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Cap 12 - Ciclo Celular
The document summarizes key aspects of the cell cycle and cell division: 1) It describes the main stages of the cell cycle - interphase and mitosis - and explains that interphase involves cell growth while mitosis involves nuclear and cellular division. 2) It explains that mitosis results in two identical daughter cells through equal distribution of chromosomes, while meiosis results in non-identical gametes through reduction of chromosome number. 3) It provides an overview of the stages of mitosis (prophase, prometaphase, metaphase, anaphase, telophase) and cytokinesis and describes the role of the mitotic spindle in separating chromosomes.
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Cap 12 - Ciclo Celular
- 1. LECTURE PRESENTATIONS For CAMPBELLBIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Chapter 12 The Cell Cycle Lectures by Erin Barley Kathleen Fitzpatrick © 2011 Pearson Education, Inc.
- 2. Overview: The KeyRoles of Cell Division • The ability of organisms to produce more of their own kind best distinguishes living things from nonliving matter • The continuity of life is based on the reproduction of cells, or cell division • “Every cell from a cell” (Virchow, 1855). © 2011 Pearson Education, Inc. Figure 12.1 How do a cell’s chromosomes change during cell division?
- 3. • In unicellularorganisms, division of one cell reproduces the entire organism • Multicellular organisms depend on cell division for – Development from a fertilized cell – Growth – Repair • Cell division is an integral part of the cell cycle, the life of a cell from formation to its own division © 2011 Pearson Education, Inc.
- 4. Figure 12.2 Thefunctions of cell division. 100 µm (a) Reproduction 200 µm (b) Growth and development 20 µm (c) Tissue renewal
- 5. Concept 12.1: Mostcell division results in genetically identical daughter cells • Most cell division results in daughter cells with identical genetic information, DNA • The exception is meiosis, a special type of division that can produce sperm and egg cells © 2011 Pearson Education, Inc.
- 6. Cellular Organization ofthe Genetic Material • All the DNA in a cell constitutes the cell’s genome • A genome can consist of a single DNA molecule (common in prokaryotic cells) or a number of DNA molecules (common in eukaryotic cells) • DNA molecules in a cell are packaged into chromosomes © 2011 Pearson Education, Inc. Figure 12.3 Eukaryotic chromosomes. 20 µm
- 7. • Eukaryotic chromosomesconsist of chromatin, a complex of DNA and protein that condenses during cell division • Every eukaryotic species has a characteristic number of chromosomes in each cell nucleus • Somatic cells (nonreproductive cells) have two sets of chromosomes • Gametes (reproductive cells: sperm and eggs) have half as many chromosomes as somatic cells © 2011 Pearson Education, Inc.
- 8. Distribution of ChromosomesDuring Eukaryotic Cell Division • In preparation for cell division, DNA is replicated and the chromosomes condense • Each duplicated chromosome has two sister chromatids (joined copies of the original chromosome), which separate during cell division • The centromere is the narrow “waist” of the duplicated chromosome, where the two chromatids are most closely attached Figure 12.4 A highly condensed, duplicated human chromosome (SEM). Sister chromatids Cohesins © 2011 Pearson Education, Inc. Centromere 0.5 µm
- 9. Figure 12.5 Chromosomeduplication and distribution during cell division. Chromosomal DNA molecules Chromosomes • During cell division, the two sister chromatids of each duplicated chromosome separate and move into two nuclei • Once separate, the chromatids are called chromosomes © 2011 Pearson Education, Inc. 1 Centromere Chromosome arm Chromosome duplication (including DNA replication) and condensation 2 Sister chromatids Separation of sister chromatids into two chromosomes 3
- 10. • Eukaryotic celldivision consists of – Mitosis, the division of the genetic material in the nucleus – Cytokinesis, the division of the cytoplasm • Gametes are produced by a variation of cell division called meiosis – Meiosis yields nonidentical daughter cells that have only one set of chromosomes, half as many as the parent cell © 2011 Pearson Education, Inc.
- 11. Concept 12.2: Themitotic phase alternates with interphase in the cell cycle • Walther Flemming, the German anatomist, was responsible for the discovery of mitosis and cytokinesis, which refers to cell division. – He used aniline dyes to isolate from the gills and fins of salamanders a substance that he called "chromatin” • In 1882, his results on the stages of mitosis were published in a book entitled, "Cell Substance, Nucleus and Cell Division” • Based on his research, Flemming concluded that each cell's nuclei comes from another cell nucleus. © 2011 Pearson Education, Inc.
- 12. Phases of theCell Cycle • The cell cycle consists of: –Mitotic (M) phase -mitosis and cytokinesis • Mitosis is conventionally divided into five phases: – Prophase, Prometaphase, Metaphase, Anaphase and Telophase • Cytokinesis overlaps the latter stages of mitosis –Interphase -cell growth and copying of chromosomes in preparation for cell division (about 90% of the cell cycle) Figure 12.6 The cell cycle. – G1 phase (“first gap”) – S phase (“synthesis”) – G2 phase (“second gap”) INTERPHASE M o yt MIT C (M) OTIC P sis ne ki sis • The cell grows during all three phases, but chromosomes are duplicated only during the S phase HAS BioFlix: Mitosis © 2011 Pearson Education, Inc. S (DNA synthesis) G1 ito • Can be divided into subphases: E G2
- 13. 10 µm Figure 12.7Exploring: Mitosis in an Animal Cell G2 of Interphase Centrosomes (with centriole pairs) Nucleolus Chromatin (duplicated) Nuclear envelope Plasma membrane Prophase Early mitotic spindle Aster Centromere Chromosome, consisting of two sister chromatids Prometaphase Fragments of nuclear envelope Kinetochore Metaphase Nonkinetochore microtubules Kinetochore microtubule Anaphase Metaphase plate Spindle Centrosome at one spindle pole Telophase and Cytokinesis Cleavage furrow Daughter chromosomes Nuclear envelope forming Nucleolus forming
- 14. Figure 12.7 Exploring:Mitosis in an Animal Cell G2 of Interphase Centrosomes (with centriole pairs) Chromatin (duplicated) Prophase Early mitotic spindle Plasma membrane Nucleolus Nuclear envelope • A nuclear envelope encloses the nucleus • Nucleolus (nucleoli) are visible • Centrosome (two centroles) duplicated, therefore two centrosomes • Duplicated chromosomes have not yet condensed Aster Centromere Chromosome, consisting of two sister chromatids • Chromatin is condensing into chromosomes • Nucleolus (nucleoli) disappear • Duplicated chromosomes appear as two identical sister chromatids • Mitotic spindle begins to form, see asters • Centrosome move away from each other Prometaphase Fragments of nuclear envelope Kinetochore Nonkinetochore microtubules Kinetochore microtubule • Nuclear envelope fragments • Microtubules from centrosomes invade nuclear area • Chromosomes more condensed, have kinetochores • Microtubules attach to kinetochores, become ‘kinetochores microtubules’ • Nonkinetochores microtubules interact with those of opposite pole of spindle
- 15. Figure 12.7 Exploring:Mitosis in an Animal Cell Metaphase Metaphase plate Spindle Centrosome at one spindle pole • Centrosomes at opposite poles of the cells • Chromosomes convened at metaphase plate, centromere lie at the metaphase plate • For each chromosome, the kinetochores of the sister chromatids are attach to,kinetochores microtubules coming from opposite poles. Anaphase Telophase and Cytokinesis Cleavage furrow Nucleolus forming Nuclear Daughter envelope chromosomes forming • Shortest stage of mitosis • Two daughter nuclei. Nuclear • Sister chromatids of each pair envelope arise. • Nucleolus (nucleoli) reappear separate (each one now is a • Chromosomes are less chromosome) • Kinetochores microtubules condensed • Remaining spindle microtubules shorten and chromosomes move toward opposite ends of are depolymerized. • Mitosis, the nucleus division into the cell • Nonkinetochores microtubules two identical nuclei is complete lengthen and the cell elongates --------------------------------------------• End of anaphase, two complete • Cytokinesis in animal cells is equivalent collections of sinchronized with telophase chromosomes
- 16. 10 µm Figure 12.7Exploring: Mitosis in an Animal Cell G2 of Interphase Prophase Prometaphase
- 17. 10 µm Figure 12.7Exploring: Mitosis in an Animal Cell Metaphase Anaphase Telophase and Cytokinesis
- 18. The Mitotic Spindle:A Closer Look • The mitotic spindle is a structure made of microtubules that controls chromosome movement during mitosis • In animal cells, assembly of spindle microtubules begins in the centrosome, the microtubule organizing center • The centrosome replicates during interphase, forming two centrosomes that migrate to opposite ends of the cell during prophase and prometaphase • An aster (a radial array of short microtubules) extends from each centrosome • The spindle includes: the centrosomes, the spindle microtubules, and the asters © 2011 Pearson Education, Inc.
- 19. • During prometaphase,some spindle microtubules attach to the kinetochores of chromosomes and begin to move the chromosomes • Kinetochores are protein complexes associated with centromeres • At metaphase, the chromosomes are all lined up at the metaphase plate, an imaginary structure at the midway point between the spindle’s two poles Figure 12.8 The mitotic spindle at metaphase. Aster Centrosome Sister chromatids Metaphase plate (imaginary) Chromosomes Kinetochores Centrosome 1 µm Overlapping nonkinetochore microtubules Kinetochore microtubules 0.5 µm © 2011 Pearson Education, Inc. Microtubules
- 20. Figure 12.9 Inquiry:At which end do kinetochore microtubules shorten during anaphase? • In anaphase, sister chromatids separate and move along the kinetochore microtubules toward opposite ends of the cell • The microtubules shorten by depolymerizing at their kinetochore ends EXPERIMENT Kinetochore Spindle pole Mark RESULTS CONCLUSION Chromosome movement Microtubule Motor protein Chromosome © 2011 Pearson Education, Inc. Kinetochore Tubulin subunits
- 21. Figure 12.9 Inquiry:At which end do kinetochore microtubules shorten during anaphase? CONCLUSION Microtubule Chromosome movement Motor protein Chromosome Kinetochore Tubulin subunits
- 22. • Nonkinetochore microtubulesfrom opposite poles overlap and push against each other, elongating the cell • In telophase, genetically identical daughter nuclei form at opposite ends of the cell • Cytokinesis begins during anaphase or telophase and the spindle eventually disassembles © 2011 Pearson Education, Inc.
- 23. Cytokinesis: A CloserLook • In animal cells, cytokinesis occurs by a process known as cleavage, forming a cleavage furrow • In plant cells, a cell plate forms during cytokinesis Video: Animal Mitosis Video: Sea Urchin (Time Lapse) Animation: Cytokinesis © 2011 Pearson Education, Inc.
- 24. Figure 12.10 Cytokinesisin animal and plant cells. (a) Cleavage of an animal cell (SEM) Cleavage furrow Contractile ring of microfilaments 100 µm (b) Cell plate formation in a plant cell (TEM) Vesicles forming cell plate Wall of parent cell Cell plate 1 µm New cell wall Daughter cells Daughter cells
- 25. Figure 12.10 Cytokinesisin animal and plant cells. (a) Cleavage of an animal cell (SEM) Cleavage furrow Contractile ring of microfilaments 100 µm Daughter cells
- 26. Figure 12.10 Cytokinesisin animal and plant cells. (b) Cell plate formation in a plant cell (TEM) Vesicles Wall of parent cell forming Cell plate cell plate 1 µm New cell wall Daughter cells
- 27. Figure 12.11 Mitosisin a plant cell. Nucleus Chromatin condensing Nucleolus 1 Prophase Chromosomes 2 Prometaphase 3 Metaphase Cell plate 4 Anaphase 10 µm 5 Telophase
- 28. Binary Fission inBacteria • Prokaryotes (bacteria and archaea) reproduce by a type of cell division called binary fission • In binary fission, the chromosome replicates (beginning at the origin of replication), and the two daughter chromosomes actively move apart • The plasma membrane pinches inward, dividing the cell into two © 2011 Pearson Education, Inc.
- 29. Figure 12.12 Bacterialcell division by binary fission. Origin of replication E. coli cell 1 Chromosome replication begins. 2 Replication continues. 3 Replication finishes. 4 Two daughter cells result. Cell wall Plasma membrane Bacterial chromosome Two copies of origin Origin Origin
- 30. The Evolution ofMitosis • Since prokaryotes evolved before eukaryotes, mitosis probably evolved from binary fission • Certain protists exhibit types of cell division that seem intermediate between binary fission and mitosis (a) Bacteria Bacterial chromosome Chromosomes (b) Dinoflagellates Microtubules Intact nuclear envelope Kinetochore microtubule (c) Diatoms and some yeasts Intact nuclear envelope Kinetochore microtubule (d) Most eukaryotes Fragments of nuclear envelope © 2011 Pearson Education, Inc. Figure 12.13 Mechanisms of cell division in several groups of organisms.
- 31. Concept 12.3: Theeukaryotic cell cycle is regulated by a molecular control system • The frequency of cell division varies with the type of cell • These differences result from regulation at the molecular level • Cancer cells manage to escape the usual controls on the cell cycle © 2011 Pearson Education, Inc.
- 32. Evidence for CytoplasmicSignals • The cell cycle appears to be driven by specific chemical signals present in the cytoplasm • Some evidence for this hypothesis comes from experiments in which cultured mammalian cells at different phases of the cell cycle were fused to form a single cell with two nuclei © 2011 Pearson Education, Inc. EXPERIMENT Experiment 1 S Experiment 2 G1 M G1 RESULTS S S When a cell in the S phase was fused with a cell in G1, the G1 nucleus immediately Entered the S phase—DNA was synthesized. M M When a cell in the M phase was fused with a cell in G1, the G1nucleus immediately began mitosis—a spindle formed and chromatin condensed, even though the chromosome had not been duplicated. Figure 12.14 Inquiry: Do molecular signals in the cytoplasm regulate the cell cycle?
- 33. The Cell CycleControl System • The sequential events of the cell cycle are directed by a distinct cell cycle control system, which is similar to a clock • The cell cycle control system is regulated by both internal and external controls • The clock has specific checkpoints where the cell cycle stops until a go-ahead signal is received © 2011 Pearson Education, Inc. G1 checkpoint Control system G1 M M checkpoint S G2 G2 checkpoint Figure 12.15 Mechanical analogy for the cell cycle control system.
- 34. Figure 12.16 TheG1 checkpoint. • For many cells, the G1 checkpoint seems to be the most important • If a cell receives a go-ahead signal at the G1 checkpoint, it will usually complete the S, G2, and M phases and divide • If the cell does not receive the go-ahead signal, it will exit the cycle, switching into a nondividing state called the G0 phase G0 G1 checkpoint G1 (a) Cell receives a go-ahead signal. © 2011 Pearson Education, Inc. G1 (b) Cell does not receive ago-ahead signal.
- 35. The Cell CycleClock: Cyclins and CyclinDependent Kinases • Two types of regulatory proteins are involved in cell cycle control: cyclins and cyclin-dependent kinases (Cdks) • Cdks activity fluctuates during the cell cycle because it is controled by cyclins, so named because their concentrations vary with the cell cycle • MPF (maturation-promoting factor) is a cyclin-Cdk complex that triggers a cell’s passage past the G 2 checkpoint into the M phase © 2011 Pearson Education, Inc.
- 36. Figure 12.17 Molecularcontrol of the cell cycle at the G2 checkpoint. M G1 S G2 M G1 S G2 M G1 MPF activity Cyclin concentration G S 1 Time (a) Fluctuation of MPF activity and cyclin concentration during the cell cycle Cdk Cyclin is degraded 2 M G Degraded cyclin G2 Cdk checkpoint MPF Cyclin (b) Molecular mechanisms that help regulate the cell cycle
- 37. Stop and GoSigns: Internal and External Signals at the Checkpoints • An example of an internal signal is that kinetochores not attached to spindle microtubules send a molecular signal that delays anaphase • Some external signals are growth factors, proteins released by certain cells that stimulate other cells to divide • For example, platelet-derived growth factor (PDGF) stimulates the division of human fibroblast cells in culture © 2011 Pearson Education, Inc.
- 38. Figure 12.18 Theeffect of platelet-derived growth factor (PDGF) on cell division. Scalpels 1 A sample of human connective tissue is cut up into small pieces. 2 Enzymes digest the extracellular matrix, resulting in a suspension of free fibroblasts. Petri dish 3 Cells are transferred to culture vessels. Without PDGF 4 PDGF is added to half the vessels. With PDGF 10 µm
- 39. Figure 12.19 Density-dependentinhibition and anchorage dependence of cell division. Anchorage dependence Density-dependent inhibition Density-dependent inhibition (a) Normal mammalian cells © 2011 Pearson Education, Inc. 20 µm • A clear example of external signals is density-dependent inhibition, in which crowded cells stop dividing • Most animal cells also exhibit anchorage dependence, in which they must be attached to a substratum in order to divide • Cancer cells exhibit neither density-dependent inhibition nor anchorage dependence (b) Cancer cells 20 µm
- 40. Loss of CellCycle Controls in Cancer Cells • Cancer cells do not respond normally to the body’s control mechanisms • Cancer cells may not need growth factors to grow and divide – They may make their own growth factor – They may convey a growth factor’s signal without the presence of the growth factor – They may have an abnormal cell cycle control system © 2011 Pearson Education, Inc.
- 41. • A normalcell is converted to a cancerous cell by a process called transformation • Cancer cells that are not eliminated by the immune system, form tumors, masses of abnormal cells within otherwise normal tissue • If abnormal cells remain at the original site, the lump is called a benign tumor • Malignant tumors invade surrounding tissues and can metastasize, exporting cancer cells to other parts of the body, where they may form additional tumors © 2011 Pearson Education, Inc.
- 42. Figure 12.20 Thegrowth and metastasis of a malignant breast tumor. Tumor Lymph vessel Blood vessel Glandular tissue Cancer cell 1 A tumor grows from a single cancer cell. Metastatic tumor 2 Cancer cells invade neighboring tissue. 3 Cancer cells spread through lymph and blood vessels to other parts of the body. 4 Cancer cells may survive and establish a new tumor in another part of the body.
- 43. • Recent advancesin understanding the cell cycle and cell cycle signaling have led to advances in cancer treatment – Intracellular receptors that can trigger cell division • Herceptin (HER2)- cell-surface receptor tyrosine kinase hormone treatment • Estrogen Receptor (ER) treated with Tamoxifen Figure 12.21 Impact: Advances in Treatment of Breast Cancer © 2011 Pearson Education, Inc.
- 44. Figure 12.UN01 INTERPHASE G1 S Cytokinesis G2 Mitosis MITOTIC (M)PHASE Prophase Telophase and Cytokinesis Prometaphase Anaphase Metaphase
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Editor's Notes
- #5 Figure 12.2 The functions of cell division. LM Amoeba reproducing Sand dollar 2 cells embryo Bone marrow blood cell production
- #7 African blood lilly Purple-chormosomes Red-pink threads- cytoskeleton Chromo-color; soma-body
- #9 Cohesins-proteins thanbind sister chromatids along the chromosome
- #12 Walther Flemming was responsible for the discovery of mitosis, which refers to cell division. in 1882. Read more: http://www.brighthub.com/science/genetics/articles/33094.aspx#ixzz1QUZH0W70
- #13 For the Cell Biology Video Myosin and Cytokinesis, go to Animation and Video Files. Human cells cycle - 24hr M- < 1hr; S10-12hrs; G2 4-6;G1 5-6hrs.
- #14 Figure 12.7 Exploring: Mitosis in an Animal Cell
- #15 Figure 12.7 Exploring: Mitosis in an Animal Cell
- #16 Figure 12.7 Exploring: Mitosis in an Animal Cell
- #17 Figure 12.7 Exploring: Mitosis in an Animal Cell
- #18 Figure 12.7 Exploring: Mitosis in an Animal Cell
- #19 For the Cell Biology Video Spindle Formation During Mitosis, go to Animation and Video Files.
- #21 For the Cell Biology Video Microtubules in Anaphase, go to Animation and Video Files.
- #22 Figure 12.9 Inquiry: At which end do kinetochore microtubules shorten during anaphase?
- #23 For the Cell Biology Video Microtubules in Cell Division, go to Animation and Video Files.
- #25 Figure 12.10 Cytokinesis in animal and plant cells.
- #26 Figure 12.10 Cytokinesis in animal and plant cells.
- #27 Figure 12.10 Cytokinesis in animal and plant cells.
- #28 Figure 12.11 Mitosis in a plant cell.
- #30 Figure 12.12 Bacterial cell division by binary fission.
- #37 Figure 12.17 Molecular control of the cell cycle at the G2 checkpoint.
- #39 Figure 12.18 The effect of platelet-derived growth factor (PDGF) on cell division.
- #43 Figure 12.20 The growth and metastasis of a malignant breast tumor.
- #45 Figure 12.UN01 Summary figure, Concept 12.2
- #46 Figure 12.UN02 Test Your Understanding, question 7
- #47 Figure 12.UN03 Appendix A: answer to Figure 12.4 legend question
- #48 Figure 12.UN04 Appendix A: answer to Figure 12.8 legend question
- #49 Figure 12.UN05 Appendix A: answer to Test Your Understanding, question 7
- #50 Figure 12.UN06 Appendix A: answer to Test Your Understanding, question 10