNA transcript stability in the cytoplasm?

A) 3' Poly A tails
B) The sequence of the 3¢ untranslated region (3¢ UTR) preceding a poly(A) tail
C) Chemical factors, such as hormones
D) Small interfering RNAs (siRNAs)
E) All of these are correct.

Question 10

Which of the following genes is expressed in reaction to the exposure of light?

A) Troponin T
B) HSPs
C) rbcS
D) Sxl
E) None of these are correct.

Question 11

How does alternative splicing modify an RNA transcript to allow for the production of different polypeptides?

A) It modifies the coding sequence of an RNA by deleting some of its exons.
B) It modifies the coding sequence of an RNA by deleting all of its introns.
C) It modifies the coding sequence of an RNA by deleting only some of the introns.
D) It modifies the non-coding sequence of an RNA by deleting all of its exons.
E) None of these are correct.

Question 12

Which level of gene regulation controls the expression of heat shock proteins?

A) Transcription
B) Post-transcription processing
C) Translation
D) Post-transcription processing and translation
E) All of these are correct.

Question 13

Where does RNA transcript modification occur in eukaryotic cells?

A) Nucleus
B) Mitochondria
C) Rough ER
D) Lysosome
E) Ribosome

Question 14

Which of the following statements is correct?

A) Prokaryotes undergo processing after transcription and eukaryotes do not.
B) Eukaryotes undergo processing after transcription and prokaryotes do not.
C) Prokaryotes undergo transcription but eukaryotes do not.
D) Eukaryotes undergo transcription but prokaryotes do not.
E) There are no differences between the expression of genes in prokaryotes and eukaryotes.

Question 15

The protein-DNA interactions that control whether or not a gene is accessible to RNA polymerase occur during which phase of gene expression?

A) Replication
B) Transcription
C) Translation
D) Replication and transcription
E) Transcription and translation

Question 16

Why is transcriptional control of gene expression more difficult in eukaryotes than in prokaryotes?
1)Genes are sequestered in the nucleus.
2)Eukaryotic cells need fairly elaborate internal signaling systems to control the transcription of DNA.
3)Environmental cues may have to pass through layers of cells in order to have an impact on the transcription of genes in a particular tissue.

A) 1
B) 2
C) 3
D) 1 and 2
E) All of these are correct.

Question 17

Which of the following is not true regarding steroid hormones?

A) They are small, lipid-soluble molecules derived from cholesterol.
B) Insulin is an example.
C) Testosterone and estrogen are examples.
D) The have little or no trouble passing through cell membranes.
E) They interact with cytoplasmic or nuclear proteins called hormone receptors.

Question 18

Which of the following is a good example of alternative splicing in eukaryotes?
1)Lac operon
2)Troponin T gene in rats
3)Sex-lethal (Sxl)gene in Drosophila

A) 1
B) 2
C) 3
D) 1 and 2
E) 2 and 3

Question 19

Which of the following is true regarding hormone response elements?

A) The more HREs present, the more vigorous transcription.
B) The fewer HREs present, the more vigorous transcription.
C) The HREs are specific sequences present in the tRNA molecule.
D) The HREs are situated far away from the genes they regulate.
E) The HREs are part of post-transcriptional control mechanisms.

Question 20

A group of proteins that help to stabilize the internal cellular environment when organisms are subjected to the stress of high temperature are known as

A) cold shock proteins.
B) heat shock proteins.
C) chaperone proteins.
D) transcription proteins.
E) hormones.

Question 21

Which of the following statements is true regarding heterochromatin?

A) It stains lightly when stained with Feulgen reagent.
B) It represents transcriptionally active regions of the chromosome.
C) Specialized chromatin structures (scs) can insulate genes from the effects of heterochromatin.
D) Euchromatic genes that are artificially placed next to heterochromatin are transcribed at abnormally high levels.
E) Heterochromatin is hypersensitive to DNAse digestion.

Question 22

The temporal sequence of puffing in polytene chromosomes is controlled by

A) ecdysone.
B) testosterone.
C) estrogen.
D) progesterone.
E) insulin.

Question 23

The use of small RNA molecules to interfere with gene expression is known as

A) DNA interference.
B) RNA interference.
C) hormone regulation.
D) HRE regulation.
E) None of these are correct.

Question 24

Which of the following is true regarding eukaryotic transcription factors?

A) Most eukaryotes have only one or a few transcription factors.
B) Many transcription factors have dimerization motifs.
C) Eukaryotic transcriptional activation does not require protein-protein interactions.
D) Transcription factors can be active only when they form homodimers.
E) Homeodomains are a class of transcription factors.

Question 25

RISC-associated RNAs that result in mRNA cleavage are usually termed

A) siRNAs.
B) miRNAs.
C) SNRPs.
D) mtDNAs.
E) STRs.

Question 26

An interaction mediated by base pairing between the single strand of RNA in the RNA-protein complex and a complementary sequence in the messenger RNA molecule prevents the expression of the gene that produced the mRNA.This is known as

A) RNA Induced Silencing Complex.
B) RNA Introduction Salination Complex.
C) Ribosomal Induced Silencing Complex.
D) Ribsomal Interfering Single Complex.
E) RNA Interference Silencing Complex.

Question 27

In the human genes for b-globin,a locus control region is characterized by

A) regulating the expression of the b-globin gene.
B) containing several DNAse I hypersensitive sites.
C) being about 15 kb in length.
D) acting upstream of the genes it affects.
E) All of these are correct.

Question 28

Enhancers are

A) domains in proteins that enhance gene transcription.
B) special cis regions in the vicinity of a gene to which transcription factors bind.
C) also capable of inhibiting gene transcription.
D) regions along a promoter to which basal transcription factors bind.
E) not able to act over long distances away from the gene.

Question 29

In transcribed DNA,nucleosomes are altered by multiprotein complexes that ultimately facilitate the action of RNA polymerase in a process known as

A) chromosome reworking.
B) chromatin remodeling.
C) chromatin editing.
D) chromosome altering.
E) None of these are correct.

Question 30

Which of the following could be a source for a siRNA or miRNA molecule?

A) Mir gene
B) Transposon
C) RNA virus
D) Transgene
E) All of these are correct.

Question 31

Whenever the RNA within the RISC pairs imperfectly with its target sequence,the mRNA is usually not cleaved; instead,translation of the mRNA is inhibited.RISC-associated RNAs that have this effect are usually termed

A) siRNAs.
B) miRNAs.
C) SNRPs.
D) mtDNAs.
E) STRs.

Question 32

The nuclease sensitivity of transcriptionally active genes depends on at least two small nonhistone proteins known as

A) HMG 14.
B) HMG 17.
C) HSP 13.
D) HMG 14 and HMG 17.
E) All of these are correct.

Question 33

Which of the following molecules participates in RNA interference?

A) siRNA
B) tRNA
C) rRNA
D) dsDNA
E) All of these are correct.

Question 34

Which of the following motifs is not characteristic of a eukaryotic transcription factor?

A) Transmembrane domain
B) Helix-turn-helix
C) Leucine zippers
D) Helix-loop-helix
E) All of these are correct.

Question 35

Which type of enzyme produces siRNA molecules in eukaryotes?

A) Restriction exonucleases
B) DNA restriction endonucleases
C) Dicer enzymes
D) Regulator enzymes
E) RNA polymerase

Question 36

DNA regions which are locally unwound because transcription has begun,and which are sensitive to low doses of DNAse 1 are known as

A) RNase hypersensitive sites.
B) RNase hyposensitive sites.
C) DNase 1 hypersensitive sites.
D) DNase 1 hyposensitive sites.
E) None of these are correct.

Question 37

Which of the following gives support to the idea that transcription takes place in "open" regions of the chromosome?
1)The fact that 3H-uridine incorporated into newly synthesized RNA is localized around the lateral loops of the lampbrush chromosomes rather than around the condensed axes in amphibian oocytes.
2)The study of polytene chromosomes in Drosophila and other Dipteran insects
3)The study of lambrush chromosomes in human oocytes

A) 1
B) 2
C) 3
D) 1 and 2
E) All of these are correct.

Question 38

Which of the following is a component of eukaryotic and prokaryotic gene regulation?

A) Alternate splicing
B) Heat shock proteins
C) Hormone responsive elements
D) Euchromatin
E) Gene-dosage compensation.

Question 39

Which of the following is true about signal transduction by hormones?

A) All hormones are linear chains of amino acids (peptides).
B) Hormones can diffuse freely in and out of cells.
C) Steroid hormone-receptor complexes can enter the cell nucleus.
D) Peptide hormones directly act on DNA to stimulate transcription.
E) Binding of a peptide hormone to its receptor causes a conformational change in the hormone molecule.

Question 40

Which of the following is true of enhancer sequences?

A) They can act over very large distances.
B) They can only act in one specific orientation.
C) They are usually between 10 and 35 bp long.
D) They can only function if located upstream of a gene.
E) They can only function if located downstream of a gene.

Question 41

All of the following statements are true regarding inactivation of X-chromosome in mammals,except:

A) X-chromosome inactivation begins at the X-inactivation center.
B) All of the genes on an inactivated X-chromosome are transcriptionally silent.
C) Inactive X-chromosomes can be easily identified in mammalian cells.
D) The Barr body represents an inactive X-chromosome.
E) Inactive X-chromosomes have a different pattern of distribution of acetylated histone.

Question 42

Which of the following can be responsible for silencing a gene?
1)Protein complexes like the Polycomb complex
2)Methylation of DNA
3)Telomeric variant surface glycoprotein like vsg

A) 1
B) 2
C) 3
D) 1 and 2
E) All of these are correct.

Question 43

In one individual euchromatic genes are artificially transposed to a heterochromatic environment,resulting in a mixture of normal and mutant characteristics.This is called

A) position-effect variegation.
B) gene amplification.
C) gene-dosage compensation.
D) inactivation of whole chromosomes.
E) signal transduction.

Question 44

Which of the following statements is true regarding dosage compensation? A)In Drosophila,one of the two X-chromosomes is randomly inactivated in females.
B)In mammals,the genes on the single X-chromosome in a male are transcribed at a higher level.
C)The X-inactive specific transcript is a functional RNA molecule that results in X-inactivation in Drosophila.
D)In C.elegans,dosage compensation results from partial repression of X-linked genes in hermaphrodites.
E)The gene product of the gene maleless is responsible for X-inactivation in mammals.

Question 45

Which of the following can increase gene expression?

A) Silencing a gene
B) Amplifying a gene
C) Imprinting a gene
D) Silencing a gene and amplifying a gene
E) All of these are correct.

Question 46

Compare and contrast the actions of steroid hormones with peptide hormones.

Question 47

How does the phenomenon of RNA interference regulate gene expression on a post-transcriptional level?

Question 48

How does alternative splicing help to modify RNA transcripts in eukaryotes.Explain your answer by using a real life example such as that of the troponin T gene in rats.

Question 49

How can an external environmental factor cause the regulation of gene expression in eukaryotes? Explain your answer by providing a real life example such as the heat shock proteins in Drosophila.

Question 50

Which of the following is a mechanism of dosage compensation?

A) Inactivation
B) Hyperactivation
C) Hypoactivation
D) All of these are correct.
E) None of these are correct.

Question 51

Null mutations in male-specific lethal loci in Drosophila lead to male-specific lethality.Why does this happen and what is known about the function of these genes?