LECTURE 25

Question 1

this is a precursor of bile salts, steroids, and vitamin D?

Answer 1

cholesterol

Question 2

this organ is critical for the distribution of dietary and de novo cholesterol?

Answer 2

liver

Question 3

what does cholesterol leave the liver as?

Answer 3

component of HDL, VLDL, free cholesterol in bile as bile salts/acids

Question 4

in cholesterol synthesis where do all carbons come from and what cofactor supplies the electrons?

Answer 4

acetate

NADPH

Question 5

where does cholesterol synthesis occur?

Answer 5

cytosol and ER

Question 6

what is the rate limiting reaction in cholesterol synthesis?

Answer 6

HMG-CoA reducetase

Question 7

what are the two anti cholesterol drugs that inhibit HMG-CoA reductase?

Answer 7

lovastatin and atorvastatin

Question 8

T/F, cholesterol can be used for energy?

Answer 8

F

Question 9

how is cholesterol removed from the body?

Answer 9

bile acids

free cholesterol

Question 10

what do we do with cholesterol other than make bile salts and in membranes?

Answer 10

steroid hormones

Question 11

cholesterol is the precursor of these 5 classes of steroid hormones, name them?

Answer 11

glucocorticoids (cortisol)
mineralcorticoids (aldosterone)
androgens (testosteron)
estrogens (estrogen)
progestins (progesterone)

Question 12

how is cortisol transported in the blood after its bound to albumin? for sex hormones?

Answer 12

transcortin

sex hormone binding protein

Question 13

what enzyme converts cholesterol to pregnenolone? this is rate limiting for all steroids

pregnenolone is then converted to what final products?

Answer 13

desmolase

aldosterone
cortisol
estradiol

Question 14

fatty acids can be modified to become what type of signal? what is this signal called and name examples?

Answer 14

intercellular signals called eicosanoids

eicosanoids

PGs
thromboxanes
leukotrienes

Question 15

this is the substrate for our bodies to make arachidonic acid?

Answer 15

linoleic acid

Question 16

what is the source for PG synthesis?

Answer 16

arachidonate

Question 17

this eicosanoids is used for smooth muscle contraction, bronchoconstriction, slow anaphylaxis, lysosomal release and WBC adhesion

Answer 17

leukotrienes

Question 18

this eicosanoidsis made by platelets, promotes aggregation and vasoconstriction at wound sites?

Answer 18

thromboxane A2

Question 19

this eicosanoids is what most tissues make it, especially kidney, causes vasodilation and is used to promote labor?

Answer 19

PGE2

Question 20

this eicosanoid is in response to tissue damage?

Answer 20

leukotrienes

Question 21

this eicosanoid is also made in most tissue, a vasoconstrictor which stimulates smooth muscle and uterine contractions?

Answer 21

PGF2

Question 22

this eicosanoid is made by endothelial cells, causes vasodilation, and inhibits platelet aggregation?

Answer 22

PGI2

Question 23

these are the two domains that comprise the prostaglandin synthase?

Answer 23

cyclooxygenase

peroxidase

Question 24

what inhibits cyclooxygenase?

Answer 24

aspirin, saids, indomethacin, phenylbutazone

Question 25

what inhibits thromboxane synthase?

Answer 25

dipyridamole

Question 26

what is the energy yield per gram for the macromolecules? fat protein carbs alcohol

Answer 26

9 kcal/g fat 4 kcal/g protein 4 kcal/g carbs 7 kcal/g alcohol

Question 27

why does glycerol go to the liver to broken down? what about the fatty acids?

Answer 27

there is no glycerol kinase in the adipocytes diffuse through adipocytes to be bound to albumin, not used by brain, RBCs. adrenal medulla

Question 28

fatty acid consumption used by what organs?

Answer 28

muscle and liver

Question 29

a shortage of medium length fatty this enzyme is implicated in 10% of SIDs cases?

Answer 29

fatty acyl synthase

Question 30

why is carnitine acyl transferase important in acyl CoA synthesis? what inhibits this?

Answer 30

it attaches the acyl group to carnitine to move from the cytosol to the mitochondrial matrix malonyl CoA

Question 31

so once in the matrix of the mitochondria, what process occurs to the acyl-CoA?

Answer 31

beta oxidation

Question 32

what are the two enzymes used in energy harvesting from the beta oxidation of the fatty acid?

Answer 32

acyl-CoA dehydrogenase L-3-hydroxylacyl CoA dehydrogenase

Question 33

what is the net energy/palmitate? what about a TG with 3 palmitates, the glycerol attached? what happens if the FA is unsaturated or odd# of carbons?

Answer 33

129 ATP 409 ATP, included in this is the glycerol which accounts for 22 ATP isomerase and epimerase for unsaturated fatty acids which reduces the energy yield by 2 ATP/c=c because the acyl CoA DHase is skipped Beta oxidation proceeds for odd chain length but the last cycle yields 1 AcCoA + 1 propionyl CoA rather than 2 AcCoA, what happens to the propionly CoA and AcCoA? it is converted to succinyl CoA