Question 1

Lack of strong hybridization by an allele-specific probe of about 20 bases to DNA to be tested indicates
A) a normal,unchanged sequence.
B) a polymorphic sequence.
C) that the probe is too short.
D) that the probe is too long.
E) The information given is not enough.

Accepted Answer

E

Question 2

If a PCR amplified sample hybridizes with two allele specific probes,one normal and one mutant sequence,a carrier is identified if
A) both probes give a signal.
B) neither sample gives a signal.
C) only the mutant probe gives a signal.
D) only the non-mutant probe gives a signal.
E) None of the choices are correct.

Accepted Answer

A carrier of a genetic mutation typically has one normal allele and one mutant allele. If a PCR amplified sample hybridizes with both a normal and a mutant sequence-specific probe, it indicates the presence of both alleles, identifying the individual as a carrier.

Question 3

Molecular geneticists equate an allele with
A) only transcribed genes.
B) only non-transcribed DNA.
C) any DNA site that is different among genomes.
D) any DNA site that is different among coding genomes.
E) any DNA site that is different among non-coding genomes.

Accepted Answer

An allele is any variation in the DNA sequence at a particular locus or site among individuals in a population. Therefore, option C is the best choice as it accurately explains what an allele is. Option A only includes transcribed genes and excludes non-coding DNA, which can also have allelic variation. Option B is not accurate as non-transcribed DNA can also have allelic variation. Option D only includes coding genomes and excludes non-coding DNA, which can also have allelic variation. Similarly, option E only includes non-coding genomes and excludes coding sequences.

Question 4

SNP is the acronym for:
A) simple Northern probe.
B) single nucleotide polymorphism.
C) sample in situ probe.
D) simple nucleotide probe.
E) small nuclear particle

Accepted Answer

SNP stands for single nucleotide polymorphism, which is a common type of genetic variation where a single nucleotide (A, C, T, or G) differs between individuals in a population. This variation can be used as a genetic marker for various purposes including disease diagnosis, drug targeting, and genealogy.

Question 5

How many bases can be part of a deletions,duplications,or insertions?
A) 1
B) 10
C) 100
D) 1000
E) 1 base or more

Accepted Answer

Deletions, duplications, and insertions can involve varying numbers of base pairs, ranging from just one to thousands or even millions. Therefore, the best choice is E - 1 base or more, as it accounts for all possible scenarios.

Question 6

If the chance of a person being polymorphic for a particular microsatellite is 50%,what is the chance that a person is polymorphic for four unlinked microsatellite loci?
A) 75%
B) 50%
C) 25%
D) 6.25%
E) 95%

Accepted Answer

Assuming the microsatellite loci are unlinked, the chance of being polymorphic at each locus is independent of the others. Therefore, the probability of being polymorphic at all four loci is the product of the probabilities of being polymorphic at each locus. 
Probability of being polymorphic at one locus = 50% = 0.5 
Probability of being monomorphic at one locus = 100% - 50% = 50% = 0.5 
Probability of being polymorphic at all four loci = 0.5 x 0.5 x 0.5 x 0.5 = 0.0625 or 6.25% 
Therefore, the correct answer is D.

Question 7

Quantitative traits can be distinguished by
A) being measurable.
B) being influenced by multiple genes.
C) not having genetic causes.
D) being measurable and not having genetic causes.
E) being measurable and being influenced by multiple genes.

Accepted Answer

Quantitative traits are traits that can be measured, such as height or weight, and they are influenced by multiple genes. Therefore, choices A, C, and D are incorrect, and the correct answer is E.

Question 8

For a gene or a locus to be considered polymorphic it must satisfy the following two conditions must be present in
A) all males and females.
B) two or more sequence variations in at least 10% of the population.
C) two or more sequence variations in at least 1% of the population.
D) two or more sequence variations in at least 10% of children,since not all may reach adulthood.
E) two or more sequence variations in at least 1% of children,since not all may reach adulthood.

Accepted Answer

A gene or a locus is considered polymorphic if it has two or more sequence variations in at least 1% of the population. This means that at least 1% of individuals in the population carry different alleles at that gene or locus.

Question 9

Pick the choice that best describes a DNA fingerprint.
A) a comparison of microsatellites from closely related individuals
B) uses CNVs that are detected by a microarray
C) uses minisatellite families and labeled probes to produce a profile
D) is a specialized application of the FISH protocol
E) DNA that is used only in criminal trials.

Accepted Answer

A DNA fingerprint uses minisatellite families and labeled probes to produce a profile that can be used for identification purposes. Microsatellites and CNVs may also be used in some forms of DNA analysis, but they are not typically referred to as DNA fingerprints. FISH is a different type of technique used to visualize specific DNA sequences. While DNA fingerprinting is often used in criminal trials, it has other applications as well.

Question 10

Phenocopy of genetic diseases can arise from
A) environmental stimuli in adulthood.
B) environmental stimuli in utero.
C) genetic alterations.
D) All of the choices are correct.
E) None of the choices are correct.

Accepted Answer

Phenocopies of genetic diseases can arise from environmental stimuli in utero, meaning that an environmental factor during pregnancy can cause a condition that appears to be a genetic disease but is not due to an underlying genetic mutation.

Question 11

In microsatellite analysis,all of the following are applicable except
A) must know the sequence of flanking markers.
B) must know the sequence of the repeat units in the microsatellite.
C) polymorphism is a matter of DNA size.
D) electrophoresis.
E) PCR.

Accepted Answer

Microsatellite analysis does not require knowing the sequence of the repeat units in the microsatellite. It primarily relies on the knowledge of the sequence of flanking markers to design primers for PCR, which amplifies the region of interest. The polymorphism detected is due to variations in the length of the DNA segment between the flanking regions, which is analyzed through electrophoresis.

Question 12

Incomplete penetrance
A) can vary from trait to trait.
B) is observed when the disease genotype does not necessarily result in a disease phenotype.
C) is only observed for late-onset diseases.
D) can vary from trait to trait and is observed when the disease genotype does not necessarily result in a disease phenotype.
E) can vary from trait to trait and is only observed for late-onset diseases.

Accepted Answer

Incomplete penetrance can vary from trait to trait and is observed when the disease genotype does not necessarily result in a disease phenotype.

Question 13

The most common method for genotyping allelic SSRs is by
A) Southern blot analysis
B) FISH protocol
C) PCR and gel electrophoresis
D) sequencing
E) gas chromatography

Accepted Answer

PCR and gel electrophoresis is commonly used to genotype allelic SSRs. PCR amplifies the SSR region and gel electrophoresis separates the amplified fragments based on their size or number of repeats, allowing for identification of different alleles. Southern blot analysis and FISH protocols are less commonly used for genotyping SSRs, while sequencing and gas chromatography are more commonly used for genotyping other types of genetic markers.

Question 14

Mapping a disease gene in humans requires
A) large families with pedigrees and DNA sequences.
B) large numbers of mapped physical markers with complete genomic coverage and small families with pedigrees and DNA sequences.
C) small numbers of mapped markers and small families with pedigrees and DNA sequences
D) a multi-generational selective breeding program.
E) either large families with pedigrees and DNA sequences or large numbers of mapped physical markers with complete genomic coverage and small families with pedigrees and DNA sequences.

Accepted Answer

Mapping a disease gene in humans can be done through either large families with pedigrees and DNA sequences or large numbers of mapped physical markers with complete genomic coverage and small families with pedigrees and DNA sequences. The combination of the two methods can also be used for more accuracy.

Question 15

Thalidomide was a common treatment for morning sickness in the 1950s.Children born to mothers given this drug showed the phenotypes of a genetic disease known as phocomelia,which involves shortened limbs.This may represent
A) incomplete dominance.
B) genetic heterogeneity.
C) penetrance.
D) phenocopy.
E) incomplete penetrance.

Accepted Answer

Thalidomide is not a genetic disease, but rather a drug-induced phenotype that mimics the symptoms of phocomelia. This is an example of a phenocopy, where a non-genetic factor (in this case, a drug) produces a phenotype that appears to be genetic.

Question 16

Which of the following is the main source of variation in microsatellites?
A) chemicals in water
B) chemicals in food
C) ultraviolet light
D) background radiation
E) faulty DNA replication

Accepted Answer

Microsatellites are short repeated DNA sequences, and the variation in the number of repeats is mainly due to the errors that occur during DNA replication. These errors can be caused by various factors, such as DNA polymerase slippage or unequal crossing over, leading to a difference in the number of repeats between individuals. Other options like A, B, C, and D do not directly affect microsatellite variation.

Question 17

Huntington disease is caused by
A) a closely linked marker allele.
B) less than 34 CAG repeats.
C) base-pair substitution.
D) a recessive allele.
E) 42 or more CAG repeats.

Accepted Answer

Huntington disease is caused by an abnormal number of CAG repeats in the Huntington gene. Normal individuals have 10-35 CAG repeats, while individuals with 42 or more CAG repeats will develop Huntington disease. Therefore, choice E is the correct answer since the others do not accurately describe the cause of the disease.

Question 18

In microsatellites,one-,two-,or three-base sequences are repeated about
A) one million times.
B) one hundred thousand times.
C) one thousand times.
D) two hundred times.
E) 15-100 times.

Accepted Answer

Microsatellites typically have repeating units of 15-100 base pairs, rather than thousands or millions of repetitive units. Therefore, the correct answer is E) 15-100 times.

Question 19

Positional cloning requires knowledge about the
A) function of a gene.
B) expression pattern of a gene.
C) map location of a gene.
D) sequence of a gene.
E) evolutionary history of a gene.

Accepted Answer

Positional cloning is a method used to identify genes based on their location on a chromosome, without prior knowledge of the gene's function, expression pattern, sequence, or evolutionary history.

Question 20

Which is the most frequent cause of DNA polymorphism?
A) single base differences
B) duplications
C) inversions
D) translocations
E) ploidy

Accepted Answer

Single base differences, also known as single nucleotide polymorphisms (SNPs), are the most frequent cause of DNA polymorphism. This is because they can occur at a much higher frequency than larger structural variations such as duplications, inversions, and translocations, which tend to be more rare events. Ploidy, which refers to changes in the number of whole sets of chromosomes, can also lead to polymorphism but it is not as common as SNPs.

Quiz 14: Organellar Inheritance

Lack of strong hybridization by an allele-specific probe of about 20 bases to DNA to be tested indicates

If a PCR amplified sample hybridizes with two allele specific probes,one normal and one mutant sequence,a carrier is identified if

Molecular geneticists equate an allele with

SNP is the acronym for:

How many bases can be part of a deletions,duplications,or insertions?

If the chance of a person being polymorphic for a particular microsatellite is 50%,what is the chance that a person is polymorphic for four unlinked microsatellite loci?

Quantitative traits can be distinguished by

For a gene or a locus to be considered polymorphic it must satisfy the following two conditions must be present in

Pick the choice that best describes a DNA fingerprint.

Phenocopy of genetic diseases can arise from

In microsatellite analysis,all of the following are applicable except

Incomplete penetrance

The most common method for genotyping allelic SSRs is by

Mapping a disease gene in humans requires

Thalidomide was a common treatment for morning sickness in the 1950s.Children born to mothers given this drug showed the phenotypes of a genetic disease known as phocomelia,which involves shortened limbs.This may represent

Which of the following is the main source of variation in microsatellites?

Huntington disease is caused by

In microsatellites,one-,two-,or three-base sequences are repeated about

Positional cloning requires knowledge about the

Which is the most frequent cause of DNA polymorphism?