QUIZ #3 Carbohydrate Structures and Metabolism
64.
What is the net NADH yield when glucose-6-phosphate is converted to lactate via glycolysis?
a. 0 NADH
b. 1 NADH
c. 2 NADH
d. 3 NADH
65.
The oxidation of G-3-P to an acid in glycolysis has a negative delta-G. The energy released in the
reaction is used for:
a. ATP synthesis
b. NADH synthesis
c. Formation of an anhydride
d. NAD+ synthesis
e. Both 2) and 3) are correct
66.
In the liver, which of the following molecules does NOT inhibit glycolysis?
a. ATP
b. low pH
c. Citrate
d. Alanine
e. All of the above will inhibit glycolysis in the liver
67.
When comparing anaerobic glycolysis with aerobic glycolysis, which of the following statements is
TRUE?
a. There is 4-fold more ATP's produced during aerobic glycolysis
b. Anaerobic glycolysis produces 6 ATP while aerobic glycolysis produces only 2 ATP
c. There is no difference in ATP production between the two pathways
d. None of the above statements are true
68.
Which of the following reactions represents an irreversible step in glycolysis?
a. G-6-P --> F-6-P
b. F-1,6-bisP --> G-3-P + DHAP
c. PEP --> pyruvate
d. DHAP --> G-3-P
e. None of the above reactions are irreversible
69.
All of the following enzymes catalyze "irreversible" steps in glycolysis EXCEPT:
a. glucokinase
b. phosphofructokinase
c. aldolase
d. pyruvate kinase
e. All of the above enzymes catalyze irreversible steps in glycolysis
70.
All of the following steps in glycolysis are physiologically irreversible EXCEPT:
a. glucose + ATP --> G-6-P + ADP
b. phosphoenol pyruvate + ADP --> pyruvate + ATP
c. 1,3-bisphosphoglyceric acid + ADP --> 3-phosphoglyceric acid + ATP
d. fructose-6-phosphate + ATP --> fructose-1,6-bisphosphate + ADP
71.
Which of the following statements is TRUE?
a. Mannose is an epimer of galactose
b. Glucose is a ketose
c. Non-superimposable, non-mirror images are called enantiomers
d. Most naturally occurring carbohydrates are of the "L" form
e. None of the above are true
72.
Sucrose contains what type of glycosidic linkage?
a. alpha-1,4
b. beta-1,4
c. alpha-1,2
d. alpha-1,6
e. None of the above are correct
73.
Which of the following is a homodisaccharide with a beta-1,4 linkage?
a. maltose
b. lactose
c. sucrose
d. cellobiose
e. amylose
74.
Inhibition of which of the following enzymes will have the LEAST effect on glycolysis?
a. phosphofructokinase
b. aldolase
c. triose-isomerase
d. G-3-P dehydrogenase
e. pyruvate kinase
75.
Which of the following is/are secreted by the mucosal cells of the digestive system?
a. sucrase
b. secretin
c. lactase
d. only 1) and 3) are correct
e. All of the above (1, 2, and 3) are correct
76.
If phosphoenol pyruvate has a delta-G of - 14KCal/mole, why aren't 2 ATPs produced from the
hydrolysis of PEP during glycolysis?
a. The enzyme, pyruvate kinase, doesn't catalyze the reaction between PEP and 2ADP
b. In an ideal situation, 2ATPs would be produced
c. The reaction is not 100% efficient
d. PEP contains only one phosphate, not two
e. All of the above are true
77.
How many possible stereoisomers exist for a C-6 ketose?
a. 3
b. 4
c. 6
d. 8
e. 16
78.
Which enzyme catalyzes the reaction:
1,3-bis-phosphoglycerate --> 3-phosphoglycerate?
a. glyceraldehyde-3-phosphate dehydrogenase
b. phosphoglycerate mutase
c. phosphoglycerate kinase
d. enolase
e. triose isomerase
79.
"THE" rate limiting step of glycolysis is activated by:
a. AMP
b. Citrate
c. Fructose-1,6-bis-phosphate
d. Alanine
e. None of the above are correct
80.
The following are all effects of insulin on a cell EXCEPT:
a. Activation of glycogen synthase
b. Autophosphorylation of tyrosine residues on the insulin receptor
c. Activation of glycogen phosphorylase
d. Activation of pyruvate dehydrogenase
e. Stimulation of glucose uptake by muscle and adipose cells
81.
Which of the following statements best describes fructose-2,6-bisphosphate?
a. It activates phosphofructokinase (I) in the heart only
b. It is formed by the direct phosphorylation of glucose-6-phosphate
c. It increases the affinity of PFK (I) for F-6-P and blocks the inhibitory effect of ATP
d. It inhibits the synthesis of citrate
e. It is an alternative substrate for aldolase
82.
Glucose + ATP --> G-6-P + ADP. This reaction is:
a. Part of glycolysis
b. Reversible
c. Has a net delta-G = ~ -4KCal/Mol
d. Both 1) and 3) are correct
e. All of the above (1, 2, and 3) are correct
83.
High concentrations of citrate in the cytoplasm inhibits which reaction?
a. F-6-P --> F-1,6-bisP
b. Glucose --> G-6-P
c. PEP --> pyruvate
d. DHAP --> G-3-P
e. None of the above
84.
In a patient with alcohol intolerance, a diminished amount of this substance causes cross-linking of
proteins in the liver.
a. Coenzyme A~SH (CoASH)
b. Acetaldehyde dehydrogenase
c. Alcohol dehydrogenase
d. Antabuse
e. Thiamine pyrophosphate (TPP)
85.
Which of the following will cause hemoglobin to "unload" oxygen?
a. increased [lactic acid]
b. increased pCO2
c. increased [2,3-bisPGA]
d. All of the above are correct
e. None of the above are correct
86.
In muscle cells, G-6-P is converted to glucose by:
a. Phosphoglucomutase
b. Glycogen phosphatase
c. Debranching enzyme
d. Glucose-6-phosphate phosphatase
e. None of the above
87.
Which of the following steps in glycolysis involve(s) the recycling of NAD+ and NADH?
a. PEP --> pyruvate
b. G-3-P -- 1,3-bisPGA
c. 2-PGA --> PEP
d. Pyruvate --> lactate
e. 1) and 4) are correct
f. 2) and 4) are correct
g. 2) and 3) are correct
88.
Which of the following does NOT result from a deficiency in fructokinase?
a. Hypophosphatemia
b. Polyuria
c. Polydipsia
d. Fructosemia
89.
All of the following are features of the hexose-monophosphate shunt EXCEPT :
a. Produces pentose phosphate for nucleic acid biosynthesis
b. Funnels pentoses into glycolysis
c. Production of NADPH for biosnthetic reactions
d. Increases reducing power for oxidative phosphorylation
e. Involves the enzyme G-6-P dehydrogenase
90.
Which of the following is an irreversible step in the pentose phophate pathway?
a. Transketolase
b. Lactonase
c. G-6-P dehydrogenase
d. Transaldolase
e. All of the above catalyze physiologically reversible reactions
91.
During fructose metabolism, why is fructose converted to F-1-P rather than F-6-P?
a. The formation of F-1-P is thermodynamically more favorable
b. The F-6-P molecule is very unstable
c. In order to by-pass the PFK-I regulatory step of glycolysis
d. F-1-P is required in order to make the F-1,6-bisphosphate of glycolysis
e. The Vmax/Km of fructose with fructokinase is greater than with hexokinase
92.
An intolerance for dietary _____ leads to hypoglycemia due to decreased availability of phosphate for
glycogen degradation.
a. Glucose
b. Fructose
c. Lactose
d. Mannose
e. Galactose