Deck 18: Regulation of Gene Expression in Eukaryotes

Question 1

The half-life of a protein is directly related to

A)what kind of cell it is produced in.
B)its tertiary structure.
C)whether it is encoded by a constitutively expressed gene.
D)its N-terminal amino acid residue.
E)the number of stabilizing cross-linkages.

Answer 1

D

Question 2

Unlike prokaryotes,most gene regulation in eukaryotes

A)takes place at the transcriptional level.
B)is controlled at the level of transcript processing.
C)is controlled by inhibitory proteins.
D)is based on posttranslational modification.
E)None of these

Answer 2

B

Question 3

The protein class(es)involved in the activation of transcription is (are)

A)general transcription factors (GTFs).
B)transactivators.
C)coactivators.
D)A and B only
E)A,B,and C

Answer 3

E

Question 4

With respect to genetics,URS stands for

A)uracil response system.
B)upstream regulatory sequence.
C)upstream repressor-binding sequence.
D)unregulated repression series.
E)uniform response system.

Question 5

mRNA regulation can be achieved at the level of

A)transport.
B)processing.
C)translation.
D)life span (degradation).
E)All of these

Question 6

Control of transcription initiation of eukaryotic protein-coding genes involves

A)enhancers.
B)promoters.
C)repressors.
D)activators.
E)All of these

Question 7

Chromosome-level gene repression involves

A)supercoiling.
B)physical blockage of gene regions.
C)chromatin formation.
D)nucleosomes.
E)All of these

Question 8

Unlike bacterial operons,eukaryotic operons

A)are all positively controlled.
B)are all negatively controlled.
C)are restricted to certain eukaryotic kingdoms.
D)are exceedingly rare.
E)None of these

Question 9

Change in the DNA-histone complex that can increase or decrease transcriptional activity is termed

A)induction.
B)gene regulation.
C)chromatin remodeling.
D)nucleosome formation.
E)None of these

Question 10

When a promoter element is bound by a positive regulatory protein,the result is

A)activation of replication.
B)activation of transcription.
C)activation of translation.
D)repression of replication.
E)repression of transcription.

Question 11

HREs are

A)hormone receptors.
B)DNA sequences in promoter regions to which steroid hormone receptors bind.
C)proteins that interact with histones.
D)elements that lead to histone deacetylation.
E)None of these

Question 12

In eukaryotic cells,steroid hormones

A)bind to cytoplasmic receptors,are transported to the nucleus,bind DNA,and regulate gene expression.
B)bind to cell surface receptors and send signals that result in regulation of genes in the nucleus.
C)act as enhancers and bind to an assortment of activators and repressors.
D)methylate DNA to regulate gene expression.
E)cause maternal effect.

Question 13

Hormones can be considered

A)inducers.
B)repressors.
C)transcription regulators.
D)translation regulators.
E)enzymes.

Question 14

Which of the following secondary structures may be a DNA-binding domain?

A)Zinc finger
B)Leucine zipper
C)Helix-turn-helix
D)A and B only
E)A,B,and C

Question 15

A similarity between regulation of the lac operon in bacteria and the regulation of galactose utilization in yeast is that both pathways

A)transcribe all the genes necessary as one polycistronic mRNA.
B)use feedback inhibition to stop making their sugars.
C)use a modified version of their sugars as inducers.
D)are subject to catabolite repression.
E)C and D only

Question 16

Removal of the 5' G-cap of mRNA transcripts

A)prevents transcript transport.
B)leads to degradation by exonucleases.
C)extends mRNA half-life.
D)leads to polyadelylation.
E)reduces mRNA half-life.

Question 17

RNA silencing involves

A)miRNAs.
B)siRNAs.
C)double-stranded RNA.
D)a protein called Dicer.
E)All of these

Question 18

Proteins that are encoded by the same gene but differ in structure and function are the product of alternative splicing in pre-mRNA processing.Such protein variants are termed

A)isoteins.
B)heteromeric proteins.
C)isozymes.
D)protein isoforms.
E)allelomorphs.

Question 19

Activators in eukaryotes

A)bind to enhancers.
B)may act as monomers
C)may act as homodimers.
D)may act as heterodimers with a DNA binding subunit and an activation subunit.
E)All of these

Question 20

Transcriptionally active genes show lower levels of DNA methylation compared with transcriptionally inactive genes.

Question 21

Explain how combinatorial gene regulation permits regulation of a large diversity of genes with relatively few regulatory proteins.

Question 22

Steroid and peptide hormone receptors are typically cytoplasmic.

Question 23

Steriod hormones are effector molecules.

Question 24

Noncoding RNAs called mRNAs are present in most eukaryote genomes and are involved in negatively regulating gene expression through degradation of mRNAs with complementary sequences.

Question 25

What essential difference between the growth and reproductive strategies of prokaryotes and multicellular eukaryotes explains why the latter have far more sophisticated regulatory mechanisms?

Question 26

What are enhancers?

Question 27

What would happen developmentally if a zygote with XY sex chromosome karyotype had a defective testosterone receptor?

Question 28

Recombinases mediate transcript processing from pre-mRNA to mature mRNA.

Question 29

Gene silencing in eukaryotes is often achieved through chromatin structure.

Question 30

Describe the use of the DNA-degrading enzyme DNase I in experiments that explore the effect of chromatin on gene inactivation.

Question 31

Imprinting is implicated in Prader-Willi and Angelman syndromes.

Question 32

longer poly(A)tails on mRNAs are associated with less translational activity.

Question 33

Embryonic development is orchestrated by a cascading series of genes,the expression of many of which are controlled in time and space by transcription factors and effector molecules of various kinds.But what controls the expression of the first regulatory genes to be transcribed in the newly fertilized zygote?

Question 34

Some genes that are expressed in the fetal stage are never expressed again in that individual's life.What do you think is the most common mechanism for preventing the expression of such genes?

Question 35

Heterochromatin is associated with

A)differential gene expression.
B)gene silencing.
C)mRNA translation.
D)heterozygotes.
E)A,B,and C only

Question 36

Eukaryotic repression generally occurs via physical blockage of the promoter.

Question 37

Plants produce steroids called phytosterols,which have various functions in plant physiology.Some phytosterols are thought to have a defensive function,however,specifically in repelling insect herbivores.How might plant-derived steroids help protect plants from insect attack?

Question 38

Describe how siRNA functions in regulation of expression and how this can be used as a tool in genetic research.

Question 39

Gene silencing is a form of regulation controlled by repressor proteins.

Question 40

Several common protein structural motifs are now known to be involved in DNA recognition and binding.What are these,and how would researchers use genomic data to help figure out if new candidate genes encode such DNA-binding proteins?

Question 41

What are some advantages and disadvantages of arranging gene clusters into operons?

Question 42

Interference RNA technology is one of the most exciting new developments in genetics in recent years.In April 2004,Cancer Research UK and the Netherlands Cancer Institute announced creation of a 24,000-molecule iRNA library,designed to inactivate about 8,000 human genes.One hope for this library is its application in combating cancer.How might iRNA be implemented in cancer treatment?

Question 43

In genetic imprinting,expression depends on the parent of origin of a given allele.How might imprinting affect the expression of a hypothetical autosomal disease that expresses in dominant fashion and recessive fashion,and how might imprinting be detected?

Question 44

Insect growth and metamorphosis is controlled by the steroid hormones ecdysone and juvenile hormone (JH).In insects like butterflies and moths that have a distinct larval (juvenile)and adult stage,the relative amount of JH determines whether the insect molts to the next juvenile stage or switches to become an adult.Can you think of a way to use this hormonal system to control caterpillar agricultural pests?

Question 45

Evolutionary biologists suspect that genetic imprinting evolved through parent-offspring conflict.What kinds of "conflict of interest" in progeny development can you imagine between mammalian parents?