AI generated Unit 3 flashcards

How do genes determine phenotypes?

Genes determine phenotypes by encoding for traits that manifest in observable characteristics.

What defines a polygenic trait?

A polygenic trait is influenced by multiple genes, often resulting in continuous variation in traits, like human height.

Describe pleiotropy in genetics.

Pleiotropy occurs when a single gene influences multiple, seemingly unrelated phenotypic traits.

How do pleiotropy and polygenic traits interact?

A single gene can have multiple effects (pleiotropy) while also contributing to a polygenic trait.

What are quantitative traits?

Quantitative traits show continuous variation and are measured on a scale, like height and weight.

How do mutations contribute to genetic variation?

Mutations introduce new alleles into a population, creating genetic diversity and phenotypic variation.

How do genetic and environmental factors create phenotypic variation?

Genetic variation provides a range of possible phenotypes that can be modified by environmental influences.

What determines coat color in oldfield mice?

The Mc1R gene with alleles B (brown) and b (tan); brown is the dominant color.

What is the function of the Mc1R gene?

The Mc1R gene encodes the melanocortin receptor protein, activating a pathway for eumelanin production.

What is the Hardy-Weinberg equation for allele frequencies?

p + q = 1, where 'p' is the frequency of the dominant allele and 'q' is the frequency of the recessive allele.

What is the Hardy-Weinberg equation for genotype frequencies?

p^2 + 2pq + q^2 = 1; where p^2 is homozygous dominant frequency, 2pq is heterozygous frequency, and q^2 is homozygous recessive frequency.

What does Hardy-Weinberg equilibrium signify?

It indicates that allele and genotype frequencies remain constant over generations in the absence of evolutionary forces.

List the five conditions for Hardy-Weinberg equilibrium.

Random mating, no natural selection, no genetic drift, no gene flow, no mutations.

How does random mating help maintain Hardy-Weinberg equilibrium?

Random mating ensures alleles combine randomly, stabilizing allele frequencies.

Define natural selection in genetics.

Natural selection is the differential survival and reproduction of individuals with advantageous traits.

What is genetic drift?

Genetic drift is the random change in allele frequencies due to chance, differing from natural selection.

Explain gene flow in populations.

Gene flow is the movement of alleles between populations, increasing genetic similarity and introducing new alleles.

What is an adaptation? Give an example.

An adaptation is a feature improving fitness; for example, echolocation in bats aids in avoiding predators.

Describe stabilizing selection.

Stabilizing selection favors intermediate phenotypes, reducing genetic variation by selecting against extremes.

What is directional selection?

Directional selection favors one extreme phenotype, shifting allele frequencies towards that phenotype.

Define disruptive selection.

Disruptive selection favors both extremes over intermediates, increasing genetic variation in the population.

What is a genetic bottleneck?

A genetic bottleneck is a sharp reduction in population size, leading to reduced genetic diversity.

Explain the founder effect.

The founder effect occurs when a small group creates a new population with different allele frequencies.

How can gene flow affect fitness in a population?

Gene flow can introduce beneficial alleles enhancing fitness or harmful alleles reducing fitness.

How does genetic drift affect alleles?

Genetic drift can cause random loss or fixation of alleles, particularly in small populations, reducing diversity.

What is the role of the environment in phenotypic expression?

The environment interacts with genetic factors to express traits, influencing phenotypic variation.

How can selective pressure affect genetic variation?

Selective pressure can lead to an increase or decrease in certain traits within a population, impacting genetic variation.

What is the significance of mutation rates in evolution?

Mutation rates determine how quickly new genetic variations arise, influencing the pace of evolutionary change.

Describe the concept of fitness in evolutionary biology.

Fitness refers to an organism's ability to survive and reproduce in its environment, contributing to the gene pool.

What is the difference between artificial selection and natural selection?

Artificial selection is human-directed breeding for desirable traits, whereas natural selection occurs through environmental pressures.