Question 1

BRCA1 and BRCA2 are considered to be tumor-suppressor genes because

Accepted Answer

A)   they prevent infection by retroviruses that cause cancer.
B)   their normal products participate in repair of DNA damage.
C)   the mutant forms of either one of these promote breast cancer.
D)   the normal genes make estrogen receptors.
E)   they block penetration of breast cells by chemical carcinogens.

Question 2

Proto-oncogenes can change into oncogenes that cause cancer. Which of the following best explains the presence of these potential time bombs in eukaryotic cells?

Accepted Answer

A)   Proto-oncogenes first arose from viral infections.
B)   Proto-oncogenes normally help regulate cell division.
C)   Proto-oncogenes are genetic "junk."
D)   Proto-oncogenes are mutant versions of normal genes.
E)   Cells produce proto-oncogenes as they age.

Question 3

A researcher introduces double-stranded RNA into a culture of mammalian cells, and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe.
-In addition, she finds what other evidence of this single-stranded RNA piece's activity?

Accepted Answer

A)   She can measure the degradation rate of the remaining single strand.
B)   She can measure the decrease in the concentration of Dicer.
C)   The rate of accumulation of the polypeptide to be translated from the target mRNA is reduced.
D)   The amount of miRNA is multiplied by its replication.
E)   The cell's translation ability is entirely shut down.

Question 4

The functioning of enhancers is an example of

Accepted Answer

A)   transcriptional control of gene expression.
B)   a post-transcriptional mechanism to regulate mRNA.
C)   the stimulation of translation by initiation factors.
D)   post-translational control that activates certain proteins.
E)   a eukaryotic equivalent of prokaryotic promoter functioning.

Question 5

A genetic test to detect predisposition to cancer would likely examine the APC gene for involvement in which type(s) of cancer?

Accepted Answer

A)   colorectal only
B)   lung and breast
C)   small intestinal and esophageal
D)   lung only
E)   lung and prostate

Question 6

Which of the following statements describes proto-oncogenes?

Accepted Answer

A)   Their normal function is to suppress tumor growth.
B)   They are introduced to a cell initially by retroviruses.
C)   They are produced by somatic mutations induced by carcinogenic substances.
D)   They can code for proteins associated with cell growth.
E)   They are underexpressed in cancer cells.

Question 7

In a series of experiments, the enzyme Dicer has been inactivated in cells from various vertebrates so that the centromere is abnormally formed from chromatin. Which of the following is most likely to occur?

Accepted Answer

A)   The usual mRNAs transcribed from centromeric DNA will be missing from the cells.
B)   Tetrads will no longer be able to form during meiosis I.
C)   Centromeres will be euchromatic rather than heterochromatic and the cells will soon die in culture.
D)   The cells will no longer be able to resist bacterial contamination.
E)   The DNA of the centromeres will no longer be able to replicate.

Question 8

The cancer-causing forms of the Ras protein are involved in which of the following processes?

Accepted Answer

A)   relaying a signal from a growth factor receptor
B)   DNA replication
C)   DNA repair
D)   cell-cell adhesion
E)   cell division

Question 9

Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when the lactose enters the cell?

Accepted Answer

A)   The repressor protein attaches to the regulator.
B)   Allolactose binds to the repressor protein.
C)   Allolactose binds to the regulator gene.
D)   The repressor protein and allolactose bind to RNA polymerase.
E)   RNA polymerase attaches to the regulator.

Question 10

Forms of the Ras protein found in tumors usually cause which of the following?

Accepted Answer

A)   DNA replication to stop
B)   DNA replication to be hyperactive
C)   cell-to-cell adhesion to be nonfunctional
D)   cell division to cease
E)   growth factor signaling to be hyperactive

Question 11

Which of the following statements about the DNA in one of your brain cells is true?

Accepted Answer

A)   Most of the DNA codes for protein.
B)   The majority of genes are likely to be transcribed.
C)   Each gene lies immediately adjacent to an enhancer.
D)   Many genes are grouped into operon-like clusters.
E)   It is the same as the DNA in one of your heart cells.

Question 12

A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in

Accepted Answer

A)   continuous transcription of the structural gene controlled by that regulator.
B)   complete inhibition of transcription of the structural gene controlled by that regulator.
C)   irreversible binding of the repressor to the operator.
D)   inactivation of RNA polymerase by alteration of its active site.
E)   continuous translation of the mRNA because of alteration of its structure.

Question 13

In humans, the embryonic and fetal forms of hemoglobin have a higher affinity for oxygen than that of adults. This is due to

Accepted Answer

A)   nonidentical genes that produce different versions of globins during development.
B)   identical genes that generate many copies of the ribosomes needed for fetal globin production.
C)   pseudogenes, which interfere with gene expression in adults.
D)   the attachment of methyl groups to cytosine following birth, which changes the type of hemoglobin produced.
E)   histone proteins changing shape during embryonic development.

Question 14

If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then

Accepted Answer

A)   the amino acid inactivates the repressor.
B)   the enzymes produced are called inducible enzymes.
C)   the repressor is active in the absence of the amino acid.
D)   the amino acid acts as a corepressor.
E)   the amino acid turns on transcription of the operon.

Question 15

Use the following information to answer the following questions.
In Drosophila after ~100 minutes postfertilization, the embryo looks like the following diagram, with all nuclei having moved to the periphery and, subsequently, four of the nuclei being sequestered at the posterior end.
  
Drosophila embryo after about 2 hours.
-Formation of the pole cells (the four sequestered cells) demonstrates the role of

Accepted Answer

A)   segmentation genes.
B)   homeotic genes.
C)   maternal effect genes.
D)   zygotic genes.
E)   all of the above.

Question 16

You are given an experimental problem involving control of a gene's expression in the embryo of a particular species. One of your first questions is whether the gene's expression is controlled at the level of transcription or translation. Which of the following might best give you an answer?

Accepted Answer

A)   You explore whether there has been alternative splicing by examining amino acid sequences of very similar proteins.
B)   You measure the quantity of the appropriate pre-mRNA in various cell types and find they are all the same.
C)   You assess the position and sequence of the promoter and enhancer for this gene.
D)   An analysis of amino acid production by the cell shows you that there is an increase at this stage of embryonic life.
E)   You use an antibiotic known to prevent translation.

Question 17

Embryonic lethal mutations result in

Accepted Answer

A)   phenotypes that prevent fertilization.
B)   failure to express maternal effect genes.
C)   death during pupation.
D)   phenotypes that are never born/hatched.
E)   homeotic phenotype changes.

Question 18

One way scientists hope to use the recent knowledge gained about noncoding RNAs lies with the possibilities for their use in medicine. Of the following scenarios for future research, which would you expect to gain most from RNAs?

Accepted Answer

A)   exploring a way to turn on the expression of pseudogenes
B)   targeting siRNAs to disable the expression of an allele associated with autosomal recessive disease
C)   targeting siRNAs to disable the expression of an allele associated with autosomal dominant disease
D)   creating knock-out organisms that can be useful for pharmaceutical drug design
E)   looking for a way to prevent viral DNA from causing infection in humans

Question 19

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture.
-In one set of experiments using this procedure in Drosophila, she was readily successful in increasing phosphorylation of amino acids adjacent to methylated amino acids in histone tails. Which of the following results would she most likely see?

Accepted Answer

A)   increased chromatin condensation
B)   decreased chromatin condensation
C)   abnormalities of mouse embryos
D)   decreased binding of transcription factors
E)   inactivation of the selected genes

Question 20

Among the newly discovered small noncoding RNAs, one type reestablishes methylation patterns during gamete formation and block expression of some transposons. These are known as

Accepted Answer

A)   miRNA.
B)   piRNA.
C)   snRNA.
D)   siRNA.
E)   RNAi.

Exam 18: Regulation of Gene Expression

In a series of experiments, the enzyme Dicer has been inactivated in cells from various vertebrates so that the centromere is abnormally formed from chromatin. Which of the following is most likely to occur?

Correct Answer
verified

One way scientists hope to use the recent knowledge gained about noncoding RNAs lies with the possibilities for their use in medicine. Of the following scenarios for future research, which would you expect to gain most from RNAs?

Correct Answer
verified

Forms of the Ras protein found in tumors usually cause which of the following?

Correct Answer
verified

You are given an experimental problem involving control of a gene's expression in the embryo of a particular species. One of your first questions is whether the gene's expression is controlled at the level of transcription or translation. Which of the following might best give you an answer?

Correct Answer
verified

A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in

Correct Answer
verified

Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when the lactose enters the cell?

Correct Answer
verified

Correct Answer
verified

Proto-oncogenes can change into oncogenes that cause cancer. Which of the following best explains the presence of these potential time bombs in eukaryotic cells?

Correct Answer
verified

In humans, the embryonic and fetal forms of hemoglobin have a higher affinity for oxygen than that of adults. This is due to

Correct Answer
verified

Which of the following statements describes proto-oncogenes?

Correct Answer
verified

The cancer-causing forms of the Ras protein are involved in which of the following processes?

Correct Answer
verified

BRCA1 and BRCA2 are considered to be tumor-suppressor genes because

Correct Answer
verified

If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then

Correct Answer
verified

Correct Answer
verified

Embryonic lethal mutations result in

Correct Answer
verified

A genetic test to detect predisposition to cancer would likely examine the APC gene for involvement in which type(s) of cancer?

Correct Answer
verified

Among the newly discovered small noncoding RNAs, one type reestablishes methylation patterns during gamete formation and block expression of some transposons. These are known as

Correct Answer
verified

A researcher introduces double-stranded RNA into a culture of mammalian cells, and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe. -In addition, she finds what other evidence of this single-stranded RNA piece's activity?

Correct Answer
verified

The functioning of enhancers is an example of

Correct Answer
verified

Which of the following statements about the DNA in one of your brain cells is true?

Correct Answer
verified

Exam 18: Regulation of Gene Expression

In a series of experiments, the enzyme Dicer has been inactivated in cells from various vertebrates so that the centromere is abnormally formed from chromatin. Which of the following is most likely to occur?

Correct AnswerverifiedShow Answer

One way scientists hope to use the recent knowledge gained about noncoding RNAs lies with the possibilities for their use in medicine. Of the following scenarios for future research, which would you expect to gain most from RNAs?

Correct AnswerverifiedShow Answer

Forms of the Ras protein found in tumors usually cause which of the following?

Correct AnswerverifiedShow Answer

You are given an experimental problem involving control of a gene's expression in the embryo of a particular species. One of your first questions is whether the gene's expression is controlled at the level of transcription or translation. Which of the following might best give you an answer?

Correct AnswerverifiedShow Answer

A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in

Correct AnswerverifiedShow Answer

Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when the lactose enters the cell?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Proto-oncogenes can change into oncogenes that cause cancer. Which of the following best explains the presence of these potential time bombs in eukaryotic cells?

Correct AnswerverifiedShow Answer

In humans, the embryonic and fetal forms of hemoglobin have a higher affinity for oxygen than that of adults. This is due to

Correct AnswerverifiedShow Answer

Which of the following statements describes proto-oncogenes?

Correct AnswerverifiedShow Answer

The cancer-causing forms of the Ras protein are involved in which of the following processes?

Correct AnswerverifiedShow Answer

BRCA1 and BRCA2 are considered to be tumor-suppressor genes because

Correct AnswerverifiedShow Answer

If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Embryonic lethal mutations result in

Correct AnswerverifiedShow Answer

A genetic test to detect predisposition to cancer would likely examine the APC gene for involvement in which type(s) of cancer?

Correct AnswerverifiedShow Answer

Among the newly discovered small noncoding RNAs, one type reestablishes methylation patterns during gamete formation and block expression of some transposons. These are known as

Correct AnswerverifiedShow Answer

A researcher introduces double-stranded RNA into a culture of mammalian cells, and can identify its location or that of its smaller subsections experimentally, using a fluorescent probe. -In addition, she finds what other evidence of this single-stranded RNA piece's activity?

Correct AnswerverifiedShow Answer

The functioning of enhancers is an example of

Correct AnswerverifiedShow Answer

Which of the following statements about the DNA in one of your brain cells is true?

Correct AnswerverifiedShow Answer

Correct Answer
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