Cells ch3

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KellyM
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195865
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Cells ch3
Updated:
2013-01-31 23:00:34
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  1. Human cell has 3 parts
    • plasma membrane
    • cytoplasm
    • nucleus
  2. Four key points of cell theory
    1) a cell is the basic structural and functional unit of living organisms.  When you define cell properties, you define the properties of life

    2) the activity of an organism depends on both the individual and the collective activities of its cells

    3) biochemical activities of cells are dictated by their shapes or forms, and by the relative # of their specific subcellar structure (principle of complimentary of structure and function)

    4) continuity of life from one generation to another has a cellular basis
  3. cells that connect body parts, form linings, or transport gases
    • fibroblasts (connective tissue)
    • erythrocytes
    • epithelial cells
  4. cells that store nutrients
    fat cells
  5. cells that fight disease
    macrophage
  6. cells that move organs and body parts
    • skeletal muscle cell
    • smooth muscle cell
  7. cells that gather information and control body function
    nerve cell
  8. plasma membrane
    defines extent of a cell, separating 2 of body's major fluid compartments:

    • 1) intracellular fluids - within the cells
    • 2) extracellular fluids - outside cells

    plays dramatic role in cellular activity

    biomolecular layer of lipids and proteins in a constantly changing fluid mosaic

    consistency similar to olive oil
  9. membrane lipids
    • 75% phospholipids (lipid bilayer)
    • -- phosphate heads: polar and hydrophilic, facing either IFC or EFC
    • -- fatty acid tails: nonpolar and hydrophilic, always facing each other (looks like squiggly lines)

    • 5% glycolipids
    • -- lipids w/polar sugar groups on outer membrane surface

    • 20% cholesterol
    • -- increases membrane stability and fluidity
  10. membrane proteins
    • Integral proteins
    • -- firmly inserted into the membrane (most are transmembrane)

    -- functions: transport proteins (channels and carriers), enzymes, or receptors

    • Peripheral proteins
    • -- loosely attached to integral proteins
    • -- include filaments on intracellular surface and glycopreteins on extracellular surface

    --functions: enzymes, motor proteins, cell-to-cell links, provide support on intracellular surface, and form part of glycocalyx
  11. functions of membrane proteins
    • 1) ion transport
    • 2) receptors for signal transduction
    • 3) attachment to cytoskeleton and extracellular matrix
    • 4) enzymatic activity
    • 5) intercellular joining
    • 6) cell-cell recognition
    • 7) enzymatic activity
    • 8) intercellular joining
    • 9) cell-cell recognition
  12. Membrane junctions
    1) Tight junction = prevent fluids and most molecules from moving b/w cells

    2) Desmosomes = function as "rivets" or "spotwelds" that anchor cells together

    3) Gap junctions = pores formed by transmembrane proteins that allow small molecules to pass from cell to cell
  13. types of membrane transport
    • Passive processes:
    • no cellular energy (ATP) required
    • substance moves down its concentration ingredient
    • Active processes:
    • energy (ATP) required
    • occurs only in living cell membranes
  14. passive processes
    • Simple diffusion:
    • -nonpolar lipid-soluble (hydrophobic) substances diffuse directly through the phospholipid bilayer

    • Carrier mediated facilitated diffusion and
    • Channel mediated facilitated diffusion:
    • -certain lipophobic molecules (glucose, amino acids, ions) use carrier or channel proteins, both of which:
    • ----exhibit specificity (selectively)
    • ----are saturable; rate is determined by # of carriers or channels
    • ----can be regulated in terms of activity and quantity

    • Osmosis:
    • -movement of solvent (water) across a selectively permeable membrane
    • -water diffuses through plasma membranes through lipid layer and through water channels called aquaporins (AQPs)
    • -water concentration is determined by solute concentration bc solute particles displace water molecules
    • -osmalarity - the measure of the total concentration of solute particles

  15. importance of osmosis
    • when osmosis occurs, water enters or leaves a cell
    • change in cell volume disrupts cell function
  16. Tonicity
    tonicity = the ability of a solution to cause a cell to shrink or swell

    isotonic = a solution with the same solute concentration than that of the cytosol

    hypertonic = a solution having greater solute concentration than that of the cytosol

    hypotonic = a solution having lesser solute concentration than that of the cytosol
  17. Nucleus
    largest organelle.  surrounded by nuclear envelope; contains fluid nucleoplasm, nucleoli, and chromatin

    • -genetic library w/blueprints for nearly all cellular proteins
    • -responds to signals and dictates kinds and amounts of proteins to be synthesized
    • -most cells are uninucleate (1 nucleus)
    • -red blood cells are anucleate (no nucleus)
    • -skeletal muscle cells, bone destruction cells, and some liver cells are multinucleate (many nuclei)
  18. nuclear envelope
    • double-membrane barrier containing pores
    • outer layer is continuous w/rough ER and bears ribosomes
    • inner lining (nuclear lamina) maintains shape of nucleus
    • pore complex regulates transport of large molecules into and out of nucleus
  19. nucleolus/nucleoli
    • dark-staining spherical bodies within nucleus
    • involved in rRNA synthesis and ribosome subunit assembly
  20. chromatin
    • seen through a light microscope, chromatin appears as a fine, unevenly stained network
    • composed of threadlike strands of DNA (30%), histone proteins (60%), and RNA (10%)
    • arranged in fundamental units called nucleosomes
    • condense into barlike bodies called chromosomes when the cell starts to divide

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