Meiosis is used in sexual reproduction to make genetically diverse gametes  genetically diverse individuals

MEIOSIS The production of eggs and sperm The “Reduction Division ” Mother Cell (2n) Gamete (1n) Starts with 46 Ends with 23 Media Links\13_08Meiosis.mpg

Pre- Germ Cell OR Pre-Reproductive Cell Mother Cell is diploid 2n = 46 BUT in this cartoon version ……… 2n= 4

Interphase Pre-Reproductive Cell

Prophase I Media Links\13-07b-ProphaseI.mov

Prophase I Sister Chromatids Non-Sister Chromatids

Synapsis - Homologous Pairs of chromosomes come together Tetrad – 4 homologous chromatids Media Links\ CrossingOver. mov

Metaphase I Media Links\13-07c-MetaphaseI.mov

Anaphase I Media Links\13-07d-AnaphaseI.mov

Telophase I Media Links\13-07e- TelophaseICytokin.mov Cytokinesis occurs

Meiosis I Summary 1. Crossing Over Occurred (Ensures Genetic Variation) 2. Separated the Homologous Pair of Chromosomes Cell went from 2N to 1N (ds) 3. Started as 2N = 46 (ds), ended as N = 23 (ds)

Interkinesis – Meiosis Intermission Are these cells 1N or 2N?

Prophase II

Metaphase II

Anaphase II

Telophase II Media Links\13-07f-MeiosisIICytokin.mov

Gametes

Meiosis II Summary 1.Separated the chromatids, Centromeres broke 2. 2 temporary daughter cells went from Haploid (ds) to Haploid (ss) 3. Started as n = 23 (ds) ended as n = 23 (ss) Media Links\13_08Meiosis.mpg

And Now It Is Time To Start The Meiosis Lab... Grab your Chromosomes Cups and begin!!!!!