Genetics (PCB3063): Chp. 27

A gene is found in two forms in a population of plants. The two alleles are denoted as B, and b. You determine that the frequency of the B allele in this population is 0.2. If this population was in a Hardy-Weinberg equilibrium, calculate the probability of a heterozygote in the next generation.

0.32

You are studying a bird population and a gene that has 2 alleles, A, which is found at a frequency of 0.4, and a, which is found at a frequency of 0.6. If this population was in Hardy-Weinberg equilibrium, what would be the probability of the genotype aa in the next generation?

0.36

Consider a population, for which you know the allele composition of three genes. Gene A has three alleles in the following proportions: A1 - 34.4%, A2 - 30%, A3 - 35.6%. Gene B has two alleles in the following proportions: B1 - 67.1%, B2 - 32.9%. Gene C has two alleles in the following proportions: C1 - 99.2%, C2 - 0.8%. Which of those genes is(are) polymorphic?

A and B only

Repetitive sequences are composed of a certain sequence that is repeated many times throughout the genome of a species. What is the typical size of the sequence that is being repeated?

A few to a few thousand base pairs

Which of the following correctly defines a population of sexually reproducing species for the purposes of population genetics?

A group of individuals that occupy the same area and can interbreed with each other

What type of recombination event can result in exon shuffling?

A nonhomologous recombination

What is the result of exon shuffling?

A novel gene that may encode a protein with a novel combination of functional domains.

Consider a population of cheetahs, inhabiting a protected area in Africa. In 2012, there were 112 cheetahs in this population. During that year, 60 of those animals reproduced and 48 new cubs were born. What constitutes the gene pool of the new generation made of those 48 new cubs?

All of the alleles of all the genes that were passed from the 60 parents to the 48 new cubs

Why are repetitive sequences, such as micro and minisatellites an extremely useful tool for studying population genetics?

Because they tend to exhibit considerable variation between individuals

Which technique characterizes human individuals by analyzing the presence and sizes of repetitive sequences in their DNA?

DNA fingerprinting

How can DNA fingerprinting be used to determine if a natural population is undergoing inbreeding depression?

DNA fingerprints can be used to determine the degree of relatedness between the population's members.

New mutations can be deleterious, neutral, or beneficial. Which of those three general types of mutations are most likely to occur?

Deleterious and neutral mutations are much more likely than beneficial mutations.

How is a protein domain related to the exons of a gene?

Each protein domain tends to be encoded by a single exon, or in some cases a few, adjacent exons.

T/F: While horizontal gene transfer is very common between different species of bacteria, it cannot occur between different species of eukaryotes, or between eukaryotes and bacteria.

False

Which of the following phenomena is responsible for introducing new genetic variation in a population?

Mutation

Two types of factors can govern microevolution. On one hand, mutation is a constant source of new genetic variation. On the other hand, mechanisms, such as natural selection and genetic drift, can act to alter existing genetic variation. How do those two types of factors compare in terms of the magnitude of their effect on allele frequencies in a population?

Mutations have a negligible effect on allelic frequencies, while mechanisms, such as natural selection and drift, can have a dramatic effect.

How is the allele frequency of a population calculated?

The number of copies of the allele in the population is divided by the total number of all the alleles for the same gene in the population.

How can we calculate the frequency of a specific genotype in a population?

The number of individuals with this genotype in the population is divided by the total number of individuals in the population.

How can micro and minisatellites be used to determine the relatedness between individuals within a population?

The sizes of those repetitive sequences tend to be more similar in closely related individuals.

Which of the following is a similarity between microsatellites and minisatellites?

They consist of many tandem repeats of a certain DNA sequence.

Consider a population and a gene that has two alleles in this population, designated as E and e. If you divide the number of all the copies of the e allele in the population by the total number of copies of both alleles (E and e) in the population, you will calculate the ______.

allele frequency of the e allele

Most mutations are ______.

deleterious or neutral

A population would be described as being in ______ if a high chi-square value is obtained when testing whether the allele and genotype frequencies are in Hardy-Weinberg equilibrium.

disequilibrium

When the hypothesis that the allele and genotype frequencies are in Hardy-Weinberg equilibrium is rejected, it can be stated that the population is in _________.

disequilibrium

The Hardy-Weinberg equilibrium is a mathematical expression which predicts that, when certain requirements are met, the allele and genotype frequencies of a gene in a population ______.

do not change over the course of many generations

Population genetics is concerned with the ______.

extent of genetic variation within a group of individuals

In order to derive the Hardy-Weinberg equation, the two scientists assumed that ______ population's gene pool.

gametes are independently chosen at random from the

The ________ _________ of a population consists of all of the alleles of every gene in all of the individuals of that population.

gene pool

Consider a population and a gene that has two alleles in this population, designated as D and d. If you divide the number of individuals with the genotype DD by the total number of individuals in the population, you will calculate the ______.

genotype frequency of the DD genotype

DNA fingerprinting can be used to determine the relationship between humans (for example paternity) because closely related individuals, such as a father and his child ______.

have more similar DNA fingerprints than do more distantly related individuals

During _______ gene transfer, genetic material from a donor organism is incorporated into a recipient organism which is not the donor's offspring.

horizontal

The transfer of genetic material from one species to another (regardless of the exact mechanism) is called ______.

horizontal gene transfer

The change in a population's gene pool from one generation to the next is known as ______.

microevolution

A short tandem repeat (STR), or ______, is a type of repetitive sequence which is less than two hundred base pairs in length and for which the unit that repeats is about 1-6 bp long. In contrast, ______ are 1-20 kbp long and are composed of a unit that is 6-80 base pairs long.

microsatellite; minisatellites

A _________ is any change in the DNA of an organism, for example, a change in DNA sequence or the structure and number of chromosomes.

mutation

Which of the following is an accurate depiction of the Hardy-Weinberg equation for a gene with two alleles?

p2 + 2pq + q2 = 1

In population genetics, a gene that exists as two or more alleles in a population is a(n) ______ gene, while one that exists predominantly as a single allele is a(n) ______ gene.

polymorphic; monomorphic

Most of the traits in a healthy natural population exhibit some level of variation, or ________, that is, they are found in two or more forms.

polymorphism

When scientists study populations, they typically observe high levels of variation in many of the traits that characterize a species. In genetics, variations in traits at the population level are known as ______.

polymorphisms

In genetics, a ________ of a sexually reproducing species consists of a group of individuals of that species, which occupy the same region, and can successfully interbreed with each other.

population

The genetics field that is concerned with the extent of genetic variation within a group of individuals and changes in that variation over time is _______ genetics.

population

The probability that a gene will be altered as a result of mutation is known as the mutation _______.

rate

The probability that a gene will be altered as a result of mutation is known as the mutation ________.

rate

Most eukaryotic species contain short sequences, typically a few base pairs to a few thousand base pairs long, that are repeated many times throughout the genome. Using a general term, these are called ______ sequences.

repetitive

Mutations occur when the DNA of an organism changes. Changes often happen in gene _______, but may also involve the structure and number of chromosomes.

sequences

A new allele can arise when an exon and its flanking introns are inserted into another gene. The new allele produces a protein which now has an additional domain (encoded by the inserted exon). This mechanism of new allele formation is known as exon _______.

shuffling

Microevolution is best described as ______.

the change in a population's gene pool from generation to generation

One way in which exon shuffling can occur is by _______ elements, which can insert exons from one gene into the sequence of another gene.

transposable

Consider a gene which is found in two forms in a population: B and b, each with a frequency of 0.5. The B allele can mutate into the b allele at a rate of 0.0001 mutations per gene per generation. What would the expected frequency of the B allele be after 100 generations (assume that the reverse mutation b to B does not occur)?

0.495

Consider a population of a hypothetical animal, whose fur color is determined by a single gene, called Col. From the list below choose all conditions that must be met in order for this population to be in Hardy-Weinberg equilibrium for the Col gene.

1. Animals in the population mate randomly, regardless of their genotype for the Col gene 2. No natural selection 3. No new mutations in the Col gene

The Hardy -Weinberg equilibrium is used as a null hypothesis, i.e., if a population is in Hardy-Weinberg equilibrium, then ______.

evolutionary change is not occurring in this population

By looking at many different proteins and the genes that encode them in a variety of eukaryotic organisms, scientists have determined that a protein domain tends to be encoded by one or a few (usually adjacent) ______.

exons

In DNA ________, an individual is characterized based on the repetitive sequences in his or her genome.

fingerprinting

Which of the following (choose all that apply) are conditions that must be met in order for a population to be in Hardy-Weinberg equilibrium for a specific gene of interest?

1. No new mutations should be appearing in the gene of interest. 2. The population must be large enough so that no genetic drift is occurring. 3. All of the different genotypes (with respect to the gene of interest) must have equal reproductive success (no selection).

Consider a gene which is found in two forms in a population: D and d, with frequencies of 0.6 and 0.4, respectively. The D allele can mutate into the d allele at a rate of 0.00001 mutations per gene per generation. What would the expected frequency of the d allele be after one generation (assume that the reverse mutation d to D does not occur)?

0.400006

Which of the following is a typical mutation rate (with proper units) for a gene in a natural population?

10^-6 per gene per generation

Horizontal gene transfer (HGT) between different species of bacteria is relatively common. Scientists estimate that about ______ of the genetic variation between modern bacteria can be attributed to HGT.

20-30%