Biochem Chapter 24 part 2

paniroya's version from 2016-11-03 20:18


Question Answer
An important mechanism of arachidonate release and eicosanoid synthesis involves _________ and _____________.
a. insulin release; high blood sugar
b. glucagon release; low blood sugar
c. tissue injury; low blood sugar
d. inflammation; tissue injury
e. all are true
All are true for aspirin EXCEPT:
a. it does not affect the peroxidase activity of prostaglandin endoperoxide synthase (COX).
b. it inhibits the activity of prostaglandin endoperoxide synthase (COX).
c. it stimulates ring opening in prostaglandin synthesis.
d. it acetylates the serine in the active site of the cyclooxygenase (COX).
e. it is classed as a non-steroidal anti-inflammatory drug (NSAID).
All are characteristics of COX-2 inhibitors EXCEPT:
a. selectively block inflammation mediated by COX-2.
b. are NSAIDs.
c. less potential for stomach lesions than aspirin.
d. less renal toxicity than COX-1 inhibitors.
e. all are correct.
The PRIMARY site, but not the only site, of cholesterol synthesis is:
a. heart.
b. intestine.
c. muscle.
d. liver.
e. adipose.
The correct sequence for synthesis of mevalonate from acetyl-CoA is:
A. HMG-CoA synthase
B. formation of 3-hydroxy-3-methylglutaryl-CoA
C. β-ketothiolase catalyzed condensation
D. HMG-CoA reductase activity
E. Formation of acetoacetyl-CoA
a. E, C, D, A, B
b. C, D, A, B, E
c. E, B, A, C, D
d. E, A, B, D, C
e. C, E, A, B, D
The committed step in cholesterol biosynthesis is catalyzed by:
a. HMG-CoA synthase.
b. mevalonate kinase.
c. HMG-CoA reductase.
d. squalene monooxygenase.
e. HMG-CoA lyase.
All are regulatory mechanisms of HMG-CoA reductase EXCEPT:
a. low [cholesterol] increases mRNA for HMG-CoA reductase.
b. high [cholesterol] increases half-life for HMG-CoA reductase.
c. high [cholesterol] results in lower mRNA for HMG-CoA reductase.
d. phosphorylation by cAMP cascade inactivates HMG-CoA reductase.
e. phosphatases activate HMG-CoA reductase.
The appropriate sequence of intermediates between mevalonate and squalene are:
A. geranyl pyrophosphate
B. isopentenyl pyrophosphate
C. 5-phosphomevalonate
D. farnesyl pyrophosphate
E. dimethylallyl pyrophosphate
a. A, C, D, B, E
b. C, B, E, A, D
c. C, E, A, D, B
d. E, C, B, D, A
e. B, C, D, A, E
Characteristics of squalene monooxygenase include all EXCEPT:
a. requires a soluble protein activator.
b. bound to the endoplasmic reticulum (ER).a
c. uses FAD and NADPH.
d. requires O2.
e. all are true.
The “statins” are a series of drugs used to:
a. inhibit fatty acid synthesis in diet drugs.
b. widely prescribed drugs used to inhibit squalene monooxygenase.
c. derivatives or mimics of mevinolin used to inhibit HMG-CoA reductase.
d. derivatives of cholesterol used to lower cholesterol levels.
e. none are true.
Order the lipoproteins from lowest density to highest density.
A. chylomicrons
a. D, A, E, B, C
b. D, E, C, B, A
c. A, E, B, D, C
d. D, C, A, E, B
e. A, D, C, E, B
Dietary lipids are “packaged” in the intestine into ________ for transport in the blood stream.
a. chylomicrons
b. HDL
c. IDL
e. LDL
Which of the following lipoproteins is INCORRECTLY defined?
a. chylomicron: transport of dietary lipids to the liver
b. HDL: scavenger of extra-hepatic cholesterol
c. LDL: transport of cholesterol to extra-hepatic tissue
d. VLDL: transport of triacylglycerols from the liver
e. all of the above are correct
The major circulatory complex for cholesterol and cholesterol esters (“bad cholesterol”) is the:
a. chylomicrons.
b. HDL.
c. IDL.
d. VLDL.
e. LDL.
Lipoproteins consist of a core of ________ and __________ surrounded by a single layer of ___________, into which is inserted _________ and _______.
a. proteins; triacylglycerols; cholesterol esters; phospholipids; cholesterol
b. triacylglycerols; cholesterol esters; phospholipids; proteins; cholesterol
c. phospholipids; cholesterol esters; triacylglycerols; proteins; cholesterol
d. cholesterol esters; proteins; cholesterol; phospholipids; triacylglycerols
e. triacylglycerols; cholesterol; proteins; cholesterol esters; phospholipids
Lipoprotein lipase hydrolyzes ________ from VLDL particles to convert the VLDL into _________.
a. cholesterol esters; HDL particles
b. cholesterol esters; LDL particles
c. triacylglycerols; LDL particles
d. triacylglycerols; chylomicrons
e. triacylglycerols; HDL particles
Characteristics of HDLs include all EXCEPT:
a. high HDLs correlates with high risk of cardiovascular disease.
b. life span of 5 to 6 days.
c. newly formed is cholesterol ester free.
d. returns cholesterol and cholesterol esters to liver.
e. accumulates cholesterol esters via LCAT action.
The general genetic defect responsible for ____________ is the absence or dysfunction of ___________ in the body such that blood cholesterol levels are typically 300 to over 800 mg/dL.
a. hypocholesterolemia; triacylglycerol lipase
b. hypercholesterolemia; lipoprotein lipase
c. LCAT; LDL receptors
d. familial hypercholesterolemia; LDL receptors
e. familial hypocholesterolemia; HDL receptors
All are correct for bile salts EXCEPT:
a. made by the liver and utilized in the intestine.
b. derived from cholesterol.
c. conjugates of bile acids with glycine and taurine.
d. highly effective as detergents.
e. insert well into membranes because they are strictly nonpolar.
Characteristics of mixed-function oxidases include all EXCEPT:
a. usually involve cytochrome P-450.
b. often catalyze hydroxylation reactions on ring-systems such as sterols.
c. use both NADPH and O2.
d. one product is CO2.
e. all are correct.
______________ is an intermediate on the biosynthetic pathway from cholesterol to both male and female hormones.
a. Aldosterone
b. Progesterone
c. Cortisol
d. Estradiol
e. Testosterone
All are characteristics of desmolase EXCEPT:
a. produces cholic acid.
b. found in mitochondria of adrenal glands.
c. has two hydroxylase activities.
d. utilizes cytochrome P-450.
e. its substrate is cholesterol.
Properties of progesterone include all EXCEPT:
a. produced from pregnenolone in ER.
b. synthesis in the adrenal cortex activated by ACTH.
c. prepares the uterus for attachment of a fertilized ovum.
d. secreted from corpus luteum in late menstrual cycle.
e. all are true.
Male baldness, prostate hyperplasia and prostate cancer have been implicated in elevated levels of __________ and treatment involves inhibition of __________.
a. glucocorticoids; gluconeogenesis
b. stanozolol; lactate dehydrogenase
c. dihydrotestosterone; steroid 5α-reductase
d. cholesterol; mevinolin
e. none of the above
All are true for the action of cortisol EXCEPT:
a. stimulates gluconeogenesis and glycogen synthesis in liver.
b. inhibits protein synthesis and stimulates protein degradation in muscle.
c. inhibits allergic and inflammatory responses.
d. exerts an immunosuppressive effect and an inhibition of wound healing.
e. all are true.
Which of the following is correctly paired with its precursor?
a. cholesterol → palmitic acid
b. arachidonic acid → prostaglandins
c. testosterone → progesterone
d. aldosterone → cholic acid
e. none of the above