1 / 46

The Cell Cycle Chapter 12

The Cell Cycle Chapter 12. Mitosis. Cell division Produce 2 daughter cells Same genetic information. Mitosis. Asexual reproduction Growth Repair. Genome. Genetic information Prokayotes Nucleoid Circular DNA No nucleus. Genome. Eukaryotes Chromosomes: DNA Associated proteins

vera-turner
Download Presentation

The Cell Cycle Chapter 12

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. The Cell CycleChapter 12

  2. Mitosis • Cell division • Produce 2 daughter cells • Same genetic information

  3. Mitosis • Asexual reproduction • Growth • Repair

  4. Genome • Genetic information • Prokayotes • Nucleoid • Circular DNA • No nucleus

  5. Genome • Eukaryotes • Chromosomes: • DNA • Associated proteins • Chromatin: • Complex of DNA & proteins • Makes up chromosomes • Humans 46 chromosomes • Dogs 78 chromosomes

  6. Eukaryotes • Somatic cells: • Body cells • 46 chromosomes • Gametes: • Sex cells • Sperm & eggs • 23 chromosomes

  7. Eukaryotes • Chromatid: • Duplicated chromosome • Centromere: • Attachment to another chromatid • Prior to cell division chromosomes replicates

  8. 0.5 µm Chromosomes DNA molecules Fig. 12-4 Chromo- some arm Chromosome duplication (including DNA synthesis) Centromere Sister chromatids Separation of sister chromatids Centromere Sister chromatids

  9. Fig. 12-5 INTERPHASE S (DNA synthesis) G1 Cytokinesis G2 Mitosis MITOTIC (M) PHASE

  10. Cell cycle • Cell cycle: • Events that occur to produce two cells • 1. Interphase (G1, S, G2) • 2. Mitosis • 3. Cytokinesis

  11. Interphase • Growth phase of the cell • G1, S, G2

  12. Interphase • Where most of cycle is spent • Rate of division depends on job of cell. • Liver cells may divide rapidly • Mature muscle cells do not divide at all • Few cells will be in mitosis at a time • Most are in interphase

  13. Interphase • G1 or Gap 1 phase • Cell is doing its job • Preparing for the S phase. • Chromosomes are single • Can last weeks to years or happen very quickly

  14. Interphase • S phase DNA replication happens • 2 sister chromatids • G2 or Gap 2 phase cell prepares for division • Mitochondria & other organelles replicate • Microtubules begin to form • Chromosomes condense

  15. Interphase

  16. Mitosis • Nucleus & its contents divide • Distributed equally • Forming two daughter cells • Prophase, metaphase, anaphase and telophase

  17. Prophase • Beginning of mitosis • Chromosomes continues to condense • Mitotic spindle forms • Begins to move chromosomes to center • Nuclear membrane disintegrates • Nucleolus disappears

  18. Prophase

  19. Metaphase • Chromosomes line up in center of cell • Centromeres become aligned along the cells center

  20. Metaphase

  21. Anaphase • Microtubules shorten • Separates the sister chromatids • Chromosomes move towards the poles

  22. Anaphase

  23. Telophase • Chromosomes are at the poles • Nuclear envelope reforms • Nucleolus reappears • Chromosomes uncoil or de-condense

  24. Telophase

  25. Cytokinesis • Cytoplasm separates • Animal cells: • cleavage furrow pinches the cells in two • Plant cells: • cell plate is formed between the cells • Grows until a new cell wall is formed

  26. Cytokinesis

  27. Fig. 12-9 Vesicles forming cell plate Wall of parent cell 1 µm 100 µm Cleavage furrow Cell plate New cell wall Daughter cells Contractile ring of microfilaments Daughter cells (a) Cleavage of an animal cell (SEM) (b) Cell plate formation in a plant cell (TEM)

  28. Binary fission • Prokaryotes produce 2 daughter cells by binary fission

  29. Binary fission • 1. Replication of the DNA • Origin of replication: • Specific location on the DNA • 2. Two DNA molecules move to the ends of the cell • 3. Septation • Formation of a new cell membrane & a septum.

  30. Binary fission • 4. Septum begins to grow inward • 5. Cell pinches into two cells.

  31. Cell cycle control system • Check points • Control point with stop & go signals • G1, G2 and M phases

  32. Fig. 12-14 G1 checkpoint Control system S G1 G2 M M checkpoint G2 checkpoint

  33. Cell cycle control system • Special proteins • Protein kinases & cyclins • Cdks – cycle dependent kinases • MPF-cyclin-Cdk complex • “M-phase promoting factor” • Regulate if cell stops or proceeds in the cycle

  34. Fig. 12-17b G1 S Cdk Cyclin accumulation M G2 Degraded cyclin G2 checkpoint Cdk Cyclin is degraded Cyclin MPF (b) Molecular mechanisms that help regulate the cell cycle

  35. Figure 12.16a G2 M G1 G1 S M S M G1 G2 MPF activity Cyclinconcentration Time (a) Fluctuation of MPF activity and cyclin concentration during the cell cycle

  36. Cell cycle control system • Go-ahead signal at G1 • Divides • No signal • G0 phase • Does not divide

  37. G1 checkpoint G0 Figure 12.17 G1 G1 Without go-ahead signal,cell enters G0. With go-ahead signal,cell continues cell cycle. (a) G1 checkpoint G1 S G2 M G1 G1 M G2 M G2 M checkpoint G2checkpoint Anaphase Prometaphase Metaphase With full chromosomeattachment, go-ahead signalis received. Without full chromosomeattachment, stop signal isreceived. (b) M checkpoint

  38. Cell cycle control system • Receives signals • The environment • Other cells • Growth factors • Density-dependent inhibition • Anchorage dependence

  39. Tumor • Abnormal growth of cells • Malfunction in control system • Abnormal cells grow uncontrollably • Benign: • Non-cancerous growth

  40. Tumor • Malignant: • Cancerous growth • Metastasis: • Spread of cancer to distant locations

  41. p53 • Protein • Works at a checkpoint at G1 • p53 determines if DNA is damaged • If so stimulates enzymes to fix it • Cell division continues • Unable to repair damage • Cell suicide occurs

  42. p53 • Helps keep damaged cells from dividing • Cancer cells p53 is absent or damaged • p53 protein is found on the p53 gene • Considered a tumor-suppressor gene • Cigarette smoking causes mutations in this gene

  43. Henrietta Lacks • 1951 developed cervical cancer • Before cancer treatment • Cells were removed • First cells to grow in vitro • Outside of the body • Cell line is now known as HeLa cell line • Helped in biomedical research

More Related