Polymorphism and Natural Selection

Flashcards covering terms and definitions related to polymorphism and natural selection, emphasizing the sickle cell trait, its genetic basis, and environmental interactions.

Polymorphism

A situation in a population or species where there exist two or more alleles of a gene, with at least two alleles having a frequency greater than 1%.

Balanced polymorphism

A situation in a population or species where there are two or more alleles of a gene, and the heterozygotes have a higher fitness than homozygotes.

Sickle cell trait

A genetic condition caused by a point mutation in the beta chain of hemoglobin, resulting in sickle-shaped red blood cells.

Heterozygote advantage

The phenomenon where heterozygotes for a trait have a higher fitness compared to homozygotes, especially in specific environments like that of malaria.

Point mutation

A change in a single nucleotide in a DNA sequence, which can lead to a different amino acid being incorporated into a protein.

Natural selection

The process by which individuals with favorable traits are more likely to survive and reproduce, passing those traits to the next generation.

Polymorphic frequency

The relative frequency of different alleles in a population, indicating genetic diversity.

Homozygote

An individual with two identical alleles for a specific gene.

Geographical association

The correlation between the distribution of a genetic trait (like sickle cell allele) and specific geographic areas or environmental factors.

G-6-PD deficiency

A genetic disorder causing a deficiency in glucose-6-phosphate dehydrogenase, which provides a selective advantage against malaria.