Comprehensive Lesson on Cell Division.pptx

A Comprehensive presentation about Cell Cycle and Cell Division

1. CELL CYCLE & CELL DIVISIONS

2. OBJECTIVES: Describe the & interrelate Cell Cycle , Cell Cycle Checkpoints & Apoptosis Differentiate the types of cell divisions: Mitosis & Meiosis

3. CELL CYCLE The life of the cell from the time it is produced in the division of parent cells to the time it divides into two new daughter cells. What are the phases & checkpoints of cell cycle?

4. CELL CYCLE & Its Checkpoints

5. CELL CYCLE & Its Checkpoints

6. apoptosis

7. IMPORTANCE OF apoptosis Crucial for embryonic development : - Errors in Apoptosis can lead to birth defects

8. IMPORTANCE OF apoptosis 2. Important for maintaining homeostasis: - Cell death is balanced with mitosis to regulate cell number. 3. Helps eliminate cells that are injured: - such injured cells include, a. cells with damaged DNA b. cells suffering from certain infections

9. MITOSIS A cell division process by which single parent divides into two diploid daughter cells. This takes place in eukaryotic cells particularly in the somatic / body cells of organism.

10. MITOSIS

11. MITOSIS

12. MEIOSIS A cell division that take place in sex cells (sperm & egg cells). This is also referred to as “reduction” cell division .

13. MEIOSIS

14. 15 Prophase I Early prophase Homologous pair. Crossing over occurs . Late prophase Chromosomes condense. Spindle forms. Nuclear envelope fragments.

15. 16 Tetrads Form in Prophase I Homologous chromosomes (each with sister chromatids)   Join to form a TETRAD Called Synapsis

16. 17 Crossing-Over Homologous chromosomes in a tetrad cross over each other Pieces of chromosomes or genes are exchanged Produces Genetic recombination in the offspring

17. 18 Metaphase I Homologous pairs of chromosomes align along the equator of the cell

18. 19 Anaphase I Homologs separate and move to opposite poles. Sister chromatids remain attached at their centromeres .

19. 20 Telophase I Nuclear envelopes reassemble. Spindle disappears. Cytokinesis divides cell into two.

20. 21 Meiosis II: Reducing Chromosome Number Prophase II Metaphase II Anaphase II Telophase II 4 Identical haploid cells

21. 22 Prophase II Nuclear envelope fragments. Spindle forms.

22. 23 Metaphase II Chromosomes align along equator of cell .

23. 24 Anaphase II Sister chromatids separate and move to opposite poles . Equator Pole

24. 25 Telophase II Nuclear envelope assembles. Chromosomes decondense. Spindle disappears. Cytokinesis divides cell into two.

25. 26 Results of Meiosis Gametes (egg & sperm) form Four haploid cells with one copy of each chromosome One allele of each gene Different combinations of alleles for different genes along the chromosome

26. Comparison of mitosis to meiosis

27. Comparison of mitosis to meiosis

28. CELL CYCLE 29 Label the parts of the Cell Cycle & briefly describe what is happening: A B C D E F G H I J

29. 30 MITOSIS

30. 31 a.________ b. ________ c. _______ d. _________ MEIOSIS I

31. 32 e.________ g. ________ h. _______ i . _________ f.________ MEIOSIS II

32. MITOSIS & MEIOSIS COMPARISON 33