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Understanding Mitosis: Cell Division and Reproduction in Organisms

Learn what mitosis is, why it is important for cell growth and repair, and how it results in the production of identical cells in both single-cell and multicellular organisms.

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Understanding Mitosis: Cell Division and Reproduction in Organisms

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  1. Mitosis • What is it? • Why is it Important? • What do YOU need to know?

  2. Mitosis = Cell Division • Why must cells divide? The cell theory states: ALL CELLS ARISE FROM OTHER CELLS… • How is that possible?

  3. Why do YOU need it? • YOU started out as ONE cell… Are you STILL one cell????? • If you fall on the pavement and scrape your knee… Does it heal? • Your stomach acid burns through the stomach lining ever few days… Are your stomach contents spilling out into your body?

  4. Cell Growth • Think about a balloon… • What happens when you fill it with too much air? • The same would happen to a cell if it kept growing – from the inside out – without dividing…

  5. Cell Repair • You know that EVERY TIME you touch something, you leave skin cells behind… • What happens when you break a bone? • How about when you need to get stiches?

  6. YOU ALWAYS NEED NEW CELLS! • Mitosis is the process by which new body cells are formed for growth or repair • THIS type of cell division results in TWO IDENTICAL cells being produced from ONE parent cell • Reproduction involving ONE parent is Asexual Reproduction (aka MITOSIS)

  7. Asexual Reproduction(Mitosis) • Happens with single-cell critters • And Multicellular organisms (us!)

  8. Asexual Reproduction = Mitosis • Mitosis is Asexual Cell Division • It happens in a series of stages… • The stages depend on the type of organism: • Prokaryotic or • Eukaryotic

  9. One Cell Becomes Two • The stages of Mitosis begin within one cell (called the Parent Cell) - The DNA is copied and the cell splits in half • The final product of THIS type of Cell Division is TWO new IDENTICAL cells (called Daughter Cells) - The Daughter Cells are clones of the Parent Cell

  10. Mitosis makes Clones • Mitosis involves a series of changes that make an identical copy of the original cell - The DNA is copied “exactly” • Mitosis makes a clone of the parent cell • ONE parent cell divides to make TWO identical daughter cells

  11. Remember DNA? Deoxyribonucleic Acid • One of two Nucleic Acids you need to know • Why does a cell need it? - Because DNA contains your hereditary information - The instructions to make the proteins that MAKE YOU!

  12. Mitosis: Prokaryotes Binary Fission Binary=two pieces/parts Fission=split Prokaryotes have no nucleus… Bacteria

  13. Binary Fission... First, DNA replicates (duplicates)… - Since Bacteria have no nucleus, the DNA replicates in the cytoplasm

  14. DNA is replicated • DNA must be replicated (copied) so that each new cell has an EXACT copy of the “instructions” (the hereditary information) • Remember, we are making clones…

  15. DNA Separates & The Parent Cell Divides in Two This division is much simpler, quicker than cell reproduction in Eukaryotes Cell Division

  16. Mitosis: Eukaryotes Animal Cells: YOU! Plant Cells

  17. Different Types Depending on the Organism • Budding • Vegetative Propagation • Mitosis Cycle in the Nucleus (US!)

  18. One Cell Becomes Two • In Eukaryotes, the stages of Mitosis begin within the NUCLEUS of the Parent Cell • The final product of THIS type of Cell Division is TWO new Daughter Cells - The Daughter Cells are identical to the Parent Cell! * They are clones!

  19. Budding • A new organism develops as an “outgrowth” of the parent - A “bud” forms which will grow to be identical to the parent • Hydra - a new individual forms • Yeast budding

  20. Budding Cont’d… Yeast Hydra

  21. Vegetative Propagation • In vegetative propagation, a part of a plant (root, stem, leaf) grows into a new plant • The new growth is identical to the parent plant • This is how potatoes, garlic and strawberries are grown

  22. Vegetative Propagation • Runners: Strawberry & Spider Plants

  23. Vegetative Propagation • Bulbs: Tulips, Daffodils, Garlic and Onions

  24. Vegetative Propagation • Tubers/Rhizomes: Potatoes and grasses

  25. Mitosis: Eukaryotes • Mitosis begins in the nucleus, where the DNA must duplicate before the cell divides

  26. “Body” Cells… (aka Somatic Cells) • Mi-TO-sis happens with ALL cells in the body (except sex cells) - Your TOE is a body part… - Mi-TO-sis has the word “to” in it… to remind you that it makes two cells! • Mitosis begins in the nucleus - Remember: The nucleus is in control

  27. Advantages of Mitosis Quick Process Makes IDENTICAL Copies

  28. Disadvantages of Mitosis Makes IDENTICAL Copies HUH????? Didn't we just say that was an ADVANTAGE????

  29. Disadvantages of Mitosis Makes IDENTICAL Copies THINK… What would this world be like if we were all identical? THINK…If we were all identical, it would be easy to wipe out humans! (or any organism!)

  30. That’s all well and dandy • But, how do all of the organelles and such get copied? • I mean, there’s A LOT of stuff inside a Eukaryotic Cell!

  31. Eukaryotic Cell Cycle • Cells go through a “cycle” after they are “born” • They only divide when the nucleus tells them to! • The nucleus decides! • The cell cycle is: “I pee on a mat, see?”

  32. The Nucleus • All of the action begins and ends with direction from the Nucleus - The Nucleus is in control • The Chromosomes in the Nucleus contain the genes which control cell activities - Remember: Your Chromosomes are made up of DNA which is a Nucleic Acid made up of Nucleotides that are found in the Nucleus!

  33. Stages of The Cell Cycle I P M A T C? • Cells spend most of their time in Interphase • This is the phase where they perform all of their life functions - (STRANGER-C) • The Stages (Phases) of Mitosis are: - Prophase - Metaphase - Anaphase - Telophase - Cytokinesis (only in Animal Cells)

  34. Interphase I • INTERPHASE is the “IN BETWEEN” phase (the period between cell divisions where cell lives) • When it is time to divide, at the end of Interphase, single stranded chromosomes (chromatids) Replicate (make an exact copy)

  35. Chromatids condense and duplicate

  36. Chromosomes The original chromatid is copied and the copy is attached (like velcro) to the original at the Centromere Centromere It is now called a Chromosome Centromere

  37. 2 identical “sister” chromatids attached at an area in the middle called a centromere • When cells divide, “sister” chromatids separate and 1 goes to each new cell

  38. Chromatin to chromosome illustration Chromatin Coils up into chromosomes Duplicates itself

  39. AFTER Interphase…Mitosis • Mitosis is cell division • Mitosis consists of 4 distinct phases: • Prophase • Metaphase • Anaphase • Telophase P M A T

  40. 4 phases of nuclear division (mitosis), directed by the cell’s DNA (PMAT) Prophase Metaphase—(Middle) Anaphase—(Apart) Anaphase—(Apart) Telophase—(Two)

  41. Prophase • In Prophase the double stranded condensed chromosomes become visible • The nuclear membrane disintegrates • In animal cells, the centriole and the spindle fibers move to opposite sides of the cell

  42. Metaphase • Metaphase is easy to recognize! • The chromosomes move toward the middle of the cell where they line up and prepare for division • Centrioles spit out Spindle Fibers that attach to the middle (centromere) of the chromosome Meta = Middle

  43. Anaphase • During Anaphase, the spindle fibers pull the chromatids apart - Chromosomes split apart • The chromatids move to opposite ends of the cell Anaphase = Apart • Each chromatid is now a single stranded chromosome containing all of the necessary genetic information

  44. Telophase • The last official stage of mitosis is Telophase - (Cytokinesis is also a part of this…but only in the Animal Cell) • In Telophase, the nuclear membrane reappears around each set of chromosomes - Forming two identical nuclei • Cytokinesis is different for Plant and Animal Cells…

  45. Cytokinesis • The last official stage of mitosis is Telophase, but in Animal Cells, one last phase splits the cell into two - Cytokinesis - Cyto=Cytoplasm - Kinesis=Split • Cytokinesis does NOT occur in Plant Cells…

  46. Why? • What do plant cells have surrounding them that we do not? ______________ • The membrane cannot ”pinch in” to create two separate cells • The plant cell needs to “Build A Wall” in the middle of the cell in order for it to split into two - This is the Cell Plate and it is made of Cellulose

  47. Stages of Mitosis (IPMAT,C)

  48. Mitosis produces identical offspring (2N2N)

  49. What’s 2N???? aka, Diploid

  50. N = The number of chromosomes in a Sex Cell • In Sexually producing organisms (US!) the Sex Cell (aka Gamete) is the sperm and the egg • The “N” number, aka Haploid, is the number of chromosomes in each Gamete - In humans, it is 23

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