Deck 27: Metabolic Integration and Organ Specialization

Question 1

Which of the following enzymes is activated upon phosphorylation by AMP activated protein kinase?

A) acetyl CoA carboxylase
B) phosphofructokinase-2
C) glycogen synthase
D) 3-hydroxy-3-methylglutaryl-CoA reductase
E) none of the above

Answer 1

B

Question 2

All of the following are paired with their preferred substrate EXCEPT:

A) brain: glucose
B) heart: fatty acids
C) resting skeletal muscle: glucose
D) anaerobic skeletal muscle: glucose
E) adipose tissue: fatty acids

Answer 2

C

Question 3

The overall thermodynamic efficiency of metabolism is determined through reaction-coupling with:

A) NADH oxidation.
B) CO₂ release.
C) reduction of O₂.
D) ATP hydrolysis and synthesis.
E) glucose oxidation.

Answer 3

D

Question 4

Which of the following metabolic pathways is strictly anabolic?

A) glycolysis
B) gluconeogenesis
C) citric acid cycle
D) pentose phosphate cycle
E) β-oxidation of fatty acids

Question 5

A constant availability of fuels in the blood is called ____ and the order of preference for fuel usage is ____.

A) phosphorylation potential; glycogen> triacylglycerols> protein
B) fuel dynamics; triacylglycerols> glycogen> protein
C) metabolic regulation; triacylglycerols> glycogen> protein
D) caloric homeostasis; glycogen> triacylglycerols> protein
E) none are true

Question 6

The brain prefers to use ____ as fuel, but under prolonged fasting or starvation it adapts to use ____.

A) fatty acids; glucose
B) glucose; β-hydroxybutyrate
C) glycogen; fatty acids
D) glucose; fatty acids
E) β-hydroxybutyrate; amino acids

Question 7

The two metabolic roles served by ATP are:

A) promoting increased reaction speed and dephosphorylation.
B) changing both K_m and V_max.
C) allosteric regulation and stoichiometric involvement.
D) preventing futile cycles and changing K_m.
E) none of the above.

Question 8

All are characteristics of brain tissue EXCEPT:

A) 2% or so of body mass.
B) 20% of oxygen consumed by brain.
C) oxygen consumption is independent of mental activity.
D) has no significant fuel reserves.
E) all are true.

Question 9

Regulatory enzymes, such as ____, in energy-producing pathways show greater activity at ____ energy charge.

A) fructose-1,6-bisphosphatase; low
B) acetyl-CoA carboxylase; low
C) pyruvate kinase; high
D) PFK-1; low
E) none of the above

Question 10

During fasting or starvation, the brain:

A) converts endogenous fatty acids into β-hydroxybutyrate.
B) utilizes β-hydroxybutyrate from the blood stream.
C) utilizes amino acids for fuel from degradation of brain protein.
D) utilizes its glycogen stores as a first responding source of fuel.
E) all of the above.

Question 11

All are major components of anabolic pathways EXCEPT:

A) NADH.
B) glycolysis and citric acid cycle intermediates.
C) ATP, GTP, CTP, UTP.
D) NADPH.
E) all are true.

Question 12

Which of the following statements is true for ATP stoichiometry in metabolic pathways?

A) It is a consequence of evolution, only.
B) A singular number is not required, only.
C) It results from biological adaptation, only.
D) It cannot be predicted from any chemical considerations, only.
E) All are true

Question 13

____ is the principal energy source for protein synthesis, ____ for phospholipid synthesis, and ____ for polysaccharide synthesis.

A) UTP; GTP; CTP
B) GTP; CTP; UTP
C) CTP; UTP; GTP
D) UTP; CTP; GTP
E) CTP; GTP; UTP

Question 14

____ and ____ are unique in that they are the only compounds whose purpose is to couple the energy-yielding processes of ____ to the energy-consuming reactions of ____.

A) NADH; ATP; catabolism; anabolism
B) ATP; [FADH₂]; catabolism; anabolism
C) [FADH₂]; NADH; anabolism; catabolism
D) ATP; NADPH; catabolism; anabolism
E) ATP; NADPH; anabolism; catabolism

Question 15

An energy charge (EC) of 0.9 is roughly 80% ATP, 17% ADP and 3% AMP. At this EC, ____ enzyme activities are low and ____ enzyme activities higher.

A) ATP generating; ATP utilizing
B) ATP generating; NADH producing
C) ATP utilizing; ATP generating
D) ATP utilizing; NADH producing
E) NADH producing; ATP generating

Question 16

The energy charge of healthy living cells is in the neighborhood of ____.

A) 0.55-0.60
B) 0.60-0.65
C) 0.65-0.75
D) 0.75-0.85
E) 0.85-0.88

Question 17

Muscle contractions occur when a motor nerve impulse causes ____ release from specialized compartments, that bind to ____, a regulatory protein initiating events that result in sliding of ____ thick filaments along ____ thin filaments.

A) Fe⁺⁺; myoglobin; actin; myosin
B) Na⁺; troponin C; IGG; actin
C) Ca⁺⁺; troponin C; myosin; actin
D) Ca⁺⁺; calmodulin; PKC; PLC
E) K⁺; Na⁺/K⁺ ATPase; subunit-α; subunit-β

Question 18

The reaction, ATP + AMP → 2ADP, is catalyzed by:

A) adenylate phosphorylase.
B) AMP-phosphotransferase.
C) ADP mutase.
D) adenylate kinase.
E) none are true.

Question 19

In photoautotrophs, ____ are fed into catabolism to generate the metabolic intermediates needed to supply ____.

A) lipids; photorespiration
B) proteins; photorespiration
C) carbohydrates; anabolism
D) carbohydrates; NADPH
E) proteins; NADPH

Question 20

All are true for the energy charge (EC) of a cell EXCEPT:

A) It is an index of adenylate phosphoric anhydrides.
B) EC has a range of 0 to 1.0.
C) It is a ratio of adenylate phosphoric anhydride bonds to total adenylate concentration.
D) It is 1.0 when all of the adenylate is ATP.
E) It is rapidly changed by adenylate kinase.

Question 21

Fatty acids are released from adipocytes when:

A) insulin levels are high.
B) glycerol-3-phosphate levels are high.
C) adipose ATP levels are high.
D) blood glucose levels are low.
E) none are true.

Question 22

Glucose is pivotal to adipocyte metabolism in all areas EXCEPT:

A) forms DHAP for reduction and esterification of fatty acids.
B) provides glucose-6-phosphate for generating NADPH from the pentose phosphate pathway.
C) synthesizes ketone bodies.
D) converts glucose to fatty acids for storage and export.
E) all are true.

Question 23

During prolonged fasting (more than 48 hours), which of the following would show a dramatically increased concentration in the blood?

A) glucose
B) fatty acids
C) ketone bodies
D) lipoproteins
E) none of the above

Question 24

All of the following are fuels for contracting muscles during strictly anaerobic metabolism EXCEPT:

A) ATP.
B) creatine phosphate.
C) glycogen.
D) glucose.
E) palmitic acid.

Question 25

Which of the following comments regarding resveratrol is INCORRECT?

A) produced in plants, particularly in grape skins, in response to stress
B) activates SIRT1 NAD⁺-dependent deacetylase activity
C) inhibits AMPK in the brain
D) has many of the same effects as caloric restriction
E) all of the above are correct

Question 26

Energy balance in the cell (ATP/ADP/AMP levels) is an important factor in the metabolic pathways we have studied. How does this regulation take place?

A) ATP, ADP and/or AMP bind to DNA to modulate transcription of genes for enzymes involved in metabolism
B) ATP, ADP and/or AMP bind to enzymes involved in metabolism, allosterically changing the enzyme activity
C) High levels of ATP result in nonenzymatic phosphorylation of the enzymes involved in metabolism, changing their activity
D) High levels of ATP result in excessive production of cyclic AMP, causing activation of pathways such as glycogenolysis and gluconeogenesis
E) None of the above

Question 27

Of the following, which tissue is correctly described?

A) brain: use of glucose and fatty acids as fuel
B) pancreas: production of insulin and glucagon
C) adipose tissue: storage of carbohydrates and triacylglycerols
D) liver: overall control of metabolism through hormone production
E) none of the above are correct

Question 28

During strictly anaerobic exercise, muscle cells preferentially:

A) carboxylate pyruvate to oxaloacetate.
B) oxidize pyruvate to acetyl-CoA.
C) decarboxylate pyruvate to acetaldehyde.
D) reduce pyruvate to lactate.
E) none of the above.

Question 29

All are characteristics associated with "brown fat" EXCEPT:

A) high levels of mitochondria rich in cytochromes.
B) presence of uncoupler protein-1, thermogenin, in the mitochondrial inner membrane.
C) energy from oxidation is converted to heat.
D) found in newborns and hibernating animals.
E) all are characteristics.

Question 30

All are characteristics of leptin EXCEPT:

A) it binds to hypothalamus, inhibits release of neuropeptide-Y and is thus an anorexic agent.
B) it is a signal molecule that limits food intake and increases energy expenditure.
C) it communicates the status of triacylglycerol levels in the adipocytes to the central nervous system.
D) if leptin levels are low, appetite is suppressed; and if leptin levels are high, appetite is increased.
E) it induces synthesis of β-oxidation enzymes and increases expression of uncoupler protein-2 (UCP-2) to increase thermogenesis.

Question 31

All are uses of glucose-6-phosphate in liver EXCEPT:

A) catabolized to acetyl-CoA for fatty acid biosynthesis.
B) generate NADPH and pentoses.
C) released as glucose to blood stream.
D) converted to glycogen.
E) all are true.

Question 32

During the fasting phase, which of the following events occurs?

A) release of hormones such as gastrin and cholecystokinin
B) release of insulin by the pancreatic β-cells
C) activation of lipolysis
D) production of glycogen
E) none of the above

Question 33

In addition to carbohydrate and lipid energy metabolism, the liver serves other purposes EXCEPT:

A) producing insulin to regulate metabolism.
B) converting amino acids into metabolic fuel.
C) ketone body production.
D) detoxification of poisons and drugs.
E) Gluconeogenesis.

Question 34

Adipocytes lack the enzyme ____ and thus require DHAP for triacylglycerol synthesis.

A) DHAP reductase
B) glycerol kinase
C) acyldihydroxyacetonephosphate transferase
D) DHAP acyltransferase
E) carnitine acyl transferase

Question 35

Heart muscle differs from skeletal muscle in the following ways EXCEPT:

A) heart is completely aerobic.
B) heart prefers fatty acids as fuel.
C) heart has more phosphocreatine than skeletal muscle.
D) heart has limited quantities of glycogen.
E) all are true.

Question 36

Under strenuous aerobic exercise, which of the following would be true for skeletal muscle?

A) only glucose will serve as a fuel source
B) only fatty acids will serve as a fuel source
C) both glucose and fatty acids will be used as fuel with the use of glucose increasing with the intensity of the exercise
D) both glucose and fatty acids will be used as fuel with the use of fatty acids increasing with the intensity of the exercise
E) none of the above

Question 37

Which of the following hormones that governs eating behavior is INCORRECTLY defined?

A) insulin: stimulation of adipocyte leptin production
B) leptin: appetite suppression when levels are high
C) ghrelin: released from stomach in response to food to further stimulate appetite
D) cholecystokinin: released from the intestines during eating to signal satiety
E) all are correct

Question 38

Energy metabolism in the heart is characterized by all of the following EXCEPT:

A) the preferred fuel is fatty acids.
B) it has minimal energy reserves.
C) it is unusually rich in mitochondria.
D) the heart consumes over 90% of the total oxygen supply during maximal physical exertion.
E) the range of activity is much less than that in muscle (200 fold).

Question 39

During the feeding phase, which of the following pathways would be inhibited in the liver?

A) glycogen synthesis
B) fatty acid synthesis
C) pentose phosphate pathway
D) gluconeogenesis
E) none of the above

Question 40

Ethanol metabolism in liver is characterized by all of the following EXCEPT:

A) decreased pH levels due to lactic acidosis.
B) two oxidation steps to convert ethanol to acetate, both reactions produce NADH.
C) decreased gluconeogenesis activity resulting in hypoglycemia.
D) decreased NADH/NAD⁺ ratio in the cell.
E) increased acetaldehyde-protein adducts impairing protein function.

Question 41

​Discuss the role of ATP in metabolism.

Question 42

Explain the regulatory function of SIRT1 in metabolism.​

Question 43

Under conditions where glucose levels are high and acetyl CoA is needed for fatty acid synthesis, which of the following pathways would NOT be active in adipose tissue?

A) Pentose phosphate pathway
B) Glycogen synthesis
C) Glycolysis
D) Glycerol synthesis from DHAP
E) All of the above would be active

Question 44

Leptin is an important hormone that indicates a generally satisfactory amount of metabolites available in the body. Which of the following is true regarding leptin?

A) Leptin is produced in adipose tissue in response to the presence of large amounts of triacylglycerols
B) One of the results of leptin production is the increase in thermogenesis in adipose tissue brought about through an increase in the expression of thermogenin
C) The primary site of leptin's action is upon the hypothalamus where it ultimately results in the release of norepinephrine
D) All of the above are correct
E) A and C are correct

Question 45

Discuss brown fat.​

Question 46

Discuss the two types of short-term regulators of eating behavior.

Question 47

Discuss energy charge.​