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Chemistry
Q:
Ketone bodies are synthesized in the:
a. cytosol of muscle.
b. mitochondria of liver.
c. endoplasmic reticulum of heart.
d. plasma membrane of brain.
e. none of the above.
Q:
What are the three most common ketone bodies?a. acetone, butyrate and acetyl-CoAb. acetoacetate, hydroxyacetone phosphate and butyratec. acetone, -hydroxybutyrate and acetoacetated. acetoacetate, acetyl-CoA and acetonee. butyrate, acetoacetate and acetone
Q:
Which of the following correctly describes the sequence of events in the conversion of a triacylglycerol to acetyl-CoA?a. lipolysis, albumin transport, carnitine shuttle, activation to acyl CoA, -oxidationb. albumin transport, carnitine shuttle, lipolysis, activation to acyl CoA, -oxidationc. lipolysis, albumin transport, activation to acyl CoA, carnitine shuttle, -oxidationd. albumin transport, activation to acyl CoA, carnitine shuttle, lipolysis, -oxidatione. none of the above are correct
Q:
What are the -oxidation products of oleic acid and how many ATP equivalents are required for activation?a. 8 acetyl CoA, 8 NADH, 7 FADH2, 1 ATP equivalentb. 9 acetyl CoA, 8 NADH, 7 FADH2, 2 ATP equivalentsc. 8 acetyl CoA, 7 NADH, 7 FADH2, 1 ATP equivalentd. 8 acetyl CoA, 7 NADH, 6 FADH2, 2 ATP equivalentse. 9 acetyl CoA, 9 NADH, 8 FADH2, 2 ATP equivalents
Q:
All are true for 2,4-dienoyl-CoA reductase EXCEPT:
Q:
Q:
All are true for methylmalonyl-CoA mutase EXCEPT:
a. does hemolytic cleavage of Co3+ -C bond.
b. vitamin B12-dependent.
c. classic B12-enzyme catalyzed rearrangement.
d. produces succinyl-CoA.
e. all are true.
Q:
Propionyl-CoA is a product of ï¢-oxidation of ____ and is ultimately converted to the TCA cycle intermediate, ____.
a. odd-chain fatty acids; citrate
b. even-chain fatty acids; isocitrate
c. odd-chain fatty acids; succinyl-CoA
d. even-chain fatty acids; succinate
e. none are true
Q:
How many NADH are generated from the complete oxidation of palmitoyl-CoA to CO2?a. 7 from -oxidation and 24 from the TCAb. 8 from -oxidation and 24 from the TCAc. 7 from -oxidation and 21 from the TCAd. 7 from -oxidation and 28 from the TCAe. 8 from -oxidation and 24 from the TCA
Q:
How many NAD+are reduced in the -oxidation of stearoyl-CoA to form nine molecules of acetyl-CoA?a. 18b. 16c. 12d. 9e. 8
Q:
For the complete oxidation of a saturated fatty acid with 16 carbons, how many times must the -oxidation cycle be repeated?a. 4b. 7c. 8d. 6e. 16
Q:
The product of -oxidation, acetyl-CoA, can be used for all EXCEPT:a. synthesis of ketone bodies.b. synthesis of amino acids.c. catabolism in the TCA cycle.d. synthesis of glucose.e. none of the above.
Q:
L-Hydroxyacyl-CoA dehydrogenase is analogous in catalytic activity to what enzyme of the citric acid cycle?
a. aconitase
b. citrate synthase
c. isocitrate dehydrogenase
d. ï¡-ketoglutarate dehydrogenase
e. malate dehydrogenase
Q:
Enoyl-CoA hydratase belongs to what class of enzymes?
a. oxidoreductases
b. hydrolases
c. lyases
d. ligases
e. transferases
Q:
All are characteristics of acyl-CoA dehydrogenase EXCEPT:a. oxidation of the bond.b. comes in at least three isozymes each specific for fatty acids of differing chain lengths.c. uses tightly bound FAD.d. electrons are transferred to electron transfer flavoprotein (ETF) and on to Q of the electron transport system.e. all are correct.
Q:
The first oxidation in the -oxidation of saturated fatty acids is catalyzed by ____ and is the conversion of ____.a.-hydroxyacyl-CoA dehydrogenase; a primary alcohol to an aldehyde.b. acyl-CoA dehydrogenase; a carbon-carbon single bond to a carbon-carbon double bond.c. acyl-CoA dehydrogenase; a secondary alcohol to a ketone.d. -hydroxyacyl-CoA dehydrogenase; an aldehyde to a carboxylic acid.e. acyl-CoA dehydrogenase; an aldehyde to a ketone.
Q:
The first three reactions of -oxidation of saturated fatty acids are analogous to which sequence of metabolic reactions already discussed?
Q:
The correct sequence for transport of fatty acyl groups from the cytosol to the matrix is:
A. carnitine acyltransferase I
B. tranaslocase of carnitine and O-acylcarnitine
C. carnitine acyltransferase II
D. fatty acyl-CoA synthesis
E. O-acylcarnitine
F. fatty acyl-CoA in matrix
a. C, B, D, A, F, E
b. D, B, F, E, A, C
c. D, E, A, C, B, F
d. D, A, E, B, C, F
e. A, D, E, B, C, F
Q:
____ carries long-chain fatty acyl groups across the ____ membrane.
a. Biotin; intestinal
b. Carnitine; plasma
c. CoA-SH; plasma
d. Carnitine; inner mitochondrial
e. TPP; outer mitochondrial
Q:
Which of the following correctly describes the sequence of events for the conversion of a fatty acid to CO2?
Q:
Where in the cell are fatty acids condensed with coenzyme A to form acyl-CoA for ï¢-oxidation?
a. mitochondrial matrix
b. cytoplasm
c. outer mitochondrial membrane
d. inner mitochondrial membrane
e. none of the above
Q:
Chylomicrons:
a. are formed in adipose tissue.
b. are primary energy sources for the brain.
c. transport dietary triacylglycerols through the bloodstream.
d. are formed in and secreted by the liver.
e. contain more phospholipid than triacylglycerol molecules.
Q:
Absorbed lipids are condensed with glycerol in the epithelial cells into ____ and re-packaged into ____ that are initially transported by the ____ system.
a. phospholipids; VLDL; lymphatic
b. triacylglycerols; VLDL; portal
c. triacylglycerols; LDL; portal
d. triacylglycerols; chylomicron; lymphatic
e. triacylglycerols; VLDL; lymphatic
Q:
The majority of lipid digestion occurs in the duodenum by the enzyme ____ that produces ____ and ____ for absorption.
a. acid lipase; diacylglycerols; fatty acids
b. triacylglycerol lipase; fatty acids; glycerol
c. triacylglycerol lipase; fatty acids; glycerol
d. pancreatic lipase; monoacylglycerols; fatty acids
e. pancreatic lipase; glycerol; fatty acids
Q:
Bile salts are important in the initial digestion of triacylglycerols in the intestine because they:
a. are coenzymes for pancreatic lipase.
b. convert the inactive lipase into the active form.
c. emulsify the triacylglycerol globules to produce greater surface area which will increase the activity of the lipase.
d. activate the cleavage at the C-2 position.
e. permit greater permeability of the triacylglycerols through the intestinal membrane.
Q:
Fatty acids are mobilized from adipose cells in response to all of the hormones EXCEPT:
a. ACTH (adrenocorticotropic hormone).
b. glucagon.
c. insulin.
d. epinephrine (adrenaline).
e. all are true.
Q:
The sequence for activation of the release of fatty acids from adipose cells is:
A. protein kinase activation
B. cAMP production
C. triacylglycerol lipase activation
D. hormone binding receptor
E. adenylyl cyclase activation
F. diacylglycerol lipase and monoacylglycerol lipase activity
a. D, E, B, A, C, F
b. D, B, A, E, F, C
c. D, B, C, F, A, E
d. D, B, F, A, C, E
e. B, F, A, D, E, C
Q:
The primary storage form of lipid is ____ and it is normally stored in the ____.
a. phospholipid; liver
b. cholesterol; muscles
c. monoacylglycerol; adipocytes
d. triacylglycerols; adipocytes
e. triacylglycerols; liver
Q:
All are substrates for gluconeogenesis EXCEPT:
a. glycerol.
b. lactate.
c. acetate.
d. pyruvate.
e. most amino acids.
Q:
The pentose phosphate pathway is an important source of ____, and for ____, an essential precursor for ATP, NAD+, FAD, CoA, DNA and RNA.
a. ATP; NADH
b. NADH; NADPH
c. NADPH; ribose-5-phosphate
d. ribose-5-phosphate; ATP
e. all are true
Q:
Gluconeogenesis is the synthesis of:
a. glucose from non-carbohydrate precursors.
b. glycogen from glucose.
c. pyruvate from glucose.
d. fatty acids from glucose.
e. glucose from fatty acids.
Q:
If both NADPH and ribose-5-P are needed which of the following best represents the net reaction of the pentose phosphate pathway?a. 4 Fruc-6-P + 2 glyceraldehyde-3-P -> 6 ribose-5-Pb. 3 Gluc-6-P + 6 NADP+-> 6 NADPH + 3 CO2 + 2 Fruc-6-P + 1 glyceraldehyde-3-P + 6 H+c. Gluc-6-P + 2 NADP+ + 2 H2O -> 2 NADPH + CO2 + ribose-5-P + 2 H+d. Gluc-6-P + 12 NADP+ + 6 H2O-> 1 2 NADPH + 6 CO2 + 12 H+ + Pie. None of the above
Q:
AMP is often used in the cytosol as an indicator of low cellular energy. Which of the following enzymes would be inhibited by AMP?
a. glucose-6-phosphate dehydrogenase
b. phosphofructokinase-1
c. glycogen synthase
d. glyceraldehyde-3-phosphate dehydrogenase
e. none of the above
Q:
Which of the following pairs of enzymes would NOTbe active in the liver at the same time?
a. aldolase and triose phosphate isomerase
b. fructose-1,6-bisphosphatase and phosphofructokinase-2
c. pyruvate kinase and phosphofructokinase-1
d. glycogen synthase and glucokinase
e. none of the above
Q:
Which of the following enzymes would be activated by phosphorylation as a result of glucagon binding to its receptor on the cell membrane?
a. pyruvate carboxylase
b. glycogen synthase
c. pyruvate kinase
d. fructose-2,6-bisphosphatase
e. none of the above
Q:
What coenzyme is found in pyruvate carboxylase that aids in many carboxylation reactions?
a. thiamine pyrophosphate
b. biotin
c. folic acid
d. lipoic acid
e. none of the above
Q:
If NADPH is needed for biosynthetic reactions but ribose-5-P is not needed, which of the following best represents the net reaction of the pentose phosphate pathway?a. 4 Fruc-6-P + 2 glyceraldehyde-3-P -> 6 ribose-5-Pb. 3 Gluc-6-P + 6 NADP+ -> 6 NADPH + 3 CO2 + 2 Fruc-6-P + 1 glyceraldehyde-3-Pc. Gluc-6-P + 2 NADP+ -> 2 NADPH + CO2 + ribose-5-Pd. both b and c will occure. None of the above
Q:
Which of the following results when glucagon binds to its receptor?
a. glycolysis is activated
b. protein synthesis is activated
c. the citric acid cycle is inhibited
d. glycogen synthesis is inhibited
e. gluconeogenesis is inhibited
Q:
Which of the following can be used as a substrate for gluconeogenesis in the liver?
a. alanine
b. glutamic acid
c. glycerol
d. succinate
e. all of the above
Q:
When a cell with the pentose phosphate pathway has need for more pentose phosphates, but no additional NADPH:
a. glucose-6-phosphate dehydrogenase is activated.
b. the oxidative and non-oxidative enzymes of the pentose phosphate pathway are active.
c. the non-oxidative enzymes produce pentose phosphates from fructose-6-phosphate and glyceraldehyde-3-phosphate.
d. all enzymes of glycolysis and pentose phosphate pathway are active.
e. none are true.
Q:
The appropriate sequence for the transketolase catalyzed reaction would be:
A. reactive enamine attack on the aldehyde group of an aldose
B. ï¢-cleavage of Schiff base intermediate to release an aldose
C. formation of Schiff base intermediate of a new ketose
D. active site lysine forms Schiff base with keto-carbonyl group
E. Schiff base hydrated to ketose and enzyme
a. C, A, B, D, E
b. D, B, A, C, E,
c. D, A, B, E, C
d. A, D, B, C, E
e. E, D, C, B, A
Q:
The transaldolase catalyzed activity is similar to what glycolytic enzyme?
a. phosphoglucomutase
b. enolase
c. glyceraldehyde-3-phosphate dehydrogenase
d. PFK-1
e. aldolase
Q:
Which of the following reactions is catalyzed by a transketolase in the pentose phosphate pathway? a. I onlyb. II and IIIc. II onlyd. I and IIIe. I and II
Q:
Transketolase belongs to what class of enzymes?
a. oxidoreductases
b. isomerases
c. hydrolases
d. transferases
e. ligases
Q:
A transaldolase is an enzyme that catalyzes:
a. transfers of three-carbon units from a ketose to an aldose.
b. isomerization of ketoses into aldoses such as the conversion of ribulose-5-phosphate to ribose-5-phosphate.
c. epimerization of ketoses such as the conversion of xylulose-5-phosphate into ribulose-5-phosphate.
d. TPP-dependent transfer of 2-carbon units to the recipient aldose.
e. transfer of keto groups from C-2 to C-3 of a ketose.
Q:
The polyol pathway is a suspected pathway for diabetic induced cataract formation and involves the enzyme:
a. aldose reductase.
b. glucose-6-phosphate dehydrogenase.
c. phosphopentose isomerase.
d. phosphopentose epimerase.
e. transaldolase.
Q:
Phosphopentose isomerase is quite similar to the reaction and mechanism of the ____ catalyzed reaction.
a. UDP-glucose epimerase
b. phosphoglycerate isomerase
c. phosphopentose epimerase
d. phosphoglucoisomerase
e. all are similar
Q:
The 6-phosphogluconate dehydrogenase reaction is an example of ____ and results in the production of ____.
a. substrate-level phosphorylation; ATP
b. oxidative-decarboxylation; NADPH
c. TPP-assisted decarboxylation; NADH
d. phosphate addition; ADP
e. none of the above
Q:
The ratio of NADP+/NADPH in liver runs about 1/67 which means that:
a. it is similar to the ratio of NAD+/NADH.
b. glucose-6-phosphate dehydrogenase will be turned on most of the time.
c. glucose-6-phosphate is rate limiting for pentose phosphate pathway.
d. glucose-6-phosphate preferentially goes to the pentose phosphate pathway.
e. glucose-6-phosphate dehydrogenase activity is dependent upon use of some of the NADPH before activity increases.
Q:
Characteristics of glucose-6-phosphate dehydrogenase include all EXCEPT:
a. located in the mitochondria.
b. strongly inhibited by [NADPH].
c. inhibited by fatty acid-CoA.
d. uses NADP+ as a coenzyme.
e. forms a cyclic ester (lactone) of 6-phosphogluconate.
Q:
Which of the following occurs as a result of cortisol release from the adrenal gland?
a. activation of gluconeogenesis
b. increased glycogen synthesis
c. activation of the urea cycle
d. increased degradation of muscle protein
e. all of the above
Q:
All are physiological changes initiated by glucagon EXCEPT:
a. activation of glycogenolysis in liver.
b. stimulation of liver gluconeogenesis.
c. long-term maintenance of steady-state levels of glucose in the blood stream.
d. activation of glycogenolysis in muscles.
e. all are true.
Q:
Among the many physiological changes elicited by epinephrine, the initiation of the adenylyl cyclase cascade includes all EXCEPT:
a. activation of glycogenolysis in liver.
b. inhibition of glycogen synthase.
c. stimulation of glycolysis by 2000 fold.
d. activation of glycogenolysis in muscles.
e. all are true
Q:
An individual with von Gierke's disease lacks the enzyme ____ which is a liver enzyme used to maintain ____. As a result, the patient is ____.
a. glycogen synthase; liver glycogen; fat
b. glycogen synthase; ATP levels; weak
c. phosphoprotein phosphatase-1; blood glucose; hypoglycemic
d. glucose-6-phosphatase; blood glucose; hypoglycemic
e. glucose-6-phosphatase; muscle glycogen; weak
Q:
Physiological effects of insulin include all EXCEPT:
a. stimulates glycogen synthesis
b. induces synthesis of glucokinase, PFK-1 and pyruvate kinase
c. stimulates active transport of glucose and amino acids into muscle and adipose tissues
d. stimulates fructose-1,6-bisphosphatase
e. inhibits glycogen phosphorylase
Q:
Insulin in the bloodstream is a response to increased blood glucose, and:
a. stimulates gluconeogenesis.
b. inhibits glycolysis.
c. stimulates glycogen synthesis in muscle and liver.
d. stimulates glycogen breakdown in liver.
e. inhibits phosphoprotein phosphatase-1.
Q:
Which of the following effectors is required for glycogen synthase activity when the enzyme is phosphorylated?
a. glucose-1-phosphate
b. glucose-6-phosphate
c. fructose-1,6-bisphosphate
d. fructose-2,6-bisphosphate
e. UDP-glucose
Q:
Glycogen synthesis and degradation must be carefully controlled at ____ and ____ to properly serve the metabolic needs for the organism.
a. glucokinase; hexokinase
b. hexokinase; glycogen synthase
c. glycogen synthase; glucokinase
d. glycogen phosphorylase; glycogen synthase
e. glycogen phosphorylase; hexokinase
Q:
A blood test for "Glycated hemoglobin" can determine the:
a. present blood glucose concentration.
b. average glucose concentration in the blood over the past several months.
c. level of AGEs in the blood stream.
d. blood glucose concentration over this last month.
e. none are true.
Q:
All are characteristics of AGEs EXCEPT:
a. AGEs mean advanced glycation end-products.
b. Glycated hemoglobin in a patient is an indication of blood glucose levels over the past few months.
c. AGEs generated by elevated blood glucose contribute to circulation, joint and vision problems of diabetics.
d. AGEs form by enzyme catalyzed Schiff base formation between sugars and proteins.
e. AGEs alter the function of the protein to which they are attached.
Q:
The initiation of glycogen synthesis occurs by transfer of glucose from UDP-glucose to the:
a. 4-position of free glucose.
b. 2-position of fructose.
c. non-reducing end of maltose.
d. serine-OH group of glycogen synthase.
e. tyrosine-OH group of glycogenin.
Q:
The energy input for the synthesis of glycogen occurs during which of the following enzyme catalyzed steps?a. phosphoglucomutaseb. UDP-glucose pyrophosphorylasec. glycogen synthased. amylo-(1,4->1,6)-transglycosylasee. none of the above require energy input
Q:
Limit dextrins are degraded by the action of ____ which has two distinct enzymatic activities known as ____ and ____.
Q:
All are true for -amylase EXCEPT:a. catalyzes hydrolysis of (1->4) linkages in starch.b. is an important component of saliva and pancreatic juice.c. catalyzes hydrolysis of (1->6) linkages in amylopectin.d. catalyzes hydrolysis of (1->4) linkages in glycogen.e. activity is reduced in highly branched regions of polysaccharides and stops four residues from any branch point.
Q:
____ phosphorylates and thus ____ the enzyme PFK-2 which simultaneously ____ F-2,6-BPase.
a. adenylate cyclase; activates; inhibits
b. adenylate cyclase; inhibits; activates
c. cAMP-dependent protein kinase; activates; inhibits
d. cAMP-dependent protein kinase; inhibits; activates
e. cAMP-dependent protein kinase; activates; activates
Q:
Cellular levels of fructose-2,6-bisphosphate (F-2,6-BP) are controlled by the tandem enzyme ____ and ____.
a. fructokinase; F-2,6-BPase
b. F-2,6-BPase; PFK-2
c. PFK-2; PFK-1
d. PFK-1; F-2,6-BPase
e. PFK-2; fructokinase
Q:
Which of the following is absolutely essential for the activation of pyruvate carboxylase?
a. high concentrations of acetyl-CoA
b. low levels of ATP
c. high levels of oxaloacetate
d. high levels of TCA cycle intermediates
e. high levels of citrate
Q:
In the Cori cycle, the liver ____ because it has a typically high ____.
a. shares the load of exercising muscle; acetate level
b. converts lactate to lactose; galactose
c. shares the load of exercising muscle; NAD+/NADH ratio
d. burns fat; ATP
e. converts glucose to lactate; NAD+/NADH ratio
Q:
Gluconeogenesis is not simply reversal of glycolysis since 2 pyruvate ï‚®glucose requires the input of ____ equivalents of ATP and ____ equivalents of GTP.
a. 0; 6
b. 2; 4
c. 3; 3
d. 4; 2
e. 6; 0
Q:
Glucose-6-phosphatase is located in the ____ and produces ____ in vesicles that diffuse to the ____ releasing their contents into the blood stream.
a. mitochondria; lactate; cytosol
b. cytosol; glucose; plasma membrane
c. endoplasmic reticulum; glucose-6-phosphate; cytosol
d. endoplasmic reticulum; glucose; plasma membrane
e. cytosol; glucose-6-phosphate; endoplasmic reticulum
Q:
The endoplasmic reticulum bound enzyme that hydrolyzes glucose-6-phosphate to glucose in liver is:
a. glucokinase.
b. glucose oxidase.
c. hexokinase.
d. phosphoglucomutase.
e. glucose-6-phosphatase.
Q:
Which of the following reactions represents the gluconeogenic alternative to the irreversible reaction of PFK-1 in glycolysis?a. fructose-6-P + ADP -> fructose + ATPb. fructose-6-P + H2O -> fructose + Pic. fructose-1,6-bisphosphate + ADP -> fructose-6-P + ATPd. fructose-1,6-bisphosphate + H2O -> fructose-6-P + Pie. none of the above
Q:
The primary regulatory point of gluconeogenesis is ____.
a. glucose-6-phosphatase
b. fructose-1,6-bisphosphatase
c. fructose-2,6-bisphosphatase
d. pyruvate carboxylase
e. PEP carboxykinase
Q:
Pyruvate carboxylase consumes a(n) ____ to drive a carboxylation so that ____ could use the energy from decarboxylation to facilitate formation of PEP.
a. NADH; pyruvate dehydrogenase
b. NADH; lactate dehydrogenase
c. ATP; pyruvate kinase
d. ATP; PEP carboxykinase
e. GTP; nucleotide diphosphate kinase
Q:
All of the enzymes of gluconeogenesis may be found in the cytosol EXCEPT ____ which is only found in the mitochondria.
a. PEP carboxykinase
b. pyruvate carboxylase
c. fructose-1,6-bisphosphatase
d. glucose-6-phosphatase
e. all are only in cytosol
Q:
If levels of ____ and/or ____ are low, pyruvate is directed primarily into ____; but if they are high, pyruvate is converted into ____ for gluconeogenesis.
a. NADH; ATP; glycolysis; OAA
b. ATP; NADPH; glycolysis; acetyl CoA
c. ATP; acetyl CoA; TCA cycle; OAA
d. NAD+; acetyl CoA; TCA cycle; acetyl CoA
e. ATP; acetyl CoA; glycolysis; malate
Q:
The reaction sequence for the pyruvate carboxylase catalyzed reaction is:A. formation of N-carbonyl biotinB. attack of HCO3- on ATPC. liberation of PiD. formation of carbonylphosphateE. C-3 carbanion of pyruvate attack on N-carbonyl biotina. B, D, A, E, Cb. B, D, A, C, Ec. D, C, B, E, Ad. D, B, C, A, Ee. E, C, B, A, D
Q:
In the pyruvate carboxylase catalyzed reaction, bicarbonate is "activated" by attachment to the ____ of ATP to form ____.
Q:
All are required for pyruvate carboxylase EXCEPT:
a. biotin covalently linked to the enzyme.
b. thiamin pyrophosphate (TPP).
c. ATP.
d. acetyl-CoA as an allosteric activator.
e. tetrameric enzyme in the mitochondria.
Q:
Which of the following enzymes is found in gluconeogenesis but not glycolysis?
a. phosphoglucoisomerase
b. glucose-6-phosphatase
c. pyruvate carboxylase
d. fructose-1,6-bisphosphatase
e. PEP carboxykinase