Understanding the Cell Cycle & Mitosis

1. Let’s get started: Put away your phone and earbuds Turn in Cell Cycle coloring to my desk Warm-up: You will have 5 minutes to put AT LEAST 1 item in in each section of your Venn diagram

2. The Cell Cycle & Mitosis

3. 2 Reasons why cells divide 1) Growth 2) Replace worn out or damaged cells http://www.adc.state.az.us/images/Off-Library.JPG

4. Cell Division in Eukaryotes • Called Mitosis • Cell Grows & copies its DNA before it can divide

5. The series of events that cells go through as they grow & divide ~ The Cell Cycle

6. The Cell Cycle: Interphase • G1 • S • G2 • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis M phase = Mitosis + Cytokinesis

7. M G2 G1 S

8. Interphase: a growth period • G1 (Growth/Gap 1) – • Cell grows in size, • makes new organelles • performs assigned function • DNA is relaxed in chromatin and is not visible

9. Interphase: a growth period • S phase (Synthesis) – • duplicates DNA to prepare for mitosis • G2 (Growth/Gap 2) – • cell prepares for mitosis

10. Talk to a partner: Explain the phases of Interphase

11. How does the cell know when it is ready to proceed to the next phase?

12. Checkpoint control system • Major checkpoints: • G1 checkpoint • Cell checks to see if DNA synthesis can begin • G2 checkpoint • Cell checks if DNA been copied correctly?

14. Chromosomes condense and become visible at the start of mitosis

15. Chromatin DNA is relaxed; DNA appears as chromatin during interphase • Chromosome visible DNA during mitosis

16. During mitosis, cell divides producing 2 identical daughter cells

17. Mitosis occurs in 4 phases • Prophase • Metaphase • Anaphase • Telophase

18. Vocab Terms • Sister chromatidsidentical halves of the duplicated parent chromosome • Centromerecell structure that joins the two sister chromatids of a chromosome

19. Prophase • DNA organizes • Chromosomes are paired with their identical copies (sister chromatids held together by the centromere) • chromatin condense into visible chromosomes. • Nuclear membrane & nucleolus disappear. • Spindle fibers form between the centrioles, located at opposite ends of the cell

21. Metaphase • Chromosomes line up in the middle of the cell. • Each chromatid is attached to a separate spindle fiber by its centromere.

23. Anaphase • Sister chromatids are pulled apart to opposite poles of the cell.

25. Telophase • 2 identical daughter cells are formed. • Cytokinesis occurs (the division of the cytoplasm) as the plasma membrane pinches in along the equator. • Nucleolus and nuclear membrane reappear, chromosomes begin to uncoil & relax back into chromatin

27. In plants… • Because plant cells have a cell wall, the plasma membrane does not pinch in. • Rather a structure known as the cell plate forms across the cell’s equator.

28. Plant in cytokinesis It’s hard to see, but there is a cell plate forming in the middle of the cell, next to the arrow.

29. Finally… • After mitosis is complete, each new daughter cell is an identical copy of the parent cell. Both cells enter interphase to carry out their assigned function until they are ready to divide.

30. All together now…

31. Talk to a partner: Explain the phases of Mitosis

32. Cell Cycle practice

33. Cell Cycle Regulation

34. What happens when the cell is not growing or dividing? Cell is resting

35. Cell enters G0 phase, where cell is resting and carrying out its normal function

36. When cells are damaged and need repair or need to be replaced, cell will reenter the cell cycle

37. Controlling Cell Growth Through Gene Regulation • Cell division stops when cells touch • Can resume if space is available (injury)

38. Section 10-3 Talk to a Partner: Do Cells Grow Indefinitely? If center cells are removed,cells near the space will start to grow again. SHOWS: Cell division genes can be turned on and off Cells grow until they touch other cells

39. What happens when the genes that control cell division become damaged? • Some cells do not respond to the signals that regulate the growth • Result ~ uncontrolled cell growth: cancer • Causes of cancer: • cigarette & tobacco use • radiation exposure (X-ray & UV light) • genetics • some viruses

41. Cancer Video

42. Stem Cells • Stem cells - unspecialized cells • Through cell differentiation – stem cells become specialized in structure and function • Two Types: Embryonic and Adult Stem Cells

44. Cornell Summary