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Questions and Answers
What is the enzyme responsible for converting γ-glutamyl-cysteine to cysteine?
What is the consequence of a deficiency in glutathione synthetase enzyme?
What is the role of γ-glutamyl transpeptidase in the γ-glutamyl cycle?
What is the function of pepsinogen in protein digestion?
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What is the source of amino acids in the amino acid pool?
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What is the byproduct of the reaction catalyzed by oxoprolinase?
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How are amino acids absorbed from the small intestine?
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What is the energy source for the sodium-amino acid carrier system?
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What is the function of the Na/K+ pump in amino acid absorption?
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Where are amino acids absorbed from in the digestive system?
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What is the result of protein digestion in the stomach?
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What is the primary fate of the products resulting from deamination?
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What is the role of transamination reactions in amino acid catabolism?
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What is the byproduct of oxidative deamination reactions?
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What is the purpose of the catabolic pathway of amino acids?
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Which of the following compounds is involved in transamination reactions?
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What is the primary function of the amino acid pool?
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What is the byproduct of the transamination reaction between glutamic acid and pyruvic acid?
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Which enzyme catalyzes the transamination reaction between glutamic acid and oxaloacetic acid?
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What is the diagnostic value of transaminases in the blood?
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What does an increase in the level of both ALT and AST indicate?
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What does an increase in the level of AST alone suggest?
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Study Notes
Amino Acid Pool and Catabolism
- Amino acids can be categorized into essential and non-essential amino acids
- Non-essential amino acids can be synthesized in the body
- Catabolism of amino acids occurs through deamination, which involves the removal of the amino group
- Deamination can occur through oxidative deamination, transamination, or transdeamination
- Oxidative deamination involves the oxidation and deamination of amino acids to form α-keto acids and ammonia
- Transamination involves the transfer of an amino group from one α-amino acid to an α-keto acid to form a new α-amino acid and a new α-keto acid
- Transdeamination involves the removal of the amino group from an amino acid to form an α-keto acid and ammonia
Amino Acid Absorption
- Amino acids are absorbed from the small intestine through passive and active transport mechanisms
- The carrier protein transport system (sodium-amino acid carrier system) is an active transport mechanism that uses energy from the Na+/K+ pump
- The glutathione transport system (γ-glutamyl cycle) is another active transport mechanism
- Oxoprolinuria is an inherited disorder caused by a deficiency of glutathione synthetase, leading to increased levels of 5-oxoproline in the blood and urine, acidosis, and neurological damage
Protein Digestion and Absorption
- Proteins are denatured by gastric HCl and then broken down into large peptides and some free amino acids by pepsin
- Large peptides are further broken down into smaller peptides and free amino acids
- Amino acids are absorbed from the small intestine through passive and active transport mechanisms
- The absorbed amino acids are transported to the liver through the portal blood
Transamination and Transaminases
- Transaminases are enzymes that catalyze the transfer of an amino group from an α-amino acid to an α-keto acid
- Examples of transaminases include alanine transaminase (ALT) and aspartate transaminase (AST)
- ALT catalyzes the reaction between glutamic acid and pyruvic acid to form alanine and α-keto glutarate
- AST catalyzes the reaction between glutamic acid and oxaloacetic acid to form aspartic acid and α-keto glutarate
- Transaminases are elevated in the blood when there is damage to cells that produce these enzymes, such as liver cells, heart muscle cells, or skeletal muscle cells
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Description
This quiz covers the process of protein digestion, including the role of enzymes and gastric HCL, and the absorption of amino acids in the small intestine. It explains how proteins are broken down into smaller peptides and amino acids, and how these are absorbed into the bloodstream.