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Biochemistry MBS > Membrane Lipids > Flashcards

Membrane Lipids Flashcards

1
Q

lipids and cancer

A
  • cancerous cells need to make a lot of membrane lipid in order to divide rapidly
  • upregulate citratelyase and down regulate FA oxidation
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2
Q

sphingosine 1 phosphate

A

contributes to cancer and inflammation

-crohns, ulcerative colitis

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3
Q

lysosomal storage diseases

A

-can not break down sphingolipids due to genetic disorders of metabolism

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4
Q

different scaffolds

A
  • glycerol

- sphingosine

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5
Q

glycerophospholipids

A
  • 2 FAs in ester linkages as positions 1 and 2

- head group in a phosphodiester linkage at position 3

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6
Q

head groups

A
  • serine
  • choline
  • ethanolamine
  • glycerol
  • inositol
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7
Q

cardiolipin

A
  • double phospholipid

- exclusive to the inner membrane of the mitochondria

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8
Q

what do fatt acid salts form

A
  • micelles

- individual units are wedge shpaed with a carboxylic head and an aliphatic tail

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9
Q

phospholipids form

A
  • membrane bilayers
  • individual units are cylindrical
  • glycerophospholipids will spontaneously form bilayers in awueous solution
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10
Q

flip flopping of membrane lipids

A
  • very unlikely to happen spontaneously
  • the enzyme flippase is required
  • this has implications in membrane properties such as in RBC’s (PC on outer and PE and PS on inner)
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11
Q

common lecithin

A
  • 1 stearoyl, 2 oleoyl-phosphatidyl choline
  • most abundant human membrane lipid
  • unsaturated FA on C2 lowers melting point creating a fluid membrane
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12
Q

lung sufractant

A
  • 1,2 palmytoil-phosphatidyl choline
  • reduced fluidity important for coating air-water interface, preventing alveolar collapse
  • deficiency can lead to respiratory distress syndrome in premature infants
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13
Q

what does the formation of glycerophospholipids start with?

A

PA or DAG

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14
Q

general mechanism for head group addition

A
  1. CDP activation of one hydroxyl by adding phosphate via kinase then CTP via cytidyltransferase
  2. second hydroxyl displaces CMP to give phosphodiester
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15
Q

starting reactants to make ethanolamine or choline

A

-start with a head group activated with CDP then add diacylglycerol

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16
Q

starting reactants for making inositol (PI), glycerol, or PGC3 (cardiolipin)

A

-start with diacylglycerol activated with CDP then add a head group

17
Q

glycerophospholipid interconversion

A
  • SAM (S-adenosyl methionine) is used as a methyl donor in several processes
  • only way to form PS is to convert it from PE
18
Q

plasmalogens

A
  • glycerophospholipids with fatty alcohol in ether linkage at C1
  • activated platelet secretion and alters membrane permeability
  • abundant plasmalogens in mitochondrial inner membrane may resist oxidative damage that would hydrolyze the ester bonds in normal PL’s
19
Q

phospholipases

A
  • PLA2 release PUFAs acted upon by oxygenases to make intracellular signaling molecules
  • PLAs rearrange FA’s
  • PLA’s are found in many venoms
20
Q

modified FA’s as intracellular signals

A
  • certain stresses induce phospholipase A to release long chin PUFAs from membrane phopholipids
  • eicosanoids
21
Q

cyclooxygenase

phospholipase

A
  • gives rise to prostaglandins and thromboxanes which act as short range intracellular signals
  • removes 2 double bonds, subscript shows number remaining
22
Q

lipoxygenases (phospholipase)

A
  • generate leukotrienes
  • important for the immune response
  • number of double bonds is unchanged
  • modulate cellular chemotaxis, cytokine release
  • mediate vascular permeability and bronchioconstriction
23
Q

DAG

A
  • second messenger

- activates PKC

24
Q

IP3

A
  • causes release of Ca2+
  • activates calmodulin kinase
  • promotes growth and development
25
Q

what are DAG and IP3 released from

A
  • PIP

- extracellular signal binds membrane spanning receptor to activate PLC which cleaves PIP into IP3 and DAG

26
Q

sphingolipids

A
  • membrane lipids not based on glycerol
  • based on sphingosine
  • common membrane component in myelin sheath, sphingolyelin with C24 FA’s provides electrical insulation
27
Q

multiple myeloma

A

-auto immune disease where you lose myelination in the CNS

28
Q

types of glycolipid, what is theur classification

A
  • sulfatides
  • globosides
  • gangliosides (charged, neuraminic acid)
  • these are a type of sphingolipid
  • glucose added as UDP glucose or UDP galactose
29
Q

blood grouping antigens

A
  • these are gangliosides and globosides

- they are markers in cellular recognition

30
Q

normal sphingolipid breakdown pathways

A
  • membrane lipids are constantly pulled from the surface into endosomes
  • some are reused others are broken down in lysosomes and their components recylcled
  • each sugar linkage in the glycosphingolipids (cerebrosides, globosides, and gangliosides) requires a seperate enzyems for removal

Biochemistry MBS (36 decks)

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