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Exploring Cell Growth & Division: Limits, Chromosomes, & Mitosis

Learn about cell growth limitations, DNA overload, the role of chromosomes, and stages of mitosis. Discover how cancer and stem cells impact cell division.

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Exploring Cell Growth & Division: Limits, Chromosomes, & Mitosis

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  1. Cell Growth and Division Chapter 10

  2. Cell Growth Does an adult have bigger cells than a child?

  3. Limits to Cell Growth • Why do cells divide instead of continuing to grow? 1. DNA overload – too much strain on DNA info to run cell. 2. Cell volume increases too rapidly for surface area (cell membrane). Inefficient material exchange. Too much stuff! • Solution: Divide or Die!

  4. Ratio of Surface Area to Volume in Cells Section 10-1 Cell Size Surface Area (length x width x 6) Volume (length x width x height) What is another reason, other than cell growth, that would cause cell division to occur? (Hint: when do we need to get new cells?) Some cells can readily divide, but some may rarely or never divide.

  5. Cell Division What is the necessary material for a new cell to have in order to function?

  6. What Are Chromosomes? • Strands of DNA • Every organism has a specific number of chromosomes. How many do humans cells have? • Before cell division occurs, DNA must be copied so each new cell will have DNA instructions. • Once copied, the two identical strands (or CHROMATIDS) are held together by a CENTROMERE. centromere Chromosome (uncopied) Draw this in your NB! Chromosome (copied) chromatids

  7. Cell Cycle – “Life of a Cell” • Interphase – growth period of cell, longest stage of cell life. 1. G1 phase – growth, more organelles 2. S phase – DNA duplication 3. G2 phase – preparation for mitosis, last check • Cell Division– division of the cell into 2 1. Mitosis – division of the nucleus 2. Cytokinesis – division of the cytoplasm

  8. Study this diagram! Pg. 245 in book Section 10-2 G1 phase M phase S phase G2 phase

  9. Mitosis • Prophase - Chromosomes become visible, centrioles move to opposite sides of cell (animal cells only), spindle forms, nuclear membrane breaks down • Metaphase - Chromosomes line up in middle, spindle fibers attach to centromeres • Anaphase - Sister chromatids are separated into individual chromosomes • Telophase - chromosomes gather at opposite sides of cell, new nuclear membranes form

  10. Mitosis Animation Interphase Animal Cell Prophase Metaphase Anaphase Telophase

  11. Onion root tip – active growing region…this means lots of mitotic cells!

  12. Hint: If you see a NUCLEOLUS, it is in interphase. If you can see snake/fingerlike chromosomes, it is in a stage of mitosis.

  13. Prophase? Metaphase? Anaphase? Telophase? 1 3 2 4 5 6

  14. Prophase? Metaphase? Anaphase? Telophase? 1 2 3 4 5 6 7

  15. Cytokinesis • Division of the cytoplasm • This process starts during telophase • In animal cells: cleavage of cell membrane. • In plant cells: a cell plate forms midway between the divided nuclei.

  16. Cell Plate Forming Cleavage or Pinching in Cell Cycle and Cell Division Animation Animation #2

  17. Question: Will the new cells have the same, more or less chromosomes than the mother cell? What happens if something goes wrong with the cell cycle?

  18. Cancer • Uncontrolled cell division • DNA is damaged by carcinogens or genetically inherited. • Cell will not respond to cell cycle regulators. • Carcinogens can be radiation, chemicals or viral

  19. Stem Cells • Cell that have not become specialized. • Stem cells can become any type of human cell. Abundant in embryos. • Possible uses in science: treating nerve damage, growing organs, treating diseases.

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