1. The Process of Making Sex Cells
Meiosis
The Process of Making Sex Cells

2. Sexual Reproduction Most organisms reproduce sexually.
This means two parents are needed to produce offspring.
This requires a sex cell from each parent.

3. What are sex cells? Sex cells are the cells that produce offspring.
The sex cell produced by males is sperm.
The sex cell produced by females is the egg.

4. What are chromosomes?
They are found in the nucleus of cells and are made of DNA
They determine all of the physical characteristics of organisms.
Alleles, or genes, are on the chromosomes.

5. What are chromosomes?
Different organisms have different numbers of chromosomes. Humans have 23 pair for a total of 46.

6. Sutton & Grasshoppers
Walter Sutton used a microscope to count the chromosomes in grasshopper cells
He counted 24 chromosomes in every cell, except the sex cells. Those cells only had 12 chromosomes.

7. What did Sutton learn?
He figured out that grasshoppers must get half their chromosomes (and alleles) from the female parent and half from the male parent.
12 chromosomes in the egg
+ 12 chromosomes in the sperm
24 chromosomes in the cells of the fertilized egg or zygote

8. What is meiosis?
The process where the number of chromosomes in body cells is reduced by half in sex cells.
This happens through a series of stages.

9. Summary of Meiosis
The chromosomes are made of DNA. DNA is a chemical that gives living things their traits.
Alleles are on the chromosomes.
You may have your mother’s eyes and your father’s nose because of the DNA you received from each parent through your father’s sperm and your mother’s egg.

10. Asexual Reproduction
Asexual reproduction is where offspring are produced by only one parent.
Since offspring receive all of their genes from that one parent, they are identical to that parent.
Two examples of asexual reproduction are budding and binary fission.

11. Budding
These are yeasts reproducing by budding.

12. Binary Fission
These are bacteria reproducing by binary fission.

13. Mr. Lee
Now that you have learned more, listen to Mr. Lee one more time.
YouTube - Mr. Lee - Genetics rap