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16 Cards in this Set
- Front
- Back
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What are the essential amino acids?
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Phenylalanine
Valine Tryptophan Threonine Isoleucine Methionine Histidine Arginine Leucine Lysine |
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What are the non-essential amino acids?
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Glycine
Alanine Serine Cysteine Aspartate Asparagine Proline Glutamate Glutamine Arginine Tyrosine |
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Which amino acids become essential if Methionine and Phenolalanine become low in diet?
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Cysteine
Tyrosine |
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What are the 3 sources and 2 utilizations of the amino acid pool?
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1. Tissue Protein Catabolism
2. Dietary Protein 3. Non-Essential Fatty Acid synthesis 1. Amino Acid catabolism 2. Nitrogen cmpd synthesis |
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What are the two maor kinds of protein degradation?
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Lysosomal Pathway - degrades proteins from outside the cell
Ubiquitin Proteosome pathway - degrades proteins from inside the cell. 1. Polyubiquitination 2. Proteosome recognition 3. Protein degraded in proteosome 4. Ubiquitin recycled 5. AAs released to pool |
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Which 3 parts of Nitrogen Metabolism take place in the liver?
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1. AAs release amino groups as ammonia
2. Ammonia is detoxified to urea 3. AA carbon skeletons are used for: - gluconeogenesis - TCA cycle - ketone bodies |
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Which 4 non-protein substances are excreted by the kidneys?
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1. Urea made in the liver
2. Ammonia as ammonium ions 3. Uric acid from purine degradation 4. Creatinine from creatine degradation |
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How are amino acids transported in the renal tubule and GIT?
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Brush border membrane absorms them through a Na+/K+ ATPase secondary transport. They follow their own gradient in the portal vein.
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What two pathologies are related to AA transport?
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Cystinuria - Deficiency of cystine transporter.
- Cystine is excreted in urine rather than reabosorbed. - Cystine stones form in renal tubules Hartnup's disease - neutral AA (tryptophan) transport defect. - increased excretion - NAD deficiency (pellagra) - because niacin is not synthesized from tryptophan, you get the 4 Ds. |
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Provide an overview of AA catabolism
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1. Tissue proteins are broken down to AAs
2. AAs lose their amino groups becoming keto acids 3. Glucogenic AAs are - turned into pyruvate and enter the TCA cycle as intermediates - used in gluconeogenesis 4. Ketogenic AAs are made into acetyl CoA or Ketone bodies. |
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Which amino acids are Ketogenic? Glucogneic? Which are both?
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Ketogenic - leucine, lysine
Both - threonine, isoleucine, phenylalanine, tryptophan, tyrosine Glucogenic - all others - Glycine, Serine, Valine, Histidine, Arginine, Cysteine, Proline, Alanine, Glutamate, Glutamine, Aspartate, Asparagine, Methionine |
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Link the important TCA cycle intermediates formed from amino acids
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Pyruvate - alanine
Acetoacetyl CoA/Acetyl CoA - leucine, lysine a-Ketoglutarate - Glutamate, glutamine Succinyl CoA - isoleucine, valine Fumarate - phenylalanine Oxaloacetate - asparagine, aspartate |
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Discuss alanine metabolism
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Alanine is turned into Pyruvate
1. Alanine transaminase (ALT) takes an amino group from a-ketoglutarate 2. The a-ketoglutarate becomes glutamate 3. The left over alanine becomes pyruvate COENZYME = B6 |
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Discuss glutamate metabolism
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A-ketoglutarate is converted to either glutamate (1 N) or glutamine (2 Ns)
Glutamate - glutamate dehydrogenase Glutamine - glutamine synthetase Both reactions are fully reversible |
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Discuss aspartate metabolism
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Asparagine is turned into oxaloacetate.
1. Asparagine ↔ Aspartate - enzyme: Asparaginase - frees one ammonia 2. Aspartate ↔ oxaloacetate - enzyme: Aspartate transaminase (AST) - coenzyme: a-ketoglutarate ↔ glutamate when it gains an ammonia, B6 Oxaloacetate is turned into asparagine. 1. Oxaloacetate ↔ Aspartate - enzyme: aspartate transaminase (AST) - coenzyme: glutamate ↔ a-ketoglutarate when it loses its ammonia, B6 2. Aspartate ↔ Asparagine - enzyme: asparagine synthetase - co-enzyme: glutamine ↔ glutamate when it loses its ammonia |