1. Cell Division
Meiosis

2. Relationship Between Meiosis and Genetics
Meiosis results in egg (females) and sperm (males) cells.
When egg and sperm combine a new human is formed.
The egg carries the genes from mom and the sperm carries the genes from dad
You are a combination of genes from your mom and your dad!
Your eye color, hair color etc. all depends on which egg cell and sperm cells combine!

3. Let Us Review Mitosis
Cellular division involving replication and division of chromosomes (DNA).
New cell contains complete set of chromosomes. (Two copies of genetic info.)
Results in DIPLOID cells (chromosomes occur in pairs)

4. Diploid Cells Chromosomes in early interphase (actually chromatin)
Chromosomes after replication (ready for mitosis)
Both are Diploid
Homologous Pairs

5. Diploid Cells cont. All body cells are diploid.
Sex cells: egg and sperm are the only haploid cells

6. Sex Cells Germ Cells Only contain one copy of genetic information
Also know as Sex Cells
Only contain one copy of genetic information
Have one chromosome of each pair or half that of diploid cells.
Haploid (N) state.

7. Why is Haploid Important?
If diploid cells are fertilized… +
2N N  N
Chromosome will keep doubling!!

8. Why is Haploid Important?
If haploid cells are fertilized… +
N N  N
Like all cells of the body!!

9. Sexual Reproduction
Reproductive process in which haploid sex cells (gametes) fuse to produce a diploid fertilized egg (zygote) +
EGG SPERM Fertilized Egg
(ZYGOTE)
GAMETES

10. 46 36 # of Chromosomes 23 23 18 18 HUMAN CAT
Total Chromosomes in a diploid cell
# of homologous pairs in a diploid cell
Total chromosomes in haploid cell
HUMAN 46
CAT 36 23 23 18 18

11. MEIOSIS Cell division that reduces the number of chromosomes in half
Occurs in sex cells (germ cells: Egg and Sperm)
Two Divisions
MEIOSIS I
MEIOSIS II
Meiosis I
Meiosis II

12. Prophase I Chromosomes form Nuclear membrane and nucleolus disappear
Synapsis – homologous chromosomes pair up
Crossing Over – exchange of DNA creating genetic variability

13. Metaphase I
Homologous chromosomes line up at the equator

14. Anaphase I / Telophase I
Homologous chromosomes separate and move to opposite poles
Cells are still diploid
TELOPHASE I:
Cell membrane pinches in

15. Interphase????
There is NO
interphase
between
Meiosis I and
Meiosis II

16. Prophase II
Cells are haploid.
Cells get ready to divide again.

17. Metaphase II
Chromosomes align at the equator
Looks like mitosis

18. Anaphase II / Telophase II
Sister chromatids move to opposite poles
TELOPHASE II:
Cell membrane
pinches in
Nuclear membrane
reappears.

19. Resulting Sex Cells
Four HAPLOID sex cells are produced.

20. MEIOSIS

21. Homework
Flipbook
White Ninja is a terrible babysitter