BIOL005A Lecture 18: Meiosis

Vocabulary practice flashcards covering essential terms, stages, and concepts of meiosis from BIOL005A Lecture 18.

Meiosis

A modified type of cell division used to produce gametes in sexually reproducing organisms, consisting of two rounds of cell division but only one round of DNA replication.

Homologous chromosomes

Pairs of chromosomes inherited from different parents that carry the same sets of genes.

Synapsis

The pairing process in meiotic prophase I that brings homologous chromosomes into close association.

Crossing over (Recombination)

A reciprocal exchange event between nonsister chromatids occurring during meiotic prophase I that allows offspring to inherit unique combinations of genes.

Bivalents

Pairs of associated homologous chromosomes formed during prophase I that align at the metaphase plate in metaphase I.

Meiosis I

The reductional division ($2n \rightarrow n$) in which homologous chromosomes segregate from one another while centromeres do not divide, producing two haploid cells with duplicated chromosomes.

Meiosis II

The equational division ($n \rightarrow n$) in which sister chromatids separate as centromeres divide without prior DNA synthesis, producing four haploid meiotic products.

Chiasma

The physical site of crossing over where paired homologous chromosomes are held together in combination with sister chromatid cohesion during prophase I.

Fertilization

The union and fusion of two haploid ($n$) gametes to produce a diploid ($2n$) zygote ($n + n \rightarrow 2n$).

Zygote

The single diploid ($2n$) cell produced by the union of two gametes during fertilization, containing $2n = 46$ chromosomes in humans.

Gamete

A haploid reproductive cell ($n$) containing one representative copy of each chromosome ($n = 23$ in humans) produced as a result of meiosis.

Meiocyte

A cell that undergoes meiosis to produce haploid meiotic products (for example, a cell starting with $2n = 4$ chromosomes).