Genetics and Evolution Terminology

A set of vocabulary flashcards defining key terminology in genetics, chromosome structure, patterns of inheritance, and evolutionary mechanisms.

Centromere

The point where chromatids are joined together during meiosis.

Chiasma

The point of contact between chromatids of homologous chromosomes during crossing over.

Chromatid

One of two copies of a replicated chromosome.

Chromosome

A thread-like structure in the nucleus made of DNA and protein that carries genetic information.

Co-dominance

In a heterozygous individual, the two alleles are equally expressed in the organism’s phenotype (e.g., roan cow RW where R = red hair and W = white hair).

Complete dominance

In a heterozygous individual, the dominant allele is always expressed while the recessive allele is masked.

Diploid

Having two sets of chromosomes.

Disruptive selection

Natural selection where both ends of a range of phenotypes are favored rather than the average phenotype.

Emigration

Movement of organisms out of a population.

Founder effect

The genetic consequence of a population starting from only a few individuals; the new population is genetically not representative of the original.

Gamete

A sex cell, e.g., sperm or egg.

Gametic mutation

Mutations that occur in the DNA of sex cells; can be passed on to the next generation if fertilised.

Gene flow

Exchange of alleles between populations through immigration and emigration.

Gene frequency

The proportion of individuals in a population with a particular allele.

Gene pool

All the genes or alleles present in a population.

Genetic drift

Change in allele frequency in a population due to chance/random events rather than selection.

Immigration

Movement of organisms into a population.

Incomplete dominance

Both alleles are partially expressed in the phenotype; heterozygous individuals show an intermediate trait (e.g., snapdragon Rr = pink).

Independent assortment

Random assignment of chromosomes to gametes during meiosis; homologous pairs line up independently.

Linked genes

Genes found on the same chromosome that are inherited together and cannot separate independently.

Meiosis

Cell division for the production of gametes; cells produced are genetically unique.

Multiple alleles

Having more than two alleles for a gene (e.g., ABO blood types).

Natural selection

Individuals best suited to environmental conditions survive and reproduce more, leading to evolutionary change.

Somatic mutation

Mutations in regular body cells (somatic cells); not passed on to the next generation.

Variation

Differences between individuals in a population.