1. Meiosis

2. What do we need to know?
(background information)
• Homologous
chromosomes: a pair of
chromosomes, one from
each parent.
• Haploid (n): one set of
chromosomes
• Diploid (2n): two sets of
chromosomes
• n = number of
chromosomes

3. Two major types of cells
• Somatic or body cells-
(most of our cells)
examples: skin,
stomach, brain, liver,
blood cells, etc.
• Sex cells or germ
cells (also called
gametes) ex. Egg and
sperm

4. Within each somatic (body) cell are
chromosomes
• Sex Chromosomes:
the X and Y that
determine the gender
of an organism.
males- XY
females- XX
• Autosomes: all of the
other chromosomes
chromosomes 1-22

5. What is Meiosis?
• Meiosis makes
germ cells, eggs
and sperm
• Meiosis is a cell
division process that
reduces the number
of chromosomes by
half
• There are two main
stages of Meiosis.

6. Meiosis I

7. Crossing Over
• During prophase of Meiosis I, the homologous
chromosomes form tetrads, which may
exchange genetic information. This increases
genetic variability and is called crossing over.

8. Independent Assortment of
chromosomes
• The chromosomes line up during
metaphase I at random which leads to
genetic variability.
Inherited from Inherited from
father (blue) mother (red)

9. Meiosis II