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16 Cards in this Set
- Front
- Back
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What is the goal of protein digestion?
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The hydrolysis of all peptide bonds to produce free amino acids
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What chemical in the stomach denatures dietary protein?
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Hydrochloric acid
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In the stomach, Pepsinogen is a zymogen activated by acid to give the enzyme Pepsin. True or False?
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True
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What enzymes take over hydrolysis of peptide bonds in the small intestine?
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Proteases such as trypsin chymotrypsin, and carboxypeptidases
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How and where are free amino acids absorbed into the blood stream?
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After active transport across cell membranes lining the intestine, the amino acids are absorbed directly into the bloodstream.
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Define "amino acid pool"
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The entire collection of free amino acids in the body
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Amino nitrogen must either be incorporated into urea and excreted or be used in the synthesis of new nitrogen-containing compounds. What are some of these compounds?
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- Nitric oxide (messenger in nervous system)
- Hormones - Neurotransmitters - Nicotinamide (in NAD+ and NADP+) - Heme (in RBCs) - Purine and pyrimidine bases (for nucleic acids) |
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Define transamination
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- the first step of amino acid catabolism
- the amino group of the amino acid and the keto group of an alpha-keto acid changes place |
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What is the enzyme responsible for catalysing transamination?
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Transaminase; are specific for alpha-ketoglutarate as the amino group acceptor and work with several amino acids
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Define oxidative deamination
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oxidatively removes the glutamate amino group as the ammonium ion to give back alpha-ketoglutarate
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In summary, what does the Urea cycle accomplish?
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- Eliminates C from CO2, N from NH4, and N from the amino acid aspartate as urea
- Breaks four high-energy phosphate bonds - Produces the citric acid cycle intermediate, fumarate |
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What links the Urea cycle with the Citric Acid Cycle?
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Fumarate and aspartate
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What are ketogenic amino acids?
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Amino acids converted to acetoacetyl-SCoA or acetyl-SCoA that enters the ketogenesis pathways
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What is a non-essential amino acid?
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One of 11 amino acids that are synthesised in the body and are therefore not necessary in the diet
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What are essential amino acids?
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An amino acid that cannot be synthesised by the body and thus must be obtained in the diet
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What are the 4 common metabolic intermediates, which play many other roles, are the precursors for synthesis of the non-essential amino acids?
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(1) Pyruvate
(2) Oxaloacetate (3) alpha-ketoglutarate (4) 3-Phosphoglycerate |
