1. Meiosis (produces sex cells)

2. Meiosis
Genetics requires that organisms inherit a single copy of each gene from each parent
Produces cells with half the number of normal chromosomes (1N or haploid)
Produces sex cells or gametes 23 23

3. Two Types of Gametes 1. Sperm Made in males testes
Produced puberty death
Made every day
100 million sperm/day

4. Two Types of Gametes 2. Egg or Ova Made in females ovaries
Starts 3rd month fetal development
~ 600,000
Release 1/month from puberty menopause
~ Use 600

5. Plant Reproduction-Yes, Sexual
Pollen-sperm
Ovules-eggs

6. Gamete Production =Gametogenesis
Spermatogenesis:
Production of sperm cells
Oogenesis:
Production of egg cell (ova)

7. Meiosis Working WITH Mitosis to Form YOU!!!!!
EGG 46 23 23
SPERM
Mitosis = Body Cells
Gametes made during Meiosis
Zygote
23 Dad’s Chromosomes correspond with Mom’s 23
Contains ½ chromosomes from Mom
½ from Dad

8. Terminology/Vocab Mitosis Meiosis Diploid Monoploid/Haploid 2N 1N or N46
Full Set of Chromosomes
Somatic Cells (Body)
Zygote
Meiosis
Monoploid/Haploid
1N or N 23
½ # Chromosomes
Sex Cells
Gametes

9. Meiosis 1 Interphase 1 G1 = Cell grows and matures S= DNA REPLICATION
Occurs in testicle or ovary cells
G1 = Cell grows and matures
S= DNA REPLICATION
G2= Cell makes new organelles

10. Meiosis 1 Prophase 1 Nucleus and nucleolus disappear
Chromatin  chromosomes
Chromosomes pair up into homologous pairs
Crossing over/genetic recombination may occur which produces gene combinations
Spindle fibers appear

11. M M M D D D Homologous Pairs -have the same structure
-1 from Mom, 1 from Dad
-Chromosome pairs 1-22 are autosomes
-Sex chromosomes
X and Y, determine gender in mammals (pair #23) D D D

12. 1 2 3 4 Dad Mom Homologous pairs/chromosomes
homologous chromosomes
sister
chromatids
Homologous pairs/chromosomes
Forms a Tetrad (4 Sister Chromatids)

13. Genetic material from the homologous chromosomes is randomly swapped

14. Meiosis 1
Metaphase 1
Homologous pairs line up at equator

15. Meiosis 1
Anaphase 1
Homologous pairs separate and move to poles

16. Meiosis 1 Telophase 1 & Cytokinesis Nucleus and nucleolus reappear
Chromosomes  chromatin
Spindle fibers fold up  centrioles
Cytokinesis = cytoplasm splits

17. Meiosis 2 SAME AS MITOSIS EXCEPT… **DNA does NOT replicate**
Interphase 2
Resting period

18. Meiosis 2 Prophase 2 Nucleus disappears Nucleolus disappears
Chromatin  chromosomes
Spindle fibers appear

19. Meiosis 2 Metaphase 2 Chromosomes line up at the equator
Line up on spindle fibers
Centromere holds in place

20. Meiosis 2
Anaphase 2
Sister chromatids separate and move to poles

21. Meiosis 2
Telophase 2 & Cytokinesis 2
Nucleus and nucleolus reappear
Chromosomes  chromatin
Centrioles
Cells split
4 cells with 1/2 the number of chromosomes – GENETICALLY DIFFERENT CELLS!!!!!!

23. BOYS: SPERMATOGENESIS Meiosis 1 Meiosis 2 Males 4 Sperm
All Equal in Size
23 Chromosomes
Meiosis 1
Meiosis 2

24. Girls: OOGENESIS Meiosis 1 Meiosis 2 Females 1 Viable Egg
23 Chromosomes
3 Polar Bodies (Duds)
Meiosis 1
Meiosis 2