Urea synthesis occurs partly in the mitochondria and partly in the cytosol of the ____.
A) glomeruli
B) tubules
C) enterocytes
D) hepatocytes
Q. 2Three important enzymes remove ammonia from body cells. One is carbamoyl phosphate synthetase I. What are the other two?
A) branched-chain alpha-keto acid dehydrogenase and phenylalanine hydroxylase
B) alanine aminotransferase and aspartate aminotransferase
C) glutaminase and threonine dehydratase
D) glutamate dehydrogenase and glutamine synthetase
Q. 3Which three amino acids cannot undergo transamination to an appreciable extent, making provision of their alpha-keto acids ineffective in lowering blood nitrogen concentrations in kidney disease patients?
A) leucine, isoleucine, valine
B) lysine, threonine, histidine
C) valine, tryptophan, phenylalanine
D) methionine, cysteine, phenylalanine
Q. 4Which organ serves as the primary site of amino acid metabolism?
A) kidney
B) muscles
C) liver
D) neuropeptides
Q. 5What is the primary mechanism for regulation of amino acids in excess of need for synthesis of protein, providing about 50 of the liver energy needs after a meal?
A) oxidation
B) decarboxylation
C) phosphorylation
D) hydrogenation
Q. 6During protein digestion, peptides are broken into free amino acids mainly ____.
A) in the mouth
B) in the stomach
C) at the brush border
D) within the enterocyte
Q. 7In general, most amino acids are absorbed from the ____.
A) stomach
B) duodenum and jejunum
C) ileum
D) colon
Q. 8Which regulatory peptides in the pancreatic phase of digestion activate the release of brush-border enzymes such as enteropeptidase?
A) trypsinogen and trypsin
B) cholecystokinin and secretin
C) carboxypeptidase A and B
D) elastin and chymotrypsin
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