Meiotic Division and Genetic Variation Flashcards

Flashcards for Biology - Meiotic Division and Genetic Variation

Homologous Pairs

Pair of chromosomes which are the same size and shape and have the same genes at the same location. Human cells have 46 chromosomes – 23 homologous pairs.

Diploid (2N)

A cell with 2 sets of chromosomes (i.e., each of the homologous pairs) in each of its cells; somatic cells.

Haploid (N)

A cell with 1 set of chromosomes in each of its cells; (i.e., one chromosome from each homologous pair) all gametes – formed due to meiosis cell division.

Allele

Different forms of the same gene (ex. eye color).

Genetic Locus

The location of a particular gene on a chromosome.

Bivalent

A pair of homologous chromosomes.

Tetrads

The four chromatids in a bivalent.

Meiotic Division

Cell division that occurs in germline cells, producing gametes with half the number of chromosomes. Diploid (2N) to Haploid (N).

Meiosis I

The first stage of meiotic division involves the separation of homologous chromosomes.

Meiosis II

The second stage of meiotic division involves the separation of sister chromatids.

Synapsis

The pairing up of homologous chromosomes during Prophase I of meiosis.

Crossing Over

The exchange of genetic material between non-sister chromatids during Prophase I, leading to genetic variation. Occurs at the chiasmata.

Chiasmata

Area where there is a physical link between two non-sister chromatids during crossing over.

Independent Assortment

The random alignment of chromosomes during Metaphase I that increases the number of possible combinations of genetic material, leading to genetic variation.

Reduction Division

The process in meiosis I where the chromosome number is reduced from diploid (2N) to haploid (N).

Fertilization

The fusion of sperm (N) and egg (N) to restore the diploid number (2N) in the zygote.

Recombinant Chromosomes

Chromosomes that have undergone exchange of genetic material between chromosomes.

Genetic Variation

Differences in genotypes and phenotypes essential for species survival from diseases and environmental changes.

Mutation

A primary source of genetic variation in populations, involving changes in DNA sequencing.

Somatic Cells

Tissue cells that have pairs of homologous chromosomes and are diploid.

Germline Cell

Cells, in diploid state, that can divide by meiotic division.