Meiosis

Metaphase II

*Second phase of meiosis II. *Identical to mitotic metaphase, except that the number of chromosomes was reduced by half during meiosis I. *Chromosomes line up at the equat

Prophase I

*1st phase of Meiosis 1 *Longest phase (90%) *nuclear membrane breaks apart, chromosomes condense and form homologous pairs *Crossing-over in meiosis 1 occurs in which phase

Diploid

*A cell that contains both sets of homologous chromosomes *Body Cell *2n

Haploid

*An organism or cell having only one complete set of chromosomes. *Sex Cell (gamete) * 1n or n

Cytokinesis in Meiosis

*Cytoplasm completely splits. * 4 new cells are formed, each with only half the number of chromosomes

Prophase II

*First phase of meiosis II. *Identical to mitotic prophase, except that the number of chromosomes was reduced by half during meiosis I.

Telophase II

*Fourth and final phase of meiosis II. *Telophase II is identical to mitotic telophase, except that the number of chromosomes was reduced by half during meiosis. I.

Meiosis II

*Second phase of meiosis consisting of chromatids separating, along with the two diploid cells splitting in two

Body Cell

somatic cell

Sex Cell

An egg or sperm cell (gamete)

Female chromosomes

XX Chromosomes

Autosomes

Any chromosome that is not a sex chromosome

Telophase I

*The fourth of meiosis I. *Telophase I is identical to mitotic telophase, except that the number of chromosoms is now reduced by half *Cell is considered to be haploid. *Chromosomes are still replicated, and the sister chromatids must still be separated during meiosis II.

Metaphase I

*The second phase of meiosis I. * During metaphase I the paired homologous chromsomes (tetrads) align at the center of the cell (the metaphase plate).

Anaphase I

*The third phase of meiosis I *Replicated homologous chromosomes are separated (the tetrad is split) and pulled to opposite sides of the cell.

Anaphase II

*Third phase of meiosis II. *During anaphase II the sister chromatids are finally spearated at their centromeres and puled to opposite sides of teh cell. *Anaphase II is identical to mitotic anaphase, excep the number of chromosmes was reduced by half during meiosis I.

Mitosis

A nuclear division resulting in the production of two somatic cells having the same genetic complement as the original cell.

tetrad

A paired set of homologous chromosomes, each composed of two sister chromatids. Tetrads form during prophase I of meiosis.

Centromere

Area where the chromatids of a chromosome are attached

Meiosis

Cell division that produces reproductive cells (sperm & egg) in sexually reproducing organisms.

Sex chromosomes

Chromosomes that determine the sex of an individual

Homologous chromosomes

Pair of chromosomes that are the same size, same appearance and same genes.

synapsis

Pairing of homologus chromosomes in a diploid cell, as occurs during prophase I of meiosis. Where crossing over can occur.

Chiasmata

Points where chromatids cross-over

crossing over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis.

Chromosomes

Structures in a cell that contain genetic information.

Interphase I

The cell prepares for division of cell by replicating the DNA

Independent Assortment

The random distribution of the pairs of genes on different chromosomes to the gametes.

Male chromosomes

XY Chromosomes