Lipids

Question 0

_______: Esters of fatty acids containinggroups in addition to an alcohol and a fatty acid.

Answer 0

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

Question 1

______: Esters of fatty acids with various al-cohols.

Answer 1

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.

Question 2

______ may be regarded as derivatives of phos-phatidic acid (Figure 14–8), in which the phosphate isesterified with the OH of a suitable alcohol.

Answer 2

Phospholipids

Question 3

Phosphoacylglycerols containing choline (Figure 14–8)are the most abundant phospholipids of the cell membrane:

Answer 3

Phosphatidyl choline, lecithin

Question 4

________ 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%).

Answer 4

Plasma lipids

Question 5

Theprotein moiety of a lipoprotein is known as an _______, constituting nearly 70% ofsome HDL and as little as 1% of chylomicrons.

Answer 5

apo-lipoprotein or apoprotein

Question 6

main apolipoprotein of LDL (β-lipopro-tein) is ____ and is found also inVLDL.

Answer 6

apolipoprotein B (B-100)

Question 7

most of theplasma_____ are of hepatic origin. They are the vehi-cles of transport of triacylglycerol from the liver tothe extrahepatic tissues.

Answer 7

VLDL

Question 8

______ (a rare dis-ease), lipoproteins containing apo B are not formed andlipid droplets accumulate in the intestine and liver.

Answer 8

abetalipoproteinemia

Question 9

_______ are in-versely related to the incidence of coronary athero-sclerosis, possibly because they reflect the efficiency ofreverse cholesterol transport

Answer 9

HDL2 concentrations

Question 10

_______ 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.

Answer 10

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.

Question 11

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)

Answer 11

HMG-CoA reductase

Question 12

polyisoprenoids dolichol and ubiquinone are formedfrom _____ by the further addition of upto 16 (dolichol) or 3–7 (ubiquinone) isopentenyldiphosphate residues, respectively.

Answer 12

farnesyl diphosphate

Question 13

is the principal sterol in the

feces;

Answer 13

Coprostanol

Question 14

The primary bile acids are synthesized in the liver fromcholesterol. These are ____

Answer 14

cholic acid (found in the largestamount) and chenodeoxycholic acid

Question 15

Rate limiting enzyme in bile acid synthesis:

Answer 15

Cholesterol-7-alpha-hydroxylase

Question 16

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.

Answer 16

sterol 27-hydroxylase

Question 17

secondary bileacids:

Answer 17

deoxycholic acid and lithocholic acid.

Question 18

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 _______.

Answer 18

enterohepatic circulation

Question 19

Bile acid that because of its insolubility, isnot reabsorbed to any significant extent.

Answer 19

Lithocholic acid

Question 20

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 _______.

Answer 20

farnesoid X receptor (FXR)