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Why do Cells Need to Grow?

Why do Cells Need to Grow?. Replace old cells Replace damaged cells Make new life. When do Cells Grow?. Cells grow, or more accurately, divide to stay small Cells need to be small to function properly Cellular organelles need to be able to communicate to each other and the outside world

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Why do Cells Need to Grow?

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  1. Why do Cells Need to Grow? • Replace old cells • Replace damaged cells • Make new life

  2. When do Cells Grow? • Cells grow, or more accurately, divide to stay small • Cells need to be small to function properly • Cellular organelles need to be able to communicate to each other and the outside world • The surface area to volume ratio needs to be high • That means, the cell needs more membrane and less cytoplasm

  3. The Cell Cycle • The cycle of growing and dividing of eukaryotic cells • It is a continuous production of new cells • Controlled by a series of signals Three Main Stages of the Cell Cycle: • Interphase • Mitosis • Cytokinesis

  4. Interphase- The Longest Stage Broken down into Three Sub-Stages • G1 Sub-Stage • Period of cell growth and maturing into a functioning cell • Some cells, like muscle cells, stop here 2. S Sub-Stage • Duplicates its DNA • DNA is copied to put into new cell 3. G2 Sub-Stage • Prepares for Division • Cell gets ready to divide

  5. Mitosis and Cytokinesis • Mitosis • When the nucleus and cellular material divides • Cytokinesis • When the cell’s cytoplasm divides

  6. MitosisThe accurate separation of the cell’s DNA • Prophase • Metaphase • Anaphase • Telophase

  7. Prophase • Longest phase of Mitosis • The copied DNA condenses into chromosomes • Chromosomes are shaped like an X • The center of the X is called the centromere • The pair of chromosomes are called sister chromatids • Nuclear membrane disintegrates • Spindle fibers (microtubules) begin to form

  8. Metaphase • Chromosomes attach to spindles (microtubules) • Chromosomes align along the equator of the cell

  9. Anaphase • The microtubules of the spindles begin to shorten • The sister chromatids are pulled apart • The chromatids are moved to the poles of the cell

  10. Telophase • Chromosomes reach end of cell • Nuclear membrane reappears • Chromosomes decondense

  11. Cytokinesis • Division of the cytoplasm • Animal cells – furrow • Plant cells – cell plate

  12. Cell Cycle Checkpoints • The cell cycle has “checkpoints” • “security” proteins at the “checkpoints” • If something goes wrong, cell cycle stops • Also regulation on when cell cycle starts and stops • What is it called when the cell cycle continues uncontrollably?

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