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Biology II - Cell Theory Review

Biology II - Cell Theory Review. Cell Theory. Term “cell” was coined in 1665 by Robert Hooke when he looked at a slice of dried cork. He observed that: All living things are made of cells. Cells are the smallest “living” unit in an organism. Cells come from previously existing cells.

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Biology II - Cell Theory Review

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  1. Biology II - Cell Theory Review

  2. Cell Theory • Term “cell” was coined in 1665 by Robert Hooke when he looked at a slice of dried cork. He observed that: • All living things are made of cells. • Cells are the smallest “living” unit in an organism. • Cells come from previously existing cells.

  3. Prokaryotes - single celled - no nucleus - no organelles - DNA is a single, circular molecule - e.g., bacteria Eukaryotes - single or multicellular nucleus & nuclear membrane organelles present - DNA packaged into chromosomes - e.g., protozoans, plants, animals Cells - “Fundamental Unit of Life”

  4. Cell Organization The cell includes two basic parts: • Cell Membrane (outer covering of cell) • Cytoplasm (also made of two parts) • Cytosol (fluid portion of the cytoplasm) • Organelles (organs or functional parts)

  5. Cell Membrane • Includes: • Outer boundary • Physical & Chemical Protection • Comprised of two layers of lipid (fat) • Plus Layer of Proteins • Proteins give the cell its unique function

  6. Cell Membrane

  7. Organelles Endoplasmic reticulum (ER) • A network of tunnels throughout the cytoplasm – for cell transport

  8. Golgi Apparatus • Involved in packaging and secretion of proteins • Golgi looks like a series of stacked plates.

  9. Mitochondria • Bean shaped, with outer & inner membranes • Cell Powerhouse – produces energy

  10. Cytoskeleton • Skeleton of the cell • Provides structure and shape

  11. Plant Cell Organelles • Plants have three special structures not found in animals: the chloroplast, the cell wall, and the central vacuole. 1. The chloroplast is the site of photosynthesis, the process of converting carbon dioxide into sugar and oxygen using sunlight It uses the green pigment chlorophyll to capture the energy from light.

  12. Plant Cell Organelles 2. Each plant cell is surrounded by a rigid cell wall. The cell wall is outside of the cell membrane. In woody plants, the cell walls can become very thick and rigid. 3. Plant cells also contain a central vacuole, which stores water. It is the storage room of the plant cell.

  13. Nucleus

  14. Nucleus • Control center of cell – “the brain” • Contains DNA/chromosomes • Genetic repository for ~ 35,000 genes in humans • Genes control the synthesis of proteins in each cell, and hence what the cells do.

  15. Human Red Blood Cells

  16. Rat Muscle Cells

  17. Next: Cell Reproduction

  18. Cell Cycle: life and reproduction of a cell Part I - DNA and nuclear division (mitosis) Part II - cytokinesis (cytoplasm duplication)

  19. Cell Cycle: Interphase • Before/Between mitosis • Time of high metabolic activity • “Normal” life of cell

  20. Cell Cycle: Mitosis • Process of cell division (nuclear division) which produces daughter cells genetically identical to the parent cell • Four Action Phases (P-M-A-T): prophase, metaphase, anaphase, and telophase, and then the times between mitosis (Interphase). • Upon completion of the phases of mitosis (nuclear division) the cell “officially” divides into two by a process called cytokinesis - division of cytoplasm and the rest of the cell

  21. Interphase Not part of mitosis Normal life of the cell

  22. Prophase *Chromosomes coil and condense further. *Nuclear membrane breaks down/ disappears. *Microtubules increase in #, spindle apparatus forms.

  23. Chromosome duplication

  24. Metaphase *Nuclear membrane completely disappeared *Chromosomes move to equator of cell & line up *Chromosomes attach to spindle via kinetochore

  25. Centromeric Region

  26. Anaphase *Movement of chromosomes via microtubules to opposite sides of the cell. One chromatid to one end the other Chromatid to the opposite end

  27. Telophase *Genetically identical at each pole *Spindle fibers disappear *Chromosomes uncoil *Nuclear envelope reforms Cytokinesis - is separate from mitosis, = cell/division of cytoplasm. Mitosis + Cytokinesis result in two identical daughter cells.

  28. Mitosis in a plant cell

  29. Mitosis in an onion root

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