Lipids Flashcards
ketogenic diets reduce ___ in children for unknown reasons
seizures
animals can’t convert f.a. into ____
glucose
fats are converted into ____ which is then processed by CAC
acetyl coA
where does biosynthesis of f.a. occur?
in cytosol
intermediates in synthesis pathway involve ____ group of ____
sulfhydryl; ACP (Acyl carrier protein)
intermediates in breakdown path involve ___ group of ___
sulfhydryl; Coenzyme A
elongation of f.a. stops w/ formation of ____; further elongation uses diff enzymes in ____
palmitate; ER
f.a. synthesized by this multienzyme complex:
fatty acid synthase
malate to pyruvate is a ___ catalyzed by ___; also makes NADPH required for f.a. synth
decarboxylation; malic enzyme
citrate is synthesized in the ____; it is transported to ____ and cleaved by ____ to make acetyl coA
mito; cyto; ATP-citrate lyase
to synth palmitate, need __ cycles, and ___ NADPH
7; 14 (2 per cycle)
in making palmitate, __ NADPH from malic enzyme, __ from PPP
8; 6
name of enzyme that catalyzes 1st (rate limiting) irreversible step of fa biosynth?
acetyl coA carboxylase
carboxylase need ___ prosthetic group
biotin
coA carboxylase activated by ___ and ___; inhibited by ___, ___ and ___
insulin, citrate; epinephrine, glucagon, palmitate
malonyl CoA inhibits ___ which blocks __ oxidation
Carnitine Acyltransferase 1; beta
carboxylase is active when ____ and inactive when ___
unphosphorylated; phosphorylated
enzyme that turns 2 acetyl coA to acetoacetyl coA
thiolase (or acylCoA acetyltransferase)
enzyme that turns acetoacetyl coA to HMG-CoA
HMG-CoA synthase
HMG-CoA to acetoacetate enzyme
HMG-CoA lyase
for energy purposes, only ___ and ____ used while acetone disappears
acetoacetate; D-3-hydroxybutyrate
this molecule is involved in synth of cholesterol and ketone bodies
HMG-CoA
levels of f.a. and ketone bodies __ when starvation
increase
oxidation of odd chain f.a. require vitamin ____
B12
for every db bond, produce __ less FADH2
1
probs with db bond oxidation?
need to be on beta C; need be in trans isomer
how to activate f.a.?
use 2 ATP to remove glycerol
in degradation, 2 C units are sequentially removed from __ end of f.a., producing __ ATP per cycle
carboxyl; 4 (1 FADH2, 1 NADH)
voltage dependent channels called ___ move acyl-coA/f.a. across ___ membrane
porins; outer
name of protein that transports acyl-carnitine and carnitine
translocase
enzyme for carnitine–>acyl-carnitine?
carnitine acyl transferase 1/2
acyl binds carnitine just outside the __ membrane, and fatty acids are metabolized in ___ to produce energy
inner; matrix
what is beta oxidation?
degradation of f.a. 2 carbons at a time to produce acetyl coA
what are the 4 basic steps of beta oxidation?
oxidation, hydration, oxidation, cleavage
first step beta-ox?
reduce FAD to create double bond (trans enoyl CoA) using Acyl-CoA dehydrogenase
second step beta-ox?
use enoyl CoA Hydratase to split water and turn db bond back to single bond
third step beta ox?
use betahydroxyacylCoA dehydrogenase to oxidize to 3-ketoacyl CoA which can be split by addition of another CoA to make 2 acylcoAs
4th step beta ox?
thiolysis of acyl-CoA, causing it to connect with acetyl coA to form 3-ketoacyl CoA
what are 7 activities that make up f.a. synthase complex?
ACP, AT, KS, MT, KR, HD, ER
enzyme that catalyzes attachment of acetyl group to sulfide group on KS
acetyl transacylase (AT)
steps in f.a. synthesis?
condensation–>reduction–>dehydration–>reduction
step one of f.a. synth is catalyzed by
beta ketoacyl synthase
condensation in first step of f.a. synth triggers release of ___ and ___
ACP; CO2
enzyme involved with step 2 f.a. synth?
beta-ketoacyl reductase
enzyme involved with step 3 f.a. synth?
beta-hydroxyacyl dehydratase
enzyme involved with step 4 f.a. synth?
enoyl reductase
product of f.a. synth is called ___ and is translocated from ___ to ___
butyryl; ACP; KS
free palmitate is released from f.a. synthase complex by ____
hydrolysis
elongation of f.a. from palmitate occurs in ___
endoplasmic reticulum (same process as making palmitate)
desaturation is catalyzed by ___ enzymes bound to the ____
desaturase; ER
essential f.a.s?
linoleate and linolenate
necessary for synthesizing prostaglandins, leukotrienes, prostacycline, thromboxanes
arachidonate
most common phsopholipid form?
phosphatidylcholine
___ catalyzes sequential attachment of f.a. to glycerol backbone via __ bond
acyltransferase; ester
1st f.a. chain is usually ___ while middle one is ____
saturated; unsaturated
name of enzyme that converts phosphatidate to DAG
phosphatidate phosphatase
triacyl/phospho synth in ___
liver
diacylglycerol is activated by ____
CTP (form CDP-diacylglycerol)
CDP-DAG rxt w/ ___ to form phospholipid
alcohol
alcohol is activated by ___ and reaction with ___ to form CDP-alcohol
phosphorylation; CTP
activated alcohol rxt w/ ___ to form phospholipid
diacylglycerol
name of enzyme from ethanolamine to phosphorylethanolamine
ethanolamine kinase
if choline is deficient, phosphatidylcholine can be synth from phophatidylethanolamine by ___ with ____
methylation; SAM (S-adenosylmethionine)
cholesterol is synth especially in __
liver
function of chol:
structure in membrane, precursor of bile salts, steroids, vit. D
chol have __ carbons, all C come from ____
27; acetyl coA
4 stages of chol synth, 1+2 in __, 3+4 in ___
cyto; ER
1st product in chol synth?
mevalonate (6C)
mevalonate is converted to ___
isoprene (5C)
isoprene is converted to ___ through ___
squalene (30C); condensation
HMG-CoA is converted to mevalonate through ___ reaction, by ___ enzyme
reduction; HMG CoA reductase
3 fates of chol:
hepatocyte plasma membrane, storage, exported through blood–>tissues
storage form of chol:
cholesterol ester
complexes of proteins and lipids that transport TAG and chol in blood
lipoproteins
4 components of lipoproteins
unesterified chol, phospholipid, chol ester, apoprotein B-100
___ and ___ transport chol, ___ and __ transport TAG
HDL; LDL; VLDL; chylomiciron
least dense lipoprotein is :
chylomicron
condition involving very high circulating chol lvls, severe atherosclerosis, defective LDL receptor
familial hypercholesterolemia
how to treat familial hypercholesterolemia?
statins (competitive inhibitors of HMG CoA)
