Meiosis

Prophase I

• homologous chromosomes pair

• nuclear envelope disappears

• crossing over occurs and genetic information is exchanged

• spindle fibers prepare to attach to the chromosomes

Metaphase I

• homologous chromosomes line up side by side along the middle of the cell

  • this allows for additional mixing of genetic material

Anaphase I

• spindle fibers attach and pull the chromosomes to opposite ends of the cell

• sister chromatids stay together

Telophase I / Cytokinesis

• nuclear envelope reforms around chromosomes

• two daughter cells seperate

Prophase II

• nuclear envelope disappears

• no cross over

• spindle fibers begin to grab onto chromosomes

Metaphase II

• chromosomes line up in a single-file line in the center of the cell

Anaphase II

• the sister chromatids are pulled apart to either side of the cell

Telophase II/ Cytokinesis II

• gametes with different genetic combinations in each are created

• the end product of meiosis is 4 daughter cells that have half the normal chromosome number (haploid) → in humans, 23