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The Cellular Level of Organization

The Cellular Level of Organization. Cell Diversity. Lots of shapes and sizes; we have about 200 different types of specialized cells. Typical Cell. Fig. 3.1. What discipline studies cells?. Cell biology (Cytology) http://www.youtube.com/watch?v=tkx14B7WFcM. What is around our cells?.

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The Cellular Level of Organization

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  1. The Cellular Level of Organization

  2. Cell Diversity • Lots of shapes and sizes; we have about 200 different types of specialized cells

  3. Typical Cell Fig. 3.1

  4. What discipline studies cells? Cell biology (Cytology) http://www.youtube.com/watch?v=tkx14B7WFcM

  5. What is around our cells? Our cells are surrounded by extracellular fluid frequently called interstitial fluid

  6. Cell Organization The cell includes three basic parts: • Plasma membrane (outer covering of cell) • Cytoplasm (cytosol & organelles) • Nucleus

  7. Plasma Membrane Functions Outer boundary; functions in: • Physical isolation • Regulates what comes in and out • Anchors cytoskeleton (think of this as scaffolding)

  8. Cell Membrane Structures The cell membrane contains: • Two layers of phospholipids(isolate the cell from extracellular fluid) • Proteins(may attach cell membrane to other structures, recognize invaders, speed up chemical reactions, bind & transport certain substances) • Cholesterol(↑ stability of cell membrane)

  9. Cell Membrane

  10. Selective Permeability = not all material can enter the cell Transport processes found in cells: • PASSIVE: simple diffusion & facilitated diffusion • ACTIVE: active transport & transport in vesicles Active = requires E; from low to high concentration Passive = does not require E; from high to low concentration

  11. Osmosis – simple diffusion of water Fig. 3.8

  12. Facilitated diffusion or Active transport - Fig. 3.10 – 3.11 Vesicular Transport (endocytosis & exocytosis) Fig. 3.12 – 3.14

  13. Cytoplasm 2 parts: • Cytosol= fluid portion, also called intracellular fluid; contains dissolved nutrients, ions, proteins, and waste products • Organelles = cell “organs” or functional parts

  14. Cytoskeleton • Gives the cytoplasm strength & flexibility Microfilaments

  15. Microvilli • ↑ the surface area for absorption of material

  16. Centrioles • Direct the movement of chromosomes during cell division

  17. Cilia & Flagella • Cilia beat rhythmically to move fluids across cell surface • Flagella move cells

  18. Ribosomes • Sites of protein synthesis • Attached to ER or free in the cytosol

  19. Endoplasmic Reticulum (ER) • Rough – contains ribosomes; chemically modifies newly made proteins and ships them to the Golgi apparatus • Smooth – no ribosomes; synthesis of lipids, detoxifies certain drugs

  20. Golgi Apparatus • Involved in packaging of proteins and production of lysosomes

  21. Lysosomes, Peroxisomes & Proteasomes • Vesicles filled with digestive enzymes • Lysosomes recycle worn out cell structures • Peroxisomesneutralize toxins such as alcohol and hydrogen peroxide (abundant in liver) • Proteasomesdestroy unneeded and damaged proteins

  22. Lysosomes & Peroxisomes Blue arrows = peroxisomes Red arrow = lysosome

  23. Mitochondria • Produce adenosine triphosphate (ATP) = our energy currency

  24. Nucleus • Control center of cell • Contains DNA needed for synthesis of 100,000 different proteins Red blood cells of humans do not have a nucleus; Skeletal muscle cells have multiple nuclei

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