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Understanding Mitosis: Cell Division Process Explained

Explore the intricacies of mitosis, the division of a single nucleus into two identical daughter cells, essential for growth, repair, and reproduction. Learn about chromosome structure, stages of mitosis, cell cycle, and cancer implications.

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Understanding Mitosis: Cell Division Process Explained

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  1. What is Mitosis? Cell Division The division of a single nucleus into two identical daughter cells Why do cells go through mitosis? Growth Repair/replacement Reproduction MITOSIS

  2. Chromosomes • Are made up of genes • Genes are made up of DNA • DNA is made up of nucleotides

  3. How many chromosomes do humans have? • 46 chromosomes • Chromosomes are only visible during cell division

  4. Chromosome Structure • Before cell division, chromosomes replicate • Each chromosome consists of two identical “sister” chromatids

  5. What would need to happen before a cell could divide? Copy it’s genetic AND cellular material

  6. Cell Cycle • Interphase • In between cell divisions • Three parts (G1 phase, S phase, G2 phase) • Mitotic Phase • Mitosis • Four Parts (Prophase, Metaphase, Anaphase,Telophase) • Cytokinesis

  7. Interphase G1 phase • Most growing occurs; cells increase in size • New proteins and organelles are made

  8. Interphase S phase • Chromosomes are replicated • Synthesis of DNA takes place • Proteins associated with chromosomes are made

  9. Interphase G2 phase • Shortest phase • Organelles (centrioles) and molecules needed for mitosis are made; checks for necessary repairs to the DNA

  10. Mitosis • Prophase • 50-60% of time required for mitosis • Chromosomes become visible • Centrioles go to opposite poles • Chromosomes attach to spindle fibers • Nucleolus disappears • Nuclear envelope breaks down

  11. Mitosis • Metaphase • Lasts only a few minutes • Chromosomes line up across the center of the cell • Microtubules connect the centrosome of each chromosomes to the poles of the spindle

  12. Mitosis • Anaphase • Centrosomes that join sister chromatids separate • Each sister chromatid becomes an individual chromosome • Chromosomes (sister chromatids) move to opposite poles

  13. Mitosis • Telophase • (reverse of prophase) • Chromosomes spread out and become a tangled dense mass of chromatin • Nuclear envelope reforms • Spindles break apart • Nucleolus becomes visible

  14. Cytokinesis • “division of cytoplasm” • In animal cells, cell membrane pinches in (“cleavage furrow”) separating the cell into two equal parts • In plant cells, • a cell plate forms down the middle of the cell • Cell plate gradually becomes a separating membrane • A cell wall forms in the cell plate

  15. Mitosis Video • http://www.youtube.com/watch?v=VlN7K1-9QB0

  16. What phase of mitosis is shown in each picture?

  17. Cell Cycle Pictures in Order

  18. What affects Cell Division? • Anchorage • Animal cells must be in contact with a solid surface to divide • Cell density • Crowded cells stop dividing • Chemical growth factors • Proteins secreted by body cells that stimulate other cells to divide

  19. Cancerous Cells • Don’t • react to normal control mechanisms • respond to regulatory signals that are part of the cell cycle • exhibit density-dependent (contact) inhibition • stop dividing when growth factors aren’t available

  20. Uncontrolled mitosis (cell division) Metastasis: spread of cancerous cells Immortal (normal cells can only divide ~50 times before dying) Cancer Video http://www.youtube.com/watch?v=LP52CyYmY_U&NR=1 Chemotherapy Video http://www.youtube.com/watch?v=tYABZdpsC9M&NR=1 What is cancer?

  21. What causes cancer? • Normally, tumor suppressors genes send messages to kill damaged cells • If tumor suppressor genes malfunction, some damaged cells • will die off • divide uncontrollably and give rise to cancer. • Oncogenes • mutated genes will cause cancer

  22. What damages the DNA? • Carcinogens – agents that cause mutations in the DNA • Ex.  radiation, hormones, viruses, and many chemicals

  23. Why are cancers so dangerous? • Cancers • displace and put pressure on normal tissues • cut off blood supply to normal tissues • interrupt organ function

  24. Resources • http://www.healthsystem.virginia.edu/internet/huntdisease/images/DNA.gif • http://www.nia.nih.gov/NR/rdonlyres/E2CBDDA6-4658-485B-B63C-14E7159C74B7/0/DNA_LOW.JPG • http://imagecache2.allposters.com/images/pic/JAG/03-PS101-5~Mitosis-Posters.jpg • http://www.stanford.edu/group/hopes/basics/dna/f_b11homolgs.jpg • http://www.cbp.pitt.edu/faculty/yong_wan/images/main_cell_cycle.jpg • http://www.le.ac.uk/ge/genie/vgec/images/cellcycle.png • http://img.tfd.com/dorland/arm_chromosome.jpg • http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20101/Bio%20101%20Lectures/Mitosis/human_chromosomes_female_X_1000_1.jpg • http://www.mun.ca/biology/scarr/F14-10_FISH_chromosome.jpg • http://library.tedankara.k12.tr/chemistry/vol1/biochem/trans98.jpg • http://student.ccbcmd.edu/~gkaiser/biotutorials/dna/mitosis/images/interphase1_pc.jpg • http://student.ccbcmd.edu/~gkaiser/biotutorials/dna/mitosis/images/interphase_ac.jpg • http://images.google.com/imgres?imgurl=http://www.ias.unt.edu/~tpp001/interphase_text.JPG&imgrefurl=http://www.ias.unt.edu/~tpp001/Mitosis_Diagram_Page.main.html&usg=__kRmHOyZqZ32q2kyUCdW_pjupMH8=&h=327&w=417&sz=27&hl=en&start=5&tbnid=8POhgQsjCqBR8M:&tbnh=98&tbnw=125&prev=/images%3Fq%3Dinterphase%26gbv%3D2%26hl%3Den • http://www.ndpteachers.org/perit/Mitosis%5BAnimalCell%5D.GIF • http://www.youtube.com/watch?v=VlN7K1-9QB0 • http://www.alternative-cancer.net/images/Cancer_cell,%20brain.jpg • http://assets.aarp.org/external_sites/adam/graphics/images/en/19349.jpg • http://whyfiles.org/coolimages/images/csi/HPV_small.jpg • http://upload.wikimedia.org/wikipedia/commons/thumb/a/ae/RadiationPenetration2-pn.png/300px-RadiationPenetration2-pn.png

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