1. LO: SWBAT explain how gametes are formed.
DN: What are gametes? Where are the gametes formed?
HW: HW Packet #1-4 (whole packet due Monday)

2. What is Sexual Reproduction?
It involves the joining of two cells to begin the
development of a new individual.
These special cells are called: Sex Cells (Gametes)

3. What are the names of these sex cells?
Egg cell
(Female)
Sperm Cell
(Male)
The joining of a sperm cell with
an egg cell is called fertilization.

4. How many chromosomes do we have in our cells?OR
23 pairs of
chromosomes
Karyotype

5. Why do we have 2 of each chromosome?
One from mom and one from dad
Each pair of chromosomes are called:
Homologous Chromosomes

6. Homologous Chromosomes:
Eye Color
Hair Color
Mom
Dad B G R
Gene
Part of a
chromosome
that codes for
a trait
Have genes that code for the same trait, but may have different versions of that trait

7. How are chromatids different than homologous chromosomes?
Chromatids are exact
copies of each other
Homologous chromosomes
same size chromosomes
genes for the same trait,
can have different versions of that trait

8. How many chromosomes do the offspring have after mitosis?
46X
Same amount as the parent cell
Humans = 46
Mitosis
46X
46X

9. Do our sex cells have 46 chromosomes?
NO!!!

10. What would happen if our sex cells did have 46 chromosomes?92 +
Offspring
Egg
Sperm
The offspring would have 92 chromosomes

11. Sexual Reproduction: 23 23 46 + Offspring Egg
A fertilized egg cell is called a Zygote
Sperm
Characteristics of Sexual Reproduction:
1) Is the creation of a new individual from parents. 2
2) Offspring are not genetically to the parents.
identical

12. Sex Cells (Gametes) Sex Cells: -SPERM and EGG
Sex cells should have 1/2 the normal number of chromosomes

13. Chromosome Number
Diploid cells: (2n) normal number of chromosomes (Body Cells)
Haploid cells: (n) ½ the normal number of chromosomes (Sex Cells)

14. Meiosis
The process by which sex cells are produced with half the number of chromosomes.

15. Meiosis is 2 Cell Divisions
1st Cell Division
2nd Cell Division
4 Haploid Cells
1 Diploid cell

16. What is the end result of meiosis?
46X
4 cells with ½ the number of chromosomes
Meiosis
23X
23X
23X
23X

17. Where does meiosis occur?
Gonads – Ovaries and Testis

18. Why is meiosis important?
Maintains the number of chromosomes from generation to generation
Provides genetic variation .

19. Crossing over – Prophase I
Synapsis – homologous chromosomes pair up
Crossing over – chromosomes overlap and exchange of genes.

21. Production of gametes (sperm & egg) By meiotic cell division
Gametogenesis
Gameto = gametes
Genesis = creation
Production of gametes (sperm & egg)
By meiotic cell division

22. Creation of an ovum or egg cell by meiotic cell division in the ovary.
Oogenesis
Creation of an ovum or egg cell by meiotic cell division in the ovary.

23. How many eggs are produced?
There is an unequal sharing of cytoplasm
1 egg & 3 non functional polar bodies

24. Egg vs. Polar Bodies
The egg is very large, has most of the cytoplasm, which will provide nutrients for the offspring.

25. Creation of sperm cells by meiotic cell division in the testes.
Spermatogenesis
Creation of sperm cells by meiotic cell division in the testes.

26. How many sperm are produced by spermatogenesis?
4 equal sized sperms with flagella for swimming.

27. Spermatogenesis vs. Oogenesis

28. Practice Problems: