1. Meiosis
Creation of Sex Cells

4. 4 from mom 4
from dad

5. Prophase I
Prophase II
Metephase II
Metaphase I
Anaphase II
Anaphase I
Telophase II
Telophase I/
Cytokinesis
Cytokinesis

6. Prophase I
• Each replicated chromosome pairs with its
•
•
corresponding homologous chromosome
This forms a “tetrad”
Homologous chromosomes undergo a process called
“crossing over”

7. During “Crossing Over”
Independent assortment - genes for different
traits can segregate independently during
the formation of gametes (meiosis)

9. Metaphase I and Anaphase I
• During Metaphase I, paired homologous
•
chromosomes line up across the center of
the cell
During Anaphase I, spindle fibers pull each
homologous chromosome pair toward
opposite ends of the cell

10. Telophase I and Cytokinesis
• Nuclear membrane forms around each
•
cluster of chromosomes
Cytokinesis follows, forming two new cells

11. Meiosis II (occurring in both new cells)
• The final four phase of meiosis II are similar
to those in meiosis I. However, the result is
four haploid (n) daughter cells

12. End Product? - gametes (sex cells)
• For males - sperm cells (all equal size)
o
o
contains ONLY 23 single chromosomes
all genetically different
• For females - genetically different egg cells
o
Only one of the cells produced is involved in
reproduction. This one cell consists of
 23 single chromosomes
 All other cell parts