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16.2 - Complex lipid synthesis and defects accompanying their degradation

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  1. Front
    Two major classes of complex lipids
    Back
    Glycerophospholipids and sphingolipids.
  2. Front
    Backbone of glycerophospholipids
    Back
    Glycerol.
  3. Front
    Backbone of sphingolipids
    Back
    Sphingosine.
  4. Front
    Structure of a glycerophospholipid
    Back
    Glycerol backbone, 2 fatty acids, and 1 phosphate plus head group.
  5. Front
    Structure of a sphingolipid
    Back
    Sphingosine backbone, 1 fatty acid, and a head group that can be a sugar or phosphate.
  6. Front
    Most abundant membrane phospholipid
    Back
    Phosphatidylcholine, comprising about 40–50 percent of membrane phospholipid.
  7. Front
    Core concept of complex lipids
    Back
    Complex lipids are membrane lipids built on either a glycerol backbone or a sphingosine backbone.
  8. Front
    Cells that synthesize phospholipids
    Back
    All cells synthesize phospholipids except mature RBCs.
  9. Front
    Why phospholipids are synthesized in almost all cells
    Back
    They are needed for cell membranes and organelles.
  10. Front
    Core concept of phospholipid synthesis location
    Back
    Phospholipids are essential for all membranes and are made in almost all cells.
  11. Front
    First step in glycerophospholipid synthesis
    Back
    Glycerol-3-phosphate combines with 2 fatty acyl-CoA to form phosphatidic acid.
  12. Front
    Key intermediate of glycerophospholipid synthesis
    Back
    Phosphatidic acid.
  13. Front
    Two possible pathways from phosphatidic acid
    Back
    DAG pathway and CDP-diacylglycerol pathway.
  14. Front
    First step of DAG pathway
    Back
    Phosphatidic acid loses phosphate to form DAG diacylglycerol.
  15. Front
    What is added to DAG in glycerophospholipid synthesis
    Back
    A head group such as choline or ethanolamine.
  16. Front
    Requirement for adding a head group to DAG
    Back
    The head group must be activated with CTP.
  17. Front
    Activated choline donor
    Back
    CDP-choline.
  18. Front
    Activated ethanolamine donor
    Back
    CDP-ethanolamine.
  19. Front
    First step of CDP-DAG pathway
    Back
    Phosphatidic acid reacts with CTP to form CDP-diacylglycerol.
  20. Front
    Head groups added in the CDP-DAG pathway
    Back
    Inositol or glycerol.
  21. Front
    Products of glycerophospholipid synthesis
    Back
    Phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, and cardiolipin.
  22. Front
    Location associated with cardiolipin
    Back
    Mitochondria.
  23. Front
    Core concept of glycerophospholipid synthesis
    Back
    Phosphatidic acid is the central intermediate that leads to all glycerophospholipids.
  24. Front
    Important phospholipid example
    Back
    Dipalmitoyl phosphatidylcholine.
  25. Front
    Function of dipalmitoyl phosphatidylcholine
    Back
    Prevents lung collapse as surfactant.
  26. Front
    Core concept of phospholipid function
    Back
    Some phospholipids have specific functions in addition to structural roles.
  27. Front
    Another name for ether glycerophospholipids
    Back
    Plasmalogens.
  28. Front
    Starting molecule for plasmalogen synthesis
    Back
    DHAP from glycolysis.
  29. Front
    Initial step of plasmalogen synthesis
    Back
    DHAP reacts with fatty acyl-CoA.
  30. Front
    Key replacement step in plasmalogen synthesis
    Back
    The fatty acyl group is replaced with a fatty alcohol.
  31. Front
    Final step in plasmalogen synthesis
    Back
    A head group is added.
  32. Front
    Ethanolamine plasmalogen association
    Back
    Myelin.
  33. Front
    Choline plasmalogen association
    Back
    Heart.
  34. Front
    Core concept of plasmalogens
    Back
    Plasmalogens are special phospholipids important in the brain and heart.
  35. Front
    First step of sphingolipid synthesis
    Back
    Palmitoyl-CoA combines with serine to form sphinganine.
  36. Front
    Precursor formed from palmitoyl-CoA and serine
    Back
    Sphinganine.
  37. Front
    Second step of sphingolipid synthesis
    Back
    A fatty acid is added to form ceramide.
  38. Front
    Central intermediate of sphingolipid synthesis
    Back
    Ceramide.
  39. Front
    How sphingomyelin is formed
    Back
    A phosphocholine head group is added to ceramide.
  40. Front
    How glycosphingolipids are formed
    Back
    Sugars are added to ceramide.
  41. Front
    Examples of glycosphingolipids
    Back
    Cerebrosides and gangliosides.
  42. Front
    Functions of sphingolipids
    Back
    Membrane structure especially in the CNS, cell signaling, and blood group antigens.
  43. Front
    Core concept of sphingolipid synthesis
    Back
    Ceramide is the central intermediate of all sphingolipids.
  44. Front
    Normal balance in sphingolipid metabolism
    Back
    Synthesis and degradation are balanced.
  45. Front
    Cause of sphingolipidoses
    Back
    Missing lysosomal enzyme.
  46. Front
    Result of missing lysosomal enzyme in sphingolipidoses
    Back
    Accumulation of sphingolipids.
  47. Front
    Typical accumulation pattern in sphingolipidoses
    Back
    Usually one lipid accumulates.
  48. Front
    Main system affected in sphingolipidoses
    Back
    The nervous system.
  49. Front
    Course of sphingolipidoses
    Back
    Progressive and often fatal early.
  50. Front
    Inheritance pattern of sphingolipidoses
    Back
    Mostly autosomal recessive.
  51. Front
    Exception to autosomal recessive inheritance in sphingolipidoses
    Back
    Fabry disease is X-linked.
  52. Front
    Core concept of sphingolipidoses
    Back
    Enzyme deficiency causes lipid buildup and cell damage, especially in the brain.
  53. Front
    General mechanism of specific sphingolipidoses
    Back
    Each disease results from one missing enzyme causing one substrate to accumulate.
  54. Front
    Substrate that accumulates in Tay-Sachs
    Back
    GM2 ganglioside.
  55. Front
    Effects of Tay-Sachs
    Back
    Neurodegeneration, blindness, and death around 3–4 years.
  56. Front
    Most common sphingolipidosis
    Back
    Gaucher disease.
  57. Front
    Substrate that accumulates in Gaucher disease
    Back
    Glucocerebroside.
  58. Front
    Features of Gaucher disease
    Back
    Enlarged liver and spleen and bone problems.
  59. Front
    Substrate that accumulates in Niemann-Pick disease
    Back
    Sphingomyelin.
  60. Front
    Feature of Niemann-Pick disease
    Back
    Neurological damage.
  61. Front
    General symptoms of sphingolipidoses
    Back
    CNS damage, developmental delay, and organ enlargement.
  62. Front
    Core concept of sphingolipidoses as a disease class
    Back
    Sphingolipidoses are lysosomal storage diseases caused by lipid accumulation.
  63. Front
    General step 1 of complex lipid synthesis
    Back
    Create a backbone of glycerol or sphingosine.
  64. Front
    General step 2 of complex lipid synthesis
    Back
    Add fatty acids by ester linkage in glycerol lipids or amide linkage in sphingolipids.
  65. Front
    General step 3 of complex lipid synthesis
    Back
    Add a head group via a phosphodiester bond.
  66. Front
    General step 4 of complex lipid synthesis
    Back
    Optional modification.
  67. Front
    Location of complex lipid synthesis
    Back
    Smooth ER and inner mitochondrial membrane.
  68. Front
    Final core idea of section 16.2
    Back
    Complex lipids are membrane lipids built from a backbone, fatty acids, and a head group.
  69. Front
    Cheat sheet: types of complex lipids
    Back
    Glycerophospholipids use glycerol and sphingolipids use sphingosine.
  70. Front
    Cheat sheet: key intermediate of glycerol lipids
    Back
    Phosphatidic acid.
  71. Front
    Cheat sheet: key intermediate of sphingolipids
    Back
    Ceramide.
  72. Front
    Cheat sheet: important phospholipid
    Back
    Phosphatidylcholine is the most abundant membrane phospholipid.
  73. Front
    Cheat sheet: important special phospholipids
    Back
    Plasmalogens are important in brain and heart, and surfactant is important in lungs.
  74. Front
    Cheat sheet: cause of sphingolipid disorders
    Back
    Lysosomal enzyme deficiency.
  75. Front
    Cheat sheet: result of sphingolipid disorders
    Back
    Lipid accumulation.
  76. Front
    Cheat sheet: examples of sphingolipidoses
    Back
    Tay-Sachs, Gaucher, and Niemann-Pick.
  77. Front
    Precursor of all glycerophospholipids
    Back
    Phosphatidic acid.
  78. Front
    Precursor of all sphingolipids
    Back
    Ceramide.
  79. Front
    What activates head groups in phospholipid synthesis
    Back
    CTP.
  80. Front
    Why sphingolipidoses mainly affect the brain
    Back
    They mainly affect the nervous system, where sphingolipids are important membrane components.
  81. Front
    What happens if a lysosomal enzyme is missing
    Back
    The specific sphingolipid substrate accumulates, causing cell damage and lysosomal storage disease.

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