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Genes, Mitosis and Cytokinesis 12/17/14 Mitosis ! CELL DIVISION! ü Mitotic division results in genetically identical eukaryotic cells or a" clone " _____ ü Mitosis is the basis of " ________ asexual! reproduction G. Podgorski, Biol. 1010 " 1 Genes, Mitosis and Cytokinesis 12/17/14 LIFESPAN OF SOME CELLS IN THE HUMAN BODY! " Prokaryotes! ü Granulocytes: eosinophils basophils, neutrophils " ü Stomach lining cells " ü Colon cells " " ü Epithelia of small intestine less" ü Platelets " " ü Skin epidermal cells " ü Lymphocytes" " " " " " " " " " " " " " " " " " " " ü Red blood cells (120 days)" ü Pancreas cells more ü Brain cells " " " " " "10 hours to 3 days" "2-3 days" "3-4 days" "1 week or "10 days" "2 - 4 weeks" "2 months - a year " "4 months " ü Prokaryotes simply divide their cells in two by binary fission " 1 year or " " " " http://instruct1.cit.cornell.edu/ "95-100 years" Eukaryotes! ü Eukaryotes must divide their nucleus" ü When nucleus divides, the DNA" ____ duplicates. This is called replication." Organelles" must also replicate" ü __________ Why do cells divide?" ü Reason #1:" ü If a cell kept getting bigger, there wouldn’t be enough DNA to provide sufficient information" " Why do cells divide?" Why do cells divide?" ü Reason #2:" ü Reason #3" ü If a cell kept getting bigger, couldn’t move nutrients and wastes across the cell membrane" G. Podgorski, Biol. 1010 ü To replace old and worn out cells." 2 Genes, Mitosis and Cytokinesis The three main components of the cell cycle. 12/17/14 After DNA is replicated it must be packaged into chromosomes. Why? Interphase duplicated chromosome What’s so important about cell division? chromatin DUPLICATING CHROMSOMES If there are 6 sister chromatids, how many chromosomes are in the cell? DNA is Condensed into Visible Chromosomes Only For Brief Periods in the Life of a Cell centromere 95% of the time, chromosomes are like this. Easily visible chromosomes are apparent perhaps 5% of the time in an actively growing cell and less in a non-growing cell. A Karyotype is an Arranged Picture of Chromosomes At Their Most Condensed State Note that almost all chromosomes come in homologous pairs. Boy or girl? A normal human karyotype G. Podgorski, Biol. 1010 3 Genes, Mitosis and Cytokinesis 12/17/14 The Cell Cycle-notes" ü Series of 3 main events that cells go through as they grow and divide." 1. INTERPHASE a. G1- growth phase; organelles replicated. b. S- chromosomes are replicated c. G2- growth; double check before division. 2, MITOSIS (PMAT) 3. CYTOKINESIS I Punched Melanie And The Cat ü 1.Prophase" ü 2.Metaphase" ü 3.Anaphase" MITOSIS highlights" - Mitosis Divides the Duplicated Chromosomes: THE DANCE OF THE CHROMOSOMES! 1. Prophase: • chromatin condenses • centrioles separate • spindle begins to form • nuclear envelope breaks down 2.Metaphase: • Lasts only a few minutes • Chromosomes line up on the metaphase plate (middle) • Spindle fibers connect to the centromere of each chromosome 3.Anaphase: • Centromeres separate • Chromosomes move to opposite sides of the cell. 4.Telophase: • Chromosomes uncoil • Nuclear envelope reappears • Spindle begins to break apart • Nucleolus becomes visible Mitosis Precisely and Evenly Divides Duplicated Chromosomes anaphase centromere interphase prophase metaphase What is a centromere? G. Podgorski, Biol. 1010 ü 4.Telophase" telophase Two New Identical Daughter Cells! Cytokinesis is NOT included in mitosis. 4 Genes, Mitosis and Cytokinesis 12/17/14 Mitosis in Action Cytokinesis" ü Division of cytoplasm" ü Occurs differently in plants than in animals" Blue shows DNA, green shows spindle fibers. Cytokinesis in plant cells: Cytokinesis in animal cells: In animal cells, a cleavage furrow forms and separates daughter cells. In plant cells, a cell plate forms and separates the daughter cells. Cleave furrow in a dividing frog cell. Onion Root Tip CANCER Cancer develops when cells in a part of the body begin to grow out of control. Brain cancer cell G. Podgorski, Biol. 1010 5 Genes, Mitosis and Cytokinesis 12/17/14 Cancer Is One Outcome of A Runaway Cell Cycle What’s in a name?" Carcinoma—any tissue " communicating with the outside" Sarcoma—supporting " tissue" Lymphoma—immune " system" Leukemia—blood" The good and the bad" Benign —locally grown; tumor remains" in the original site of growth" Malignant a.k.a. “The bad”—ability to " spread" ü STOP!" Metastasize—when a tumor has spread from " its original growth site" Cell division is a fundamental process! ü All cells come from pre-existing cells" ü It is necessary to replace worn out cells in multicellular organisms" ü It is required for growth in multicellular organisms" ü It is necessary for reproduction in unicellular or multicellular organisms " G. Podgorski, Biol. 1010 Cell Cycle" ü Series of events that cells go through as they grow and divide" ü Cell grows" ü Prepares for division" ü Divides to form daughter cells" ü Daughter cells restart the cycle" 6 Genes, Mitosis and Cytokinesis 12/17/14 Proteins and Their Production – The Primary Reason for DNA DNA and Its Faithful Replication – Because DNA stores genetic information and is faithfully replicated, information is passed largely unaltered from cell-to-cell, generation-to- generation. Cell division requires coordinated division of chromosomes (mitosis) ….. DNA Replication – Simple in Principle, Complicated in Practice …… and division of the cytoplasm (cytokinesis). The Link Between DNA Replication and Chromosome Duplication QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. G. Podgorski, Biol. 1010 7 Genes, Mitosis and Cytokinesis QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. G. Podgorski, Biol. 1010 12/17/14 QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. 8