Meiosis and Genetic Variation

Flashcards covering key vocabulary and concepts relating to meiosis and genetic diversity.

Meiosis

A type of nuclear division that reduces the chromosome number in half to produce gametes.

Gametes

Reproductive cells (sperm and eggs) that unite during fertilization.

Fertilization

The process where two gametes unite to form a new individual.

Chromosomes

Structures made of DNA and proteins that carry genetic information.

Homologous chromosomes

Chromosome pairs that contain the same genes but may have different alleles.

Alleles

Different versions of a specific gene found on homologous chromosomes.

Diploid (2n)

A cell that contains two homologs of each chromosome.

Haploid (n)

A cell that contains one of each type of chromosome.

Crossing over

The exchange of chromosome segments between homologous non-sister chromatids during prophase I of meiosis.

Independent assortment

The random separation of homologous chromosomes during meiosis, resulting in genetic variation.

Nondisjunction

An error in meiosis where homologous chromosomes or sister chromatids fail to separate properly.

Aneuploidy

A condition where cells have an abnormal number of chromosomes, often caused by nondisjunction.

Purifying selection hypothesis

The theory that sexual reproduction helps eliminate harmful alleles more effectively than asexual reproduction.

Changing-environment hypothesis

The idea that genetic diversity from sexual reproduction allows offspring to adapt better to changing environments.

Zygote

A diploid cell formed by the union of two gametes.

Bivalent

A paired set of homologous replicated chromosomes during meiosis I.

Chiasmata

Points where homologous chromosomes exchange genetic material during crossing over.

Karyotype

A visual display of an organism's complete set of chromosomes.

Ploidy

The number of complete sets of chromosomes in a cell.

Polyploid

An organism or cell having more than two complete sets of chromosomes.

Gametes

Sperm and eggs - the reproductive cells in sexually reproducing organisms.

Mitosis

A process of cell division that results in two genetically identical daughter cells.

Meiosis I

The first division in meiosis, resulting in two haploid cells.

Meiosis II

The second division in meiosis, separating sister chromatids, resulting in a total of four haploid cells.