Concepts in Biochemistry, Chapter 20

1. Which metabolic process is a central pathway because of its role in both catabolism and anabolism?
A.Glycolysis
B.Gluconeogenesis
C.Phosphogluconate pathway
D.Citric acid cycle
E.b oxidation of fatty acids
F.Amino acid degradation
G.Oxidative phosphorylation


2. Determine if each metabolic branch point is correctly matched with its characteristics. Enter “yes” if the match is correct, and “no” if the match is incorrect.
_____ Glucose 6-phosphate and Entry point for metabolism of carbon skeletons of aspartate and asparagine
_____ Pyruvate and Links anaerobic and aerobic metabolism
_____ Acetyl CoA and Common product of carbohydrate, fat, and some amino acids
_____ Oxaloacetate and Carbohydrate metabolism

Answer:


3. The energy needs of the brain are:
A.Vary according to glycogen storage levels
B.Are maintained by membrane potentials
C.Constant
D.Decline during sleep


4. The Cori cycle describes the release of lactate from active muscle into the bloodstream and its subsequent uptake by the liver. The lactate in the liver is then used for:
A.Glycogen synthesis
B.ATP phosphorylation
C.Phosphocreatine synthesis
D.Glucose synthesis


5. Under fasting conditions, b oxidation of fatty acids is the primary energy source. All of the following are characteristic of such conditions except:
A.Increased rate of the citric acid cycle
B.Bad breath
C.Increased gluconeogenesis
D.Glucose synthesis from amino acids


6. What do insulin, glucagon, and epinephrine have in common?
A.They increase blood glucose levels.
B.They act through signal transduction.
C.They are all proteins.
D.They are all released by the pancreas.


7. Why do untreated diabetics develop ketosis?
A.They do not consume enough glucose.
B.They have increased glycogen levels.
C.The cells cannot utilize glucose.
D.Fatty acid synthesis is increased.


8. In humans, obesity is not caused by leptin levels, but by malfunctioning signal mechanisms. Which of the following do you think might be affected by high leptin concentrations binding to receptor?
A.Activation of acetyl CoA to malonyl CoA
B.Lipase
C.Phosphogluconate pathway
D.Cholesterol synthesis



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