1. Meiosis reduces the number of Chromosome sets from diploid to haploid

2. Firsts 4 Stages of Meiosis  First 4 steps

3. First 4 stages  Interphase 1. Chromosomes replicate during S phase but remain uncondensed, each replicated chromosome consists of two genetically identical sister chromatids. 2. Centrosome replicates forming two centrosomes.

4. The First 4 Stages  Prophase I 1. 90% of the time required for meiosis 2. Chromosomes begin to Condense 3. Line up gene by gene 4. They cross over (red and the blue) 5. The crisscross regions, Chiasmatas, hold the chromosomes in place until anaphase I. (tetrads)

5. The First 4 Stages  Metaphase I 1. Chromosomes line up on the metaphase plate, with one chromosome on either side. 2. Chromatids are attached to kinetochore microtubules from one pole.

6. The First 4 Stages  Anaphase I 1. Chromosomes move toward the poles 2. Homologous chromosomes move to opposite poles.  Telophase and Cytokinesis 1. They split like normal, with the homologous chromosomes in the different sister cells. 2. (animal/plant)

7. Meiosis II

8.  Prophase II 1. Spindle apparatus forms, Chromosomes move toward metaphase plate  Metaphase II 1. Chromosomes on the metaphase plate 2. NO CRISSCROSS, two sister cells are not genetically the same 3. Kinetochores attach to microtubules.

9. Meiosis II  Anaphase II 1. Centromeres finally separate 2. Sister Chromatids of each chromosome now move as two individual chromosomes toward opposite poles.  Telophase II and Cytokinesis 1. Nuclei forms, Makes 4 daughter cells and each one is genetically different from all the rest.

10. Comparing Mitosis to Meiosis Mitosis  Produces identical cell as there parent. Meiosis  Reduces # of Chromosomes sets from 2 diploid to one haploid.  Produces different cells than parent and other daughter cells.  Synapsis and Crossing over (synapsis is the process of the chromosomes crisscrossing)  Tetrads on the Metaphase plate (Tetrads is the crossover region makes an X)  Separation of homologues

11. Genetic Variation produced in Sexual life cycles contributes to evolution  Species that reproduce sexually, the behavior of chromosomes during meiosis and fertilization is responsible for most of the variation that arises each generation.  There are 3 mechanisms that contribute to the genetic variation – independent assortment of chromosomes - crossing over - random fertilization

12. Independent assortment of Chromosomes  Metaphase I, when the homologous pairs, one is maternal and one is paternal chromosome(mother and father), and is put on the plate.  There is a 50-50 chance on which side will be on what. When it splits into the 2 daughter cells its called independent assortment.  Each cell represents one outcome of all possible combinations of maternal and paternal chromosomes. *Humans - 46 chromosomes, 23 combinations or 2 X 23 rd power = 8 million combinations

14. Crossing Over  Recombinant chromosomes- individual chromosomes that carry genes(DNA) derived from 2 different parents. ^ that is a result from crossing over.  The crossover just produces new combinations of maternal or paternal genes.  Humans cross over 1 to 3 times on each chromosome.

15. Random fertilization  Adds more genetic variation arising form meiosis.  The fusion of a single male gamete with a female one will produce a zygote with a about 64 TRILLION diploid combinations!  Truly unique combination of genes

16. Evolutionary Significance of Genetic Variation Within Populations  Natural Selection, individuals best suited to the local environment leave there genes.  Leads to accumulation of those genetic variations favored by the environment

17. SONGS!  http://www.youtube.com/watch?v=iCL6d 0OwKt8 http://www.youtube.com/watch?v=iCL6d 0OwKt8  http://www.youtube.com/watch?v=LOC aSUZOFLA http://www.youtube.com/watch?v=LOC aSUZOFLA

18. Song Lyrics  When they see us up on youtube they say cell mates really killin it  First we drop mitosis now we putting out another hit  Mitosis got fame pretty quick, but this ones gonna fasta  In the first process a cell was split, and this is like a relative  Call this one a relative? Yeah its a relative  They do the same thing basically, like they in a family  Whats double of mitosis? How do sex cells duplicate?  Everybody knows the answer, meiosis without mistake  If you all dont understand, yeah I guess we will explain  Did a little research and cell split experts we became  Then after we make the rap, intelligent we will remian  Cause when it comes to science raps, you know the cell mates run the game!

19.  Same thing, same stuff, just mitosis doubled up  Prophase, metaphase, same process from the last dub  Anaphase, telophase, its the reason your alive  No sexual reproduction, life on earth would simply stop  After interphase, before its all split across  Chromosomes have to break, this is known as first prophase  Crossing over then occurs, genetic code forever wrote  Spindle fibers pull away, the mother cell forever broke  Phase 1 is now complete, lets put the process on repeat  DNA dont duplicate, chromos align at center plate  The two new cells divide and then, this thing happens over again  Meiosis was a success, 4 daughter cells is all thats left

20.  I feel like in meiosis it is quite like  Mitosis cept that it does this whole thing twice  I feel like most students dont know this process  So Ill explain it to you all with optimal finesse  Its got homologous pairs, and you know they split  But remaining intact are sister chromatids  First, second telophase the cell begins to split into two pieces  They release, just at least after cytokinesis  When you let your sex cells go  You wont ever have to wonder if theyre gonna regrow  Cause you know with meiosis they will always restore  Happens in everyone so Meiosis is hard to ignore  Twenty-three chromos there, homie, in each daughter cell, homie  You can ask Mr. Waggoner anaphase centromeres divide  Centromeres divide  Now its meiosis right (meiosis right)  Its reproduction time (reproduction time)  Now you know this rhyme (know this rhyme)  Cause with every line, every line I put on

21. Works cited  http://www.google.com/imgres?um=1&hl=en&safe=off&biw=1440&bih=817&tbm=isch&tbni d=pv_7YoYp_K0mGM:&imgrefurl=http://gabrielarogers.blogspot.com/2011_03_01_archive.h tml&docid=cTx3L2v5dKIYSM&imgurl=http://3.bp.blogspot.com/-6VECSMU10HY/TY-RXY- t24I/AAAAAAAAAEg/Q0qe4erqknw/s1600/independent_assortment.jpg&w=800&h=551&ei= D6G4Tt_FGYimsQL_xfSxCA&zoom=1&iact=hc&vpx=390&vpy=155&dur=583&hovh=186&hov w=271&tx=155&ty=101&sig=109748501573580030227&page=1&tbnh=136&tbnw=197&start=0 &ndsp=24&ved=1t:429,r:1,s:0  http://www.google.com/imgres?um=1&hl=en&safe=off&sa=X&biw=1440&bih=817&tbm=isc h&tbnid=56FK40XoecaQbM:&imgrefurl=http://faculty.irsc.edu/FACULTY/TFischer/bio%25201 %2520files/bio%25201%2520resources.htm&docid=E_O4XayU0bbXjM&imgurl=http://faculty.ir sc.edu/FACULTY/TFischer/images/meiosis%2525202.jpg&w=800&h=507&ei=c6W4TpOFEMePs QL19_XcCA&zoom=1&iact=hc&vpx=604&vpy=156&dur=345&hovh=179&hovw=282&tx=118 &ty=90&sig=109748501573580030227&page=1&tbnh=127&tbnw=201&start=0&ndsp=26&ved =1t:429,r:2,s:0  http://www.google.com/imgres?um=1&hl=en&safe=off&biw=1440&bih=817&tbm=isch&tbni d=9rfWawdXn1i50M:&imgrefurl=http://course1.winona.edu/sberg/241f08/Lec- note/Meiosis.htm&docid=br1g6Va8SmQTjM&imgurl=http://course1.winona.edu/sberg/ILLUST /Fig13- 6.gif&w=750&h=337&ei=iqW4TqXkJOGIsAKS9YHFCA&zoom=1&iact=hc&vpx=966&vpy=206& dur=123&hovh=150&hovw=335&tx=144&ty=68&sig=109748501573580030227&page=1&tbnh =82&tbnw=182&start=0&ndsp=31&ved=1t:429,r:6,s:0