Genetics: Key Concepts

Gene and Alleles

• A gene is a unit of heredity that occupies a specific locus on a chromosome.
• A locus is a specific location on a chromosome where a gene is located.
• Alleles are different forms of a gene that occupy the same locus on homologous chromosomes.

Hardy-Weinberg Equilibrium

• The Hardy-Weinberg equilibrium is a population genetics model that describes the frequencies of alleles and genotypes in a population that is not evolving.
• The five conditions for Hardy-Weinberg equilibrium are:
  1. No mutation
  2. No gene flow
  3. No genetic drift
  4. Random mating
  5. No natural selection

Population Genetics

• Population genetics is the study of the genetic variation within populations.
• Genetic variation is the presence of different alleles in a population.
• The gene pool is the total genetic variation within a population.

Genetic Variation

• Genetic variation can be caused by mutation, gene flow, genetic drift, and non-random mating.
• Mutation is a change in the DNA sequence.
• Gene flow is the movement of alleles between populations.
• Genetic drift is the random change in allele frequencies in a population.
• Non-random mating is when individuals mate with each other based on their genotype.

Natural Selection

• Natural selection is the process by which individuals with traits that are better suited to their environment are more likely to survive and reproduce.
• Natural selection can lead to the evolution of new species.

Evolution

• Evolution is the change in the genetic composition of a population over time.
• Evolution can be caused by natural selection, genetic drift, and mutation.

Other Key Concepts

• Genotype is the genetic makeup of an individual.
• Phenotype is the observable characteristics of an individual.
• Fitness is the ability of an individual to survive and reproduce in its environment.
• Adaptation is a trait that helps an individual to survive and reproduce in its environment.