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15 Cards in this Set

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Lipid structure
FFA or esterified to glycerol
16 - 20 AAs
saturated or unsaturated
phosphoglycerides
FAs at 1 and 2, phosphoryl group at 3
(e.g. phosphocholine)
sphingolipids
ceramide + various groups attached
- sphingomyelin (ceramide + phosphocholine)
- cerebrosides (ceramide + sugar)
- gangliosides (ceramide + many sugars)
structure of cholesterol
four rings w/ aliphatic side chain
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)
Chylomicron synthesis
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
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
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
citrate --> OAA + acetyl CoA
enzyme = citrate lyase

location = cytoplasm

(+) insulin
OAA + NADH --> malate + NAD+
malate dehydrogenase

cytoplasm
malate + NADP+ --> pyruvate + NADPH + CO2
malic enzyme

cytosol
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
Fatty acid synthase
1 acetyl CoA + 7 malonyl CoA

1) transacylation
2) condensation
3) reduction, dehydration, reduction (rpt x 7)
1 acetyl CoA + 7 malonyl CoA + NADPH
palmitate

(+) insulin
ACP + CE
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