Genetics Smartbook 17

Consider an X-linked recessive allele that is present in 5% of the males in a population. Assume Hardy-Weinberg equilibrium and a 1:1 sex ratio in the population. What is the frequency of the allele in the females of that population?

0.0025

Hemophilia is an X-linked recessive disorder. In a population, the frequency of hemophilia in females is 0.49%. Assuming that this population is in Hardy-Weinberg equilibrium and that the sex ratio is 1:1, what is the frequency of hemophilia in males?

7%

What is CODIS?

A database of DNA markers that is used in forensic analysis

Which of the following are assumptions of the Hardy-Weinberg Law?

No new mutations appear in the gene pool The population is composed of diploid individuals No migration of individuals takes place into or out of the population

Which of the following conditions deviate from the Hardy-Weinberg assumptions?

Small groups of individuals move to become founders of new populations New mutations appear occasionally at every locus Individuals preferentially mate with others of the same phenotype

A variant at a specific locus, gene, region or nucleotide position is called a(n) ___

allele

The two main ways in which new variants of genes can appear in a population is through the generation of new alleles by ___ The two main ways in which new variants of genes can appear in a population is through the generation of new alleles by ____

mutation migration

The progressive increase in fitness from one generation to the next is the result of a process called ___

natural selection

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

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

Genetic drift is the _____ in a population.

random change of allele frequencies

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

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

Individuals with some genotypes are more likely to survive to reproductive age than others. Individuals with some genotypes are more fertile than others. Individuals with some genotypes are more likely to find mates than others.

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

The relative (compared to other genotypes) likelihood that a genotype will contribute alleles to the next generation

In a newly established population which meets the Hardy-Weinberg assumptions, genotype frequencies might dramatically change in the first generation, but allele frequencies will not. This is known as the principle of conservation of ____

allele proportions

Natural selection can favor the maintenance of two or more alleles in a population, for example, when heterozygote advantage is observed. This type of natural selection is called

balancing balancing

The Hardy-Weinberg law 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

Deviations to Hardy-Weinberg conditions change the genetic composition of populations over time and are thus essential for the ____ of living forms.

evolution

In the absence of a selection agent (eg. antibiotic or insecticide), the frequency of a resistant R allele decreases rapidly in a population, so that RR genotypes could virtually disappear. This suggests that the RR genotype imposes a(n) ____ on individuals, and resistance is subject to a negative selection.

fitness cost

A group of individuals from a larger population can migrate to a new area and establish a colony, which will be highly susceptible to genetic drift. This is known as the ______ effect.

founder

Sometimes, a small group of individuals separates from a larger population and migrates to a different site, where it establishes a colony. The new population can become susceptible to genetic drift via the ___

founder effect

In order to derive the Hardy-Weinberg equation, the two scientists assumed that _____.

gametes are independently chosen at random from the population's gene pool

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

gene pool

Any random change in the frequencies of alleles in a population is called ____

genetic drift

Consider a newly established island population on that is sufficiently large and meets the other assumptions of a Hardy-Weinberg population. After one generation of random mating, ______.

genotype frequencies might change dramatically, but allele frequencies will remain the same

The Hardy-Weinberg Law assumes ______.

large populations, random mating, no mutations in the gene pool, and no natural selection

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

mean fitness

DNA sequences obtained from Neanderthal specimens have revealed that these individuals very likely had red hair and fair skin based on the presence of particular variants of the ___

melanocortin 1 receptor gene

Any change in the DNA of an organism, for example, a change in DNA sequence or the structure and number of chromosomes, is called a(n)____

mutation

In genetics, a group of individuals of a sexually reproducing species, which occupy the same region, and can successfully interbreed with each other, is called a(n)

population

A finite number of individuals that is used to make inferences about the population as a whole is known as a(n) ___

sample

When studying populations, geneticists ______.

sample individuals randomly without consideration of genotype or phenotype

Hardy and Weinberg derived their famous equation by extending Mendel's first law, which is called the law of ___

segregation

Genetic ancestry refers to ______.

the actual inheritance of genomic segments from biological ancestors

Population genetics is the study of ______.

the transmission of genetic variation between generations

According to the Hardy-Weinberg law, in the absence of forces acting to change allele frequencies, the proportions of different genotypes in a population _____.

will remain constant over time and between generations