Population Genetics and Human Chromosomal Inheritance Patterns

What is the focus of Population Genetics?

The study of allele frequencies and genetic variation within populations.

Define 'gene pool'.

The total collection of alleles in a population.

What does allele frequency measure?

How often a specific allele appears in a population.

What is the Hardy-Weinberg principle?

A principle that describes how allele frequencies remain constant in a population under certain conditions.

List the assumptions of Hardy-Weinberg equilibrium.

1. Infinitely large population size. 2. No migration. 3. No mutation. 4. Random mating. 5. Equal fitness among genotypes.

What is the formula for allele frequency in a population?

The number of copies of a specific allele divided by the total number of alleles in the population.

How do you calculate genotype frequency?

The number of individuals with a specific genotype divided by the total number of individuals in the population.

What is the significance of the Hardy-Weinberg equilibrium?

It allows predictions of genotype frequencies based on allele frequencies.

What is the formula to predict future genotypic frequencies?

p² + 2pq + q² = 1, where p and q are the frequencies of the dominant and recessive alleles, respectively.

What is the relationship between allele frequency and phenotype frequency?

Changes in allele frequency can lead to changes in phenotype frequency over generations.

How many alleles does an individual have for a diploid gene?

Two alleles.

What does it mean if a population is in Hardy-Weinberg equilibrium?

The allele frequencies remain constant from generation to generation.

What is the expected frequency of the TT genotype if the T allele frequency is 0.6?

0.36 (0.6 * 0.6).

What is the expected frequency of the tt genotype if the t allele frequency is 0.4?

0.16 (0.4 * 0.4).

What is the expected frequency of the Tt genotype if the T and t allele frequencies are 0.6 and 0.4, respectively?

0.48 (2 * 0.6 * 0.4).

What is the role of reproduction in shaping a gene pool?

Reproduction allows for the mixing of alleles and can influence allele frequencies.

What factors can cause changes in allele frequencies?

Natural selection, genetic drift, mutation, and gene flow.

What is the importance of genetic variation in a population?

It contributes to the population's ability to adapt to changing environments.

What does it mean for a trait to be dominant?

It is expressed in the phenotype even if only one copy of the allele is present.

What does 'non-taster' mean in the context of the bitter taste gene?

An individual with the genotype 'tt' who cannot taste the bitter compound.

What is the expected outcome if a population experiences migration?

It can introduce new alleles and alter allele frequencies.

How does random mating affect allele frequencies?

It ensures that allele frequencies remain stable, as mates are chosen without regard to genotype.

What is the significance of equal fitness among genotypes?

It means that all genotypes have the same reproductive success, preventing natural selection from affecting allele frequencies.

How does mutation affect allele frequencies?

Mutations can introduce new alleles into a population, potentially changing allele frequencies.

What is the effect of natural selection on allele frequencies?

Natural selection can increase the frequency of advantageous alleles and decrease the frequency of disadvantageous alleles.

What is the relationship between genotype and phenotype?

Genotype determines the phenotype, which is the observable trait expressed by an organism.

What is the Hardy-Weinberg Equation?

p² + 2pq + q² = 1, used to predict genotypic frequencies in a population.

What does 'p' represent in the Hardy-Weinberg Equation?

The frequency of the dominant allele in a population.

What does 'q' represent in the Hardy-Weinberg Equation?

The frequency of the recessive allele in a population.

What is the frequency of the TT genotype if the T allele frequency is 0.6?

0.36 (calculated as 0.6 * 0.6).

What is the frequency of the tt genotype if the t allele frequency is 0.4?

0.16 (calculated as 0.4 * 0.4).

What is the frequency of the Tt genotype?

0.48 (calculated as 2 * p * q).

What are the conditions for Hardy-Weinberg Equilibrium?

Large population, random mating, negligible mutations, no gene flow, and no natural selection.

What is genetic drift?

A random process that causes allele frequencies to change due to chance events.

What is the Founder Effect?

When a small group establishes a new population, leading to different allele frequencies than the original population.

What is a genetic bottleneck?

A sharp reduction in population size that decreases genetic variation and can lead to fixation of harmful alleles.

What is gene flow?

The movement of genes between populations through migration.

What is natural selection?

The process where individuals with advantageous traits are more likely to survive and reproduce.

What is the role of mutations in evolution?

Mutations introduce genetic variation, which can be inherited and affect allele frequencies.

What is the significance of genetic variation?

It allows populations to adapt to changing environments and is essential for evolution.

What does 'assortative mating' mean?

Individuals mate with others that have similar phenotypes.

What is the impact of non-random mating on allele frequencies?

It can lead to changes in allele frequencies and affect genetic diversity.

How does natural selection differ from genetic drift?

Natural selection is a non-random process that favors advantageous traits, while genetic drift is random.

What is the effect of a catastrophic event on genetic drift?

It can drastically reduce population size and alter allele frequencies by chance.

What is the frequency of the Bb genotype in a population where q = 0.3?

The frequency of Bb can be calculated using the Hardy-Weinberg proportions.

What is the most common genotype in a population with alleles B and b?

The most common genotype is typically BB or Bb, depending on the allele frequencies.

What is the least frequent genotype in a population with alleles B and b?

The least frequent genotype is typically bb, depending on the allele frequencies.

What is the impact of inbreeding on a population's genetic diversity?

Inbreeding can reduce genetic diversity and increase the likelihood of genetic disorders.

What is the significance of the African Cheetah population in genetic drift studies?

Their reduced genetic diversity due to past bottlenecks makes them a key example of genetic drift.

What is the definition of 'allele frequency'?

The proportion of a specific allele among all allele copies in a population.

What does 'differential reproduction' refer to?

The concept that not all individuals reproduce to their full potential due to environmental limitations.

How can the Hardy-Weinberg equation be used in real-world applications?

It can estimate allele frequencies, detect shifts in populations, and measure carrier frequencies of diseases.

What is the relationship between genetic variation and evolution?

Genetic variation is essential for evolution as it provides the raw material for natural selection to act upon.

What is the primary advantage of sexual reproduction?

It produces genetically distinct offspring from both parents.

What are the two sexual phenotypes in most organisms?

Female (egg producing) and Male (sperm producing).

What are autosomes?

Chromosomes that are the same in males and females (22 pairs).

What are sex chromosomes?

Chromosomes that differ in males and females (1 pair).

What is the heterogametic sex?

The sex that produces two different types of gametes with different sex chromosomes.

What is the homogametic sex?

The sex that produces gametes containing the same sex chromosome.

What determines male phenotype in humans?

The presence of the Y chromosome and specifically the SRY gene.

What is the SRY gene?

The Sex-determining Region of Y that encodes the testis-determining factor (TDF).

What is X-inactivation?

The process by which one of the two X chromosomes in female cells is inactivated.

What are Barr Bodies?

Inactivated X chromosomes found in the nuclei of female cells.

What is the Lyon Hypothesis?

The hypothesis that one of the X chromosomes in each female somatic cell becomes inactive during development.

What is dosage compensation?

A mechanism that equalizes the amount of protein produced by X-linked genes in both sexes.

What is the significance of the Tuskegee Clinical Study?

It was an unethical study that tracked untreated syphilis in African American men without their informed consent.

What was the proposed goal of the Tuskegee Clinical Study?

To study the progression of untreated syphilis and the effectiveness of treatment.

What happened to the participants in the Tuskegee Study during the 1940s?

They were not given penicillin, which was an effective treatment, and suffered painful complications.

What is a pedigree analysis?

A diagram that shows the occurrence of a genetic trait across generations in a family.

What are the patterns of inheritance that can be determined from a pedigree?

Autosomal recessive, autosomal dominant, X-linked recessive, X-linked dominant, and Y-linked.

What is the role of the SRY gene in male development?

It triggers male development and the formation of testes.

What is the significance of pseudoautosomal regions (PARs) in sex chromosomes?

They are regions that share homology between X and Y chromosomes, allowing for pairing during meiosis.

How does X-inactivation affect tortoiseshell cats?

It leads to the expression of different fur colors based on which X chromosome is active in different cells.

What is the genetic composition of XX and XY individuals?

XX individuals are typically female, while XY individuals are typically male.

What law was signed on July 12th, 1974, to protect human subjects in research?

The National Research Act

What is a major limitation in studying human genetics related to generation time?

Individuals reach sexual maturity around 10-14 years, leading to a long wait for the F2 generation.

What is a pedigree?

A pictorial representation of a family history that outlines the inheritance of one or more characteristics.

What is a proband in pedigree analysis?

The person who is the starting point for the genetic study.

Why are pedigrees important in studying inherited diseases?

They help determine the genetic basis of a disease, predict modes of inheritance, and assess risks for future offspring.

What defines autosomal chromosomes?

Chromosomes that are not sex chromosomes (22 pairs).

What is the genotype for a dominant trait?

AA or Aa.

What is the genotype for a recessive trait?

aa.

What is the inheritance pattern for autosomal recessive traits?

Affected individuals have two copies of the recessive allele, and heterozygous individuals are carriers.

What is the inheritance pattern for autosomal dominant traits?

Affected individuals need only one copy of the dominant allele, and an affected child must have at least one affected parent.

How are X-linked recessive traits inherited?

Passed from mother to both sons and daughters, with males affected more due to being hemizygous.

How are X-linked dominant traits inherited?

Passed from father to all daughters and from affected mothers to both sons and daughters.

What defines Y-linked traits?

Traits on the Y chromosome, passed from affected fathers to all sons, affecting only males.

What is the genotype for an affected female with X-linked recessive inheritance?

XaXa.

What is the genotype for an affected male with X-linked recessive inheritance?

XaY.

What is the probability that a child will have hemophilia if a woman with hemophilia mates with a man with normal blood clotting?

Depends on the genotypes of the parents; typically, the probability for a male child is higher.

What is the widow's peak trait in terms of inheritance?

It is an autosomal trait.

What are the five patterns of inheritance in genetics?

Autosomal recessive, autosomal dominant, X-linked recessive, X-linked dominant, and Y-linked.

What is the significance of X-inactivation?

It ensures dosage compensation for X-linked genes in females.