Cell differentiation notes

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Chapter 3

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Cell differentiation notes

  1. 1. Cell Cycle & Differentiation Chapter 3 Unit 1
  2. 2. The Cell Cycle <ul><li>A set of events that occur during a cell’s lifetime </li></ul><ul><ul><li>From the time a cell is “born” until it divides </li></ul></ul><ul><ul><li>Cycle is repeated for each cell </li></ul></ul><ul><ul><li>Includes: </li></ul></ul><ul><ul><ul><li>Growth </li></ul></ul></ul><ul><ul><ul><li>Preparation </li></ul></ul></ul><ul><ul><ul><li>Division </li></ul></ul></ul>
  3. 3. The Cell Cycle
  4. 4. The Cell Cycle <ul><li>Consists of three major stages: </li></ul><ul><ul><li>Interphase* </li></ul></ul><ul><ul><li>Mitosis* </li></ul></ul><ul><ul><li>Cytokinesis </li></ul></ul><ul><li>*Each of these are broken into several distinct phases </li></ul>
  5. 5. The Cell Cycle <ul><li>Interphase </li></ul><ul><ul><li>Cell’s spend about 90% of the cycle in here </li></ul></ul><ul><ul><li>Broken down into three phases </li></ul></ul><ul><ul><ul><li>Gap 1 </li></ul></ul></ul><ul><ul><ul><li>Synthesis </li></ul></ul></ul><ul><ul><ul><li>Gap 2 </li></ul></ul></ul>
  6. 6. Interphase <ul><li>Gap 1 </li></ul><ul><ul><li>AKA “Growth” 1 </li></ul></ul><ul><ul><li>Cells in this phase are growing in size </li></ul></ul><ul><ul><li>Producing lots of ATP </li></ul></ul><ul><ul><li>Dividing and reproducing cell organelles </li></ul></ul>
  7. 7. Interphase <ul><li>Synthesis </li></ul><ul><ul><li>Cells in this phase are copying all the DNA found in the nucleus </li></ul></ul><ul><ul><li>Synthesis is referring to the building of new DNA molecules </li></ul></ul><ul><ul><li>Necessary to ensure that both cells that result from division have 100% of DNA </li></ul></ul>
  8. 8. Interphase <ul><li>Gap 2 </li></ul><ul><ul><li>AKA “Growth” 2 </li></ul></ul><ul><ul><li>Cells in the phase are checking to make sure their DNA has been replicated correctly </li></ul></ul><ul><ul><li>Check to make sure organelles are copied </li></ul></ul>
  9. 9. The Cell Cycle <ul><li>Assuming everything is ready at the G2 phase, the cell will proceed to division </li></ul><ul><ul><li>Cell division in humans is called mitosis </li></ul></ul><ul><ul><li>Has four phases </li></ul></ul><ul><ul><ul><li>Prophase </li></ul></ul></ul><ul><ul><ul><li>Metaphase </li></ul></ul></ul><ul><ul><ul><li>Anaphase </li></ul></ul></ul><ul><ul><ul><li>Telophase </li></ul></ul></ul>
  10. 10. Mitosis <ul><li>Prophase </li></ul><ul><ul><li>Pro- means first </li></ul></ul><ul><ul><li>DNA thickens into chromosomes </li></ul></ul><ul><ul><ul><li>Remember, it has been replicated. </li></ul></ul></ul><ul><ul><ul><li>Look like X’s </li></ul></ul></ul><ul><ul><ul><li>Each side of the X is called a chromatid </li></ul></ul></ul><ul><ul><li>Nuclear membrane dissolves </li></ul></ul>
  11. 11. Prophase
  12. 13. Mitosis <ul><li>Metaphase </li></ul><ul><ul><li>Meta- means middle </li></ul></ul><ul><ul><li>Spindle Fibers form </li></ul></ul><ul><ul><ul><li>Attach to centromere of chromosome </li></ul></ul></ul><ul><ul><ul><li>Move chromosomes to cell’s equator </li></ul></ul></ul><ul><ul><li>Centrioles found at opposite ends of cell </li></ul></ul>
  13. 14. Metaphase
  14. 15. Mitosis <ul><li>Anaphase </li></ul><ul><ul><li>Spindle Fibers shorten, pulling chromosomes in half </li></ul></ul><ul><ul><ul><li>Sister chromatids split apart </li></ul></ul></ul><ul><ul><ul><li>Chromatids move toward opposite sides of cell </li></ul></ul></ul><ul><ul><ul><li>***Chromatids are now called chromosomes </li></ul></ul></ul>
  15. 16. Anaphase
  16. 17. Mitosis <ul><li>Telophase </li></ul><ul><ul><li>Chromosomes reach the cell’s poles </li></ul></ul><ul><ul><li>Two new nuclei form…one around each set of chromosomes at opposite ends </li></ul></ul><ul><ul><li>Chromosomes unwind </li></ul></ul><ul><ul><li>Spindle fibers dissolve </li></ul></ul>
  17. 18. Telophase
  18. 19. Cytokinesis <ul><li>The final stage of cell division </li></ul><ul><li>Literally means “cytoplasm divides” </li></ul><ul><ul><li>Cell pinches in half </li></ul></ul><ul><ul><li>The “pinch” is called a cleavage furrow </li></ul></ul>
  19. 20. Differentiation <ul><li>Humans are conceived when a sperm and egg unite, forming a single-celled zygote </li></ul><ul><li>Zygotes are unspecialized </li></ul><ul><li>When we are born, we have more than 260 specialized cell types </li></ul><ul><li>How??? Differentiation </li></ul>
  20. 21. Differentiation <ul><li>Cells specialize by differentiating into certain cell types </li></ul><ul><ul><li>They turn off parts of DNA that they don’t need </li></ul></ul><ul><ul><li>Use only the parts of DNA that are needed to become a specific cell </li></ul></ul><ul><ul><li>*Cells that are specialized generally can’t change and become other cell types </li></ul></ul>
  21. 22. Differentiation <ul><li>Stem Cells </li></ul><ul><ul><li>Unspecialized cells that can can become ANY type of cell in the body </li></ul></ul><ul><ul><li>Stem cells found in every organ in body </li></ul></ul><ul><ul><li>Stimulated to divide when… </li></ul></ul><ul><ul><ul><li>Growth is needed </li></ul></ul></ul><ul><ul><ul><li>Damage needs to be repaired </li></ul></ul></ul>
  22. 23. Differentiation <ul><li>When a stem cell divides… </li></ul><ul><ul><li>Two cells are produced through mitosis </li></ul></ul><ul><ul><li>One cell is a new stem cell (unspecialized) </li></ul></ul><ul><ul><li>One cell is called a progenitor cell </li></ul></ul><ul><ul><ul><li>Somewhat specialized </li></ul></ul></ul><ul><ul><ul><li>Will divide many more times, with each daughter cell become more and more specialized </li></ul></ul></ul><ul><ul><li>*Cells “decide” to become specialized at the end of the G1 phase of cell cycle </li></ul></ul>See Page 69 in textbook!!!
  23. 24. Apoptosis <ul><li>Defined as programmed cell death </li></ul><ul><ul><li>Happens at the end of G1 in cell cycle </li></ul></ul><ul><ul><li>Occurs for many reasons </li></ul></ul><ul><ul><ul><li>Sculpting organs from overgrown tissue in the fetus </li></ul></ul></ul><ul><ul><ul><li>Removes webbing between fingers as fetus </li></ul></ul></ul><ul><ul><ul><li>Destroys skin cells following a sunburn </li></ul></ul></ul>

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