1. Comparing Plant & Animal Cells
Reviewing Mitosis
Comparing Plant & Animal Cells

2. Animal vs. Plant Mitosis
Animal Cells
Have centrioles!
Cytokinesis simple pinching of cell membranes
Plant Cells
No centrioles
Equatorial plate
Cytokinesis must form 2 membranes PLUS 2 cell walls

3. Meiosis
Formation of Gametes

4. Definitions Gamete Sperm Ovum (plural ova) Testes Ovaries Zygote
Fertilization
Haploid
Diploid

5. Meiosis Two nuclear divisions Creates haploid gametes
In animals, sperm and ova
In plants, spores
Crossing Over occurs
4 daughter cells are created.

6. Crossing-Over
Section 11-4

7. Meiosis Leads to Genetic Recombination!!!

8. Meiosis I: Separation of Homologues
Prophase I
Chromosomes Condense
Nuclear Envelope Disappears
Spindle Formed (Asters seen here)
Homologues Pair Up
Crossing-over occurs here!

9. Figure Meiosis
Section 11-4
Meiosis I

10. Metaphase I
Homologous chromosomes move to equator

11. Figure Meiosis
Section 11-4
Meiosis I

12. Chromatids do not separate from centromeres!
Anaphase I
Homologues separate
Chromatids do not separate from centromeres!

13. Figure Meiosis
Section 11-4
Meiosis I

14. Telophase I THIS IS REDUCTION DIVISION!
Nuclear envelope usually does not reform.
Chromosome number in 2 new cells is now half because chromatids did not separate.
THIS IS REDUCTION DIVISION!
Cytokinesis may or may not occur.

15. Figure Meiosis
Section 11-4
Meiosis I

16. Meiosis II
No replication of chromosomes!!!!
Proceeds just like mitosis
Starts and ends with haploid cells

17. Figure 11-17 Meiosis II Meiosis II Section 11-4 Prophase II
Metaphase II
Anaphase II
Telophase II
Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.
The chromosomes line up in a similar way to the metaphase stage of mitosis.
The sister chromatids separate and move toward opposite ends of the cell.
Meiosis II results in four haploid (N) daughter cells.

18. Ovum Formation Meiotic stages are the same
One daughter cell keeps ALL of the cytoplasm
Other 3 daughter cells only have genetic material – Polar Bodies (Barr Bodies)

19. Sperm Formation Cytoplasm and Nuclear Material Divides evenly.
Flagella are added last to the cells following differentiation
Define “differentiation” in your notes here.

20. Fertilization
The haploid sperm and egg fuse to create a diploid zygote.