genetics smartbook 6?

microsatellite; minisatellites

.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.

G - 0.20; g - 0.80

A gene is present in a population in two forms. The frequency of allele G is 0.3, while the frequency of allele g is 0.7. The most fit genotype is gg, with a relative fitness of 1. The relative fitness of the heterozygotes is 0.6, and that of the dominant homozygotes is 0.3. In this case of directional selection (which favors the g allele), what would the frequencies of the two alleles (G and g) be after one generation?

beneficial

According to the principles of natural selection, a mutant allele will increase in the population if it is ______ to reproduction and survival.

a mutation occur, individuals are most likely to reproduce, overtime the frequency of the mutant allele increses

Arrange the principles of natural selection in the order in which they occur, with the first step at the top.

the maintenance of two or more alleles in a population

Balancing selection favors ______.

0.8

Consider a population and a gene present in this population as two alleles: F and f. For every 10 Ff individuals that survive to reproduce, 8 FF and 4 ff individuals survive to reproduce as well. If we assume that all individuals that survive to reproduce have roughly the same number of offspring, what is the relative fitness of the FF genotype in this case?

quantitative traits that are influenced by more than one gene

Disruptive selection typically acts on ______.

0.495

Gene B is found in two allelic 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 Ballele be after 100 generations? Assume that the reverse mutation from b to B does not occur.

dd, wdd = 1.0

In a specific population, a gene is present as two alleles: D and d. For every 100 dd individuals that survive to reproduce, 18 DD and 99 Dd individuals survive to reproduce as well. Which of these three genotypes has the highest Darwinian fitness and what is its value (w)? Assume that all individuals that survive to reproduce have roughly the same number of offspring.

two or more alleles are maintained in a heterogeneous environment

In disruptive selection, ______.

disequilibrium

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

gametes are formed from alleles independently chosen at random from

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

Both inbreeding and outbreeding alter the relative proportions of genotypes in a population. Neither inbreeding nor outbreeding affect the allele frequencies in a population.

Inbreeding and outbreeding can cause certain features of populations to deviate from Hardy-Weinberg equilibrium. From the list below, choose the statements that describe commonalities between inbreeding and outbreeding. Assume that no other evolutionary processes are acting on the genes in question.

homozygotes that exhibit a trait that is of interest to a breeder

Inbreeding is useful in agriculture because it can result in a high proportion of

directional selection

Individuals at one extreme of a phenotypic distribution are more likely to survive and reproduce in a particular environment due to

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

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

changes in genetic variation within a group of individuals over time

Population genetics is a field that is concerned with ______.

a few to a few thousand base pairs

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?

directional

Sometimes individuals at one extreme of a phenotypic distribution are favored in a particular environment, for example, selection will strongly favor insects that have very high resistance to an insecticide. In such cases, the type of selection that operates is ______ selection.

depression

Sometimes, a population can experience high levels of inbreeding if the population's size has been reduced for some reason. This can lead to lower reproductive success, causing an even larger decrease in the population's size, a phenomenon known as inbreeding

gene pool

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

mean fitness

The ______ of a population is the sum of the frequencies of all genotypes, each one multiplied by its respective relative fitness.

microevolution

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

rate

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

Darwinian fitness

The relative likelihood that a genotype will contribute its alleles to the next generation, as compared to other genotypes, is known as

horizontal gene transfer

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

False

True or false: 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.

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

Two types of factors can govern microevolution. On one hand, mutation is a constant source of new genetic variation. On the other hand, mechanisms that alter existing genetic variation, 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?

the extent to which a genotype is selected against

What does the selection coefficient measure?

polymorphisms

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 ______.

heterozygote advantage

When the heterozygotes for a specific gene have higher fitness than either of the corresponding homozygous genotypes, we are observing a situation called ______. (Assume that it is a single gene with two alleles.)

Each pond in area X should have different allele frequencies, while the allele frequencies in all ponds in area Z are likely to be very similar

You are studying two areas inhabited by a species of frog. In area X, ponds inhabited by the frogs are far apart and frogs rarely move from one pond to another. In area Z, ponds inhabited by these frogs are connected by a man-made system of channels, which allow free movement of frogs between ponds. Which of the following accurately describes differences in allele frequencies between different ponds within each area?

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

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

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 is the allele frequency of a population calculated?

sequences

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

high

Suppose a chi square analysis is performed to test whether the observed genotypes in a population are consistent with the predictions of Hardy-Weinberg equilibrium. Which type of chi square value will be obtained if a population is in disequilibrium?

do not change

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 ______ over the course of many generations.

evolutionary change is not occurring in this population

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

The heterozygous genotype (HbAHbS) is more resistant to malaria than either of the homozygous genotypes.

The HbS allele for the human β-globin gene is found in relative high frequencies in certain human populations living in areas where malaria is endemic, despite the fact that individuals homozygous for this allele exhibit sickle cell anemia. What explains this observation?

sBBp = sbbq

Which of the following formulas describe the situation in which a population undergoing balancing selection due to heterozygote advantage reaches equilibrium? In this case, we have a single gene, with two alleles, B and b, with frequencies of p (for the B allele) and q (for the b allele).

random change of allele frequencies

Genetic drift is the ______ in a population.

horizontal or lateral

Genetic material from a donor organism is incorporated into a recipient organism which is not the donor's offspring during gene transfer.

less than 1

The mean fitness of a population undergoing directional selection is ______.

mutation

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

A - 0.48; a - 0.52

A population is undergoing a directional selection for a gene with two alleles, allele A has a frequency of 0.4, and allele a has a frequency of 0.6. The relative fitness values for the three genotypes are as follows: wAA = 1, wAa = 0.5, and waa = 0.5. What would be the expected frequencies of the two alleles after one generation?

The mean fitness of the population will increase.

A population is undergoing directional selection for a gene with two alleles: G and g. The most fit genotype is GG (relative fitness 1), while the Gg and gg genotypes both have relative fitness values of 0.5. Which of the following is expected to happen after several generations (assuming that the environment, in which this population lives, is not changing)?

0.400006

A specific gene is found in two forms in a population, Dand d, with frequencies of 0.6 and 0.4, respectively. The Dallele 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 Ddoes not occur.

20-30%

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.

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

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

Some genotypes are more likely to survive to reproductive age than others. Some genotypes are more likely to find mates than others. Some genotypes are more fertile than others.

Which of the following are likely reasons for differences in the reproductive success of different genotypes in a population?

Individuals must migrate from one population to another. Migrants must be fertile and pass their genes to the next generation.

Which of the following are required for gene flow to occur?

As the frequency of a genotype increases, its fitness decreases.

Which of the following best describes the relationship between a genotype's fitness and its frequency in negative frequency-dependent selection?

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

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

I10−6 per gene per generation

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

mutation of a sequence within an intron change in the wobble position without affecting the amino acid sequence of the encoded protein missense mutation that causes an amino acid substitution which does not affect the proper folding of the protein

Which of the following would be a neutral mutation?

Natural selection favors individuals with a heterozygous genotype.

Which of the following would not be true for a population that is in Hardy-Weinberg equilibrium for a specific gene?

because they tend to exhibit considerable variation between individuals

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

Population 1 is more susceptible.u

You are observing two populations of the same animal species. Population 1 consists of 46 individuals, while population 2 consists of 3325 individuals. Which population is more susceptible to genetic drift?

A = 0.58; a = 0.42

You are studying a gene with two alleles, A and a, in a population of plants. The relative fitness coefficients of the three genotypes for this gene are as follows: wAA = 0.5; wAa = 1; waa = 0.3. If this population is undergoing balancing selection due to heterozygote advantage, what would the expected equilibrium frequencies of A and a be?

A new allele, which promotes higher fitness in organisms that carry it, is introduced in a population (for example, by a random mutation).

Which of the following is a situation in which directional selection may be observed?

genotype; DD genotype

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 ______ frequency of the ______.

allele; p allele

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

all of the alleles of every gene that were passed from the 60 parents to the 48 new cubs

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?

proportion of the conglomerate population that is due to migrants from the donor population frequency of D in the donor population frequency of D in the original recipient population

Consider two populations of the same species and a gene that is found in two alleles in both populations (alleles Dand d). Choose all values that need to be known in order to calculate the change in the frequency of the allele D if some individuals migrate from one of the populations into the other.

repetitive

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. The general name for these types of sequences is ______ sequences.

polymorphism

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.

They are under stabilizing selection, which should decrease their genetic diversity.

The weight of a human baby at birth is a quantitative trait determined by the activity of many genes. Babies with very low or very high birth weights have a decreased chance of survival, while babies with intermediate birth weights have much better chances of survival. What can you hypothesize about the genetic diversity of genes that determine birth weight in humans?

This gene is under balancing selection due to heterozygote advantage in those areas.

Which of the following best explains the high prevalence of the HbS allele of the human β-globin gene in populations living in areas of high malaria prevalence?

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

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

Inbreeding lowers the mean fitness of a population when homozygotes have a lower relative fitness value.

Which of the following is a major disadvantage of inbreeding in natural populations?

Certain genotypes are more likely to continue to live after surviving to reproductive age.

Which of the following is not a reason for differences in the reproductive success of different genotypes in a population?

the relative likelihood that a genotype will contribute alleles to the next generation as compared to other genotypes

Which of the following is the best definition of Darwinian fitness as it relates to population genetics?

nonsense mutation missense mutation frameshift mutation

Which of the following mutations are likely to cause a defective protein to be ma de?

missense mutation that causes an amino acid substitut ion which does not affect the proper folding of the protein change in the wobble position without affecting the amino acid sequence of the encoded protein mutation of a sequence within an intron

Which of the following would be a neutral mutation?