Anatomy Ch 3

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cswett
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32931
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Anatomy Ch 3
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2010-09-10 10:49:25
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Anatomy plasma membrane cell structure
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Lecture notes and book from chapter 3
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  1. fluid mosaic model
    • structural model of the plasma membrane
    • the molecular arrangement of the plasma membrane resembles an ever-moving sea of fluids and a mosaic of many different proteins
    • some proteins float freely, some are anchored
  2. plasma membrane
    • made of
    • 1. phospholipids (75%) - amphipathic
    • 2. cholesterol - (20%) - slightly amphipathic - stay in the nonpolar tail region
    • 3. glycolipids - (5%) - carbohydrate/lipids - ONLY in membrane layer that faces the EXTRACELLULAR liquid - make the two layers asymetric (different)
  3. integral proteins
    peripheral proteins
    • parts of plasma membrane that are fully embedded in it - removing them will destroy the membrane
    • integral proteins are amphipathic
    • peripheral proteins are not firmly embedded - attached to one side or the other - can be removed without hurting the membrane
  4. Transmembrane protein
    • span the entire lipid bilayer and protrude into the cytosol and extracellular fluid
    • many integral proteins are transmembrane proteins
  5. glycoproteins
    glycocalyx
    • proteins with carb groups attached to the end that protrude into the extracellular fluid
    • glycocalyx is a glycoprotein "signature" that allows cells to recognize one another - hydrophillic and attracts a thin layer of fluid to the surface of many cells - red blood cells slippery
  6. Functions of Membrane Proteins
    • Ion channels
    • Transporter
    • Receptor
    • Cell Identity marker
    • Linker
    • Enzyme
  7. Ion channels
    • integral protein
    • water filled pores that move specific ions through the plasma membrane
    • selective - diff levels of specifity - cation channel - moves all cations through - sodium channel - moves only sodium
    • most plasma membranes have specific channels for several common ions
    • most numerous ion channels - K+ or Cl - - fewer for Na+ and Ca2+
  8. Transporter
    • integral protein
    • moves ions and polar substances across the membrane by changing shape
  9. Receptor
    ligand
    • integral protein - not necessarily transmembrane
    • each receptor recognizes and binds a specific ligand that alters cells function in some way
    • ligand - a specific molecule that binds to a receptor
  10. Cell identity markers
    • glycoprotein & glycolipids - distinguished your cells from anyone else's
    • enable cell to recognize other cells of the same type during tissue formation
  11. Linker
    • Integral or peripheral
    • anchor proteins in the plasma membrane of neighboring proteins to one another - anchors filaments inside and outside the plasma membrane providing structural stability and shape for the cell
  12. Enzymes
    • integral or peripheral
    • catalyze specific chemical reactions at the inside or outside surface of the cell (depends on which direction active site faces)
    • substrate in - product out
  13. membrane fluidity
    • FLUID AND DYNAMIC
    • phospholipids and membrane proteins are not rigidly fastened - move around - spaces open and close so water and materials can move through
    • proteins are not constant - numbers change - increased or decreased upon needs of the cell
  14. Membrane Permiability
    • selective permiable
    • 1. non-polar, uncharged particles can cross membrane anywhere (O2, CO2, steroids)
    • 2. slightly permiable to water and urea(waste product from breakdown of amino acids) travel through small gaps that open and close
    • 3. other molecules need help to cross
  15. concentration gradient
    • difference in concentration of a chemical from one place to another
    • Extracellular fluid - higher concentration of O2 and Na+ (sodium ions)
    • Intracellular fluid - higher concentrations of CO2 and K+ (potassium ions)
  16. membrane potential
    electrical gradient
    • difference in electrical charges inside and outside the plasma membrane
    • at rest:
    • + postive = extracellular
    • - negative = intracellular
    • electrical gradient is the difference in electrical charges of two regions - membrane potential is difference across a membrane
  17. electrochemical gradient
    combines influence of concentration and electrical charge gradient on the movement of an ion
  18. passive transport
    diffusion across a membrane - substance moves down its concentration gradient using only kinetic energy - no input of energy from the cell
  19. active tansport
    ATP used to drive substances up the concentration gradient
  20. Diffusion across a plasma membrane is influenced by:
    • 1. Steepness of the concentration gradient (steep moves faster)
    • 2. Temperature
    • 3. Mass of the diffusing substance (large particles move slow)
    • 4. Surface area
    • 5. diffusion distance (greater distance takes longer)
  21. Osmosis
    Tonicity
    • movement of water across a membrane - move from high to low to reach equalibrium
    • Tonicity - measure of the solutions ability to change the volume of a cell by altering their water content
    • Isotonic - concentration same on both sides - no flow of water
    • Hypotonic solututuin - less solute in solution so water moves into cell
    • Hypertonic - more solute in solution so water moves into cell
  22. Hemolysis
    Crenation
    • RBC in a hypertonic solution - water enters cell and causes it to burst
    • Crenation - cells in a hypertonic solution - water leaves cell and cell shrivles
  23. aquaporins
    plasma membrane proteins that allow water to move through quickly
  24. hydrostatic pressure
    osmotic pressure
    • pressure exerted by the weight of water - U tube - weight will cause water to move back across membrane - equilibrium is reached when the hydrostatic pressure and the osmosis move at the same rate
    • osmotic pressure - the amount of pressure needed to stop osmosis - U tube - amount of pressure needed to force both tubes to have equal water
  25. Edema
    excess interstitial fluid in the brain - given a hypertonic solution so water leaves interstitial fluid and enters blood where is can be extracted by the kidneys
  26. Diffusion through the lipid bylayer
    non-polar, hydrophobic molecules can move through without use of ATP
  27. Diffusion through membrane channels
    • Ion-specific channels - may be gated or permanently open
  28. Facilitated Diffusion
    Transport Maximum
    • substances bind to carrier proteins embedded in plasma membrane
    • carrier proteins change shape and release them on the other side
    • REQUIRES NO ATP
    • Transport occurs DOWN a concentration gradient
    • TRANSPORT MAXIMUM - the number of transporters in the plasma membrane places an upper limit on the rate that facilitated diffusion can occur - at that point it cant go faster even if solute concentration is increased - the process becomes saturated
  29. Active Transport
    Primary Active Transport
    Secondary Active Transport
    • ATP USED
    • primary - pumps ions AGAINST concentration gradient
    • sodium/potassium pump - Na+/ K+/ ATPase
    • cells expend 40 % of ATP on sodium/ potassium pumps - pumps Na+ out and K+ in against concentration gradient
    • Secondary - indirectly uses energy from primary transport - high concentration of Na+ outside so some diffuses back into cell - carries with it other substances against their concentration gradient
  30. Symporters
    Antiporters
    • In secondary active transport - if transporters move two substances in the same direction they are symporters
    • Antiporters move two substances in opposide directions against their concentration gradient
  31. Endocytosis
    Receptor - mediated endocytosis
    Phagocytosis
    Pinocytosis
    • Process that brings bulky substances into the cell - uses vessicles
    • Receptor-mediated endocytosis - receptors in plasma membrane catch ligands - for vessicle
    • Phagocytosis - eating - engulfs particle to break it down - non-specific
    • Pinocytosis - drinking - takes droplets of extracellular fluid into cell
  32. Vessicle
    Exocytosis
    • vessicle - small, spherical sac made of plasma membrane
    • Exocytosis - process that takes bulky substances out of the cell - secretory cells, nerve cells (neurotransmitters)
  33. phagocyte
    • specific cells that are able to carry out phagocytosis
    • macrophages - located in body tissues
    • neutrophils - type of white blood cell
  34. pseudopod
    false feet - projections of the cells plasma membrane and cytoplasm
  35. Transcytosis
    vessicle move substance into, across, and out of the cell
  36. intracellular fluid
    • cytosol - cytoplasm that surrounds organelles 55% of cell volume
    • cytoplasm refers to cytosol and all organelles except nucleus
    • mostly water 75 - 90% with ions, nutrients, ATP, and wastes
  37. cytoskeleton
    • network of protein filaments that extent throughout the cytosol
    • give support, shapes, and movement to the cell
  38. Three parts of cytoskeleton
    • 1. Microfilaments - small - around edge of cell - give shape and support
    • 2. Intermediate Filaments - thicker than micro - strong - attached to cell membrane and project into cells - help attach cells to one another
    • 3. Microtubules - tubes - grow out form centrosome - give cell shape - involved in movement (flagella & celia) - mitotic spindle
  39. Microvilli
    fingerlike projections of the plasma membrane - increase surface area of membrane - increases places for transport across the membrane - abundant on cells involved in absorption
  40. centrosome
    • critical for cell division
    • composed of two centrioles (tubes 9 triplets) at right angles
    • microtubule processing plant
  41. Celia
    • hair-like projections on cell surface - microtubules
    • function to propell fluid over surface of the cell
  42. flagella
    • microtubules
    • single whip-like extenstion
    • moves entire cell - only human cell is sperm
  43. Ribosome
    • site of protein synthesis
    • made of protein and RNA
    • can be free or attached
  44. RER
    • attached ribosomes - makes plasma membrane for cell
    • makes phospholipids and secretes proteins make by attached ribosomes
  45. SER
    • 1. synthesizes steroids, fatty acids
    • 2. detoxifies drugs in liver cells
    • 3. stores calcium in muscle cells
  46. Golgi Complex
    • flattened membrane sacs
    • processes & ships proteins make by RER
    • cis - in - faces RER
    • trans - out - faces plasma membrane
  47. Lysosome
    • vesicle forms by golgi complex
    • contains digestive enzymes - digest food, worn out organelles, entire cells
    • autophagy - lysosome digest a worn out organelle and releases the components into the cytosol to be resued
    • autolysis - lysosome destroys entire cell - tissue deterioration just after death
  48. mitochondron
    • double membrane
    • can self replicate
    • more mitochondira in tissue that expends more energy (muscles)
    • cristae inner membrane - lots of folds- site of ATP production
    • matrix - large inner fluid filled cavity
  49. nucleus
    parts of the nucleus
    • most cells have one - some blood cells have none and skeletal muscle cells can have more than one
    • Nuclear Envelope - double membrane
    • nuclear pores - openings in the nuclear envelope - control movement of substances between the cytoplasm and nucleus
    • nucleoli - produce ribosomes - made of protein, DNA, RNA
    • chromatin - mass of DNA, protein, and RNA - when cell is in interphase chromatin is a granular mass - during - when getting ready to divide the chromatin coils up into the double helix of DNA
  50. genes
    chromosomes
    chromatin
    genome
    • genes - cell's hereditary units
    • chromosomes - genes are arranged along chromosomes (human somatic cells have 46 chromosomes)
    • chromatin - inside the nucleus - complex of DNA, proteins, and RNA
    • genome - total genetic information carried in a cell
  51. chromatids
    replicated DNA that is still attached at the centromere
  52. nucleosome
    histones
    linker DNA
    chromatin fiber
    • nucleosome - double- stranded DNA (double helix) wrapped twice around a core of histones
    • histones - a core of 8 proteins that DNA wraps around
    • Linker DNA - holds adjacent nucleosomes together
    • chromatin fiber - in cells that arent dividing, histone promotes coiling of nucleosomes into larger fiber

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