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15 Cards in this Set
- Front
- Back
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Lipid structure
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FFA or esterified to glycerol
16 - 20 AAs saturated or unsaturated |
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phosphoglycerides
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FAs at 1 and 2, phosphoryl group at 3
(e.g. phosphocholine) |
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sphingolipids
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ceramide + various groups attached
- sphingomyelin (ceramide + phosphocholine) - cerebrosides (ceramide + sugar) - gangliosides (ceramide + many sugars) |
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structure of cholesterol
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four rings w/ aliphatic side chain
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TAG digestion
(major dietary fat) |
-emulsified by bile salts
-TAG --> 2-MAG + FFA by pancreatic lipase (and colipase) -FFA packaged into micelles (w/ cholesterol, fat-sol vitamins, bile salts) -micelles --> microvilli --> FFAs, 2-MAG absorbed (bile salts recycled by liver) |
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Chylomicron synthesis
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FAs (micelles) --> fatty acyl CoA by fatty acyl CoA synthease (thiokinase)
Fatty acyl CoA + 2-MAG --> DAG + fatty acyl CoA --> TAG TAG packaged into nascent CM --> lymph |
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Fatty acid synthesis:
glucose --> acetyl CoA |
glucose --> pyruvate via glycolysis
pyruvate --> acetyl CoA by PYRUVATE DH, and OAA by PYRUVATE CARBOXYLASE acetyl CoA + OAA --> citrate --> out of mitochondria citrate + ATP --> OAA + acetyl CoA by CITRATE LYASE (+) insulin OAA + NADH --> malate + NAD+ by MALATE DH malate + NADP+ --> pyruvate + NADPH + CO2 by MALIC ENZYME NADPH = reducing equivalents for FA synthesis (+ those from HMP shunt) acetyl CoA = carbons for FA synthesis |
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Fatty acid synthesis:
FA synthase complex |
ACP = acyl carrier protein
- phosphopanthetheine residue CE = condensing enzyme - cystein residue the -SH groups on both form thioesters w/ acyl groups |
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citrate --> OAA + acetyl CoA
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enzyme = citrate lyase
location = cytoplasm (+) insulin |
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OAA + NADH --> malate + NAD+
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malate dehydrogenase
cytoplasm |
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malate + NADP+ --> pyruvate + NADPH + CO2
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malic enzyme
cytosol |
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acetyl CoA + ATP --> malonyl CoA + CO2
**rate-limiting step in FA synthesis** |
acetyl CoA carboxylase
BIOTIN req'd in cytosol (+) insulin, citrate (allosteric, partial activator) (-) palmitoyl CoA, glucagon/epi, phosphorylation |
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Fatty acid synthase
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1 acetyl CoA + 7 malonyl CoA
1) transacylation 2) condensation 3) reduction, dehydration, reduction (rpt x 7) |
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1 acetyl CoA + 7 malonyl CoA + NADPH
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palmitate
(+) insulin |
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ACP + CE
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1) acetyl group in CE site, malonyl group in ACP
2) condensation, acetyl group transferred to ACP = acetoacetyl group 3) reduction --> ACP-butyryl group --> translocated to CE site = CE-butyryl group 4) malonyl CoA enters empty ACP site --> cycles again |
