Membranes and Cytoplasm

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medstudent2017
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Membranes and Cytoplasm
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2015-11-26 08:08:01
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Membranes and Cytoplasm
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  1. Karyon in Greek means
    Kernal or nut
  2. Prokaryotes are different from Eukaryotes in what important aspects
    Prokarytes had no nucleus, Eukaryotes do. Cell walls are present in pro, cell membrane in Eukaryotes. There are no chloroplasts in the Eukaryotes.
  3. Why do some products harm prokaryotes but not Eukaryotes
    They are produced to harm bacterial enzymes that assist in cell wall biosynthesis and protein synthesis specific to bacteria
  4. Define Antibiotic
    A soluble substance derived from mold or bacterium that inhibits the growth of other micro organisms
  5. Why do some people feel sick on antibiotics
    Sometimes a few of the antibiotics cross the cell membrane and interfere with the mitochondria inhibiting ribosomes and ATP production
  6. Though thought to be ancient bacteria, mitochondria differ from them today in that
    Two membranes instead of just one.
  7. What performs oxidation phosphorilation
    Mitochondria
  8. A plasma membrane is made up of what
    Cholesterol, phospholipids, and proteins
  9. What is a phospholipid made up of
    A glycerol backbone, two long non-polar fatty acid hydrocarbon chains, and a variable phosphate containing polar group.
  10. What makes the phospholipid groups different
    The head groups differing
  11. What is the only negatively charged head group of a phospholipid
    Phosphatidylserine
  12. What are the common Choline containing phospholipids
    • Phosphatidycholine
    • Sphingomyelin
  13. What are the common non-choline containing phospholipids
    • phosphatidylserine
    • phosphatidylethanolamine
    • Phosphatidylinositol (less common)
  14. How much cholesterol is there in a cell membrane in comparison to phospholipids
    50%
  15. What do cell walls lack that contributes to a plasma membranes rigidity
    Cholesterol
  16. Cholesterol specifically prevents what from passing through the membrane
    Ions
  17. Cholesterol has what primary functions in the membrane
    • 1. They immobilize the first few hydro carbon groups of the phospholipid molecules decreasing permeability to water soluable molecules
    • 2. Cholesterol prevents crystalization of hydrocarbons and phase shifts in the membrane
  18. Phospholipids can twist and swap with a neighbor but they cannot
    Flip to the opposing side (rarely they can), Cholesterol can though.
  19. Where does synthesis of the phospholipids and cholesterol take place
    ER. Enzymes in the cytoplasm of the ER create the membrane
  20. What kind of a distribution of phospholipids consists in the plasma membrane
    There is an asymmetric distribution between the two sides, cytoplasmic half and extracellular half
  21. Does unsaturated or saturated tails on phospholipids increase the membrane fluidity. Why
    Unsaturated, The double bond causes the acyl tail to bend increasing the space between phospholipids and in turn increasing fluidity. Kinky is Good!
  22. Under what conditions would cholesterol tend to decrease the membranes fluidity
    Below 37 degrees Celcius and at high concentrations of cholesterol
  23. What is the ratio of proteins to lipids by mass in a cellular membrane
    1:1
  24. What is an integral protein
    They span the membrane entirely, and can only be removed by a detergent
  25. Shape change of a protein on the outside of the membrane has what effect
    A change of a protein on the outside will automatically alter the inside, allowing it to bond with a second messenger on the inside of the cell
  26. What four molecules are considered hydrophobic and don't need assistance to pass a membrane
    • O2
    • CO2
    • N2
    • Benzene
  27. What three molecules pass the cell membrane moderately well as they are small and uncharged
    • H2O
    • Urea
    • Glycerol
  28. Name two large uncharged polar molecules that a are the least permeable to a cell membrane but can pass through without assistance
    • Glucose
    • Sucrose
  29. What two factors allow a molecule to pass through a cell wall
    Its size (smaller the better), and its association with water (the smaller the better)
  30. What is the membrane potential of the inside of a normal healthy cell
    -60Mv
  31. What are the most abundant ions in the body
    • Na+
    • K+
    • Ca+2
  32. What are some charecteristics of Peripheral membrane proteins
    • 1. Do not penetrate bilayer
    • 2. Are not covalently liked to other membrane components
    • 3. Can be dissassociated from membranes with high salt
    • 4. Are located both on the inside and outside of the cell
  33. Carbohydrates are found only on what side of a plasma membrane
    Outer leaflet
  34. The addition of carbohydrates groups to proteins or lipids on a cell membrane forms
    Glycoproteins and Glycolipids (are always found on the outer membrane)
  35. What are the four ways that proteins can restrict their lateral mobility on a membrane
    • 1. Aggregate into large groups
    • 2. Tether together by interactions with other marcomolecules on the outside
    • 3. Ditto, but on the inside
    • 4. Interact with proteins on the surface of another cell
  36. What is a lipid raft?
    Specialized areas where proteins, lipids and cholesterol aggregate
  37. What is the difference from a cytosol to a cytoplasm
    They are both the inside the cell excluding the nucleus, however the cytosol excludes all membrane bound organelles too. Used interchangably though
  38. What are the primary lipids in a lipid raft
    Sphingomyelin and cholesterol
  39. Cytoskeleton has what functions
    • 1. Determines shape
    • 2. Helps with movement of the organelles
    • 3. Provides motility of motile cells (fibroblasts, macrophages, and sperm are motile cells)
  40. What are the three sets of filaments, and their functions
    • Intermediate filaments- (Provide mechanical strength)
    • Microtubules- (Determine the position of intracellular organelles and direct transport)
    • Microfilaments- (Determine the shape of the cells surface and are necessary for locomotion)
  41. Which filaments are the smallest and largest
    • Microfilaments smallest
    • Microtubules largest
  42. Which filament survives the death of the cell
    Intermediate filament (make up hair, claws fur, scales, ect)
  43. What links intermediate filaments to ajoining cells and is very important for holding cells together
    Desmosomes
  44. Why are Intermediate Filaments used by pathologists for characterizing tissues
    They retain the IF framework of the cells of origination
  45. Keratins are the Intermediate Filaments found in what cells
    Epithelium
  46. Vimentin are the Intermediate Filaments found in what cells
    Mesenchymal cells
  47. Desmin are the Intermediate Filaments found it what cells
    Muscle
  48. Glilial fibrillary acidic proteins are the Intermediate Filaments found in what cells
    Glial Cells (connective tissue of the nervous system)
  49. Neurofilaments are the Intermediate Filaments for what cells
    Nuerons
  50. Lamins are the Intermediate Filaments found in what cells
    Every cell type!! They line the inside of the nuclear envelope and the only IF not cytoplasmic
  51. Which cytoplasmic filaments constantly grow and shrink. (Usually in 50/50 increments)
    Microtubules (MT's) and Actin filaments
  52. How do MT's grow and shrink
    By heterodimers only on the + end
  53. Microtubules differ from Intermediate Filaments in their growth in what way
    Out of an organized structure, with a centrosome, a spindle pole, or the basal body of cilium
  54. What are centrioles
    They are the center of a MTOC and are oriented at right angles of each other surrounded by a cloud of protein where the (-) of the MT is found anchored
  55. What is a MTOC
    • MicroTubule Organizing Center
    • aka Centrosomes
    • This is the (-) end where Microtubules anchor
  56. What is gamma-tubulin
    It is found in the pericentrolar matrix (centriole) and is the site where filaments begin to grow
  57. On a microtubule what causes growth, and shrinkage
    • GTP Grow
    • GDP Shrinks
  58. What are the two types of MT motors and what is their energy source
    • Kinesin transports toward (+)
    • Dynein transports toward (-)
    • Both use ATP!!
  59. Microtubles are arranged how in the flagellum and cilia
    9+2 array
  60. Basal bodies anchor cilia and flagella in what fashion?
    9x3
  61. What causes the bending in flagellum
    Dynein
  62. What is responsible for for shaping microvilli
    Actin filaments
  63. What is treadmilling
    One actin adds to the (+) end and then travels to, and falls off at the (-) end at the same rate
  64. What is an ARP
    • Actin related protein
    • They begin the assembly of actin filaments
  65. Actin differs from MT in its assembly in what way
    • They are assembled near the plasma membrane (where ARPS are), MT near the nucleus
    • MT's has an MTOC
  66. What is the difference between G actin and F actin
    • G - is unassembled globular actin monomers
    • F - is assembled actin filaments
  67. Actin filaments are often associated with what, giving it motion
    Myosin
  68. Gelsolin perfoms what for Actin
    Cuts filaments into two
  69. What is Spectrin
    It is a binding protein for actin and supports the network for the plasma membrane of red blood cells.

    This is the reason red blood cells can squeeze into capillaries and come out retaining their shape
  70. Why are MT drugs important
    They are used in many cancer treatments because they inhibit the ability of the cells to form a mitotic spindle for cell division
  71. What are some drugs used on microtubules
    • Taxol - binds and stabilizes microtubules
    • Colchicine, Vinblastin, Nocodazole - prevent polymerization

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