Metabolic Pathway Integration Flashcards
When blood glucose is abnormally high, the pancreas releases:
(a) adrenaline.
(b) glucagon.
(c) glucose.
(d) insulin.
(e) trypsin
D
When blood glucose is abnormally low, the pancreas releases:
(a) adrenaline.
(b) glucagon.
(c) glucose.
(d) insulin.
(e) trypsin
B
The largest energy store in a well-nourished human is:
(a) ATP in all tissues.
(b) blood glucose.
(c) liver glycogen.
(d) muscle glycogen.
(e) triacylglycerols in adipose tissue
E
The principle target tissues of insulin include
(a) skeletal muscle.
(b) liver.
(c) adipose tissue.
(d) brain
(e) (a), (b) and (c) only
E
Glucose 6-phosphate is an intermediate in which of the following processes?
(a) Gluconeogenesis
(b) Glycolysis
(c) Fatty acid synthesis
(d) Glycogenolysis
(e) Both (a) and (b) are correct
W
In glycolysis moles of NADH are produced per mole of glucose consumed.
(a) 1
(b) 2
(c) 3
(d) 4
(e) 5
B
The conversion of acetyl CoA to malonyl CoA is inhibited by _____
(a) glucagon
(b) adrenaline
(c) palmitoyl-CoA
(d) All of the above are correct.
(e) None of the above are correct
D
Adrenaline triggers an increased rate of glycolysis in muscle by:
(a) activation of hexokinase.
(b) activation of phosphofructokinase-1.
(c) conversion of glycogen phosphorylase a to glycogen phosphorylase b.
(d) inhibition of the Cori Cycle.
(e) the Pasteur effect
B
Glucokinase:
(a) acts in the conversion of liver glycogen to glucose 1-phosphate.
(b) converts fructose-6-phosphate to glucose-6-phosphate
(c) converts glucose 6-phosphate to fructose 6-phosphate.
(d) is a hexokinase isozyme found in liver hepatocytes.
(e) is found in all mammalian tissues
D
The _____ is the site of most gluconeogenesis in mammals.
(a) liver
(b) pancreas
(c) cytosol of all cells
(d) small intestine
(e) kidney
A
Which of the following statements about metabolism in the mammalian liver is false?
(a) Most plasma lipoproteins are synthesized in the liver.
(b) The enzymatic complement of liver tissue changes in response to changes in the diet.
(c) The liver synthesizes most of the urea produced in the body.
(d) The presence of glucose 6-phosphatase makes liver uniquely able to release glucose into the bloodstream.
(e) Under certain conditions, most of the functions of the liver can be performed by other organs
E
Gluconeogenesis shares some, but not all, enzymes with the glycolytic pathway. It would appear to be more efficient if both pathways used all of the same enzymes since the pathways
are essentially the reverses of each other. Why don’t both pathways use all of the same enzymes?
(a) The reactions where enzymes differ occur in different parts of the cell for glycolysis versus gluconeogenesis.
(b) Enzymes can catalyse a reaction only in one direction, so naturally the two pathways have some enzymes that differ.
(c) In tissues where gluconeogenesis occurs, the glycolytic enzymes are present at extremely low concentrations.
(d) Three of the reaction steps in gluconeogenesis would have prohibitively large, positive free energies if they used glycolytic enzymes for their catalysis.
(e) The mechanism underpinning reciprocal regulation emphasises the concept of intelligent design
D
Under starvation conditions, about how long does it take in humans for the body to deplete the glycogen store in the liver?
(a) approx. 1 minute
(b) approx. 1 hours
(c) approx. 24 hours
(d) approx. 1 week
(e) approx. 1 month
C
Acetyl CoA is derived from _____
(a) glucose 6-phosphate.
(b) acetoacetate.
(c) alanine.
(d) fatty acids.
(e) pyruvate.
(f) all of the above options are correct
F
What hormone or enzyme activates the GLUT4 protein to facilitate transport glucose into cells?
(a) adrenaline
(b) insulin
(c) protein kinase A
(d) PFK-2
(e) glucagon
B
Glucagon is excreted when blood glucose is (high, low), while insulin is secreted when blood glucose is (high, low).
(a) high; high
(b) high; low
(c) low; low
(d) low; high
(e) none of the above are correct
D
Which of the options is an acceptable concentration for glucose in the blood of a normal individual?
(a) 5 μM
(b) 5 mM
(c) 50 mM
(d) 0.2 g/dL
(e) (b) and (d) are correct
B
Which of the following tissues can produce glucose by gluconeogenesis?
I. kidney
II. liver
III. adipose tissue
IV. muscle
V. brain
(a) I, II, III, IV, V
(b) I, II, IV, V
(c) I, II
(d) II, IV
(e) II only
C
The maturation of insulin from its precursor (preproinsulin) involves
(a) acetylation.
(b) oxidation.
(c) phosphorylation.
(d) proteolysis.
(e) reduction
D
Which of the following metabolic conversions provides the maximum rate of ATP production (mmol/sec) for muscle contraction?
(a) conversion of muscle glycogen to CO2
(b) conversion of muscle glycogen to lactate
(c) conversion of creatine phosphate to creatine
(d) conversion of fatty acid to CO2
(e) conversion of ketone bodies to acetyl CoA
C
Which of the following is TRUE regarding pancreatic β cells?
(a) Insulin is secreted by the β cells in response to the increase in β cell glucose receptor binding.
(b) Glucagon is secreted by the β cells in response to the increase in β cell glucose receptor binding.
(c) Insulin is secreted by the β cells in response to high glucose levels.
(d) Insulin is secreted by the β cells in response to low glucose levels.
(e) Glucagon is secreted by the β cells in response to high glucose levels
C
Which of the following are effects of insulin secretion?
I. Muscle and adipose tissue are stimulated to take up glucose.
II. Glycogen synthesis increases in the liver.
III. Gluconeogenesis is inhibited in the liver and kidney.
IV. Lipolysis increases in the adipose tissue.
(a) I, II
(b) I
(c) I, II, III
(d) I, III
(e) II, IV
C
Having a high blood glucose level is called _____.
(a) hyperglycemia
(b) diabetic ketoacidosis
(c) hypoglycemia
(d) macrosomia
(e) normoglycemia
A
Which of the following metabolic processes is promoted by insulin?
(a) catabolism of muscle protein
(b) fatty acid oxidation
(c) gluconeogenesis
(d) glycogenesis
(e) lipolysis
Answer (d)
The primary hormonal effects of insulin are the conversion of carbon energy into storage molecules. These actions include the incorporation of glucose into glycogen and the activation of lipogenesis pathways to increase the synthesis of triglycerides