Deck 19: Regulation of Mammalian Fuel Metabolism

Question 1

Which of the following pathways is active in the muscle only during the well-fed state?

A) glycolysis
B) fatty acid oxidation
C) glycogen storage
D) ketone body synthesis
E) fatty acid synthesis

Answer 1

glycogen storage

Question 2

Under anaerobic conditions, _____ is produced in the muscle and is then used by the liver for _____.

A) glycerol; triacylglycerol synthesis
B) lactate; gluconeogenesis
C) citrate; fatty acid synthesis
D) oxaloacetate; gluconeogenesis
E) glycogen; glycogenolysis

Answer 2

lactate; gluconeogenesis

Question 3

What type of receptor is the insulin receptor?

A) tyrosine kinase receptor
B) G-protein coupled receptor
C) serine/threonine phosphatase receptor
D) nuclear receptor
E) MAP kinase coupled receptor

Answer 3

tyrosine kinase receptor

Question 4

The $\alpha$ cells of the pancreatic islets secrete _____ in response to _____ glucose levels.

A) insulin; high
B) insulin; low
C) glucagon; high
D) glucagon; low
E) epinephrine; low

Question 5

How does insulin cause an increase in the rate of glucose transport into cells?

A) binds to the glucose transporter causing a conformational change resulting in greater transport velocity
B) activates Na/K ATPase to increase glucose active transport
C) recruits glucose transporters from intracellular vesicles to the cell membrane
D) activates an insulin-dependent porin that allows for rapid glucose transport
E) all of the above

Question 6

Which of the following is an activator of glycogen synthase?

A) AMP
B) UDP-glucose
C) cAMP-dependent protein kinase
D) glucose-6-phosphate
E) all of the above

Question 7

Glycogen phosphorylase has its greatest activity when _____; glycogen synthase has its greatest activity when _____.

A) phosphorylated; not phosphorylated
B) phosphorylated; phosphorylated
C) not phosphorylated; phosphorylated
D) not phosphorylated; not phosphorylated
E) neither enzyme is controlled by phosphorylation

Question 8

The effect of epinephrine upon the liver is most similar to which of the following hormones?

A) insulin
B) glucagon
C) leptin
D) resistin
E) ghrelin

Question 9

Which of the following is a second messenger?

A) cortisol
B) epinephrine
C) ghrelin
D) cyclic AMP
E) none of the above

Question 10

In the liver, activation of AMP-dependent protein kinase occurs when levels of _____ are elevated, resulting in the activation of _____.

A) AMP; acetyl-CoA carboxylase
B) ADP; phosphofructokinase-2
C) ATP; glycogen phosphorylase
D) AMP; fructose-1,6-bisphosphatase
E) ADP; lactate dehydrogenase

Question 11

What hormone is most likely responsible for the body weight set-point?

A) adiponectin
B) cholecystokinin
C) leptin
D) ghrelin
E) all of the above

Question 12

What organelle is found in much higher amounts in brown adipose tissue than white adipose tissue?

A) mitochondria
B) lysosome
C) endoplasmic reticulum
D) chloroplast
E) none of the above

Question 13

Which of the following aspects of brown adipose tissue is responsible for its ability to generate heat?

A) brown adipose tissue contains many small fat droplets instead of one large globule
B) blood flow to brown adipose tissue is larger than to white adipose tissue
C) brown adipose tissue has receptors for norepinephrine
D) the uncoupling protein allows fatty acid oxidation without ATP production
E) none of the above

Question 14

Which of the following is the most common type of diabetes in the US?

A) type 1
B) type 2 resulting from a genetic defect in the insulin receptor
C) type 2 without a genetic defect in the insulin receptor
D) type 3
E) all of the above are about equal in prevalence

Question 15

What happens to excess glucose in the eye that causes diabetics to develop cataracts?

A) oxidized to glucuronic acid causing aggregation of lens proteins
B) reduced to sorbitol causing aggregation of lens proteins
C) non-enzymatic glycosylation of lens proteins
D) oxidized and cyclized to a lactone causing modification of lens proteins
E) none of the above

Question 16

The synthesis of what liver enzyme is inhibited by the drug metformin, an activator of AMPK?

A) phosphofructokinase
B) glycogen phosphorylase
C) acetyl-CoA carboxylase
D) pyruvate carboxylase
E) glucose-6-phosphatase

Question 17

TN $\alpha$ prevents the proper activity of IRS-1 triggering resistance to what hormone?

A) norepinephrine
B) glucagon
C) leptin
D) insulin
E) all of the above

Question 18

Cancer cells express a variant form of pyruvate kinase that has increased activity compared to that of normal cells.

Question 19

In cancerous cells, glucose is often converted into ___which is important for ___.

Question 20

Cancer cells require increased activity of ___ which is achieved by the inhibition of ___.

Question 21

Glutamine, a source of nitrogen for nucleotide synthesis, is also converted to aspartate, another source of nitrogen for nucleotide synthesis. This conversion requires glutamate dehydrogenase and several enzymes of the citric acid cycle.