Chapter 12: The Cell Cycle

1. Chapter 12:The Cell Cycle

2. Important Point: If you are having trouble understanding lecture material: Try reading your text before attending lectures. And take the time to read it well!

3. Chromosome Sorting • The goal of cell division typically is to equally partition two more-or-less identical copies of genetic material between two daughter cells • Prokaryotes are comparatively simple, with only one chromosome, so have a relatively easy time sorting daughter chromosomes to daughter cells • Eukaryotes, with their longer DNA and multiple chromosomes, don’t have it nearly so easy • Much of the complex “dance” of Mitosis is a consequence of the need to make sure that each daughter cell ends up with the same number and type of chromosomes as the parent

4. Cell Division

5. Chromosome, Bacterial

6. Chromosomes, Eukaryote Here “chromosome” and “DNA” are not 100% synonymous

7. Chromosomes vs. Chromatin • Chromosomes • Tightly packaged DNA • Found only during cell division • DNA is not being used for macromolecule synthesis • Chromatin • Unwound DNA • Found throughout Interphase • DNA is being used for macromolecule synthesis

8. Though chromosomes are “all about” DNA, in fact much this structure consists of protein Chromosomes, Eukaryote Form via replication, not by formed chromatids coming together

9. How Long is a Chromatid a Chromatid? • A chromatid is a chromatid as long as it is held in association with a sister chromatid at the centromere Centromere Chromatid Chromosome Chromatid • When two sister chromatids separate (after metaphase) they go from being a single chromosome to being two different chromosomes

10. Genome = DNA Chromosomes, Eukaryote Chromosome = DNA + protein (visible light microscope) Chromatin = DNA + protein (but less than for chromosome) DNA

11. Centromere Centrosome Centriole Kinetochore Kinetochore microtubules Mitotic spindle Nonkinetochore microtubles Spindle apparatus Spindle fibers Some Vocabulary

12. Centromere Centrosome Centriole Kinetochore Kinetochore microtubules Mitotic spindle Nonkinetochore microtubles Spindle apparatus Spindle fibers Some Vocabulary Recall that the centrosome is the center of the microtubule array of a cell

13. Centromere Centrosome Centriole Kinetochore Kinetochore microtubules Mitotic spindle Nonkinetochore microtubles Spindle apparatus Spindle fibers Some Vocabulary Recall that these consist of microtubules and that a pair makes up a centrosome Keep in mind that the term centriole is not an exact synonym of centrosome and that centrosome is not a synonym of the term centromere

14. Centromere Centrosome Centriole Kinetochore Kinetochore microtubules Mitotic spindle Nonkinetochore microtubles Spindle apparatus Spindle fibers Some Vocabulary Responsible for moving chromosomes relative to mitotic spindle

15. Centromere Centrosome Centriole Kinetochore Kinetochore microtubules Mitotic spindle Nonkinetochore microtubles Spindle apparatus Spindle fibers Some Vocabulary These are the portion of the mitotic spindle that is connected to chromosomes during mitosis

16. Centromere Centrosome Centriole Kinetochore Kinetochore microtubules Mitotic spindle Nonkinetochore microtubles Spindle apparatus Spindle fibers Some Vocabulary These are the microtubles that are responsible for separating chromosomes as well as pushing the centrosomes toward opposite ends of cells

17. Centromere Centrosome Centriole Kinetochore Kinetochore microtubules Mitotic spindle Nonkinetochore microtubles Spindle apparatus Spindle fibers Some Vocabulary Microtubules of mitotic spindle that are not connected to the chromosomes but instead responsible for pushing centrosome apart

18. Centromere Centrosome Centriole Kinetochore Kinetochore microtubules Mitotic spindle Nonkinetochore microtubles Spindle apparatus Spindle fibers Some Vocabulary The mitotic spindle as visible through a light microscope

19. Centromere Centrosome Centriole Kinetochore Kinetochore microtubules Mitotic spindle Nonkinetochore microtubles Spindle apparatus Spindle fibers Some Vocabulary Bundles of microtubles making up the spindle apparatus; it is the bundling that makes them visible through a light microscope

20. Eukaryote Cell Cycle “G” stands for “Gap”

21. Stages of Mitosis

22. Mitosis (first half)

23. Mitosis (second half)

24. Mitotic Spindle

25. Aster(s)

26. Kinetichore

27. Cytokinesis, Animals Cytokinesis can occur simultaneous to telophase

28. Cytokinesis, Plants

29. Binary Fission

30. G2 of Interphase Nucleus defined Nucleoli present Replicated Centrosomes Asters present DNA duplicated DNA still chromatin

31. Prophase Chromatic condensation Nucleoli disappear Mitotic spindle forms Centrosome separation

32. Prometaphase Nuclear envelope fragments Microtubules invade nucleus Microtubles interact chromosomes Kinetochores at centromeres Chromosomes jerky movements Nonkinet. microtubule interaction

33. Metaphase Centrosomes opposite poles Metaphase plate Chromosomes straddle MP Kinetochores attached KMT Spindle apparatus Brief, static phase

34. Anaphase Begins with “sister” separation Chromatids now chromosomes “Sisters” to opposite poles Movement centromere first Non-kinet. microtu. lengthening Further separation of poles

35. Telophase Non-kinet. microtu. lengthening “Sisters” at opposite poles Nuclear env. reformation Reforms from endomembrane Chromosome decondensation Cytokinesis already under way

36. Cleavage Furrow Cytokinesis

37. Name the Phases!

38. Most cells in the body are in G0 Check Points & G0

39. Comparative Division

40. Probability Theory (ch. 14 preview) • Statistical Independence • Range of Probabilities (0..1) • Law of Multiplication • Calculation for Events not Happening • The Law of Addition

41. The End