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16 Cards in this Set
- Front
- Back
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Structure of TAG (triacylglycerols) |
3 FA's esterified to glycerol 1: saturated 2: unsaturated 3: either |
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TAG storage |
Form oily droplets, anhydrous = major E reserve for body |
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Sources of glycerol phospate |
- initial acceptor of FA's in TAG synthesis - liver & adipose tissue: from glucose -> DHAP, glycerol phosphate dehydrogenase => glycerol phosphate - liver: glycerol, glycerol kinase => glycerol phosphate |
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TAG synthesis |
FA + CoA, ATP -> FA-CoA + AMP, PPi - 3 additions to glycerol-Pi => TGA w/ acetyl transferase (& phosphatase before the last step) |
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Fates of TAG in liver, intestines, adipose tissue |
adipose tissue: depot fat (storage) liver: little storage; most produces VLDL (w/ cholesteryl esters, cholesterol, phospholipid, protein [apolipoprotein B-100]) intestines: transported w/ chylomycrons |
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Classes of phospholipids |
glycerophospholipids [phosphoglicerides]: glycerol as a backbone; phosphatidic A-derived sphingophospholipids: sphingosine backbone |
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Glycerophospholipids formation |
Phasphatidic A + alcohol (attached to the P) Either one needs to be activated by CDP- Synthesized in the sER -> Golgi -> membranes/excreted |
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Cardiolipin |
= PA + glycerol + PA (in mito) (2 phosphatidylglycerols connected by the common alcohol, glycerol) - antigenic - inner mito & bacterial membranes |
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Sphingophospholipids synthesis |
sphingosine + FA (@ amino group) -> ceramide -> OH group @ C1 esterified -> sphingomyelin - in cell PM, high affinity to cholesterol - constituent of myelin Ceramide can also be linked w/ glucose/galactose @ C3 -> glycolipids |
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Degradation of phosphoglycerides |
Phospholipases -| phosphodiester bonds @ C1/2 -> lysophosphoglyceride -> lysophospholipases -> ... - forming (substrates of) messengers - remodeling |
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Degradation of sphingomyelin |
Sphingomyelinase (type of PLC) -| phosphorylcholine -> ceramide -> ceramidase -> sphingosine + FA - messengers - if malfunctional: Niemann-Pick disease (A/B) |
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Structure of cholesterol |
~ a kind of sterols 4 fused hydrocarbon rings A, B, C - 6-membered rings D - 5-membered ring + 8C branched HC @ C17 of D, OH @ C3 of A, etc. |
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Cholesteryl Esters (CE) |
Form of most plasma cholesterol (FA @ C3 of A) -> even more hydrophobic |
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Cholesterol synthesis |
Synthesized in all tissues, cyto All C's from acetate; reducing equivalents: NADPH 2 Acetyl-CoA -> aceloacetyl-CoA + Acetyl-CoA, HMG-CoA synthase -> HMG-CoA + HMG-CoA reductase, 2 NADPH -> mevalonic A, CoA (rate-limiting step) ->> 2 ATP -> 5-pyrophosphomevalonate ->> ATP -> CO2 + IPP -> DPP; + IPP -> GPP; + IPP -> FPP; 2 FPP -> squalene ->> NADPH -> lanosterol ->> cholesterol |
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Regulation of cholesterol synthesis |
Major control pt: HMG-CoA reductase ~rate-limiting enzyme - Sterol-dependent regulation of gene expression (SREBP2 -> SRE => ↑) - ↑ cholesterol -> ↓ stability - Sterol-independent de-/phosphorylation (Pi-|) - Hormonal regulation - Inhibition by drugs |
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Degradation of cholesterol |
Conversion -> bile A's/salts -> excretion in feces Modification by bacteria -> coprostanol, cholestanol => all: neutral fecal sterols - precursor for oxysterols & steroid hormones |
