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BIOLOGY CHAPTER 15 LEARNING CURVE QUESTIONS
Terms in this set (41)
The genotype of an organism constitutes its observable characteristics.
Short repeated sequences of DNA that vary in number from one chromosome to the next are called:
variable number tandem repeats.
The differences among individuals in the number of copies of a region of a genome are known as:
Nondisjunction is when sister chromatids fail to separate during anaphase of cell division.
Alleles are alternate molecular forms of a gene.
What does "RFLP" stand for?
restriction fragment length polymorphism
In microarrays, the oligonucleotides that are attached have the fluorescent tag, whereas the DNA fragments being tested do not.
In a person with the genotype XXY, we can tell that nondisjunction took place in the mother.
While a mutation will not always change the phenotype of an individual, it will always change the genotype.
Only polymorphisms that add or remove restriction sites can be useful in DNA typing.
is a method that detects a single SNP.
Trisomy 21 (Down syndrome) is the only example of an autosomal trisomy in which the fetus develops to term and is born alive.
can be subject to environmental conditions.
_________ are short repeated sequences of DNA that vary from one chromosome to the next.
Variable number tandem repeats
A single nucleotide polymorphism (SNP) and a point mutation are the same thing.
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.
Some mutations have no effect on the organism and are therefore considered neutral.
Much of the genetic variation seen in the human population is neutral.
How many alleles are there of each SNP?
A couple has a baby that is monosomic for the X chromosome. This most likely occurred during meiosis because:
there was nondisjunction of the sister chromatids.
Some alleles in the heterozygous state are beneficial, whereas in the homozygous state they are harmful.
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.
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.
If a human has the genotype XXXY, they would have:
2 inactivated X chromosomes and be male.
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.
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.
Gel electrophoresis is the preferred method for detecting single nucleotide polymorphisms.
First division nondisjunction will only yield gametes with an extra chromosome, whereas second division nondisjunction will only yield gametes missing a chromosome.
A phenotype always refers to something that you can see with your eyes, like hair color or eye color.
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?
A SNP stands for a:
single nucleotide polymorphism
In mammals, females have two copies of the X chromosome, whereas males have only one copy. Dosage compensation is accomplished in mammals by:
females possessing a randomly inactivated X chromosome in all cells.
Which of the following is an advantage of DNA typing?
Only small amounts of DNA are needed.
If an individual is homozygous for a certain trait, it means that:
the individual received the same allele from each parent.
Harmful mutations are always quickly weeded out of a population.
Genetic studies have identified an allele (Δ32) that seems to provide protection against AIDS. 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 early pathogen.
Imagine that you know two sisters―Rose and Sam―both of whom smoke. Furthermore, 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.
Up until 20-30 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.
Which of the following is never used for DNA typing?
Variable tandem repeats and restriction fragment length polymorphisms are synonymous―both consist of repeated fragments of DNA with the same sequence (i.e., GTAGTAGTA).
Saying that a SNP is associated with a disease means that if you possess that particular SNP, you will end up with that disease.