Membranes: Chemical Composition of Membranes

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Membranes: Chemical Composition of Membranes
2013-09-21 13:02:07
Cell Bio

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  1. a.      __ assemblies in which components are held in __ by __
                                                                  i.      core of membrane consists of __= __ of membrane and provides __that does what?
    • lipid-protein
    • thin sheet
    • noncovalent bonds
    • sheet of lipids in bilayer
    • structural backbone
    • barrier 
    • prevents random movements of water-soluble materials into and out of cell
  2. a.      __carry out specific functions
    b.      each type of cell contains a __, which has special activities 
    • proteins 
    • unique complement of membrane proteins
  3. a.      __ varies depending on type of cell membrane, organism, and type of cell
    this is due to __ of these membranes
    • ratio of lipid to protein
    • basic functions
  4. Examples of differences in membrane.
    1.      ex: mitochondria: high protein/ lipid ratio for transport as opposed to RBC, which are lots of myelin for electrical insulation for the nerve cell it encloses
  5. The membrane also contains __.
    carbs attached to lipids nad proteins
  6. a.      Membranes contain different __, all of which are __(both hydrophilic and hydrophobic regions); 
    • lipids
    • amphipathic
  7. Three typesof lipids
    • phosphoglycerides
    • sphingolipids
    • cholesterol
  8. 1.      phosphoglycerides
    a.      most membrane lipids contain __, making them __
                                                                                                                                          i.      because built on __, they are called __

    1.      not __(3 fatty acids and not amphipathic), but membrane glycerides are __—only two of the hydroxyl groups are esterfied to __; the third is esterfied to __
    • phosphate group
    • phospholipids
    • glycerol
    • phosphoglycerides
    • triglycerides 
    • diglycerides
    • fatty acids
    • hydrophilic phosphate group
  9. a.      without any additional substitutions beyond the phosphate and the two fatty acyl chains, the molecule is called __, which is virtually absent in most membranes
    phosphatidic acid
  10.                                                                                                                                       i.      instead, __ have an additional group linked to the phosphate, most commonly either __(4)
    1.      each of these groups is small and __and can form a highly water-soluble domain at one end of the molecule, called the __
    a.      PS and PI: __ (charge)
    b.      PC and PE: __ (charge)
    • membrane phsophoglycerides
    • choline, ethanolamine, serine, or inositol
    • hydrophilic
    • head group
    • - charge
    • neutral
  11. a.      fatty acyl chains are __ approx. 16-22 carbons
                                                                                                                                          i.      a membrane fatty acid may be fully __(no = bonds), __(one =), or __(several =)
    b.      __often contain one unsaturated and one saturated fatty acyl chain
    • hydrophobic, unbranched hydrocarbons
    • saturated 
    • monounsaturated 
    • polyunsaturated 
    • phosphoglycerides
  12. 1.      health benefits of unsaturated fatty acids (__ and __)
    a.      __ and __  and incorporated into __ and __ molecules of certain membranes, in brain and retina
    b.      they are __ because last = is 3 carbons away from omega (CH3) end of the fatty acid chain
                                                                                                                                          i.      with fatty acid chains at one end of the molecule and a polar head group at the other, all __exhibit a distinct __
    • EPA and DHA
    • five and six double bonds
    • PE and PC
    • omega-3-fatty acids
    • phosphoglycerides 
    • amphipathic character
  13. a.      Sphingolipids
                                                                  i.      how abundant
                                                                ii.      derivatives of __, an amino alcohol that has a long hydrocarbon chain
                                                              iii.      consists of __linked to a __ by its __group, called a __

    • sphingosine
    • sphingosine 
    • fatty acid
    • amino 
    • ceramide
  14.                                                               i.      various kinds have different groups esterified to the __ of the __

    1.      if the substitution is __, the molecule is __¸ which is the only phospholipid of the membrane not built with a __
    2.      if substitution is carb= __
    a.      simple sugar: __
    b.      small clusters that have __: __
    • terminal alcoholsphingosine moiety
    • phosphorycholine
    • sphingomyelin
    • glycerol backbone
    • glycolipid
    • cerebroside
    • sialic acid
    • ganglioside
  15. Sphingolipids cont. 

                                                                  i.      __and similar structure to __
    1.      fatty acyl chains of sphingolipids are __and more __ than __
    • amphipathic 
    • phosphoglycerides
    • longer 
    • highly saturated
    • phosphoglycerides
  16.                                                               i.      Glycolipids
    1.      crucial roles in cell function
    a.      __system rich in them
    2.      role in certain __; the toxins that cause __ and __ enter their target cell by first binding to cell-surface gangliosides, as does the flu
    • nervous 
    • infectious diseases
    • cholera and botulism
  17. a.      Cholesterol
                                                                  i.      may be up to __% of the lipid molecules in the plasma membrane
                                                                ii.      plant cells contain __, but biologists disagree
                                                              iii.      cholesterol molecules are oriented with their __outward membrane surface and remainder in __
    1.      __rings of a cholesterol molecule are __ and __,and they interfere with the __
    • 50
    • cholesterol-like sterols
    • small hydrophilic hydroxyl group 
    • bilayer
    • hydrophobic 
    • flat and rigid
    • movements of the fatty acid tails of the phospholipids
  18. a.      Nature of Lipid Bilayer
                                                                  i.      each type of cell membrane has own characteristic __composition, differing in __, __, and particular species of __
    1.      estimated that some membranes have hundreds of different phospholipids
    • lipid 
    • types of lipids
    • nature of head groups
    • fatty acyl chains
  19.                                                               i.      __ are more simple structural elements; important in biological properties
    1.      lipid composition etermines __ of membrane and __
    membrane lipids provide precursors for__that regulate cellular function 
    • membrane lipids
    • physical state
    • activity
    •  highly active chemical messengers
  20. a.      Measurements
                                                                  i.      combined fatty acyl chains of lipid bilayer= about __
                                                                ii.      each row of head groups= __
                                                              iii.      total of about __
    • 30 angstroms
    • 15 angstroms
    • 60
  21.                                                               i.      presence in membranes of the __lipid molecules
    1.      never have a __--> form __
                                                                ii.      because of __ of lipid bilayer, membranes are __and their overall shape can change, as occurs during __or __
    1.      facilitates regulated __ or __ of membranes
    • amphipathic 
    • free edge; unbroken
    • interconnected networks
    • flexibility
    • deformable 
    • locomotion 
    • cell division
    • fusion or budding
  22. Importance in terms of maintenance
    maintaining proper internal composition of a cell, in separating electric charges across the plasma membrane, etc
  23. Ability to __
    ex: phospholipid molecules assemble spontaneously to form walls of vesicles, called __
    • self-assemble
    • liposomes
  24. a.      liposome walls have __ that is organized similarly to membrane bilayer
    b.      membranes can be inserted into __and their functions studied iin simpler environment than membrane
    • continuous lipid bilayer
    • liposomes
  25. a.      liposomes develop as __ to deliver __ or __ within the body, which can be linked to the __ or contained at high concentration within its __
                                                                                                                                          i.      the walls are constructed to contain __ that allow the liposomes to __ to the surfaces of particular target cells where the drug or DNA is intended to go
    • vehicles drugs or DNA molecules
    • wall of the liposome
    • lumen
    • specific proteins
    • bind selectively
  26.                                                               i.      Asymmetry of Membrane Lipids
    1.      lipid bilayer: __

    a.      __ cannot penetrate the plasma membrane and are only able to digest lipids that reside in the __
    • two distinct leaflets have distinctly different lipid composition
    • lipid-digesting enzymes
    • outer leaflet of the bilayer
  27.                                                                                                                                       i.      compared to the inner leaflet, the outer leaflet has a high concentration of__ and a low concentration of __

    1.      it follows that the lipid bilayer can be thought of as composed of __ having different physical and chemical properties
    • PC (and sphingomyelin)
    • PE and PS
    • two more or less stable, independent monolayers
  28. 1.      different classes of lipids have different properties
    a.      all glycolipids of plasma membrane are in __ and serve as __
    b.      phosphatidylethanolamine, which is in the __, tends to promote the __, which is important in __ and __
    • outer leaflet
    • receptors for extracellular ligands
    • inner leaflet
    • curvature of the membrane
    • membrane budding and fusion
  29. a.      phosphatidylserine in the __ has a net __charge at physiologic pH, which makes it a candidate for __
    b.      appearace of PS on the outer surface of aging lymphocytes does what, whereas its appearance on the outer surface of platelets leads to __
    • inner leaflet
    • negative 
    • binding positively charged lysine and arginine residues
    • marks the cells for destruction by macrophages
    • blood coagulation
  30. a.      PI in the __ can be __at different sites on the __ring, which converts the lipid into a __
    play a key role in __ from plasma membrane to cytoplasm and __ to the cytosolic face of the plasma membrane
    • inner leaflet
    • phosphorylated
    • inositol 
    • phosphoinositide
    • transfer of stimuli
    • recruitment of proteins
  31. a.      Membrane Carbs
                                                                  i.      depending on species and cell type, carbs in membrane range between __% by weight
    1.      more than __% of membrane carbs are linked to proteins to form __; remaining are __ to form __
    • 2-10
    • 90
    • glycoproteins
    • covalently linked to lipids
    • glycolipids
  32.                                                               i.      all carbs of plasma membrane face outward into __; carbs of internal cell membrane face away from __
    • extraellular space
    • cytosol
  33. 1.      addition of carb, __, is the most complex
    2.      carbohydrate of glycoproteins are short, branched, __
    a.      these __attached to membrane proteins and lipids can display extensive variability in __ and __
    • glycosylation
    • hydrophilic oligosacchardies
    • oligosaccharides 
    • composition and structure
  34. a.      even the same protein can display __in different cells and tissues
    b.      oligosaccharides may be attached to several different __ by two major types of __
                                                                                                                                          i.      important role in __ of a cell with its environment and __ to different cellular compartments
    1.      ex: blood type determined by this
    • different chains of sugars 
    • amino acids
    • linkages
    • mediating interactions
    • sorting of membrane proteins