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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)
Starts with 46
Gamete (1n)
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
Non-Sister
Chromatids
Chromatids
Synapsis - Homologous Pairs of
chromosomes come together
Tetrad – 4 homologous chromatids
Media
Links\13-10CrossingOver.
mov
Metaphase I
Media Links\13-07c-MetaphaseI.mov
Anaphase I
Media Links\13-07d-AnaphaseI.mov
Telophase I
Media Links\13-07eTelophaseICytokin.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
chromosomes (ds) align on equator
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!!!!!