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Published byAldous Dean Modified over 8 years ago
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Do Now If you have not already handed in your WebQuest packet, bring it to my desk. Make sure your name is on it!
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Cellular Reproduction Chapter 9
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9.1: Cellular Growth MAIN IDEA: Cells grow until they reach their size limit, then they either stop growing or divide.
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Cell Size DON’T COPY Most cells – only 100 micrometers in diameter Why are they so small??? Do large or small cells perform tasks more efficiently?
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Surface Area : Volume DON’T COPY This ratio is extremely important to cells To calculate for a cube: Surface area = ? Volume = ?
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Surface Area : Volume DON’T COPY Surface Area of cube = L x W x 6 Volume = L x W x H
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Calculate SA:V ratio
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Surface Area : Volume DON’T COPY What happened to the ratio when the cells became larger?
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Surface Area : Volume DON’T COPY As cell grows, volume increases faster than surface area, so this ratio becomes smaller LARGER ratio (smaller cells) – more beneficial to cells Cell needs large surface area to get enough nutrients and expel wastes efficiently
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Cell’s Life Cycle Cells grow only so big; too big makes cell inefficient If cell reaches size limit it: Stops growing OR Divides When cells divide, they make an exact duplicate of themselves. Result = 2 identical cells
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Eukaryotes’ Cell Cycle Cycle of cells growing and dividing After 1 complete cycle, 1 cell becomes 2 cells 3 main parts: Interphase Division (Mitosis) Cytokinesis
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Interphase Cell spends most of its life in interphase Called “resting” phase, but cell is chemically active Metabolism (chemical reactions) Preparation for division
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3 Parts of Interphase
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Interphase G1: Cell grows, active metabolism, organelles duplicated S: DNA replicated G2: Has twice as much DNA as G1 phase cell, prepares for mitosis, triggers division and ends interphase
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Mitosis (M) Phase Mitosis – nucleus and nuclear material divide Chromosomes can be seen under microscope Divided into 4 sub-stages
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Chromatin
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Chromosomes
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Cytokinesis Cytokinesis - when cytoplasm divides
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9.2: Mitosis and Cytokinesis MAIN IDEA: Eukaryotic cells reproduce by mitosis, the process of nuclear division, and cytokinesis, the process of cytoplasm division.
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Mitosis Nuclear division Continuous process Seen in stages Result = 2 genetically identical daughter cells
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Stages of Mitosis 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase
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Prophase Pro = first Chromatin coils, shortens, and thickens into chromosomes Nuclear membrane starts to disappear
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Prophase Spindle fibers (microtubules) form in cytoskeleton, and chromosomes’ centromeres attach to fibers Spindle apparatus = all microtubule fibers and centrioles (in animal cells)
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Prophase
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Metaphase Meta = change Pairs of chromosomes move to center of cell, along equator, perpendicular to spindle fibers
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Anaphase Ana = up Chromatids separate, each pair moving to opposite ends of cell along spindle fibers
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Telophase Telo = end Chromosomes reach opposite ends of the cells; new nuclear membrane starts forming to make 2 identical nuclei
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Cytokinesis Cytoplasm divides in half, duplicated organelles move apart
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Plant and Animal Cells Similar process of mitosis, but some differences Animal cells have 2 centrioles Plant cells form a cell plate during cytokinesis (preliminary cell wall); animal cells pinch across middle instead to separate
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Prokaryotes Binary fission Chromosome replicates Cell elongates Membrane/wall forms in middle, dividing cell
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Name the phase
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9.3: Cell Cycle Regulation MAIN IDEA: The normal cell cycle is regulated by cyclin proteins.
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Normal Cell Cycle Timing and rate of cell cycle controlled by 2 substances: Cyclins – proteins Cyclin-dependent kinases (CDKs) – enzymes that bind to cyclin Different combinations signal different activities during the cell cycle
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Activities Controlled by CDK/Cyclin: Start of cell cycle DNA replication Protein synthesis Nuclear division (mitosis) End of cell cycle
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Abnormal Cell Cycle: Cancer Cells divide repeatedly and uncontrollably No ability to stop the progression of division at checkpoints (which allow normal cells to stop dividing if something goes wrong) Cancer cells overcrowd normal cells, stopping their normal function and killing the organism
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Causes of Cancer Changes/mutations in DNA affect proteins that control cell cycle Carcinogens – substances or agents that cause cancer
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What are Some Common Carcinogens?
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Tobacco Exposure to x-ray radiation Exposure to UV radiation (from Sun) Air pollution Alcohol Food with many preservatives
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Genetics Higher risk of mutations over time – so more likely for older people to develop cancer Can run in families
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Apoptosis Programmed cell death Occurs in development – webbing between fingers/toes Occurs in plants losing leaves Prevents damaged cells from dividing Prevents cancer
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Stem Cells Unspecialized cells – specialize under right conditions Embryonic – result shortly after fertilization; cells eventually specialize into tissues (controversial research) Adult – always found in some tissues Can be used to treat certain diseases/conditions
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