exam 3 Flashcards
A mutation that changes a serine codon to an argninine codon is a
A. silent mutation.
B. missense mutation.
C. nonsense mutation.
D. frameshift mutation.
B
Which of the following is not an example of a somatic mutation?
A. A mutation in an embryonic muscle cell
B. A mutation in a sperm cell
C. A mutation that is passed from parent to offspring
D. Both B and C
D
Which of the following is a cause of spontaneous mutations?
A. A tautomeric shift
B. An error in DNA replication
C. UV light
D. both A and B
D
What is a key characteristic(s) of the repeat sequences that promote trinucleotide repeat expansion?
A. They are AT rich
B. They contain at least one C and one G
C. They do not conform to the AT/GC rule
D. Both B and C
B
Which of the following is/are a possible reason why a mutation may have a position effect?
A. The mutation is located next to the gene’s promoter
B. The mutation is a translocation that moves the gene from a euchromatic region to a heterochromatic region
C. The mutation alters the start codon.
D. All of the above are mutations that can have a position effect
B
An Ames test was carried out on a suspected mutagen, which we will call mutagen A. In each case, one million bacteria were plated on media that lacked histidine. The following numbers of colonies were observed to grow.
Trial Control With mutagen A
1 7 43
2 9 19
3 4 27
4 5 33
5 7 44
You don’t need to conduct a t-test now, but you can probably guess what the results would be. Which of the following conclusions would you draw?
A. The difference between the control and experimental data is not statistically significant, so mutagen A is probably not a mutagen.
B. The difference between the control and experimental data is not statistically significant, so mutagen A is probably a mutagen.
C. The difference between the control and experimental data is statistically significant, so mutagen A is probably not a mutagen.
D. The difference between the control and experimental data is statistically significant, so mutagen A is probably a mutagen.
D
Below are 4 steps that occur in the nucleotide excision repair system. What is their correct order?
A. Removal of the damaged region
B. Endonuclease cleavage on either side of the lesion
C. Sensing of a DNA lesion
D. Use of the opposite strand (without a lesion) as a template to make new DNA
- ABCD
- CBAD
- CABD
- BCAD
2
A key difference between the Holliday model and the double strand break model for homologous recombination is the way that
A. the sister chromatids initially line up
B. the DNA is initially broken
C. heteroduplexes are formed
D. the resolution step occurs
B
According to the Holliday model for homologous recombination, what is/are the possible end result(s) of the resolution step?
A. nonrecombinant chromosomes with a heteroduplex region
B. recombinant chromosomes with a heteroduplex region
C. recombinant chromosomes without a heteroduplex region
D. Both A and B are possible
D
The phenomenon of gene conversion can result from which of the following mechanisms?
A. nucleotide excision repair only
B. gap repair synthesis only
C. mismatch DNA repair only
D. both mismatch DNA repair and gap repair synthesis
C
The restriction enzymes shown below cut DNA in the following manner. The slashes indicate where cutting occurs.
BamHI G\GATCC
CCTAG\G
EcoRI G\AATTC
CTTAA\G
HaeII GGCGC\C
C\CGCGG
PstI CTGCA\G
G\ACGTC
Which of these enzymes would generate sticky ends that would be the most stable when they bind to complementary sticky ends?
A. BamHI
B. HaeII
C. EcoRI
D. PstI
B
Which of the following steps is not needed to make a cDNA (complementary DNA) library?
A. attach linkers to the cDNA
B. cut cDNA and vector with a restriction enzyme, and ligate the cDNA into the vector
C. isolate chromosomal DNA and digest with a restriction enzyme
D. isolate mRNA and make cDNA using reverse transcriptase and a poly-dt primer
C
What is the purpose of using Gibson assembly?
A. to clone two or more DNA fragments into a vector in a specific order
B. to assemble the sequence of a genome across a defined region
C. To determine if the sequence of two DNA segments overlap with each other
D. to edit the sequence of a gene in two or more places
A
Which of the following events does not occur in a single cycle of PCR?
A. annealing of the primers
B. synthesis of complementary strands
C. denaturation of the DNA
D. addition of dideoxynucleotides
D
A primer used in dideoxy DNA sequencing is 20 nucleotides long and has the following sequence: 5’-GGATCCATGACTAGTCCGAC-3’. A segment of DNA is cloned into a vector and then the vector DNA is denatured and subjected to dideoxy DNA sequencing method. Below is the DNA sequence from a region of the vector. The primer-annealing site is shown in bold and underlined.
3-CCCGATCGGCCTAGGTACTGATCAGGCTGAATGACT-5’
Based on the sequence above, what would be the size(s) of the band(s) (i.e., the number of nucleotides in each band) in which dideoxyT had been added to the sequencing reaction?
A. 1, 2, and 5
B. 21, 22, and 25
C. 3 and 7
D. 23 and 27
B
Researchers conducted Northern blotting on a sample of cells from mouse kidney, brain, and liver using a probe that is complementary to a gene that encodes a glucose transporter. All of the samples were taken from the same mouse. The following results were obtained:
image:
big bar at 800nt for kidney
thin bar at 1000nt for brain
big bar at 1000nt for liver
If we assume that equal amounts of total cellular RNA was loaded into each lane, which of the following statements is false?
A. the pre-mRNA is alternatively spliced
B. the glucose transporter is highly expressed in brain cells
C. the glucose transported is highly expressed in kidney cells
D. the glucose transporter is highly expressed in liver cells
B
Which component of the CRISP-Cas system causes the system to bind to a target gene?
A. Cas9 protein
B. spacer region of the sgRNA
C. TracrRNA region of the sgRNA
D. linker region of the sgRNA
B
glofish are zebrafish that contain a gene from either a coral or jellyfish. This is an example of
A. gene replacement
B. gene addition
C. a gene knockout
D. both A and B
B
Reproductive cloning is a method of using the genetic material from somatic cells to produce offspring that are genetically identical to the donor parent. How does this approach work?
A. a somatic cell, such as a mammary cell, is made totipotent by treating it with hormones
B. A somatic cell, such as a mammary cell, has its nucleus removed and then the nucleus from an oocyte is inserted into it.
C. a somatic cell, such as a mammary cell, is fused with an egg cell that has its nucleus removed
D. A sperm and egg cell are fused with a somatic cell that had its nucleus removed
C
Which of the following is NOT a characteristic of an mRNA vaccine, like the one used against COVID-19?
A. The mRNA is taken up by cells, such as muscle cells, which express the protein encoded by the mRNA.
B. the mRNA is encapsulated in a lipid nanoparticle
C. the mRNA encodes a viral spike glycoprotein
D. the mRNA is released into the bloodstream
D
The alpha-globin gene is humans and beta-globin gene in humans can be described as
A. homologs
B. paralogs
C. members of a gene family
D. all of the above
D
A DNA microarray is a slide that is dotted with
A. mRNA from a sample of cells
B. fluorescently labeled cDNA
C. known sequences of DNA
D. known cellular proteins
C
If a computer program is designed to recognize a directional arrangement of bases, such as any inverted repeats in transposable elements, this is an example of
A. pattern recognition
B. search by signal, also known as sequence recognition
C. search by content (eg codon bias)
D. both A and B
A
For a rare inherited disease, the theoretical concordance for an autosomal recessive disease among identical twins is
A. 25%
B. 50%
C. 75%
D. 100%
D
Which of the following would be consistent with the idea that a human disease has a genetic component?
A. identical twins share the disease symptoms more often than fraternal twins
B. the disease is less likely to occur in relatives living apart than in relatives living together
C. A correlation cannot be found between the presence of a mutation in a particular gene and the occurrence of the disease.
D. All of the above are consistent
A
What is the purpose of a genome-wide association study?
A. to determine the likelihood that a genetic variant will be passed from parents to offspring
B. To identify genetic variants that may be associated with a disease or other type of trait
C. To determine the likelihood that siblings will carry a genetic variant that is associated with a disease or other type of trait
D. To identify family members (in a pedigree) that carry a genetic variant that is already known to cause a disease
B
Which of the following is not an example of personalized medicine?
A. Using a certain type of chemotherapy based on the genetic characteristics of a tumor
B. Giving a diabetic patient insulin that was made by genetically modified bacteria
C. Giving a patient a certain dosage of a drug based on their genotype
D. Prescribing medicines or activities to prevent a disease (such as heart disease) based on a person’s genotype
B
The BRCA-1 gene in humans is a tumor-suppressor gene that can play a role in certain types of inherited breast cancers. Which of the following statements regarding this gene is false?
A. A pre-disposition to develop breast cancer due to a BRCA-1 mutation displays a dominant inheritance pattern in a pedigree.
B. The mutation in BRCA-1 that promotes cancer is a loss-of-function mutation.
C. The severity of cancer increases in successive generations, a phenomenon called anticipation.
D. At the cellular level, the BRCA-1 mutation is recessive.
C
The Rb gene is a tumor suppressor gene that encodes the Rb protein that negatively regulates E2F. Which of the following genotypes would promote cancer at the cellular level? Note: A superscript with a minus sign denotes a loss-of-function allele.
A. Rb-Rb- E2F- E2F-
B. Rb+Rb- E2F- E2F-
C. Rb+Rb- E2F+ E2F-
D. Rb-Rb- E2F+ E2F-
D
A gene pool is
A. all of the genes in a single individual
B. all of the genes in the gametes from a single individual
C. all of the genes in a population of individuals
D. the random mixing of genes during sexual reproduction
C
In a population in Hardy-Weinberg equilibrium, the percentage of individuals exhibiting a recessive disorder is 4%, which is the same as 0.04. What is the frequency of heterozygotes?
p^2 + 2pq + q^2 = 1
A. 0.96
B. 0.48
C. 0.32
D. 0.16
C
What is Darwinian fitness?
A. the relative allele frequencies in a population
B. the relative reproductive success of a genotype
C. the level of heterozygosity of the gene pool
D. the rate of population growth
B
Which of the following would not promote polymorphism?
A. directional selection
B. diversifying (disruptive) selection
C. heterozygote advantage
D. negative frequency-dependent selection
A
Within a particular population, darkly colored rats are more likely to survive than more lightly colored individuals. This scenario is likely to result in
A. directional selection
B. stabilizing selection
C. disruptive (diversifying) selection
D. balancing selection
A
A gene exists in two alleles and the heterozygote has the highest fitness. This scenario is likely to result in
A. directional selection
B. stabilizing selection
C.disruptive (diversifying) selection
D. balancing selection
D
Within a particular population, lightly colored snails are more likely to survive in brightly lit meadows, whereas darkly colored snails are likely to survive in dark forests. This scenario is likely to result in
A. directional selection
B. stabilizing selection
C.disruptive (diversifying) selection
D. balancing selection
C
Which of the following is a common mechanism of genetic drift?
A. the bottleneck effect
B. the founder effect
C. negative-frequency dependent selection
D. both A and B
D
Which of the following is not expected to occur as a result of bidirectional migration?
A. It tends to reduce allele frequency differences between two populations.
B. It tends to increase the rate of genetic drift.
C. It can enhance genetic diversity within a population because new mutations in one population can be introduced to neighboring population.
D. All of the above are expected to occur as a result of bidirectional migration.
B
Which of the following is directly caused by inbreeding?
A. a change in allele frequencies
B. a greater proportion of heterozygotes
C. a greater proportion of homozygotes
D. both A and C
C
For a quantitative trait that is polygenic, which of the following would tend to promote a continuum of phenotypes?
A. Increasing the number of genes that affect the trait
B. Decreasing the effects of environmental variation
C. Increasing the mutation rate
D. both A and B
A
Which of the following statistics is computed as a squared deviation?
A. mean
B. correlation coefficient
C. variance
D. standard deviation
C
In a strain of tomatoes, the variance for fruit weight is 441 g2, and the mean weight is 412 g. How heavy would a tomato have to be to rank in the top 2.3%?
A. Equal to or greater than 433 g
B. Equal to or greater than 454 g
C. Equal to or greater than 475 g
D. Equal to or greater than 824 g
B
Researchers determined the correlation coefficient (r) for egg weight between chickens and those of their female offspring; it was found to be 0.49 with an N value of 38. Based solely on this observation, which of the following statements is/are false.
A. Due to the statistical significance, you may conclude a cause-and-effect relationship: genetics is playing a role in egg weight.
B. There is a positive correlation between genetic relatedness (female parent/female offspring) and egg weight.
C. If the data had been collected on a much smaller population in which N = 5, an r value of 0.49 would not have been statistically significant.
D. all of the above are true
A
A QTL (quantitative trait locus) is a __________ where one or more genes affecting a quantitative trait are ________.
A. site in a cell, located
B. site on a chromosome, located
C. site in a cell, expressed
D. site on a chromosome, expressed
B
which of the following statements regarding heritability is/are false
A. Heritability applies to a specific population raised in a particular environment.
B. Heritability in the narrow sense takes into account all types of genetic variance.
C. Heritability is a measure of the amount that genetics contributes to the outcome of a trait.
D. both B and C are false
D
In a population of humans, the correlation between height for males and their adult male offspring is 0.24. What is the narrow sense heritability for weight in this population?
Note: hN2 = robs/rexp
A. 0.12
B. 0.34
C. 0.48
D. 0.96
C
Let’s consider the trait of weight in horses. In a particular population, the mean weight was 450 kg. Animals with a mean weight of 490 kg were used as parents and produced offspring that had a mean weight of 460 kg. What is the narrow-sense heritability (hN2) for body weight in this population of cows?
Note: hN2 = (Xo − X)/(Xp − X)
Where
- X is the mean weight of the starting population
- Xo is the mean weight of the offspring
- p is the mean weight of the selected parents
A. 0.25
B. 0.5
C. 0.75
D. 1.0
A
With regard to heterosis, which of the following scenarios is/are consistent with the dominance hypothesis?
A. AA and Aa have the same fitness, and aa has a lower fitness.
B. AA and aa have the same fitness, and Aa has a lower fitness.
C. A1A2 has a higher fitness compared to A1A1 and A2A2.
D. both B and C are correct
A
For selective breeding to be successful, the starting population must
A. have genetic variation that affects the trait of interest
B. be very large
C. have the potential for phenotypic variation caused by environmental effects
D. have little phenotypic variation
A
