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

2. You have 2 types of cells: somatic cells and gametes.
Are body cells (heart, liver, stomach, skin, etc)
Not passed on to children.
Gametes-come from germ cells (located in the ovaries and testes)
Gametes are sex cells: egg and sperm.
Gametes have DNA that can be passed to offspring.
body cells
sex cells (sperm)

3. Your cells have autosomes and sex chromosomes
Your cells have autosomes and sex chromosomes. Your body cells have 23 pairs of chromosomes.
Autosomes: chromosomes that contain genes NOT directly linked to sex of organism
Homologous chromosomes: pairs of chromosomes have the same structure…like your shoes (“homo” means same)
For each homologous pair, one chromosome comes from each parent.
Chromosome pairs 1-22 are autosomes.
3. Sex chromosomes: X and Y, determine gender in mammals. XX = girl, XY =boy

4. Body cells are diploid; gametes are haploid.
Diploid cell:
2n (n =number of chromosomes each parent has)
Body cells are diploid….means have 2 sets
Made in Mitosis…start and end with the same #

5. Haploid cells:
n (n =number of chromosomes each parent has)
cells have one copy of every chromosome
Gametes are haploid.
Made in Meiosis…end up with HALF the number…half sounds like haploid

6. Comparison of Mitosis and Meiosis:

7. Meiosis makes haploid cells from diploid cells.
Meiosis occurs in sex cells.
Meiosis produces gametes.