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Chapter 15: Learning Curve
Terms in this set (51)
Harmful mutations are always quickly weeded out of a population. (T/F)
Mutations that destroy or create a cleavage site for a restriction enzyme are the source of:
restriction fragment length polymorphisms.
Saying that a SNP is associated with a disease means that if you possess that particular SNP, you will end up with that disease. (T/F)
Nondisjunction is when sister chromatids fail to separate during anaphase of cell division. (T/F)
Alleles are alternate molecular forms of a gene. (T/F)
_____ are short repeated sequences of DNA that vary in number from one chromosome to the next.
Variable number tandem repeats
CNV stands for:
copy number variation.
What is one reason why women with the genotype XXX are not phenotypically different from an XX female?
Because only one X is active in each cell, regardless of how many X chromosomes there are in a cell.
An organism that has two different alleles of a given gene has a _____ genotype.
Only polymorphisms that add or remove restriction sites can be useful in DNA typing. (T/F)
A SNP stands for a:
single nucleotide polymorphism.
Which of the following statements is true regarding nondisjunction?
None of the answer options is correct.
None of the answer options is correct.
A gene is a segment of DNA that codes for a protein or RNA; alleles are alternate forms of a gene.
What does RFLP stand for?
restriction fragment length polymorphism
Gel electrophoresis is the preferred method for detecting single nucleotide polymorphisms. (T/F)
Trisomy 21 (Down syndrome) is the only example of an autosomal trisomy in which the fetus develops to term and is born alive. (T/F)
Any mutation that has no effect on the organism is considered neutral. (T/F)
Much of the genetic variation seen in the human population is neutral. (T/F)
The differences among individuals in the number of copies of a region of a genome are known as:
If a human has the genotype XXXY, they would:
have 2 inactivated X chromosomes and be male.
Some alleles in the heterozygous state are beneficial, whereas in the homozygous state the same alleles can be harmful. (T/F)
Variable tandem repeats and restriction fragment length polymorphisms are synonymous—both consist of repeated fragments of DNA with the same sequence (i.e., GTAGTAGTA). (T/F)
A karyotype is a technique by which a researcher can see and count chromosomes. (T/F)
The ability to perceive a bitter taste from certain chemicals including PTC has been linked to certain alleles. Which of the following would provide an explanation for the fact that almost all nonhuman primates have the "taster" phenotype, whereas the human population has a significant percentage of "nontaster" phenotypes?
The advantage to being able to taste bitter compounds would keep you from eating poisonous compounds, an advantage not needed in the human population anymore.
Which of the following is an advantage of DNA typing?
Only small amounts of DNA are needed.
The biggest difference between CNV and VNTRs is the size of the DNA being studied. (T/F)
Which of the following could explain how some (although not many) people can have Down syndrome and have a normal chromosome number?
An unbalanced translocation carrying most of chromosome number 21.
Genetic studies have identified an allele (Δ32) that seems to provide protection against HIV. Which of the following would most likely explain the reason why our population has this mutation?
This mutation likely benefited the human population against some other related pathogen.
You are working in a medical research lab and have to determine if a patient is heterozygous or homozygous for a particular restriction site. You isolate a region of DNA from each chromosome, the middle of which could contain the restriction site, if the patient has it. If you treat the DNA with the restriction enzyme, how many fragments will be produced if the patient is heterozygous for the presence of the restriction site?
For a SNP with three alleles, how many different diploid genotypes are possible?
There are no discernible phenotypic effects for an individual with the genotype XYY. (T/F)
While a mutation will not always change the phenotype of an individual, it will always change the genotype. (T/F)
CNVs are chromosomal mutations that are always due to duplications. (T/F)
In a person with the genotype XXY, we can tell that nondisjunction took place in the mother. (T/F)
Until 20 or 30 years ago, people with cystic fibrosis (CF) wouldn't live long enough to reproduce. CF is a homozygous recessive condition, leading researchers to think that over time the incidence of CF would decrease because the allele would be removed from the gene pool. The results actually indicate that the rate of CF is on the rise. Based on what you know about why certain genotypes and phenotypes persist in a population, which of the following could be a likely explanation for why the rate of CF is on the rise?
The heterozygous condition is beneficial, much like what we see with sickle cell trait.
Imagine that you know two sisters—Rose and Sam—both of whom smoke. Rose has a mutation in the gene for alpha-1 antitrypsin, whereas Sam does not. Which of the following statements is true regarding these sisters?
It is possible that neither Rose nor Sam will develop emphysema; however, the fact that both sisters smoke—added to the mutation that Rose carries—increases their chances of developing this disease.
The difference between a single nucleotide polymorphism (SNP) and a point mutation is that:
a point mutation is when a base pair is changed to a different base pair, whereas a SNP is when the base pair differs among individuals in a population.
Which of the following is true regarding RFLPs?
A polymorphism results in one site being recognized by a restriction enzyme, but not in others.
VNTRs and RFLPs are remarkably rare within the human genome; the majority of human polymorphisms take the form of point mutations, and these are most often used for DNA typing. (T/F)
A new gene is discovered that dramatically aids in the digestion of fish. You hypothesize that populations with a history of being near the shoreline would have more copies of this gene than populations found farther inland. How would you classify this genetic difference?
Which of the following is used for DNA typing?
After doing PCR on the same region between two individuals, you notice that each person's DNA yielded pieces of different sizes. Which of the following is the most likely explanation?
This is an example of VNTRs.
The number of tandem repeats in an individual will:
vary from chromosome to chromosome.
A patient is about to receive chemotherapy and the doctor is concerned with dispensing the correct dosage. Certain people cannot metabolize this type of chemical because they have a mutation that changes a codon for valine into one for aspargine. How would such a mutation be classified?
A newly arisen point mutation always creates a SNP. (T/F)
SNPs arise from:
For any SNP, what is the maximum number of alleles possible?
SNPs within a gene called FOXO correlate with increased longevity in humans. You are a researcher in a lab and wish to determine if you possess this SNP. Based on this correlation, where must the SNP be located in the genome in relation to the FOXO gene?
It is impossible to tell without further analysis.
Imagine that you are a detective who has identified a suspect in a homicide. You acquire a small amount of blood from the crime scene and hand it over to your lab. The lab carries out PCR for one polymorphism, and it returns as a match to your suspect. Is this enough to arrest your suspect?
No, your lab should assess additional polymorphisms; a single polymorphism does not constitute a DNA fingerprint.
Which of the following statements explains why restriction enzymes are not useful for genome-wide studies of genetic variation?
Using restriction enzymes will only tell us differences in sequence variation in restriction sites.
Which of the following explains the difference between VNTRs and RFLPs?
In VNTRs, we are looking at the number of times a sequence is repeated; in RFLPs we are looking at size differences resulting from different restriction sites being present.