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

2. Mom
Dad
Human body cells have 23 pairs of chromosomes and 46 total
Each pair of chromosomes is called Homologous pairs and have copies of the same genes
In each pair, one chromosome comes from each parent.
*Homo= same

3. You have two types of specialized cells:
Somatic cells and Germ cells
Will become…

4. Somatic cells- are body cells and make up most of your body tissues and organs.
Liver cells
Lung cells
Heart cells etc…
Red blood cells
skin cells bone cells intestinal cells

5. Somatic (body) cells are Diploid (2n) cells have two copies of every chromosome (23 from mom, 23 from dad) for a total of 46 chromosomes
*di= 2 n n 2n

6. Germ cells- are the cells in your reproductive organs
located in the ovaries and testes
Develop into gametes

7. Gametes are sex cells: egg and sperm
Both have DNA that can be passed to offspring.
Egg
Sperm

8. Gametes are Haploid (n) cells have one copy of every chromosome.
Have 22 autosomes + 1 sex chromosome = 23 chromosomes each 23 23

9. You have two types of specialized cells:
Somatic cells Germ cells
Undergo meiosis
Cells in reproductive organs (ovaries/testies)
Become gametes (sperm/eggs)
Haploid
23 chromosomes
Each are Unique
Undergo mitosis
body cells
Diploid
46 chromosomes
Identical to parent cell

10. You have two types of chromosomes:
Autosomes and Sex Chromosomes

11. Chromosome pairs 1-22 are called autosomes
Contain genes not directly related to your gender

12. XX XY XX= female XY= male Pair #23=Sex chromosomes: X and Y
determine gender
Control the development of sexual characteristics
XX= female
XY= male XX XY

13. Where are germ cells located in the human body (2 places)
Points to Ponder
Where are germ cells located in the human body (2 places)
Do you think that Y chromosomes contain genes that are critical for an organism’s survival? Explain.

14. Where are germ cells located in the human body (2 places)
Points to Ponder
Where are germ cells located in the human body (2 places)
In the reproductive organs: The ovaries in women and the testes in men.
2. Do you think that Y chromosomes contain genes that are critical for an organism’s survival? Explain.
No, a Y chromosome is not necessary for survival. Females do not have a Y chromosome, and they are able to survive.

15. Mitosis= makes more diploid cells.
Produces genetically identical cells
Results in diploid cells (46 chromosomes each)
Takes place throughout an organism’s lifetime
Involved in asexual reproduction
Somatic (body) Cells

16. DNA replicates
2 identical daughter cells

17. Meiosis= makes haploid cells (23) from diploid germ cells (46).
produces gametes (sperm/eggs)
Produces genetically unique cells
Takes place only at certain times in an organism’s life cycle
Involved in sexual reproduction
Germ cells

18. (diploid- 46)
Germ cell
4 haploid (23)
unique daughter cells