2. 12/9/14 Objective: What is the structure of a chromosome and what is its role in the cell cycle? Do Now: How many cells does mitosis produce?

3. Cell Division: 1 cell divides into 2 identical DAUGHTER cells Getting from there to here…

4. For reproduction –asexual reproduction one-celled organisms For growth –from fertilized egg to multi-celled organism For repair & renewal –replace cells that die from normal wear & tear or from injury Why do cells divide? amoeba

5. Nucleus Cell Chromosomes Chromosomes are made of DNA!!

6. Thread-like structures found in the nucleus of cells that contain DNA

7. A combination of DNA and protein that make up a chromosome

8. The Cell Cycle Interphase 90% of cell cycle cell doing its “everyday job” makes proteins, etc Prepares for duplication if triggered

9. Interphase can be divided into subphases –G 1 phase –S phase –G 2 phase

10. Interphase Divided into 3 phases: –G 1 = (Growth) cell grows –S = DNA Synthesis copies chromosomes –G 2 = (Growth) prepares for division cell grows (more) G0G0 signal to divide

11. double- stranded mitotic human chromosomes

12. Mitotic Phase - Stage where the cell is actually dividing

13. Before you can share your notes, You have to make a copy

14. -Chromatin condenses -Can see sister chromatids -Nuclear membrane breaks down -Spindle fibers form Prophase

15. Protein fibers cross cell to form mitotic spindle –coordinates movement of chromosomes Microtubules: protein fibers that make up the spindle

16. -Sister Chromatids: two identical joined chromosomes

17. -Centromere: the region where the 2 chromatids are joined together

18. Metaphase Chromosomes align along middle of cell –metaphase plate meta = middle plane –spindle fibers coordinate movement

20. Anaphase Sister chromatids separate –move to opposite poles –pulled at centromeres

21. Telophase Chromosomes arrive at opposite poles –Nuclear membrane reforms –Chromosomes disperse no longer visible under light microscope Spindle fibers disperse

22. Cytokinesis Animals Splitting of cytoplasm cleavage furrow forms (shallow groove near old metaphase plate) splits cell in two

23. Cytokinesis in Animals

24. Mitosis in whitefish blastula

25. Cytokinesis in Plants Plants –cell plate forms new cell wall

27. The Cell Cycle Control System The sequential events of the cell cycle –Are directed by a distinct cell cycle control system, which is similar to a clock Control system G 2 checkpoint M checkpoint G 1 checkpoint G1G1 S G2G2 M

28. The clock has specific checkpoints –Where the cell cycle stops until a go-ahead signal is received G 1 checkpoint G1G1 G1G1 G0G0 (a) If a cell receives a go-ahead signal at the G 1 checkpoint, the cell continues on in the cell cycle. (b) If a cell does not receive a go-ahead signal at the G 1 checkpoint, the cell exits the cell cycle and goes into G 0, a nondividing state. G0 phase: a non-dividing state

29. Fig. 12-15 G1G1 G0G0 G 1 checkpoint (a)Cell receives a go-ahead signal G1G1 (b) Cell does not receive a go-ahead signal

31. Cancer A disease caused by the disruption of the mechanism that normally controls the cell cycle Leads to uncontrolled cell divison

32. Tumor A mass produced by out-of-control cell reproduction

33. Types of Tumors Benign tumor: An abnormal mass of normal cells that can usually be removed by surgery Malignant tumor: masses of cells from the reproduction of cancer cells (can spread if not removed or killed)

34. Metastasis The spread of cancer beyond their original site

35. Prevention/Early Detection/Treatment

36. Getting Started

37. Interphase

38. Prophase

39. Metaphase

40. Drawing Metaphase

41. Anaphase

42. Telophase

43. Cytokinesis