Genetics and Evolution Concepts

These flashcards cover important vocabulary and concepts related to genetics and evolution, summarizing key terms and their definitions from the provided lecture notes.

Gene

A segment of DNA that contains the instructions for building proteins, which influence traits in an organism.

Allele

Different forms of a gene that exist at the same locus on homologous chromosomes.

Homozygous

An organism that has two identical alleles for a trait.

Heterozygous

An organism that has two different alleles for a trait.

Genotype

The genetic makeup of an organism; the combination of alleles.

Phenotype

The observable traits of an organism, determined by its genotype.

Dominant allele

An allele that expresses its phenotype even when heterozygous with a recessive allele.

Recessive allele

An allele that only expresses its phenotype when homozygous.

Gene pool

The total collection of alleles in a population.

Hardy-Weinberg Principle

A mathematical model that describes the genetic variation of a population under ideal conditions.

Pre-zygotic barrier

A mechanism that prevents mating or fertilization between species.

Post-zygotic barrier

A mechanism that occurs after fertilization, preventing the hybrid zygote from developing into a viable, fertile adult.

Sympatric speciation

The process of speciation that occurs when populations that coexist in the same geographic region diverge into new species.

Polyploidy

A condition in which an organism has extra sets of chromosomes.

Natural selection

The process by which individuals with favorable traits are more likely to reproduce.

Genetic drift

A random change in allele frequency in a population.

Bottleneck effect

A drastic reduction in population size that reduces genetic diversity.

Founder effect

Reduced genetic diversity that occurs when a small group of individuals becomes isolated from a larger population.

Directional selection

A type of natural selection that favors one extreme phenotype over the others.

Stabilizing selection

A type of natural selection that favors intermediate variants by acting against extreme phenotypes.

Disruptive selection

A type of natural selection that favors extreme phenotypes over intermediate ones.

Convergent evolution

The process by which unrelated organisms evolve similar traits.

Linnaean classification

A hierarchical system for naming and classifying organisms.

Binomial nomenclature

The two-part naming system for species, consisting of the genus name and species name.

Phylogeny

The evolutionary history and relationships among species.

Eukaryotes

Organisms whose cells contain a nucleus and organelles.

Prokaryotes

Single-celled organisms that lack a nucleus.