GEN EXAM 4 QUIZZES

Question 1

A gene is inducible and under negative control. Which of the following pairs will allow expression of this gene?

A. activator + inhibitor
B. activator + repressor
C. repressor + inducer
D. repressor + corepressor

Answer 1

C. repressor + inducer

Question 2

Riboswitches have been shown to affect regulation of ______.

A. transcription and translation
B. only RNA splicing
C. only transcription
D. only translation

Answer 2

A. transcription and translation

Question 3

Which of the following is found in an operon?

A. promoter
B. terminator
C. two or more genes
D. operator
E. All of the answers are correct.

Answer 3

E. All of the answers are correct.

Question 4

A mutation in the lacI gene prevents the gene product from binding allolactose. What will the expression level of the operon be in the absence of lactose?

A. No transcription
B. Transcription will occur only in the presence of glucose
C. Positive regulation
D. Constitutively active

Answer 4

A. No transcription

Question 5

A deletion in an operon removes the terminator. How will that affect the transcript that is produced from the operon?

A. The transcript will be produced and normal in length
B. The transcript will be produced, but will contain a deletion
C. The transcript will be produced, but longer than normal
D. The transcript will not be produced
E. The transcript will be produced, but shorter than normal

Answer 5

C. The transcript will be produced, but longer than normal

Question 6

What is the gene responsible for attenuation in the trp operon?

A. trpR
B. trpD
C. trpL
D. trpC

Answer 6

C. trpL

Question 7

If the Trp codons in the trpL gene were mutated to encode another amino acid, what would the result be?

A. The trp operon would only be transcribed when tryptophan in the cell was high.
B. The trp operon would never be transcribed.
C. The trp operon would always be transcribed.
D. The trp operon would only be transcribed when tryptophan in the cell was low.

Answer 7

B. The trp operon would never be transcribed.

Question 8

In a particular E. coli strain, a mutation in the thiMD operon results in improper formation of the stem loop secondary structure making it impossible to bind TPP. There are two enzymes encoded by the thiMD operon. How many of the enzymes encoded in the thiMD operon are translated?

A. One
B. Zero
C. Two
D. Three

Answer 8

C. Two

Question 9

The regulation of protein function, not gene expression is called ______ regulation.

A. translational
B. transcriptional
C. posttranslational
D. posttranscriptional

Answer 9

C. posttranslational

Question 10

Antisense RNA does which of the following?

A. binds to a complementary RNA and prevents its translation
B. occupies the A and P sites of the ribosome
C. inhibits the formation of the open complex in transcription
D. prevents the correct folding of a newly formed peptide

Answer 10

A. binds to a complementary RNA and prevents its translation

Question 11

If a bacterium is placed in an environment that contains both glucose and lactose, the regulation of the lac operon will allow which nutrient to be processed first?

A. glucose
B. lactose
C. Both will be processed equally.
D. Neither will be processed in this environment.

Answer 11

A. glucose

Question 12

In Jacob, Monod, and Pardee’s experiment, how many functional copies of lacI were there in the merozygote?

A. 2
B. 1
C. 3
D. 0

Answer 12

B. 1

Question 13

Regulation of gene expression may occur at which of the following level?

A. transcription
B. translation
C. posttranslation
D. All of the answers are correct.

Answer 13

D. All of the answers are correct.

Question 14

What stem-loop conformations favor attenuation in the trp operon?

A. 1-2 and 2-3
B. 2-3
C. 1-2
D. 3-4

Answer 14

D. 3-4

Question 15

Allosteric regulation is accomplished by

A. a small molecule that fits into a site on the enzyme that is not the active site.
B. a small molecule that covalently modifies a site on the enzyme that is not the active site.
C. a large protein that blocks an enzyme’s active site.
D. a small molecule that fits into an enzyme’s active site.

Answer 15

A. a small molecule that fits into a site on the enzyme that is not the active site.

Question 16

In the Jacob Monod merozygote experiment, what was indicated by the presence of a yellow color when b-ONPG was added?

A. The lac operon was completely turned off.
B. The researcher added too much b-ONPG.
C. Beta-galactosidase was present.
D. Expression of the lac operon is constitutive whether lacI is functional or not.

Answer 16

C. Beta-galactosidase was present.

Question 17

A deletion in an operon removes the promoter. How will that affect the transcript that is produced from the operon?

A. The transcript will not be produced
B. The transcript will be produced, but shorter than normal
C. The transcript will produced, but will contain a deletion
D. The transcript will be produced, but longer than normal
E. The transcript will be produced and normal in length

Answer 17

A. The transcript will not be produced

Question 18

Translational regulatory proteins recognize specific areas of what molecule?

A. tRNA
B. Ribosome
C. rRNA
D. mRNA
E. None of the answers are correct.

Answer 18

D. mRNA

Question 19

How many promoters are in an operon?

A. 3
B. 1
C. It depends on how many genes there are in the operon
D. 2

Answer 19

B. 1

Question 20

In Jacob, Monod, and Pardee’s experiment, what would have been the conclusion if all four tubes produced a yellow color when β-ONPG was added?

A. LacI provides the binding site for the repressor
B. Expression of the lac operon is constitutive whether lacI is functional or not
C. LacI encodes a diffusible repressor
D. The researcher added too much β-ONPG

Answer 20

B. Expression of the lac operon is constitutive whether lacI is functional or not

Question 21

Which of the following is not an example of translational regulation in prokaryotes?

A. Binding of antisense RNA to mRNA
B. Altering the structure of the mRNA
C. Phosphorylation of an enzyme
D. Sterically blocking the ribosome

Answer 21

C. Phosphorylation of an enzyme

Question 22

Which DNA repair process utilizes MutL, MutH, and MutS proteins in E. coli?

A. nucleotide excision repair
B. direct repair
C. nonhomologous end joining (NHEJ)
D. base excision repair
E. homologous recombination repair
F. mismatch repair

Answer 22

F. mismatch repair

Question 23

Which process is used to replicate DNA that contains distortions due to unrepaired DNA damage?

A. Translesion synthesis
B. Nonhomologous end joining
C. Nucleotide excision repair
D. Homologous recombination repair

Answer 23

A. Translesion synthesis

Question 24

Which types of mutations are least likely to be subjected to natural selection?

A. Insertion
B. Nonsense
C. Missense
D. Silent

Answer 24

D. Silent

Question 25

Beechdrops is a parasitic plant that cannot perform photosynthesis but relies on its host the Beech tree. However, beechdrops still retains many if not all of the genes for photosynthesis. Snapdragons and gladiolas are common garden flowers that rely on their ability to perform photosynthesis. If you were to compare the gene sequences for these three plants for ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) a protein necessary for photosynthesis what would you predict?

A. The differences between gladiolas and snapdragons would most likely be missense mutations while those in beechdrops may be silent or missense
B. The differences between gladiolas and snapdragons would most likely be silent mutations while those in beechdrops may be silent or missense
C. Since these three plants are not highly related the sequences for RuBisCO would be very different between them
D. The differences between gladiolas and snapdragons would most likely be in the second nucleotide of codons while beechdrops would have a higher number of mutations in the third nucleotide of the different codons

Answer 25

B. The differences between gladiolas and snapdragons would most likely be silent mutations while those in beechdrops may be silent or missense

Question 26

How does position effect influence gene expression?

A. The movement of the genetic material on the chromosome by inversions or translocations may place a coding sequence near a new regulatory region, thus activating the expression of the gene.
B. The movement of the gene may place it into a region that is highly condensed.
C. The movement of a gene may remove it from its normal promoter, thus silencing the gene.
D. All of the answers are correct.

Answer 26

D. All of the answers are correct.

Question 27

Which of the following is correct regarding the rate of mutation?

A. Mutation rates are consistent across species.
B. Mutation rates are constant.
C. Rates of mutation per cell generation typically range from 10^−5 to 10^−9.
D. Mutation rates are not influenced by environmental conditions.

Answer 27

C. Rates of mutation per cell generation typically range from 10^−5 to 10^−9.

Question 28

After screening a colony of bacteria for a given gene, you discover 100 mutant colonies out of 3 million total colonies. What is the mutation rate for this gene in the population?

A. 1.0 x 10^-5
B. 1.0 x 10^5
C. 3.3 x 10^-5
D. 3.0 x 10^5

Answer 28

C. 3.3 x 10-5

Question 29

What would be a set of anticipated results from a “Lederberg” experiment?

A. Total number of colonies on a plate: 1500 Total number of resistant colonies on replica plate with T1: 15
B. Total number of colonies on a plate: 1500 Total number of resistant colonies on replica plate with T1: 1500
C. Total number of colonies on a plate: 1500 Total number of resistant colonies on replica plate with T1: 0
D. Total number of colonies on a plate: 500 Total number of resistant colonies on replica plate with T1: 1500

Answer 29

A. Total number of colonies on a plate: 1500 Total number of resistant colonies on replica plate with T1: 15

Question 30

Which of the following is not an example of a cause of a spontaneous mutation?

A. aberrant recombination
B. transposable elements
C. DNA replication errors
D. tautomeric shifts
E. UV light

Answer 30

E. UV light

Question 31

The conversion of cytosine to uracil in DNA is an example of _____.

A. depurination
B. tautomeric shifts
C. deamination
D. None of the answers are correct.

Answer 31

C. deamination

Question 32

Four cancer patients are treated with an experimental drug. Patients #2 and #4 have an extremely serious adverse reaction to the drug. Another patient (#5) requests to enter the trial and you do not wish to treat this patient if there is any indication that the new patient will have the same side effect. The haplotypes for the region where the allele that controls this sensitivity has been mapped and the haplotypes for this region for these patients are given below. Should you enter patient #5 into the trial?
1: 1A 2B 3C 4B/1A 2B 3A 4C
2: 1A 2C 3B 4B/1B 2A 3B 4A
3: 1B 2A 3A 4B/1C 2B 3A 4A
4: 1B 2C 3B 4B/1A 2B 3A 4C
5: 1A 2B 3A 4C/1B 2A 3B 4A

A. Yes, #5 shares no haplotype combinations with #2 and #4.
B. Yes, since there are no shared haplotypes between #2 and #4 these haplotypes are not correlating with the drug sensitivity.
C. No, # 5 shares the 1A haplotype with #2 and #4.
D. No, # 5 shares the 3B haplotype with

Answer 32

A. Yes, #5 shares no haplotype combinations with #2 and #4.

Question 33

You are working in a lab where you are studying a disease that is known to be caused by a single nucleotide change, although the effect this change ultimately has on the protein’s structure/function is unknown. You have DNA samples from multiple patients that you suspect of having this disease. What is the most efficient way to test the samples for the relevant mutation?

A. Karyotyping
B. Amniocentesis
C. Western blotting
D. DNA sequencing

Answer 33

D. DNA sequencing

Question 34

Which technique can be used at the earliest stage in a pregnancy to provide a sample for fetal genetic testing?

A. amniocentesis
B. chorionic villus sampling
C. Both chorionic villus sampling and amniocentesis are performed at the same stage in a pregnancy.

Answer 34

B. chorionic villus sampling

Question 35

For a single-gene disorder, the concordance among monozygotic twins should be

A. 75%.
B. 50%.
C. 0%.
D. 100%.
E. 25%.

Answer 35

D. 100%.

Question 36

In the analysis of a family, you notice that males are more likely to contract a certain disease, and the daughters of affected males produce 50% of their sons affected with the disease. This disease is displaying which of the following patterns of inheritance?

A. X-linked recessive
B. autosomal recessive
C. autosomal dominant
D. None of these choices are correct.

Answer 36

A. X-linked recessive

Question 37

A gene that promotes the development of cancer when it sustains a gain-of-function mutation is called a

A. proto-oncogene
B. tumor suppressor gene.
C. housekeeping gene.
D. caretaker gene.

Answer 37

A. proto-oncogene

Question 38

The term that indicates that cancer has begun to migrate to other parts of the body is ______.

A. malignant
B. invasive
C. clonal
D. metastatic
E. benign

Answer 38

D. metastatic

Question 39

An example of personalized medicine would be

A. performing an appendectomy on a patient with appendicitis.
B. treatment of diabetics with synthetic instead of natural insulin.
C. treatment of an infection based on the drug resistance of the bacterium.
D. determining the CYP2C9 alleles present to help set the patient’s coumarin dose.

Answer 39

D. determining the CYP2C9 alleles present to help set the patient’s coumarin dose.

Question 40

Epigenetics may play a role in cancer by

A. directly resulting in gene deletions.
B. directly inducing inversion mutations.
C. causing translocations.
D. causing a change in gene expression patterns.

Answer 40

D. causing a change in gene expression patterns.

Question 41

Caspases are active during which of the following?

A. viral integration
B. the normal cell cycle
C. apoptosis
D. DNA replication

Answer 41

C. apoptosis

Question 42

What would be the result if the U-rich sequence after the fourth stem loop in the trp operon was replaced by a UG-rich sequence?

A. Attenuation would occur if tryptophan was high.
B. Attenuation would occur if tryptophan is low.
C. Attenuation would not occur if tryptophan was high.
D. None of the answers are correct.

Answer 42

C. Attenuation would not occur if tryptophan was high.

Question 43

Enzymes involved in metabolism are most likely regulated via _____.

A. feedback inhibition
B. acetylation
C. methylation
D. None of the answers are correct.

Answer 43

A. feedback inhibition

Question 44

Chromatin remodeling complexes alter nucleosomes, this occurs when

A) remodeling proteins bind to TFIID to promote or inhibit nucleosome formation.
B) complexes of ATP-dependent protein degrade histones and release the DNA from nucleosomes.
C) complexes of ATP-dependent proteins may reposition, evict, or change nucleosome composition.
D) remodeling proteins increase the supercoiling of the DNA, which can inhibit nucleosome formation.

Answer 44

C) complexes of ATP-dependent proteins may reposition, evict, or change nucleosome composition

Question 45

In cancer cells, one allele of a tumor suppressor gene called p53 is frequently mutated so that the protein is inactive, not produced, or deleted. The other allele usually has a normal sequence and the promoter remains intact, but the gene is not expressed. Sequencing with sodium bisulfite modification of DNA can be used to detect which cytosines are methylated. If cancer cell DNA is sequenced, which of the following results would be expected?

A) There will be no differences in the methylation pattern of the promoter of p53 from a cancer cell and a normal cell
B) Cytosines in the coding region will have an increased methylation
C) Cytosines in or near the promoter region will be methylated
D) Cytosines in or near the promoter will not be methylated

Answer 45

C) Cytosines in or near the promoter region will be methylated

Question 46

One difference between developmental and environmental epigenetic changes is that

A) developmental epigenetic control is a normal process that occurs in all offspring.
B) environmental epigenetic control is the result of developmental processes interacting with the environment.
C) the differences between the two lie in the mechanisms that each uses.
D) environmental epigenetic control is a normal process that occurs in all offspring.

Answer 46

A) developmental epigenetic control is a normal process that occurs in all offspring.

Question 47

What is the difference between the trithorax (TrxG) and polycomb (PcG) complexes of proteins?

A) Methylation of H3 on lysine 27 can result in activation of transcription
B) TrxG complex proteins activate gene expression by methylating lysine 4 on H3, while PcG complex proteins repress gene expression by methylating lysine 27 on H3.
C) Methylation of lysine at position 4 on H3 results in silencing of gene expression
D) TrxG proteins methylate lysine 27 on histone H3 while PcG complexes methylate lysine 4 on H3

Answer 47

B) TrxG complex proteins activate gene expression by methylating lysine 4 on H3, while PcG complex proteins repress gene expression by methylating lysine 27 on H3.

Question 48

The Avy allele of the Agouti gene involves the insertion of a transposable element upstream from the normal Agouti promoter. The transposable element carries a promoter that causes the overexpression of the Agouti gene. Mice carrying this allele tend to have coat colors that are more yellow than mice that don’t have this transposable element. If pregnant female mice are fed a diet that contains chemicals that inhibit DNA methylation, how would you expect that this diet would affect the coat color of offspring carrying the Avy allele?

A) Their fur would be more yellow because the Agouti gene would tend to be over expressed.
B) Their fur would be less yellow (darker brown) because the Agouti gene would tend to be over expressed.
C) Their fur would be less yellow (darker brown) because the Agouti gene would tend to be under expressed.
D) Their fur would be more yellow because the Agouti gene would tend to be under

Answer 48

A) Their fur would be more yellow because the Agouti gene would tend to be over expressed.

Question 49

Following mitosis, the two daughter cells usually have __________ pattern of facultative heterochromatin and __________ pattern of constitutive heterochromatin as was present in the mother cell.

A) a different; the same
B) the same; the same
C) a different; a different
D)the same; a different

Answer 49

B) the same; the same

Question 50

Which of the following statements are correct?

A) Changes in gene expression based on environmental conditions are not considered normal while developmental changes are.
B) Environmental epigenetic gene regulation is typically reversible while developmental epigenetic gene regulation is typically not reversible.
C) Environmental epigenetic changes can vary due to the exposure of the organism to different environmental conditions, while those programmed during development are the result of stimuli generated by the organism itself.
D)Environmental epigenetic gene regulation only occurs in reptiles and insects, while developmental epigenetic regulation occurs in all animals.

Answer 50

C) Environmental epigenetic changes can vary due to the exposure of the organism to different environmental conditions, while those programmed during development are the result of stimuli generated by the organism itself.

Question 51

Where is the IRE located in the regulation of ferritin translation?

A) 5′ end of mRNA
B) 5′ end of DNA
C) 3′ end of mRNA
D) 3′ end of DNA

Answer 51

A) 5′ end of mRNA

Question 52

Regulatory transcription factors may influence gene expression in which of the following ways?

A) by directly interacting with TFIII to inhibit its binding to the core promoter
B) influencing the ability of the RNA polymerase to perform elongation
C) directly recruiting RNA polymerase to the promoter without interacting with any other proteins
D) recruiting proteins to the promoter that enhance chromatin compaction

Answer 52

D) recruiting proteins to the promoter that enhance chromatin compaction

Question 53

Which of the following is incorrect regarding the glucocorticoid hormones?

A) The homodimer interacts with GRE, activating transcription.
B) After interacting with the receptor, they release HSP90.
C) The receptors form a homodimer that travels to the nucleus.
D) They interact with receptors located in the plasma membrane of the cell.

Answer 53

D)They interact with receptors located in the plasma membrane of the cell.

Question 54

Acetylation of histones results in

A. formation of a closed chromatin structure.
B. termination of transcription.
C. removal of histones from the histone octamer.
D. formation of an open chromatin structure.

Answer 54

D. formation of an open chromatin structure.

Question 55

Genomic imprinting is a result of

A. nucleosome location.
B. histone activation.
C. DNA methylation.
D. serine to leucine changes in the genetic code.

Answer 55

C. DNA methylation.

Question 56

What genes appear to be controlled by the Xic?

A. Xist
B. Xist and Tsix
C. TsiX
D. Xic

Answer 56

B. Xist and Tsix

Question 57

What gene(s) is/are encoded in the Xic?

A. Xce
B. Xist
C. Tsix
D. Both the Tsix and Xist are genes are in the Xic region

Answer 57

D. Both the Tsix and Xist are genes are in the Xic region

Question 58

The Avy allele of the Agouti gene involves the insertion of a transposable element upstream from the normal Agouti promoter. The transposable element carries a promoter that causes the overexpression of the Agouti gene. Mice carrying this allele tend to have coat colors that are more yellow than mice that don’t have this transposable element. If pregnant female mice are fed a diet that contains chemicals that increase DNA methylation, how would you expect that this diet would affect the coat color of offspring carrying the Avy allele?

A. Their fur would be less yellow (darker brown) because the Agouti gene would tend to be under expressed.
B. Their fur would be more yellow because the Agouti gene would tend to be over expressed.
C. Their fur would be more yellow because the Agouti gene would tend to be under expressed.
D. Their fur would be less yellow (darker brown) because the Agouti gene would tend to be over expressed.

Answer 58

A. Their fur would be less yellow (darker brown) because the Agouti gene would tend to be under expressed.

Question 59

Regulatory transcription factors may be regulated by

A. lipid modifications.
B. phosphorylation.
C. binding of carbohydrates.
D. sulfation.

Answer 59

B. phosphorylation.

Question 60

Which DNA sequence would also work in place of the following bi-directional enhancer?

5’ GTTC 3’
3’ CAAG 5’

A. 5’ CTTG 3’
3’ GAAC 5’

B. 5’ GAAC 3’
3’ CTTG 5’

C. 5’ CAAG 3’
3’ GTTC 5’

D. 5’ CTTC 3’
3’ GAAG 5’

Answer 60

B. 5’ GAAC 3’
3’ CTTG 5’

Question 61

CAP affects which operon(s)?

A. the lac operon
B. the trp operon
C. both the lac and the trp operon
D. neither the lac nor the trp operon

Answer 61

A. the lac operon

Question 62

What are histone variants?

A. histone proteins that have slightly different amino acid sequences but are found in nucleosomes throughout the chromosomes
B. histone proteins that have been modified by acetylation and phosphorylation
C. histone proteins that have been modified by acetylation
D. histone proteins that have slightly different amino acid sequences and have specialized functions

Answer 62

D. histone proteins that have slightly different amino acid sequences and have specialized functions

Question 63

What is the molecular mechanism for imprinting a gene?

A. Nitration
B. Phosphorylation
C. Acetylation
D. Methylation

Answer 63

D. Methylation

Question 64

Expression of ______ would inhibit X-chromosome inactivation.

A. Xic
B. Xist
C. Tsix
D. All of the answers are correct.
E. None of the answers are correct.

Answer 64

C. Tsix

Question 65

A queen bee is larger than the female worker bees in a hive. The queen develops functional ovaries that allow her to produce up to 2000 eggs a day. What determines which bees become queen bees?

A. The larvae raised on a diet of royal jelly
B. A single dominant allele of the Queen gene
C. The egg that hatches first
D. The larvae raised on a diet of pollen and nectar

Answer 65

A. The larvae raised on a diet of royal jelly

Question 66

Regions of chromatin that are more compact are called __________; they are usually found __________ in the nucleus.

A. euchromatin; centrally
B. euchromatin; at the periphery
C. heterochromatin; centrally
D. heterochromatin; at the periphery

Answer 66

D. heterochromatin; at the periphery

Question 67

What are some types of the molecular changes that underlie epigenetic gene regulation?

A. DNA methylation and depurination of cytosine residues
B. depurination and chromatin remodeling.
C. DNA methylation and chromatin remodeling
D. depurination of cytosine and thymidine residues

Answer 67

C. DNA methylation and chromatin remodeling

Question 68

What is a major difference between the general and regulatory transcription factors?

A. General transcription factors act as heterodimers while regulatory transcription factors act as monomers.
B. General transcription factors only regulate the housekeeping genes while regulatory transcription factors control all of the other genes.
C. General transcription factors are essential for any transcription for all genes while regulatory transcription factors regulate transcription of specific genes.
D. General transcription factors regulate basal genes while regulatory transcription factors control all of the other genes.

Answer 68

C. General transcription factors are essential for any transcription for all genes while regulatory transcription factors regulate transcription of specific genes.

Question 69

What process repairs damage from UV radiation?

A. direct repair
B. base excision repair
C. nonhomologous end joining (NHEJ)
D. homologous recombination repair
E. nucleotide excision repair

Answer 69

E. nucleotide excision repair

Question 70

Which DNA repair process identifies daughter strands by methylation?

A. homologous recombination repair
B. mismatch repair
C. direct repair
D. nucleotide excision repair
E. nonhomologous end joining (NHEJ)
F. base excision repair

Answer 70

B. mismatch repair

Question 71

A translocation that moves a gene from an area of euchromatin to heterochromatin would typically cause _____ in the expression of the gene.

A. no change
B. an increase
C. a reduction

Answer 71

C. a reduction

Question 72

The results of the replica plating experiments by the Lederbergs supported which of the following theories?

A. random mutation theory
B. physiological adaptation theory
C. both theories
D. neither theory

Answer 72

A. random mutation theory

Question 73

Most trinucleotide repeat expansion repeats involve expansion of which of the following?

A. GAA
B. any codon containing three of the same bases
C. ATG
D. CAG

Answer 73

D. CAG

Question 74

A temporary change in the structure of a nitrogenous base is called ______.

A. depurination
B. a tautomeric shift
C. deamination
D. None of the answers are correct.

Answer 74

B. a tautomeric shift

Question 75

What is the difference between genetic testing and genetic screening?

A. Genetic testing is concerned more with individuals and genetic screening is concerned with populations.
B. Genetic screening is concerned more with individuals and genetic testing is concerned with populations.
C. They use different tests and techniques to detect genetic mutations.
D. Genetic testing is concerned more with nonlethal syndromes and diseases, and genetic screening is concerned with lethal diseases and syndromes.

Answer 75

A. Genetic testing is concerned more with individuals and genetic screening is concerned with populations.

Question 76

In the United States, most newborns undergo a test for primary congenital hypothyroidism, a condition where people are unable to produce enough thyroid hormone. On a nationwide basis, this is an example of __________.

A. genetic testing
B. preimplantation genetic diagnosis
C. amniocentesis
D. genetic screening

Answer 76

D. genetic screening

Question 77

Which of the following would indicate that a disease has a genetic, rather than environmental, cause?

A. The disease is cured by taking an antibiotic.
B. The disease occurs as frequently between close relatives as it does in unrelated individuals.
C. The disease occurs at the same rate in individuals that are exposed to a similar environment.
D. The disease has a specific age of onset.

Answer 77

D. The disease has a specific age of onset.

Question 78

How would a mutation that increases the rate of GTP hydrolysis by the Ras protein affect the EGF signaling pathway and how would it affect cell growth?

A. The signaling pathway would stay turned on and cell growth would be inhibited.
B. The signaling pathway would stay turned on and cell growth would be stimulated.
C. The signaling pathway would be turned off faster and cell growth would be inhibited.
D. The signaling pathway would be turned off faster and cell growth would be stimulated.

Answer 78

C. The signaling pathway would be turned off faster and cell growth would be inhibited.

Question 79

What are the general ways that tumor suppressors and oncogenes act?

A. Tumor suppressors inhibit the cell cycle and oncogenes stimulate the cell cycle.
B. Oncogenes inhibit the cell cycle and tumor suppressors stimulate the cell cycle.
C. Both tumor suppressors and oncogenes stimulate the cell cycle.
D. Both tumor suppressors and oncogenes inhibit the cell cycle.

Answer 79

A. Tumor suppressors inhibit the cell cycle and oncogenes stimulate the cell cycle.

Question 80

What kind of mutation would be expected both within oncogenes and tumor suppressor genes that would result in gain-of-function or loss-of-function, respectively?

A. Silent
B. Amplifications
C. Missense
D. Neutral

Answer 80

C. Missense

Question 81

Genome wide association studies are used __________.

A. to identify single nucleotide polymorphisms that are near disease causing genes
B. to identify the mutation that causes a disease
C. to describe the number of alleles for a specific gene
D. to find the total variation that occurs in human genomes

Answer 81

A. to identify single nucleotide polymorphisms that are near disease causing genes

Question 82

The process of _______ removes amniotic fluid from a pregnant mother to examine fetal cells for genetic problems.

A. chorionic villus sampling
B. in vitro fertilization
C. amniocentesis
D. preimplantation genetic diagnosis

Answer 82

C. amniocentesis

Question 83

Gene X can exist as a normal allele and also as a dominant mutant allele that causes a disease. You purify protein X from a homozygous normal individual and also from an individual that is homozygous for the mutant allele. You have an assay to determine the function of protein X. When you assay 1 mg of the purified protein from a normal homozygote, the activity is 100%. When you mix together 0.5 mg of the normal protein and 0.5 mg of the mutant protein, the activity is 13%. Based on this experiment, what type of dominant mutant is this?

A. Dominant negative
B. Gain of function
C. Haploinsufficiency
D. Could be B and C

Answer 83

A. Dominant negative

Question 84

The general function of the p53 protein could be described as

A. a negative regulator of cell division.
B. maintaining genome integrity
C. a positive regulator of cell division.

Answer 84

B. maintaining genome integrity

Question 85

Mutations that change the configuration of a protein at a specific temperature are called ____ mutations.

A. deleterious
B. beneficial
C. conditional
D. neutral

Answer 85

C. conditional

Question 86

Which of the following integrate into the double-helix of DNA, interfering with DNA replication?

A. acridine dyes
B. 5BU
C. nitrous acid
D. EMS

Answer 86

A. acridine dyes

Question 87

You are a doctor tasked with diagnosing a patient that comes to you with mental impairment. Upon performing genetic tests, you find he has approximately 300 repeats of GCC in one of his genes. His father and grandfather had similar mental impairment but were never diagnosed with a condition prior to their death. His grandmother, mother, and sisters are unaffected. What disease do you predict that this patient has?

A. SBMA
B. FRAXA
C. HD
D. FRAXE
E. SCA1

Answer 87

D. FRAXE

Question 88

If the individuals in the picture above had a child, that child could have which haplotype listed (assuming no crossing over)?

A. 1A2A3A4A; 1B2B3A4B
B. 1A2A3A4A; 1C2C3C4A
C. 1A2B3B4C; 1C2C3C4A
D. 1A2B3C4A; 1C2C3B4C

Answer 88

B. 1A2A3A4A; 1C2C3C4A

Question 89

Which of the following is typically associated with an autosomal recessive pattern of inheritance?

A. an affected individual with one affected parent will have 50% of its offspring affected
B. an affected offspring has one or more affected parents
C. two affected heterozygous individuals will have 25% of their offspring unaffected
D. an affected offspring has two unaffected parents

Answer 89

D. an affected offspring has two unaffected parents

Question 90

An oncogene form of Ras would have which of the following characteristics?

A. decreased GTPase activity
B. increased GTPase activity
C. decreased exchange of GDP for GTP
D. an increased number of copies in the cell

Answer 90

A. decreased GTPase activity

Question 91

Tamoxifen is a medication used for treating cancer. Many women were found to have resistance to this drug, and research showed that women with a mutation in their CYP2D6 gene could not break down Tamoxifen. Therefore Tamoxifen was not a useful treatment for their cancer. Women can now be screened for this mutation, allowing clinicians to use a therapy that is effective for each woman. This type of treatment is an example of __________.

A. haplotype association studies
B. loss of heterozygosity
C. karyotyping
D. personalized medicine

Answer 91

D. personalized medicine

Question 92

The term that refers to the linkage of alleles or molecular markers along a single chromosome is

A) loss of variation.
B) association group.
C) haplotype.
D) recombination group.

Answer 92

C) haplotype.

Question 93

You are analyzing a human pedigree for a new disease and discover that the disease occurs with the same frequency in both sexes and that 25% of the children from two unaffected heterozygous parents have the disease. This disease is displaying ____ inheritance.

A) sex-linked dominant
B) autosomal recessive
C) sex-linked recessive
D) autosomal dominant

Answer 93

B) autosomal recessive

Question 94

The term for the use of information about a person’s genotype and other clinical data in order to select a medication is referred to as

A) minimalized drug therapy.
B) molecular profiling.
C) personalized medicine.
D) best medical practices.

Answer 94

C) personalized medicine.

Question 95

What gene is most responsible for X-chromosome inactivation?

A) Xce
B) Xist
C) Xic
D) Tsix

Answer 95

B) Xist

Question 96

Imagine all the histone H3 molecules in the cell have a mutation that changes their lysine-9 residue to an alanine. Assuming this cell could still live, what would be the result?

A) The ability of the cell to form euchromatin would be hindered.
B) The ability of the cell to imprint genes would be hindered.
C) The ability of the cell to form heterochromatin would be hindered.
D) There would little effect because lysine and alanine are similar amino acids.

Answer 96

C) The ability of the cell to form heterochromatin would be hindered.

Question 97

Epigenetic inheritance may occur at which of the following stages?

A) Oogenesis
B) Spermatogenesis
C) Embryogenesis
D) All of the answers are correct.

Answer 97

D) All of the answers are correct.

Question 98

What effect will a mutation in IRP that prevents it from binding to iron have on an individual?

A) Ferritin will not be made, so iron intake must be maximized.
B) There will be excess ferritin, so iron intake must be lowered.
C) Transferrin will not be made, so iron intake must be maximized.
D) There will be excess transferrin, so iron intake must be lowered.

Answer 98

D) There will be excess transferrin, so iron intake must be lowered.

Question 99

What is an example of a suppressor mutation?

A) an intragenic mutation that restores protein structure
B) an intergenic mutation that increases the activity of a protein performing the same function as the mutated protein
C) an intergenic mutation that alters a transcription factor to activate the expression of a compensating protein
D) All of the answers are possible suppressor mutations.

Answer 99

D) All of the answers are possible suppressor mutations.

Question 100

In the following sequence of DNA, the italicized base has been mutated. What type of mutation is this?

5’ - G A T C T C C G A A T T - 3’ original strand
5’ - G A T C T C C C A A T T - 3’ mutated strand

A) transition
B) transversion
C) neither

Answer 100

B) transversion

Question 101

Which of the following is an example of a base analog?

A) EMS
B) 5BU
C) nitrogen mustards
D) nitrous acid

Answer 101

B) 5BU

Question 102

Which environmental agent shown can induce mutations?

A. UV radiation
B. X-rays
C. gamma rays
D. All of the answers are correct.

Answer 102

D. All of the answers are correct.

Question 103

Anticipation is associated with which of the following?

A. TRNE mutations
B. up-promoter mutations
C. intergenic suppressors
D. nonsense mutations

Answer 103

A. TRNE mutations

Question 104

There is a spectrum of syndromes in humans known as Xeroderma pigmentosum. The individuals that have XD most commonly have mutations in their nucleotide excision DNA repair mechanisms that make them particularly susceptible to environmental mutagens such as UV light. Individuals have to be careful with how much sunlight they are exposed to since they have an extremely elevated chance for developing skin cancer. There have been several cell lines that have been established from XD patients that can be studied in tissue culture. In an experiment, several different cell lines of unknown origin were tested for their ability to undergo unscheduled DNA synthesis (UDS), an assay for DNA repair. In this essay, the amount of radioactive nucleotides that are incorporated into DNA after the cell sustains a mutagenic event are measured. The amount of radioactivity incorporated is measured by the number of counts per minute (CPM)

A. A
B. B
C. C
D. D

Answer 104

A. A

Question 105

In the nucleotide excision repair system, which of the following proteins is responsible for recognizing a thymine dimer to be repaired?

A) UvrA/UvrB
B) UvrC
C) UvrD
D) None of the answers are correct.

Answer 105

A) UvrA/UvrB

Question 106

The wild-type eye color of Drosophila is red. A single-base mutation occurs that produces a white eye color. Which of the following is correct regarding this mutation?

A) It is an example of a mutation that alters protein function.
B) Individuals with white eyes are called reversions.
C) It would be an example of a silent mutation.
D) All of the answers are correct.

Answer 106

A) It is an example of a mutation that alters protein function.

Question 107

Translocations and inversions may cause which of the following?

A) TRNE
B) genome mutations
C) position effect
D) anticipation

Answer 107

C) position effect

Question 108

Which DNA repair process often leads to deletion in chromosome sequence?

A. homologous recombination repair
B. nonhomologous end joining (NHEJ)
C. nucleotide excision repair
D. direct repair
E. mismatch repair
F. base excision repair

Answer 108

B. nonhomologous end joining (NHEJ)

Question 109

If a point mutation increases the number of offspring an organism can produce, it would be called a _____ mutation.

A. deleterious
B. conditional
D. lethal
E. neutral
F. beneficial

Answer 109

F. beneficial

Question 110

What are some of the steps in eukaryotic transcriptional control?

A. A transcriptional activator recruits general transcription factors and RNA polymerase II. Finally, as transcription elongation occurs, histone cores remain with the DNA.
B. A transcriptional repressor recruits nucleosome remodeling proteins that alter nucleosome positioning, modification, and composition. This allows for the formation of a closed chromatin complex, and binding of general transcription factors and RNA polymerase II. Histone cores remain on the gene as transcript elongation occurs.
C. A transcriptional activator recruits nucleosome remodeling proteins that alter nucleosome positioning, modification and composition. This allows for the formation of an open chromatin complex, and binding of general transcription factors and RNA polymerase II. Finally, as transcription elongation occurs, histone cores are evicted from the DNA to allow the RNA polymerase to transcribe the gene.

Answer 110

C. A transcriptional activator recruits nucleosome remodeling proteins that alter nucleosome positioning, modification and composition. This allows for the formation of an open chromatin complex, and binding of general transcription factors and RNA polymerase II. Finally, as transcription elongation occurs, histone cores are evicted from the DNA to allow the RNA polymerase to transcribe the gene.

Question 111

Gene methylation can be detected through the use of restriction endonucleases. Usually these are used in pairs where one enzyme will digest only unmethylated DNA in its recognition sequence while the other is insensitive to methylation. Which of the following statements is correct?

A. The enzyme that is insensitive to methylation serves as a control to make sure the inability of the other enzyme to digest DNA is not due to a mutation.
B. This experimental design is able to identify the number of methylated C residues in a particular region of DNA.
C. The experimental design is flawed because there should be a third enzyme that would serve as a positive control
D. These are used in pairs because experiments have to be replicated and this one way of performing a replication of the experiment.

Answer 111

A. The enzyme that is insensitive to methylation serves as a control to make sure the inability of the other enzyme to digest DNA is not due to a mutation.

Question 112

In humans, a recent study has shown that maternal anxiety during pregnancy can diminish the methylation of the ICR located between the H19 and Igf2 genes of the embryo and fetus. How would this affect the expression of the maternal and paternal alleles of the Igf2 gene after the baby is born?

A. It would not affect the expression of the maternal allele, but the paternal allele would be overexpressed.
B. It would not affect the expression of the maternal allele, but the paternal allele would be inhibited.
C. It would not affect the expression of the paternal allele, but the maternal allele would be overexpressed.
D. It would not affect the expression of the paternal allele, but the maternal allele would be inhibited.

Answer 112

B. It would not affect the expression of the maternal allele, but the paternal allele would be inhibited.

Question 113

Which of the following is an example of epigenetic inheritance?

A. Expression of the Igf2 gene based on methylation of the ICR and DMR regions
B. Control of mRNA stability by an RNA-binding protein
C. Activation of transcription by a general transcription factor
D. Inheritance of flower color as studied by Mendel

Answer 113

A. Expression of the Igf2 gene based on methylation of the ICR and DMR regions

Question 114

Which of the following are molecular mechanisms used in epigenetic gene regulation?

A) DNA methylation
B) Covalent histone modification
C) Chromatin remodeling
D) All of the answers are correct.

Answer 114

D) All of the answers are correct.

Question 115

What general transcription factor is most often affected by regulatory transcription factors?

A) TFIIB
B) TFIID
C) TFIIE
D) TFIIF

Answer 115

B) TFIID

Question 116

For a recessive single-gene disorder, the concordance among dizygotic twins should be

A) 75%
B) 100%
C) 50%
D) 25%
E) 0%

Answer 116

D) 25%

Question 117

Consider the following DNA sequence, which codes the first portion of a long protein beginning at the ATG (AUG in mRNA) start codon.

5’ ATG CCC CGC AGT AGG GGG TGG AGA 3’

Which of the mutated sequences listed is most likely to be a deleterious mutation?

A) 5’ ATG CCC CGC AGT AGG GGG TGA AGA3’
B) 5’ ATG CCG CGC AGT AGG GGG TGG AGA3’
C) 5’ ATG CCC CGC AGT AGG GAG TGG AGA3’

Answer 117

C) 5’ ATG CCC CGC AGT AGG GAG TGG AGA3’

Question 118

Locus heterogeneity can cause difficulties in pedigree analysis since

A. the inheritance of more than one gene is being analyzed.
B. the cause of the disease may not have a genetic origin.
C. the inheritance of only one gene is being analyzed.
D. the cause of the disease may have environmental as well as genetic origins.

Answer 118

A. the inheritance of more than one gene is being analyzed.

Question 119

In imprinting of the Igf2 gene in mice, are the ICR and DMR methylated on the maternal or paternal chromosome? Which chromosome expresses Igf2?

A. Maternal, paternal
B. Maternal, maternal
C. Paternal, maternal
D. Paternal, paternal

Answer 119

D. Paternal, paternal

Question 120

If CAP could not bind to its CAP site, then what would be the result? Assume lactose is present in each scenario.

A. Transcription would be difficult to repress in the absence of glucose.
B. Transcription would be difficult to activate in the absence of glucose.
C. Transcription would be difficult to repress in the presence of glucose.
D. Transcription would be difficult to activate in the presence of glucose.

Answer 120

B. Transcription would be difficult to activate in the absence of glucose.

Question 121

CpG islands are associated with which of the following?

A. DNA methylation
B. steroid hormone activity
C. termination of translation
D. nucleosome location

Answer 121

A. DNA methylation

Question 122

What would be the result of a mutation in HSP90 that prevented its binding to the glucocorticoid receptor?

A. The hormone would not be able to bind to the glucocorticoid receptor.
B. Expression of the regulated genes would become constitutive.
C. The nuclear localization signal would no longer function.
D. Glucocorticoid receptor could not form a dimer.

Answer 122

B. Expression of the regulated genes would become constitutive.

Question 123

A particular gene has a mutation in its NFR that causes it to bind abnormally tightly to histones. What effect would you expect this mutation has on the expression of this gene?

A. the promoter of the gene will be constantly available to transcription factors and RNA polymerase
B. the effect on gene expression is impossible to predict
C. the gene would encode a different protein instead
D. the expression of the gene would be abnormally low or absent
E. the expression of the gene would be abnormally high

Answer 123

D. the expression of the gene would be abnormally low or absent

Question 124

Most genes imprinted by methylation are silenced. What is one exception to this rule?

A. Igf2
B. H19
C. Agouti
D. Xist

Answer 124

A. Igf2

Question 125

Combinatorial factors include activators and repressors as well as

A. small effector molecules, proteins that alter the composition of nucleosomes, DNA methylation, and basal transcription factors
B. small effector molecules, proteins that alter the composition of nucleosomes, but not DNA methylation
C. proteins that alter the composition of nucleosomes and DNA methylation, but not small effector molecules
D. small effector molecules, proteins that alter the composition of nucleosomes, and DNA methylation

Answer 125

D. small effector molecules, proteins that alter the composition of nucleosomes, and DNA methylation

Question 126

The complete loss of either a guanine or adenine from DNA is an example of

A. Depurination
B. Tautomeric shifts
C. Deamination
D. None of the answers are correct.

Answer 126

A. Depurination

Question 127

A particular cell contains all of the standard histones but lacks several histone variants. Which of the following MAY be true of this cell?

A. The cell will express different sets of genes than other cells in the same organism.
B. The cell will be completely unable to remodel its chromatin.
C. The cell will have an enhanced ability to chemically modify its histones.
D. The cell will not be able to divide.
E. The cell will be unable to express any of its genes at all.

Answer 127

A. The cell will express different sets of genes than other cells in the same organism.

Question 128

Which of the following is part of the process of X-chromosome inactivation?

A. Compaction of the active X chromosome into a Barr body
B. Expression of Xist from both chromosomes at the start of the process
C. Binding of multiple Xist transcripts to Xic on the X chromosome that will be inactivated
D. Binding of Tsix transcripts to the X chromosome to be inactivated after the Xist transcripts binds to Xic

Answer 128

C. Binding of multiple Xist transcripts to Xic on the X chromosome that will be inactivated

Question 129

A disease that is lethal only in the homozygous condition is most likely which of the following?

A. autosomal recessive
B. X-linked
C. autosomal dominant
D. None of these choices are correct.

Answer 129

A. autosomal recessive

Question 130

Haplotypes can be useful in the identification of disease genes since

A. the most concordant marker(s) is the disease gene.
B. no pedigree information needs to be known.
C. the most concordant marker(s) is typically the one that is closest to the disease gene.
D. the least concordant marker(s) is typically the one that is closest to the disease gene.

Answer 130

C. the most concordant marker(s) is typically the one that is closest to the disease gene.

Question 131

Prions are thought to cause neurological diseases by

A. converting to a misfolded form that forms aggregates.
interfering with neuronal transmission.
B. converting to a misfolded form that is more soluble than the normally folded protein.
C. competing for the binding of a hormone that helps maintain neuronal integrity.

Answer 131

A. converting to a misfolded form that forms aggregates.
interfering with neuronal transmission.

Question 132

The term for a protein infectious agent that causes disease is

A. kuru
B. prion
C. scrapie
D. proteon

Answer 132

B. prion