Quarter 4 - THE CELL DIVISION GRADE 8.pptx

Quarter 4 - THE CELL DIVISION GRADE 8.pptx

1. What do you mean by digestion? What are the organs involved in digestive system? Does mouth involved in the process of digestion? REVIEW

2. CELL DIVISION Cell Division — involves the distribution of identical genetic material or DNA to two daughter cells. New cells are produced for growth and to replace damaged or old cells

3. FUNCTION OF CELL DIVISION Cell reproduction Cell growth Cell repair

4. CELL CYCLE CONTROL SYSTEM Checkpoint - a critical control point in the Cell Cycle where ‘stop’ and ‘go-ahead’ signals can regulate the cell cycle. 3 Major Checkpoints or the Interphase Stage G1 Checkpoint S Phase G2 Checkpoint M phase Checkpoint

5. The G1 Checkpoint 1 st growth stage after cell division. Cells mature by making more cytoplasm & organelles.

6. The S Phase The synthesis stage. DNA is copied or replicated.

7. 2 nd growth stage Occurs after DNA has been replicated. All cell structures needed for division are made. The G2 Checkpoint

8. The M phase Checkpoint Ensures that all of the chromosomes are attached to the mitotic spindle fiber.

9. MITOSIS Produce 2 genetically identical daughter cells with the same number of chromosomes. It is how somatic cells divide.

10. MITOSIS Only occurs in eukaryotes Doesn’t occur in some cells such as brain cells. Associated with asexual reproduction Divide the parent cell once.

11. Prophase The preparatory stage. Chromatin in the nucleus begins to shorten and thicken and finally forming rod-like structures called chromosomes.

12. Metaphase The spindle fiber is fully developed and the chromosomes begin to attach themselves to it. The plane of alignment is called metaphase plate.

13. Anaphase Separation of sister chromatids. Centromeres divide. The daughter chromosomes then move towards the poles.

14. Telophase Daughter chromosomes complete their migration to the poles. New nuclear membrane forms around them while the spindle fibers disappear .

15. CYTOKINESIS The division of cytoplasm. Both mitosis and cytokinesis last for around two hours.

16. MEIOSIS

17. MEIOSIS Produces haploid gametes or spores with only one set of chromosomes. Involves two successive division of a diploid nucleus.

18. MEIOSIS Creates sex cells . Associated with sexual reproduction Each new cells contains a unique set of genetic information . Divide the parent cell twice.

19. 2 main stages of Meiosis Meiosis I Halves the number of chromosomes. Meiosis II Halves the amount of genetic information of each chromosomes of each cell.

20. MEIOSIS I

21. Prophase I It includes the following substages : Leptotene Zygotene Pachytene Diplotene Diakinesis

22. Substage 1: Leptotene Each chromosome is made up of sister chromatids. These are long threadlike structures which result from the replication if DNA during the S phase of cell cycle.

23. Substage 2: Zygotene Homologous chromosomes come closer. The chromosomes begin to pair off through the process known as synapsis.

24. Substage 3: Pachytene Crossing over takes place during this stage where a segment of a sister chromatid of one chromosome is exchanged with the same segment of the sister chromatid of the homologous chromosome through the formation of a cross-linkage of the segments called a chiasma

25. Substage 4: Diplotene The chromosomes begin to uncoil or repel one another and move apart.

26. Substage 5: Diakinesis the paired chromosomes disperse in the nucleus and distribute evenly.

27. Metaphase I the paired chromosomes arrange themselves along with the equatorial plate.

28. Anaphase I the spindle fibers form and attach to the centromeres of the chromosomes.

29. Telophase I when the chromosomes reach their respective poles . Cytokinesis follows and two daughter cells are formed.

30. Meiosis II The second meiotic division that forms four daughter cells. Same process on the meiosis I consists of the following stages. Prophase II, Metaphase II, Anaphase II, and Telophase II.

31. Why do we need Meiosis? It is the fundamental basis of sexual reproduction. It is responsible for the formation of sex cells or gametes.

32. Mitosis – is what helps us grow. Meiosis – is why we are all unique

33. Q AND A SESSION

34. What happened during the S Phase? Why do cell divide? What are the functions of cell division?

35. What is the difference between mitosis and meiosis in terms of the number of daughter cells?

36. QUIZ TIME! EVALUATE

37. CATEGORY 5 4 3 2 Graphics All graphics are related to the topic and easy to understand. All graphics are related to the topic and some are easy to understand. Most graphics are related to the topic. Most graphics are not related to the topic. Attractiveness The diagram is exceptionally attractive in terms of design, layout and neatness. The diagram is attractive in terms of design, layout and neatness. The diagram is acceptably attractive though it may be a bit messy. The diagram is distractingly messy or very poorly designed. Rubric