Question 1

An individual is charged with murder, based on DNA typing of a blood sample that is more than 20 years old. The accused claims that the evidence is no longer relevant because: (Select all that are legitimate arguments, even if unlikely.)

Accepted Answer

DNA can degrade over time, increasing the chance of unreliable results. Mislabeling is a legitimate concern with old evidence. DNA from siblings can be difficult to distinguish, especially with degraded samples.

Question 2

In the diagram below, the horizontal lines represent DNA strands in a double-stranded molecule, the vertical lines mark the positions of cleavage sites for a particular restriction enzyme, the arrows show the positions of primers used in the polymerase chain reaction to amplify the region, and the numbers are the number of nucleotides between successive restriction sites. Suppose that the population contains a restriction fragment length polymorphism (RFLP) for this region of DNA. Some DNA molecules contain the site Y, whereas other DNA molecules lack this site. If we use the symbol Y⁺ to denote the allele containing the Y site and Y^- to denote the allele lacking it, then what bands would be observed in the heterozygous genotype Y⁺/ Y^- after amplification and cleavage with the restriction enzyme?

Accepted Answer

The heterozygous genotype Y⁺/Y^- would have two different sized fragments after amplification and cleavage with the restriction enzyme. The Y⁺ allele would yield fragments of 5 kb, 3 kb, and 2 kb, while the Y^- allele would only yield fragments of 5 kb and 2 kb. Therefore, the bands observed in the heterozygous genotype would be 5 kb, 3 kb, and 2 kb.

Question 3

On police procedural TV shows, the brilliant detective sometimes gets a DNA sample from a paper coffee cup that the suspect has touched. Is this fantasy made up for television, or is it scientifically sound?

Accepted Answer

It is scientifically sound and possible to obtain DNA from a paper coffee cup that a suspect has touched. Advances in technology have made it easier and faster to obtain DNA samples even from minor sources like a discarded coffee cup. However, there may be legal and ethical considerations to obtaining DNA samples without consent.

Question 4

A genetic polymorphism that eliminates a restriction site in DNA is a:

Accepted Answer

The answer of A genetic polymorphism that eliminates a restriction...

Question 5

The accompanying gel diagram shows the bands obtained for a single variable number tandem repeat (VNTR) in evidence obtained at a crime scene (W) and genomic DNA from four suspects A-D.  Which suspect CANNOT be ruled out as the source of the DNA in the sample?

Accepted Answer

The answer of The accompanying gel diagram shows the bands...

Question 6

SNPs can be detected by microarrays, which are wafer-like substrates to which millions of short stretches of DNA are attached. A microarray consists of many different squares, each one containing a different sequence of single-stranded DNA to which fluorescently labeled strands of DNAs from patients with different SNPs can hybridize. If one square will hybridize with an SNP having a C-G base pair at a particular site and an adjacent square will hybridize with an SNP having a T-A base pair at the same site, which of the following genotypes will hybridize with both squares and make them fluoresce?

Accepted Answer

The heterozygous C-G/T-A genotype will have one allele with a C-G base pair at the site where the first square hybridizes and the other allele with a T-A base pair at the site where the adjacent square hybridizes. Therefore, this genotype will hybridize with both squares and make them fluoresce. The homozygous genotypes (C-G/C-G and T-A/T-A) will only hybridize with one of the squares, not both. None of the answer options hybridize with both squares, so D is not correct.

Question 7

The genotype of a fetus can be screened for SNPs associated with some diseases.

Accepted Answer

Genotype screening for SNPs associated with certain diseases is possible through different methods such as prenatal testing using chorionic villus sampling (CVS) or amniocentesis. These tests can identify genetic variations that increase the risk of developing certain conditions such as cystic fibrosis, sickle cell anemia, or Down syndrome.

Question 8

Many SNPs are regarded as "neutral" in the sense of having little or no effect on the likelihood of survival or reproduction of the different genotypes. Could you ever say for certain that a particular SNP is "neutral"?

Accepted Answer

It is impossible to definitively state that a particular SNP is "neutral" because even small effects may be undetectable with current methods (D), and scientifically, proving a negative, such as the absolute absence of any effect, is inherently challenging (E).

Question 9

The gel diagram below shows the bands obtained for a single variable number tandem repeat (VNTR) in evidence obtained at a crime scene (W) and genomic DNA from four suspects (A-E).  Which suspect CANNOT be ruled out as the source of the DNA in the sample?

Accepted Answer

The answer of The gel diagram below shows the bands...

Question 10

Identical twins have the same:

Accepted Answer

The answer of Identical twins have the same:
...

Question 11

In England, a man who is upset about the amount of dog feces on his lawn supposedly collected hair samples from neighborhood dogs and compared their DNA types with that of the feces, thereby identifying the offending dog (and the negligent owner). It this possible?

Accepted Answer

This is possible through a process called dog DNA testing, which is used to identify the breed and identify individual dogs. The process involves collecting a sample of dog saliva or cheek cells, and comparing it to a database of known dog DNA types. While it may not be a common practice, it is not impossible.

Question 12

Genomic regions with a variable number of tandem repeats (VNTRs) used in DNA typing are highly polymorphic with many different possible genotypes existing in a population. However, matching patterns of bands for any one VNTR between the DNA in a sample and the genomic DNA of a particular individual is not sufficient to establish that the two come from the same individual. The primary reason is that:

Accepted Answer

VNTRs are highly polymorphic, meaning there are many different possible genotypes within a population. This makes it possible for two individuals to have the same VNTR genotype by chance, even if they are not related. Therefore, matching patterns of bands for any one VNTR between the DNA in a sample and the genomic DNA of a particular individual is not sufficient to establish that the two come from the same individual.

Question 13

The figure below represents analysis of blood from a victim of a crime and from two suspects. Criminologists created this gel using restriction fragments from a variable number tandem repeat (VNTR) site.  Which suspect is definitely innocent?

Accepted Answer

The answer of The figure below represents analysis of blood...

Question 14

A weapon (W) left behind at a crime scene is typed for a variable number tandem repeat (VNTR). The DNA from the weapon includes bands from the victim (V) as well as those from the perpetrator.  Which of the suspects A-E has VNTR bands that are consistent with those of the perpetrator?

Accepted Answer

To determine which suspect has VNTR bands consistent with those of the perpetrator, we need to compare the DNA from the weapon to the DNA of each suspect. The VNTR bands of the perpetrator will match those found in the weapon.

Comparing the VNTR bands found in the weapon (11eab3ac_dcb7_c8be_be6e_51dc0f85a390_TB5080_00) to those of suspect A (f6ab3ac_dcb7_c8be_be6e_51dc0f85a390_TB5080_01), we can see that they differ in the first two positions.

Comparing the VNTR bands found in the weapon to those of suspect B (11eab3ac_dcb7_c8be_be6e_51dc0f85a390_TB5080_00), we can see that they match exactly. Therefore, suspect B is the best match and likely the perpetrator.

Comparing the VNTR bands found in the weapon to those of suspects C, D, and E (b6ab3ac_dcb7_c8be_be6e_51dc0f85a390_TB5080_00, 11eab3ad_dcb7_c8be_be6e_51dc0f85a390_TB5080_00, and 11eab3bc_dcb7_c8be_be6e_51dc0f85a390_TB5080_00, respectively), we can see that they differ in various positions. Therefore, they are not consistent with the perpetrator's VNTR bands.

Question 15

The accompanying gel diagram shows the bands obtained for a single variable number tandem repeat (VNTR) in evidence obtained at a crime scene (W) and genomic DNA from three suspects A-C. 
 Which suspect CANNOT be ruled out as the source of the DNA in the sample?

Accepted Answer

The answer of The accompanying gel diagram shows the bands...

Question 16

Using PCR to amplify the same region of the genome from different individuals can identify differing lengths due to different numbers of repeated sequences referred to as:

Accepted Answer

PCR amplification of variable number tandem repeats allows for the identification of differing lengths due to different numbers of repeated sequences, making option A the correct answer. Restriction fragment length polymorphisms (B) are DNA fragments that vary in length among individuals due to differences in the location of recognition sites for restriction enzymes. Single-nucleotide polymorphisms (C) are single-letter changes in DNA sequence that can occur at a specific position in the genome. Copy-number variations (D) are differences in the number of copies of a particular gene or chromosomal segment among individuals. First-division nondisjunctions (E) refer to errors in meiosis that can result in gametes with abnormal numbers of chromosomes.

Question 17

Although a match between the DNA in a sample and the genomic DNA of a particular individual for a single variable number tandem repeat (VNTR) is not sufficient to establish identity, a mismatch is definitive. The primary reason is that:

Accepted Answer

The answer of Although a match between the DNA in...

Question 18

A technician who is doing DNA typing uses the polymerase chain reaction to amplify genomic DNA corresponding to three different variable number tandem repeats (VNTRs) in the human genome. The pair of primers for each VNTR is labeled with a different fluorescent dye, so that the bands from one VNTR fluoresce blue, those from another fluoresce red, and those from the third fluoresce green. A sample (W) containing DNA from an unknown individual is compared to genomic DNA from five individuals (A-E). Which individual's VNTR bands match those in the sample?

Accepted Answer

The answer of A technician who is doing DNA typing...

Question 19

With regard to alleles that encode different forms of beta-hemoglobin in humans and their relation to malaria, which of the following are examples of phenotypes?

Accepted Answer

Phenotypes refer to observable characteristics or traits of an organism. A) Sickle-cell anemia is a phenotype because it is a physical manifestation of the underlying genotype. C) Susceptibility to malaria is also a phenotype because it describes how likely an individual is to be affected by malaria, which is influenced by their genetic makeup. D) Sickled red blood cells are a direct observable characteristic of the sickle-cell trait or disease, making it a phenotype. B) AA, AS, SS are genotypes, not phenotypes, as they describe the genetic makeup rather than observable traits. E) is not a phenotype but rather specifies an allele, which is a variant form of a gene.

Question 20

An individual (T) is bequeathed a large amount of money, and five people (A-E) present themselves, each claiming to be T's long-lost twin. For the variable number tandem repeat (VNTR) shown below, which individual has genomic DNA that is consistent with the claim?

Accepted Answer

The answer of An individual (T) is bequeathed a large...

Quiz 15: Genetic Variation

An individual is charged with murder, based on DNA typing of a blood sample that is more than 20 years old. The accused claims that the evidence is no longer relevant because: (Select all that are legitimate arguments, even if unlikely.)

On police procedural TV shows, the brilliant detective sometimes gets a DNA sample from a paper coffee cup that the suspect has touched. Is this fantasy made up for television, or is it scientifically sound?

A genetic polymorphism that eliminates a restriction site in DNA is a:

The accompanying gel diagram shows the bands obtained for a single variable number tandem repeat (VNTR) in evidence obtained at a crime scene (W) and genomic DNA from four suspects A-D. Which suspect CANNOT be ruled out as the source of the DNA in the sample?

The genotype of a fetus can be screened for SNPs associated with some diseases.

Many SNPs are regarded as "neutral" in the sense of having little or no effect on the likelihood of survival or reproduction of the different genotypes. Could you ever say for certain that a particular SNP is "neutral"?

The gel diagram below shows the bands obtained for a single variable number tandem repeat (VNTR) in evidence obtained at a crime scene (W) and genomic DNA from four suspects (A-E) . Which suspect CANNOT be ruled out as the source of the DNA in the sample?

Identical twins have the same:

In England, a man who is upset about the amount of dog feces on his lawn supposedly collected hair samples from neighborhood dogs and compared their DNA types with that of the feces, thereby identifying the offending dog (and the negligent owner) . It this possible?

The figure below represents analysis of blood from a victim of a crime and from two suspects. Criminologists created this gel using restriction fragments from a variable number tandem repeat (VNTR) site. Which suspect is definitely innocent?

A weapon (W) left behind at a crime scene is typed for a variable number tandem repeat (VNTR) . The DNA from the weapon includes bands from the victim (V) as well as those from the perpetrator. Which of the suspects A-E has VNTR bands that are consistent with those of the perpetrator?

The accompanying gel diagram shows the bands obtained for a single variable number tandem repeat (VNTR) in evidence obtained at a crime scene (W) and genomic DNA from three suspects A-C. Which suspect CANNOT be ruled out as the source of the DNA in the sample?

Using PCR to amplify the same region of the genome from different individuals can identify differing lengths due to different numbers of repeated sequences referred to as:

Although a match between the DNA in a sample and the genomic DNA of a particular individual for a single variable number tandem repeat (VNTR) is not sufficient to establish identity, a mismatch is definitive. The primary reason is that:

With regard to alleles that encode different forms of beta-hemoglobin in humans and their relation to malaria, which of the following are examples of phenotypes?

An individual (T) is bequeathed a large amount of money, and five people (A-E) present themselves, each claiming to be T's long-lost twin. For the variable number tandem repeat (VNTR) shown below, which individual has genomic DNA that is consistent with the claim?