Genetic Variation

Topic 2

Allele

An alternative for or version of a gene found at a specific spot on a chromosome.

Allele Frequency

the proportion or percentage of a specific gene variant (allele) compared to the total number of all allele variants for that gene in a population.

Chiasma

the X-shaped, physical point of contact and link between non-sister chromatids of homologous chromosomes where genetic material is exchanged during crossing over

Continuous Variation

a range of phenotypes where there are no distinct, separate categories

Crossing over

exchange of genetic material between non-sister chromatids of homologous chromosomes during prophase I of meiosis, which results in recombinant chromosomes and new combinations of alleles

Diploid

one that contains two complete sets of chromosomes

Discontinous Variation

differences in traits within a population that fall into distinct, clear-cut categories with no intermediate values

Gamete

an organism's reproductive cells that unite during sexual reproduction to create a new offspring

Gene

the basic physical and functional unit of heredity. Genes are made of specific sequences of DNA (or RNA in some viruses) and are packaged onto structures called chromosomes inside the cell's nucleus

Gene Pool

the total collection of all genes and their different forms (called alleles) shared by all the members of a single reproducing population or species

Genetic Variation