1. MEIOSIS NOTES (11.4)

2. (Meiosis Notes 11.4) Reproduction
Asexual- all of the parent DNA goes to offspring (miTosis-mainTains)
Sexual -used to create sex cells(mEiosis-rEduce)

3. 2 TYPES OF CELLS
BODY CELLS
SEX CELLS

4. -Also called somatic cells -Made by mitosis
Body Cells
-All cells other than sex cells
-Also called somatic cells
-Made by mitosis
This scanning electron micrograph (courtesy of Dr. Marion J. Barnhart) shows the characteristic
biconcave shape of red blood cells.

5. -Contain 2 copies of each chromosome -homologous chromosomes
Body Cells
-Contain 2 copies of each chromosome
-homologous chromosomes
-have diploid #, 2n
EX. Humans =46

6. -Eggs and sperm -Made by meiosis -Have haploid #, n -EX. Humans =23
Sex Cells
-Gametes
-Eggs and sperm
-Made by meiosis
-Have haploid #, n
-EX. Humans =23

7. How do we get 46 Chromosomes?
Egg (haploid #) + Sperm(haploid #)
ZYGOTE (diploid #)
Ex. Humans
=46

8. -starts with 1 diploid cell and ends up with 4 haploid cells
Meiosis  sex cells
mEiosis = rEduction division
-starts with 1 diploid cell and ends up with 4 haploid cells
**Meiosis I and Meiosis II

9. Meiosis I

10. MEIOSIS II

11. Meiosis Diagram

12. ADVANTAGE: genetic variation
CROSSING OVER
Occurs during Prophase I of meiosis
Tetrads form and DNA is exchanged XX
ADVANTAGE: genetic variation

13.                                                               
Adapted from: Morgan T.H., Sturtevant A.H., Muller H.J., and Bridges C.B., "The Mechansim of Mendelian Heredity", 1915.
Crossing Over

14. Egg Formation (unequal cytokinesis)

15. Comparing Mitosis and Meiosis
HOW MANY CELLS ARE MADE?
Mitosis 2
Meiosis 4

16. Comparing Mitosis and Meiosis
ARE RESULTING CELLS GENETICALLY THE SAME OR DIFFERENT?
Mitosis-
Genetically the same
Meiosis -
Genetically different

17. Comparing Mitosis and Meiosis
WHAT TYPES OF CELLS RESULT IN THE PROCESS? (BODY CELLS OR GAMETES)
Mitosis = Body cells
Meiosis = Gametes

18. Comparing Mitosis and Meiosis
WHAT ARE THE ADVANTAGES OF EACH PROCESS?
Mitosis-
Growth and repair
Meiosis-
Formation of sex cells and genetic variation