Question 1

Which is the most frequent type of DNA polymorphism?

Accepted Answer

Single base differences, also known as single nucleotide polymorphisms (SNPs), are the most frequent type of DNA polymorphism, accounting for over 90% of all known genetic variation in humans. SNPs occur when a single nucleotide at a particular position in the genome differs between individuals.

Question 2

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

Accepted Answer

The main source of variation in microsatellites is faulty DNA replication, which can lead to variations in the number of repeated units in the microsatellites. Chemicals in water or food, ultraviolet light, and background radiation can cause mutations in DNA, but they are not specifically associated with microsatellite variation.

Question 3

Mapping a disease gene in humans requires

Accepted Answer

Mapping a disease gene in humans requires large numbers of mapped physical markers with complete genomic coverage and small families with pedigrees and DNA sequences. This is because having a large number of mapped markers helps to pinpoint the location of the disease gene more accurately and efficiently, while small families with pedigrees and DNA sequences are needed to identify patterns of inheritance and establish a linkage between the disease and specific genetic markers.

Question 4

How many bases do deletions, duplications, and insertions most frequency involve?

Accepted Answer

Deletions, duplications, and insertions most frequently involve a single nucleotide base.

Question 5

Positional cloning requires knowledge about the

Accepted Answer

Positional cloning involves identifying the location of a gene on a chromosome without prior knowledge of its function or sequence.

Question 6

Deletions and duplications are most often caused by

Accepted Answer

Unequal crossing over can result in deletions and duplications. This occurs when homologous chromosomes misalign during meiosis and crossover at different points, resulting in one chromosome with an extra copy of a segment and the other with a missing segment. Ultraviolet light and chemical damage can cause mutations, but are not typically associated with deletions and duplications. Spontaneous errors in DNA replication can result in small mutations, but not large-scale deletions and duplications.

Question 7

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

Accepted Answer

Microsatellites contain short tandem repeats of 15-100 bases, which are repeated multiple times. Therefore, the best choice is E, as it directly corresponds to the definition of microsatellites.

Question 8

The classical form of the metabolic disease phenylketonuria is caused by a mutation in the gene encoding the enzyme phenylalanine hydroxylase (PAH), which converts phenylalanine to tyrosine.A variant form of phenylketonuria is caused by a mutation in a separate gene that encodes a different enzyme involved in the synthesis of a cofactor needed for PAH to function.Which of the following phenomena is illustrated by these two forms of phenylketonuria?

Accepted Answer

The two forms of phenylketonuria are caused by mutations in different genes, illustrating locus heterogeneity. This means that mutations at different genetic loci can lead to the same disease phenotype. This is different from allelic heterogeneity, where mutations at the same gene can lead to different disease phenotypes. Nonanonymous polymorphism refers to genetic variation that is linked to a known gene, while anonymous polymorphism refers to genetic variation that is not linked to a known gene. Compound heterozygosity occurs when an individual carries two different mutations at the same gene, resulting in a recessive disease phenotype. None of these concepts apply to the given scenario.

Question 9

Examine this pedigree.Given the disease and marker phenotypes of her children, what was the most likely marker phenotype of individual V-3?

Accepted Answer

The answer of Examine this pedigree.Given the disease and marker...

Question 10

SNP is the acronym for:

Accepted Answer

SNP stands for single nucleotide polymorphism, which refers to a variation in a single nucleotide (i.e., A, C, G, or T) in a DNA sequence between individuals. This variation can be used as a genetic marker to study the relationship between genotype and phenotype, as well as to identify genetic factors associated with disease susceptibility, drug response, and other traits of interest.

Question 11

Why is possible to find a unique genetic profile for an individual using the information about a relatively few SSRs?

Accepted Answer

The high variability of SSRs (Short Sequence Repeats) in the population means that the combination of these repeats is unique to each individual, allowing for a unique genetic profile to be established with relatively few SSRs.

Question 12

If a single DNA molecule is amplified by PCR, how many DNA molecules will there be after six cycles?

Accepted Answer

The number of DNA molecules doubles after each cycle of PCR. So after 1 cycle, there will be 2 DNA molecules; after 2 cycles, there will be 4 DNA molecules; after 3 cycles, there will be 8 DNA molecules; after 4 cycles, there will be 16 DNA molecules; after 5 cycles, there will be 32 DNA molecules; and after 6 cycles, there will be 64 DNA molecules. Therefore, the answer is D, 64.

Question 13

What is true of DNA arrays?

Accepted Answer

DNA arrays can be used to compare the expression of mRNA from all the genes in cells under two or more different environmental conditions. This allows for the identification of genes that are differentially expressed, or upregulated/downregulated, in response to specific environmental factors. This information can be used to gain insights into the molecular mechanisms underlying environmental responses and cellular processes.

Question 14

In using PCR for preimplantation embryo analysis for diseases, one limitation is that

Accepted Answer

The answer of In using PCR for preimplantation embryo analysis...

Question 15

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

Accepted Answer

To be considered polymorphic, there must be two or more sequence variations in at least 1% of the population.

Question 16

Most polymorphisms do not result in a phenotypic difference since they are typically

Accepted Answer

Polymorphisms that do not result in a phenotypic difference are often either silent mutations in coding regions or are in non-coding regions, as these changes do not alter the amino acid sequence of the resulting protein or affect gene expression. Missense mutations and mutations in promoter regions can have phenotypic effects and are thus less likely to be polymorphic if they result in a functional difference. Nonsense mutations result in premature termination of protein synthesis and are typically not polymorphic since they usually result in a non-functional protein.

Question 17

One consequence of an individual who has compound heterozygosity at the CFTR locus is

Accepted Answer

Compound heterozygosity means that an individual has two different mutated alleles on the two copies of the CFTR gene. This can result in a more severe form of cystic fibrosis, as each different allele may have different effects on the function of the CFTR protein. As a result, drugs that target one specific mutation may not work for the other mutation, making treatment more difficult. The other options are not necessarily true – having compound heterozygosity does not necessarily mean that all children will be affected, the parents may or may not have CF, and the condition can still be diagnosed through genetic testing.

Question 18

PCR cannot be successfully performed without

Accepted Answer

PCR requires knowledge of the sequence of the region to be amplified in order to design the specific primers needed for the reaction. The other options listed are not requirements for successful PCR.

Question 19

How could PCR be used for the detection of a SNP?

Accepted Answer

PCR alone cannot determine the presence of a SNP. The PCR product would need to be sequenced to identify if a SNP is present within the amplified region. Southern blotting and agarose gel electrophoresis may only provide information about the size and presence of the PCR product, but not specifically if a SNP is present.

Question 20

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

Accepted Answer

A carrier of a genetic mutation will have one normal allele and one mutant allele, so both probes will hybridize and give a signal.

Quiz 10: Analyzing Genomic Information