As part of an experiment, healthy volunteers undergo a 12-hour fast and then drink a solution containing radiolabeled alanine. Consecutive blood samples are drawn every 15 minutes for the next 3 hours. Initial blood samples detect the radiolabeled alanine, but analysis of later samples shows that the radiotracer is present in blood primarily in the form of glucose. Before alanine can be converted to glucose, its amino group is transferred to which of the following?

Question

As part of an experiment, healthy volunteers undergo a 12-hour fast and then drink a solution containing radiolabeled alanine.  Consecutive blood samples are drawn every 15 minutes for the next 3 hours.  Initial blood samples detect the radiolabeled alanine, but analysis of later samples shows that the radiotracer is present in blood primarily in the form of glucose.  Before alanine can be converted to glucose, its amino group is transferred to which of the following?

Quizplus · Accepted Answer

Eductional Objective: Alanine is the major amino acid responsible for transferring nitrogen to the liver for disposal.  During the catabolism of proteins, amino groups are transferred to alpha-ketoglutarate to form glutamate.  Glutamate is then processed in the liver to form urea, the primary disposal form of nitrogen in humans.  Free ammonia is also excreted into the urine by the kidney for regulation of acid-base status.

As Part of an Experiment, Healthy Volunteers Undergo a 12-Hour