Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
26 Cards in this Set
- Front
- Back
Recognize the importance of glutamine and alanine as carriers of amino nitrogen. |
a. During overnight fast, muscle proteins are degraded to create free amino acids to maintain “amino acid pool”
ii. Used as carriers for nitrogen between the liver and kidneys for gluconeogenesis iii. Alanine major gluconeogenic AA |
|
Explain the general rules of biosynthesis for non-essential amino acids. |
a. Synthesized from glucose and ammoniab. 2 of the 11 (cysteine and tyrosine) require an essential for synthesis (methionine and phenylalanine respectively) i. During times of malnutrition (inadequate dietary AA intake) body is most affected by lack of the 9 essential AAs, and inability to synthesize cysteine and tyrosine ii. Cysteine requires Methionine and Tyrosine requires Phenylalanine |
|
List the amino acids that are essential/non-essential and glucogenic/ketogenic. |
a. Essential: i. phenylalanine, valine, tryptophan, threonine, isoleucine, methionine, histidine, leucine, lysine b. Non-essential: i. alanine, arginine*, aspartate, asparagine, cysteine, glutamate, glutamine, glycine, proline, serine, tyrosine All A’s, All G’s P.S. CysTyr (like sister) ii. Arginine can be synthesized de novo, but called essential because infant synthesis is too slow c. Ketogenic (produce acetyl CoA, acetoacetate, and/or B-hydroxybutyrate): i. leucine and lysine (LEUCy LYS) d. Both keto/glucogenic: i. tyrosine, phenylalanine, isoleucine, tryptophan, threonine [ISO (I saw) THREe PHat TYRes on my TRYP to RehoBOTH beach] or [ISO (I’m so) tyred of trying to phart thrillers] e. Glucogenic (AAs that are converted to TCA intermediates): i. alanine, arginine, asparagine, aspartate, cysteine, glutamate, glutamine, glycine, proline, serine, valine, histidine, methionine From SMD17: AAAAGGG! Can Someone Please Verify His Marriage? ii. either feed into TCA, or generate glucose |
|
Explain the importance of the enzymatic reaction in amino acid metabolism. |
Enzymatic reactions must occur to AAs before they can be used for energy (because they contain N (2 reactions occur to remove the N (Aminotransferase/transaminase rxn, glutamate deH rxn) |
|
For aminotransferase reactions explain: their biochemical importance. |
|
|
For the oxidative deamination reaction, relate that: 1) glutamate is the only amino acid that undergoes rapid oxidative deamination, 2) the glutamate dehydrogenase enzyme has allosteric activators and inhibitors, and 3) the clinical ramifications of mutations in the glutamate dehydrogenase enzyme. |
Genetic mutations in the glutamate dehydrogenase enzyme can cause hyperinsulinism and hyperammonemia |
|
Explain the glutamate dehydrogenase cycle and understand the importance of regenerating a-ketoglutarate. |
Purpose - take amino group from one amino acid and transfer it to another carbon skeleton, in order to: Eliminate the amino group and generate energy create a different amino acid |
|
List the reasons why ammonia is neurologically and biochemically toxic. |
Free ammonia in the blood is toxic at concentrations greater than 70 μM (20-50 μM normal) Ammonia has depressant effects on the CNS (similar to barbituates) Ammonia alters activity of GABA (inhibitory neurotransmitter) Ammonia decreases activity of TCA cycleAmmonia in the blood results in high levels of glutamine, which is directly toxic to the brain A failure to generate urea leads to an accumulation of ammonia in the blood (hyperammonemia) Ammonia is normally rapidly removed from the blood by the liver (glutamine and alanine carry amino nitrogen to the liver) In the liver, ammonia is removed by the generation of urea |
|
Describe the two ways to eliminate ammonia: 1) through the liver, |
Elimination of ammonia through the liver – Urea Cycle Primary mode of elimination: Carried out within the cytosol and mitochondrion of liver cells Glutamate dehydrogenase (GDH) converts glutamate to alpha-ketoglutarate and NH4NH4 is converted to urea, which is excreted in urine Elimination of ammonia through the kidney Secondary mode of elimination: In the kidney, glutamine is hydrolyzed by renal glutaminase releasing ammonia to the urineThe excretion of am |
|
Identify the importance of alanine and glutamine in amino nitrogen transport. |
Alanine transports 1 Nitrogen and glutamine transports 2.
Amino group from Glutamate + pyruvate = Ala Glutamine synthase makes glutamine from glutamate. |
|
Diagram the urea cycle including enzymes. |
|
|
During metabolic acidosis, explain: How the urea cycle is regulated |
|
|
Explain how the inhibitor of purine catabolism, allopurinol, is used to diagnose carriers of OTCD. |
|
|
Explain why the body does not use the kidney for excretion of ammonium ion under normal metabolic conditions. |
|
|
Describe elimination of ammonia through the kidney |
Elimination of ammonia through the kidney:
|
|
For aminotransferase reactions explain the amino acids that undergo the reaction |
Amino Acids that undergo aminotransferase reactions18 out of 20 amino acids undergo transamination reactionsLysine and threonine are exceptionsThe aminotransferase is named from the original acid donor |
|
For aminotransferase reactions explain the requirement for PLP |
Requirement for PLP (Vitamin B6)All aminotransferases require PLP coenzymePLP acts as the intermediate by forming Schiff bases |
|
For aminotransferase reactions explain the reason ALT and AST are two of the most important transaminases. |
ALT and AST are two of the most important aminotransferasesALT = alanine aminotransferasePresent in almost all tissuesRequires PLPreversible reaction, but during catabolism this enzyme functions to generate glutamate and pyruvateAlanine is the major gluconeogenic amino acidAST = Aspartate aminotransferasePresent in the liver and kidneyRequires PLPReversible reactionAspartate levels are important in liver because aspartate donates one of the two nitrogen atoms in the formation of urea |
|
Diagram all intersections of Glycolysis/TCA cycle and amino acid metabolism |
|
|
Diagram the rate limiting step of the urea cycle. |
|
|
Ketogenicvs. Glucogenic amino Acids. |
|
|
Urea cycle disorders
|
|
|
Effects of Deficient Urea cycle |
|
|
What are the clinical symptoms of Ammonia accumulation in the brain? |
|
|
What is the treatment for hyperammonemia? |
|
|
Name as many UCDs as possible. |
|