1. Meiosis vs. Mitosis

2. I. Mitosis vs. Meiosis Mitosis Cell division 46 chromo2 cells,
46 chromo. Each
Keeps chromo. # same
Found in body cells
Most common
No genetic variation
Meiosis
Cell division
46 chromo 4 cells,
23 chromo each
Chromo. # cut in half
Found in sex/germ cells ONLY
Least common
Most genetic variation
ANIMATION OF COMPARISON
ANIMATION 2 OF COMPARISON

4. II. Chromosomes Karyotypes:
Display of chromosomes lined up in homologous pairs
Half inherited from male Half from female
Used for viewing #, size,
shape, and banding
patterns of chromosomes

5. Homologous Chromosomes:
matching pair of chromosomes, one inherited from each parent

6. Body cells/Somatic Cells= “Diploid”or 2N having two sets of chromosomes, body cells
Humans 46 chromosomes

7. Sex cells/Sperm + Egg= “Haploid”or N having one set of chromosomes, sex cells ( gametes) Ex: Humans 23 chromosomes

8. when haploid sperm and egg meet, combining N chromosomes
Fertilization:
when haploid sperm and egg
meet, combining N chromosomes
with N chromosomes
= 2N zygote
Zygote: fertilized egg, 2N
____
____
____ 23 23 46
sperm
egg
zygote

9. Diploid vs. Haploid Exercises
Drosophilia have a diploid number of 8. What is the haploid?
Onions have a haploid number of 8. What is the 2N?
A horse’s 2N is 64. What is the 1N?
A body cell of an alligator has 32 chromosomes. Is this the diploid or haploid number? 4 16 32
Diploid

10. II. Meiosis Definition:
cell division to produce egg (ovule) or sperm (pollen)
Meiosis I & Meiosis II

11. Oogenesis: Production of Egg
Female meiosis in the ovaries
Resulting cells:
1 egg, 3 polar bodies
Haploid

12. Spermatogenesis: Production of Sperm
Male meiosis in testes
Resulting cells:
4 haploid sperm cells
Animation spermatogenesis

13. Meiosis I (PMAT I & C)
Prophase I: homologous chromosomes meet up and form tetrads. Crossing over occurs.
What is the point of
crossing over?

15. Meiosis II (PMAT II & C)
What if Meiosis did not occur?