Lipids Flashcards
_______: Esters of fatty acids containinggroups in addition to an alcohol and a fatty acid.
Complex lipids
Phospholipids: Lipids containing, in additionto fatty acids and an alcohol, a phosphoricacid residue. They frequently have nitrogen-containing bases and other substituents, eg, inglycerophospholipids the alcohol is glyceroland in sphingophospholipids the alcohol issphingosine.
Glycolipids
(glycosphingolipids):
Lipidscontaining a fatty acid, sphingosine, and car-bohydrate
______: Esters of fatty acids with various al-cohols.
Simple lipids
Fats: Esters of fatty acids with glycerol. Oilsare fats in the liquid state.
Waxes: Esters of fatty acids with higher mole-cular weight monohydric alcohols.
______ may be regarded as derivatives of phos-phatidic acid (Figure 14–8), in which the phosphate isesterified with the OH of a suitable alcohol.
Phospholipids
Phosphoacylglycerols containing choline (Figure 14–8)are the most abundant phospholipids of the cell membrane:
Phosphatidyl choline, lecithin
________ consist of triacylglycerols (16%), phos-pholipids (30%), cholesterol (14%), and cholesterylesters (36%) and a much smaller fraction of unesteri-fied long-chain fatty acids (free fatty acids) (4%).
Plasma lipids
Theprotein moiety of a lipoprotein is known as an _______, constituting nearly 70% ofsome HDL and as little as 1% of chylomicrons.
apo-lipoprotein or apoprotein
main apolipoprotein of LDL (β-lipopro-tein) is ____ and is found also inVLDL.
apolipoprotein B (B-100)
most of theplasma_____ are of hepatic origin. They are the vehi-cles of transport of triacylglycerol from the liver tothe extrahepatic tissues.
VLDL
______ (a rare dis-ease), lipoproteins containing apo B are not formed andlipid droplets accumulate in the intestine and liver.
abetalipoproteinemia
_______ are in-versely related to the incidence of coronary athero-sclerosis, possibly because they reflect the efficiency ofreverse cholesterol transport
HDL2 concentrations
_______ over a long periodleads to the accumulation of fatty acids in the liver thatare derived from endogenous synthesis rather than fromincreased mobilization from adipose tissue. There is noimpairment of hepatic synthesis of protein after ethanolingestion. Oxidation of ethanol by alcohol dehydrogen-ase leads to excess production of NADH.
Ethanol consumption
The NADH generated competes with reducingequivalents from other substrates, including fatty acids,for the respiratory chain, inhibiting their oxidation, anddecreasing activity of the citric acid cycle.
This isthe principal regulatory step in the pathway of choles-terol synthesis and is the site of action of the most effec-tive class of cholesterol-lowering drugs, the HMG-CoAreductase inhibitors (statins)
HMG-CoA reductase
polyisoprenoids dolichol and ubiquinone are formedfrom _____ by the further addition of upto 16 (dolichol) or 3–7 (ubiquinone) isopentenyldiphosphate residues, respectively.
farnesyl diphosphate
is the principal sterol in the
feces;
Coprostanol
The primary bile acids are synthesized in the liver fromcholesterol. These are ____
cholic acid (found in the largestamount) and chenodeoxycholic acid
Rate limiting enzyme in bile acid synthesis:
Cholesterol-7-alpha-hydroxylase
A second path-way in mitochondria involving the 27-hydroxylation ofcholesterol by _____ as the first step isresponsible for a significant proportion of the primarybile acids synthesized.
sterol 27-hydroxylase
secondary bileacids:
deoxycholic acid and lithocholic acid.
Although products of fat digestion, including choles-terol, are absorbed in the first 100 cm of small intestine,the primary and secondary bile acids are absorbed al-most exclusively in the ileum, and 98–99% are re-turned to the liver via the portal circulation. This isknown as the _______.
enterohepatic circulation
Bile acid that because of its insolubility, isnot reabsorbed to any significant extent.
Lithocholic acid
The principal rate-limiting step in the biosynthesis ofbile acids is at the cholesterol 7-hydroxylase reac-tion (Figure 26–7). The activity of the enzyme is feed-back-regulated via the nuclear bile acid-binding recep-tor _______.
farnesoid X receptor (FXR)
