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The Cell Theory

The Cell Theory. Hairy T-cell. Definition. = Three part theory about cells 1. All living things are made of cells. Part 2 of the Theory. 2. The cell is the basic structural and functional unit of life. Part 3 of the Theory. 3. All cells come from pre-existing cells. yeast cells dividing.

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The Cell Theory

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  1. The Cell Theory Hairy T-cell

  2. Definition = Three part theory about cells 1.All living things are made of cells.

  3. Part 2 of the Theory 2. The cell is the basic structural and functional unit of life.

  4. Part 3 of the Theory 3. All cells come from pre-existing cells. yeast cells dividing

  5. Who came up with this theory? All plants are made of cells! 1. Schleiden (circa 1838) Onion skin cells

  6. Who came up with this theory? All animals are made of cells! 2. Schwann Human red blood cells

  7. Who came up with this theory? 3. Virchow All cells come from pre-existing cells!

  8. How big are cells? • Microscopic (mostly) • Measured in microns µm • (micrometers). • A µm is one millionth of a meter = • 10-9 m = one thousandth of 1 mm.

  9. How big are cells? Smallest free-living cell = Mycoplasma genitalium Size = 0.2 to 0.3 µm

  10. How big are cells? • Bacteria e.g. Eschericia coli (aka E.coli) • Size=1 µm by 3 µm

  11. How big are cells? • Human red blood cell = 8 µm in diameter

  12. How big are cells? • Largest cell = yolk of an ostrich egg

  13. Ostrich, egg, humans

  14. Ostrich emerged from egg

  15. How can we study cells? Problem: They are microscopic! Solution: Use a microscope!

  16. Types of Microscopes • Compound light microscope • Light passes through lenses to magnify image up to 1000X • Can observe living cells

  17. Types of Microscopes 2. Electron microscope • Uses a beam of electrons to magnify image > 1000X • Kills cells being observed

  18. Common features of all cells Small size – allows materials to move via diffusion • Diffusion = process by which molecules move from levels of high concentration to levels of low concentration until equilibrium is reached

  19. Diffusion • Google Image Result for http://www.indiana.edu/~phys215/lecture/lecnotes/lecgraphics/diffusion.gif

  20. Common features of all cells 1. Cell Membrane – selectively/differentially permeable (lets some things in and out)

  21. Common features of all cells 2.Cytoplasm – semi-fluid material in which cell organelles float

  22. Common features of all cells 3. Nucleic acid containing genetic code : Which nucleic acid? DNA

  23. Common features of all cells 4. Cytoskeleton – proteins that support the cell (Microtubules & microfilaments)

  24. Common features of all cells 5. Ribosomes – make proteins

  25. Chromosomes & DNA • everything in the cell is controlled by the cell’s DNA • DNA = large molecules that carry genetic information • these molecules are strung together to form chromosomes • humans have 46 chromosomes (usually) karyotype

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