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Transcript
Image from: http://www.bcps.org/offices/lis/models/life/images/grow.JPG CELL GROWTH & DIVISION 10-1 & 10-2 Image by Riedell DNA in PROKARYOTES • BACTERIAL DNA is CIRCULAR • HAVE ONE CHROMOSOME • NO NUCLEUS; ATTACHED TO CELL MEMBRANE http://www.origin-life.gr.jp/3202/3202121/fig6.jpg DNA in EUKARYOTES (Plants & Animals) • DNA is ROD-SHAPED CHROMOSOMES • MANY PAIRS • FOUND IN NUCLEUS http://cellbio.utmb.edu/cellbio/chrom2.jpg Chromosome structure CHROMATIDS • ___________________ 2 identical arms • __________________ CENTROMERE constricted area holds chromatids together HOMOLOGOUS •__________________ PAIR 2 of each chromosome (one from mom; one from dad) HOMOLOGOUS CHROMOSOMES • SAME SIZE • SAME SHAPE • CARRY GENES for the SAME TRAITS IDENTICAL • BUT NOT ______________! (Don’t have to have the SAME CHOICES) http://arnica.csustan.edu/biol3020/cell_division/cell_division.htm http://sps.k12.ar.us/massengale/genetics%20tutorial.htm CELL DIVISION in PROKARYOTES Bacteria reproduce using BINARY FISSION __________________________________ http://fig.cox.miami.edu/~cmallery/150/mitosis/fission.jpg CELL CYCLE ______________ = series of events that cells go through as they grow and develop cells alive cell cycle CELL CYCLE INTERPHASE – non-dividing phase G1- Grow bigger Cell is “doing its job” DNA is spread out as chromatin S - Synthesis (copy DNA) & chromosomal proteins G2- Grow bigger, make organelles & molecules needed for cell division INTERPHASE: (IN between dividing) Set up cell membrane on desk (Use black string to make a big oval on the desk). DNA will switch back and forth between chromatin (long) and chromosomes (short) pieces during the activity. In interphase DNA is spread out as chromatin. Cells start with 6 chromosomes. (Count out 3 long purple and 3 long green strings and place in center of cell) Nuclear membrane is visible (Place pink yarn piece around the DNA) During S phase DNA is copied. Hold up each chromatin yarn piece and place a "copy" along side of it. (Use the 3 extra long purple/green strings) Replace DNA in nucleus CELL DIVISION MITOSIS – Nuclear division Prophase Metaphase Anaphase Telophase Cytokinesis – Cytoplasm divides G0 – cell stops dividing (Ex: nerve cell) INTERPHASE (G1 - S - G2) In between divisions Cells are in this phase most of the time Can see nucleus DNA spread out as chromatin Can’t see chromosomes DNA gets copied (S) Cell gets ready to divide Pearson Education Inc publishing as Pearson Prentice Hall PROPHASE 1st dividing phase http://www.life.uiuc.edu/plantbio/102/lectures/08mit&veg102.html DNA scrunches into chromosomes Centrioles appear in centrosome region & move to poles Nuclear membrane & nucleolus disappear Spindle fibers form & attach to chromosomes • PROPHASE: (First dividing phase- Pros are #1) Chromatin condenses into chromosomes (Replace longer yarn pieces in nucleus with shorter ones) Remember to keep the chromatid "copies" together. Nucleus/nucleolus disappears. (Remove pink yarn piece around chromosomes) • Centrioles/Spindle appear (students play role of spindle with their fingers) CENTROSOME ________ region organizes spindle Spindle MICROTUBULES are part of cytoskeleton http://www.coleharbourhigh.ednet.ns.ca/library/organelle_worksheet.htm METAPHASE Chromosomes line up in middle ___________ Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall http://www.science.siu.edu/plant-biology/PLB117/JPEGs%20CD/0247.JPG METAPHASE (MIDDLE) Chromosomes line up in middle of cell. {Spindle (fingers) move chromosomes to middle of cell} ANAPHASE Centromeres split apart Centrioles pull chromatids_______ Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall http://www.science.siu.edu/plant-biology/PLB117/JPEGs%20CD/0247.JPG ANAPHASE (APART) Chromatid arms separate and move to opposite ends of cell (Use fingers to separate chromatid arms) TELOPHASE (reverse prophase steps) two nuclei See ______ Nuclear membrane & nucleolus return Chromosomes spread out as chromatin Centrioles disappear Spindle fibers disappear Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall http://www2.bc.cc.ca.us/cnewton/Biology%2011/Mitosis.html -Count chromosomes. You started with 6 (3 large, medium, small purple & 3 large, medium, small green) -How many does your cell have now? (Should have 3 purple and 3 green; check to make sure you have one L, M, S purple and one L, M, S, green) CYTOKINESIS Cytoplasm splits into 2 cells ANIMAL CELLS pinch cytoplasm in two with a ______________________ CLEAVAGE FURROW CYTOKINESIS Cytoplasm splits into 2 cells PLANT CELLS can’t pinch because they have a sturdy ____________ CELL WALL Plant cells separate cytoplasm by CELL PLATE growing a _______________ down the middle. http://www.eastcentral.edu/acad/depts/BI/plant_mitosis_nolabels.html CYTOKINESIS (Cytoplasm splits) Animal cells use a cleavage furrow. (Have students push cell membrane together in middle to make two cells) Plant cells make a cell plate (Have students use their orange string to make a wall instead of pinching) Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Cytokinesis Go to Section: Spindle Centriole Telophase Nuclear envelope reforming Centriole Individual chromosomes Anaphase Metaphase Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Cytokinesis Go to Section: Spindle Centriole Telophase Nuclear envelope reforming Centriole Individual chromosomes Anaphase Metaphase Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Cytokinesis Go to Section: Spindle Centriole Telophase Nuclear envelope reforming Centriole Individual chromosomes Anaphase Metaphase Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Cytokinesis Go to Section: Spindle Centriole Telophase Nuclear envelope reforming Centriole Individual chromosomes Anaphase Metaphase Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Cytokinesis Go to Section: Spindle Centriole Telophase Nuclear envelope reforming Centriole Individual chromosomes Anaphase Metaphase Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Cytokinesis Go to Section: Spindle Centriole Telophase Nuclear envelope reforming Centriole Individual chromosomes Anaphase Metaphase Concept Map Section 10-2 Cell Cycle includes is divided into Go to Section: is divided into Concept Map Section 10-2 Cell Cycle includes Interphase M phase (Mitosis) is divided into is divided into G1 phase Go to Section: S phase G2 phase Prophase Metaphase Anaphase Telophase 10- 3 REGULATING the CELL CYCLE http://www.travel-net.com/~andrews/images/animations/traffic.gif Control of Cell Division If center cells are removed, cells near the space will start to grow again. Cells grow until they touch other cells SHOWS: Cell division genes can be turned on and off Section 10-3 10-7 Control of Cell Division Why didn’t the cells keep dividing until they spilled over the edge of the petri dish? When the cells came into contact with other cells, they responded by not growing. What happened to the cells between the first petri dish and the second petri dish? Cells divided until a thin layer of cells covered the bottom of the dish. What caused the difference shown b/w the third and fifth petri dishes? Cells began dividing again until they filled the empty space. CELL DIVISION GENES EXAMPLE: Cell division genes can be turned on in case of injury. ________ Cells near injury are stimulated to divide to heal and replace damaged/missing cells and shut off when the repair has been made. CELL CYCLE REGULATORS Levels of this protein rose and fell with the cell cycle so it was named __________ CYCLIN because it seemed to control the cell cycle. A whole family of CYCLINS have since been discovered that regulate the TIMING of CELL CYCLE _____________________ in EUKARYOTIC CELLS Pearson Education Inc; Publishing as Pearson Prentice Hall OTHER REGULATORS INTERNAL ______________ REGULATORS Proteins that respond to events inside the cell. Allow cell cycle to proceed only if certain processes have happened EX: Cell can’t enter mitosis until all the chromosomes have been copied OTHER REGULATORS EXTERNAL ______________ REGULATORS Proteins that respond to events outside the cell. Signals tell cell to speed up or slow down the cell cycle EX: Growth factors stimulate cells to divide Especially important during wound healing and embryo development http://www.suite101.com/files/topics/6234/files/tail_HumanTail.gif EXTERNAL REGULATORS Molecules on the surface of neighboring cells act as signals to slow down or stop the cell’s cycle. These signals prevent excessive growth and keep tissues from disrupting each other. Pearson Education Inc; Publishing as Pearson Prentice Hall Cancer cells have lost control of their cell division genes SEM Image by: Riedell CHO (Chinese Hamster Ovary) cells in culture NO CONTACT INHIBITION Cancer cells don’t stop when they touch nearby cells. . . they just keep growing! See a video That’s what makes a tumor. http://www.exn.ca/news/images/2000/08/02/20000802-cancer.jpg Cancer cells • Don’t stop dividing • Like a “car with no brakes” • Can spread to new places (METASTASIS) • ______________ Carcinogens are substances that can damage DNA and cause cancer Ex: Cigarette smoke (OR CHEW), Radiation, chemicals in environment, even viruses, http://www.dfci.harvard.edu/abo/news/publications/pop/fall-winter-2004/images/metastasis_1.jpg Cancer cells Cancer is complicated and can have many causes, but all cancers have one thing in common . . .… They have lost control over their _____________. CELL CYCLE Many cancers cells have a damaged or defective gene called p53 _____, so they can’t respond to normal cell signals to control their growth.