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Transcript
MITOSIS-CELL DIVISION #1-WHY DO CELLS DIVIDE? A. Diffusion limits cell size Replace Repair Grow and develop The larger a cell becomes, the more demands on its DNA Trouble moving nutrients and wastes across the cell membrane Organization DNA is the cells library of information If the cell gets too large, it will put too many demands on the cell A cell needs to stay small to meet the “DNA” needs of the cell B. Surface areaThe total area of the surface of a three dimensional object Affects the rate of food (Oxygen, Water) and wastes moving in and out of the cell. C. VolumeAmount of space occupied Larger volume slows the rate of materials moving in and out D RatioSurface area/volume As the length of the cell increases, the volume increases faster surface area Larger ratio-quick movement of materials Small ratio-slow movement of materials Cells divide because they cannot get food to the center of their cytoplasm quickly enough #2-CELL DIVISION A. 46 chromosomes which make up (23 pairs) B. Chromosomes # stays the same a. Before it becomes too large, a growing cell doubles its chromosomes and organelles then divides. b. Cell then splits, forming two daughter cells C. Common Location for Cell Division Intestinal Lining-every 24 hours Skin Sperm cells Blood cells/bone marrow makes blood cells Liver-sometimes Cells that never divide Muscle cells Cardiac cells Kidney Nerve cells Parent Cell=46 Chromosomes Can split into two daughter cells, which are identical When a new cell is created……it has (46) chromosomes Cell Cycle Checkpoints G1-The cell grows S-Synthesis-Chromosomes are duplicated G2-The cell grows Check Points G1 1) Checks for cell size 2) Checks that genetic material is healthy G2 1) Check that DNA is duplicated 2) Cell size 3) Check that genetic material is healthy (No mutations) M-Mitosis1) Check to make sure that the spindle fibers were attached to the chromosomes If the cell could NOT get through a check point 1) Apoptosis-The cell dies 2) Repair A. Interphase “Eye ball” 90% of the time 1. Gap 1-cell grows, doubles organelles 2. Synthesis- (S-phase)-duplication of the DNA in the cells chromosomes 3. GAP 2-cell grows, microtubules assembled B. Stages of Mitosis 1. Prophase (pasta phase) Visible chromosome Nucleus disappears 2. Metaphase “middle”-Chromosomes line up at the equator 3. Anaphase “apart” 5 Telephase “two new cells are forming” Cytokinesis-the cytoplasm cuts in half Cyto-cell Kinesis-to cut Very last part of the cell cycle In plants A structure known as the cell plate forms midway between the divided nuclei Cytokines is in Animals Animal cells contract and pinch in ½ (half) TERMS Spindle-network of microtubules that move chromosomes during mitosis and meiosis Equator: centerline of cell where chromosomes line up during metaphase Poles: The opposite ends of the cell Centrioles-animal cells only, move the spindle and chromosomes during division Cleavage Furrow-The pinching in of animal cells during cytokinesis. Cell Plate-disk in plant cells that divide the cell into daughter cells during cytokinesis. Centromere-region where two sister chromatids are joined tightly together. VI-Results of Mitosis A. Production of 2 new daughter cells B. Daughter cells are exactly the same as original parent cell C. Mitosis is how organisms grow, develop and repair When the cell cycle goes wrong…………………………….. -Normal cells will reproduce until they touch other cells -When this happens, they stop growing Uncontrolled Cell Growth Cancer is a disorder in which some of the body’s own cells lose the ability to control growth. Cancer cells do not respond to the signals that regulate the growth of most cells. Divide uncontrollably Form masses of cells called tumors Metastasis-tumor cells break loose and spread in body. Benign-Non-cancerous Malignant-Cancerous Tumor Causes of Cancer: Genetics Chemicals-Absestos, cigarettes, pesticides Radiation Diet Certain viruses (HPV) Prevention of Cancer Genetic screening Do not smoke, Do not drink too much, proper diet prevent sunburns Treatment for Cancer Chemotherapy Radiation