1. MEIOSIS DIVISION OF THE SEX CELLS
WHY I DON’T LOOK EXACTLY LIKE BOTH OF MY PARENTS

2. PONDER THIS…..
IF A NEW HUMAN IS CREATED FROM A MOMMY CELL AND A DADDY CELL COMING TOGETHER (EGG & SPERM)…..
HOW DO YOU AVOID DOUBLING YOUR CHROMOSOME NUMBERS?

3. SPERM & EGG UNITE = +
46 chromosomes
46 chromosomes
92 chromosomes

4. Meiosis reduces chromosome number and creates genetic diversity.

5. Homologous Chromosome: Chromosomes that are similar (NOT identical)
Homologous chromosomes
SISTER CHROMATIDS:
Half of a chromosome
Sister chromatids

6. Cells go through 2 rounds of division in Meiosis:
Meiosis I -
divides Homologous chromosomes:
Prophase I
Metaphase I
Anaphase I
Telophase I
Meiosis II - divides sister chromatids:
Prophase II
Metaphase II
Anaphase II
Telophase II
Homologous chromosomes
Sister chromatids

7. Meiosis I

8. 1. Prophase I Centrioles move, spindle fibers start to form
Chromosomes condense
Homologous chromosomes begin to pair up and form TETRAD
From Mother
From Father

9. 2. Metaphase I Chromosomes align along the center of the cell
Each side of cell has chromosomes from both parents
Crossing-over occurs

10. 3. Anaphase I Paired homologous chromosomes separate from one another
Move towards opposite ends
Chromatids remain attached

11. 4. Telophase I
Spindle fibers fall apart
Cell goes through cytokinesis

12. MEIOSIS II

13. 5. Prophase II Centrioles and centrosomes move to opposite sides
Spindle fibers start to assemble

14. 6. METAPHASE II
CHROMOSOMES LINE UP ALONG THE MIDDLE OF CELL

15. 7. ANAPHASE II SISTER CHROMATIDS PULLED APART FROM EACH OTHER
MOVE TO OPPOSITE ENDS

16. 8. TELOPHASE II NUCLEAR ENVELOPE FORMS SPINDLE FIBERS BREAK
CYTOKINESIS OCCURS = 4 HAPLOID GAMETES

17. Haploid cells develop into mature gametes = Gametogenesis Gametes differ between male and female
SPERM BECOME MOTILE
CONTRIBUTE TO DNA
EGGS CONTRIBUTE TO DNA, ORGANELLES & CYTOPLASM