Biochem chapter 27

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Question Answer
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
All are major components of anabolic pathways EXCEPT:
a. NADH.
b. glycolysis and citric acid cycle intermediates .
e. all are true.
_______ is the principal energy source for protein synthesis, ______ for phospholipid synthesis, and ______ for polysaccharide synthesis.
___ 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
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
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.
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
The two metabolic roles served by ATP are:
a. promoting increased reaction speed and dephosphorylation.
b. changing both Km and Vmax.
c. allosteric regulation and stoichiometric involvement.
d. preventing futile cycles and changing Km.
e. none of the above.
The reaction, ATP + AMP → 2ADP, is catalyzed by:a. adenylate phosphorylase.
b. AMP-phosphotransferase.
c. ADP mutase.
d. adenylate kinase.
e. none are true.
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 Answer
Regulatory enzymes, such as ________, in energy-producing pathways show greater activity at _________ energy charge.
a. TPI; high
b. acetyl-CoA carboxylase; low
c. pyruvate kinase; high
d. PFK-1; low
e. all are true
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. R; U
b. R; S
c. U; R
d. U; S
e. S; R
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
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
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
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
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.
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
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.
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 Answer
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.
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.
What is the general order of available energy sources in muscles during strenuous exertion?
a. glycogen > ATP > glucose > fatty acids > phosphocreatine
b. ATP > phosphocreatine > glycogen >glucose > fatty acids
c. phosphocreatine > glucose > ATP > fatty acids > glycogen
d. ATP > glycogen > phosphocreatine > fatty acids > glucose
e. phosphocreatine > ATP > fatty acids > glucose > glycogen
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.
The 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).
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.
Adipocytes lack the enzyme ____________ so that the futile cycle of triacylglycerol hydrolysis and synthesis is prevented.
a. DHAP reductase
b. glycerol kinase
c. glucose-6-phosphate dehydrogenase
d. acetyl-CoA carboxylase
e. carnitine acyl transferase
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
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.
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 Answer
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
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.
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
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.
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

Study Objectives

Question Answer
How is energy charge defined?Phosphorylation potential, which is defined by the relative concentrations of ATP, ADP, and Pi. Higher levels signifying more ATP, and therefore a greater phosphorylation potential.
AMP-activated protein kinase AMPKcellular energy senor. Metabolic inputs to this sensor determine whether its output, protein kinase activity, takes place. AMPK is inactive when cellular energy levels are high, as signaled by high ATP concentrations.