1. Gamete Formation (Meiosis)
Journal 6-5
Gamete Formation
(Meiosis)

2. Meiosis 2 consecutive cell divisions Reduction divisions
The number of chromosomes in a cell is halved
Forms gametes

3. Unit 5 - Reproduction (Topics 3-4)
Gametes –
Sex Cells
23 chromosomes
Ex: Sperm and Ovum
Zygote –
Cell formed from fusion of ovum and sperm
46 chromosomes
Fertilized egg
Somatic Cells
Cells with all 46 chromosomes
Body cells
Ex: skin cells, muscle cells, nerve cells

4. Chromosomes in Humans
Diploid cells (2n) = 46 or 2 sets of 23 chromosomes
23 from a male gamete (sperm)
23 from a female gamete (ovum)
Haploid cells (n) = 23 or 1 set of chromosomes (sperm and egg)

5. Tetrads 2 Replicated Homologous Chromosomes = 1 Tetrad
Replicated sets of chromosomes
2 Replicated Homologous Chromosomes =
1 Tetrad

6. Meiosis 1 Chromosomes replicate to form tetrads Crossing over occurs
Division separates tetrads

7. Meiosis 2
Division separates sister chromatids

8. Spermatogenesis Process that forms sperm, the male gamete
One diploid cell produces 4 sperm via meiosis

9. Oogenesis Process that forms ovum, the female gamete
One diploid cell produces one ovum