1. 6.3 Meiosis Key Concepts and Vocabulary
What is produced in meiosis?
How does chromosome number change in meiosis?
How does meiosis produce genetic diversity?
How does meiosis differ from mitosis?
Key Vocabulary: Gamete Spermatogenesis Oogenesis Zygote Crossing over

2. Meiosis Division of the cell nucleus Produces 4 different gametes
Diploid cells divide to produce haploid cells
What are the two types of gametes?
How do haploid cells compare to diploid cells?

3. Meiosis in Humans In Males: In Females: Occurs in the testes
& Produces:
four sperm cells
Spermatogenesis
Begins at puberty
In Females:
Occurs in the ovaries
& Produces:
one egg cell and three polar bodies
Oogenesis
Begins before birth

4. Meiosis in Humans
How many times to the cells divide in meiosis?

5. Chromosome Number Meiosis reduces the number of chromosomes in gametes
The starting body cells are diploid (2 sets)
The ending sex cells are haploid (1 set)
Why is it important to reduce the number of chromosomes when you produce gametes?
So body cells will have the right # of chromosomes after fertilization!

6. Chromosome Number Body Cells Sex Cells Alligator 16 Bat 44 Carrot 18
Horse 32
Goldfish 48
Human 46
Copies of Chromosomes

7. Fertilization - Union of sperm and egg cells
Produces a zygote -_FIRST CELL_______
Is a zygote haploid or diploid? + =

8. Chromosome Number
If sex cells were not haploid, then resulting offspring would have too many chromosomes.

9. Stages of Meiosis Cells divide twice in meiosis
Meiosis includes all the same stages as mitosis: 1. 2. 3. 4. 5.

10. Stages of Meiosis

11. Meiosis I Pair up Exchange Crossing Over
Most of the events in meiosis are the same as mitosis
The only differences happen in prophase:
Diploid chromosomes ________________________
_________________ genetic information
This is called _________________________
Pair up
Exchange
Crossing Over

12. Crossing Over Why is crossing over important in meiosis?
creates diversity in a population

13. Meiosis I The rest of the phases of meiosis I are the same as mitosis:
Metaphase -
Anaphase -
Telophase -
Cytokinesis -

14. Meiosis I

15. Meiosis II 2 diploid cells divide into 4 haploid cells
The phases are the same as mitosis and meiosis I (Just 1 more division)

16. Meiosis II

17. Mitosis vs. Meiosis