1. KEY CONCEPT Sex cells have half the number of chromosomes that body cells have.

2. You have body cells and gametes.
Body cells (also called somatic cells) are all the cells in your body except sex cells.
Sex cells (also called gametes).
located in the ovaries and testes.
Gametes are: egg and sperm.
body cells
sex cells (sperm)
sex cells (egg)

3. Your cells have autosomes and sex chromosomes.
Human body cells have 23 pairs of chromosomes.
Homologous chromosomes are pairs with the same structure and kind of info.
For each homologous pair, one chromosome comes from each parent.
Chromosome pairs 1-22 are autosomes.
Sex chromosomes, pair #23, determine gender in mammals.

4. Diploid Cells
Contain both homologous chromosomes
All body cells are diploid. Examples:
Human body cells have 46 chromosomes (23 pairs).

5. Haploid Cells
Contain only one of the homologous chromosomes.
Only sex cells (sperm and egg) are haploid.
Human sex cells have 23 chromosomes.

6. Every species of living organism has a different number of chromosomes
Every species of living organism has a different number of chromosomes. This is NOT dependent on size or complexity.
Organism
Chromosome Number
Human 46
Goldfish 94
Dog 78
Earthworm 36
Lettuce 18
Carrot

7. Mitosis vs. Meiosis
Mitosis makes diploid cells;
Meiosis makes haploid cells.