Term
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Definition
| Phenylalanine, Valine, Tryptophan, Threonine, Isoleucine, Methionine, Histidine, Arginine, Lysine, Leucine |
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Term
| When can cysteine become essential? |
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Definition
| Cysteine becomes essential when methionine becomes low. |
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Term
| When can tyrosine become essential? |
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Definition
| Tyrosine becomes essential when phenylalanine becomes low. |
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Term
| Which protein type is more stable, extracellular or intracellular? |
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Definition
| Extracellular is more stable. Most is associated with the skeleton and other supporting tissues (collagen major component). |
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Term
| Describe Cystic Fibrosis. |
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Definition
| Hardening of pancreas therefore pancreatic enzymes need to be administered exogenously (Bicarbonate, Trypsin, Chymotrypsin, Elastase, Carboxypeptidase A & B) |
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Term
| Briefly describe protein digestion. |
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Definition
| 1) Protein -> Peptides (pepsin and HCl in stomach). 2) Peptides -> Di/Tri Peptides and AA's (aminopeptidase in lumen of small intestine). 3) Di/Tri Peptides -> AA's (Di/Tri Peptidases in intestinal wall) |
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Term
| What is Hartnup's Disease? |
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Definition
| Defect in transport of neutral and aromatic AA's from gut and renal tubules. Symp's similar to pellagra (no Trp = no niacin). Rx = niacin. |
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Term
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Definition
| Defect in transport of basic AA's and cystine (disulfide-linked dimer of cysteine). |
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Term
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Definition
| Absence of lysine. Plants alone don't have a lot of it. |
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Term
| What are the three ways to move free NH4+ around in the body? |
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Definition
| 1) Glutamate dehydrogenase, 2) Glutamine synthase/Glutaminase, 3) Carbamoyl phosphate synthase I & II. (What do they all do?) |
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Term
| Where are Carbamoyl phosphate synthase I and II located? |
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Definition
| I) Mitochondria (urea cycle); 2) Cytoplasm (pyrimidine nucleotide biosythesis) |
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Term
| What is the role of Pyridoxal Phosphate and what vitamin is it? |
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Definition
| Vitamin B6 is involved in: 1) transaminations, 2) decarboxylations, 3) dehydration of B-hydroxyamino acids, 4) racemizations of A-amino acids, 5) removal of H2S from cysteine. |
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Term
| What AA's have amino groups removed by pyridoxal phosphate transaminases? |
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Definition
| A CAT VITAL PAL (Ala, Cys, Arg, Trp, Val, Iso, Tyr, Asp, Lys, Phe, Asn, Leu) |
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Term
| Why do most transaminations converge on glutamate? |
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Definition
| A-Ketoglutarate is frequently used as a reactant. It swaps its hydroxyl group with the amino group of the AA (e.g. alanine) to form glutamate (and pyruvate). |
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Term
| How does glutamate dehydrogenase work? |
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Definition
| NH4+ + NADPH + H+ A-KG < -- > glutamate + NADP+ + H20 |
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Term
| Where is glutamate dehydrogenase located and how is it regulated? |
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Definition
| Located in Mitochondria. ADP and GDP activate (more A-KG). ATP and GTP deactivate (more glutamate) Bottom line: Less energy = More oxidation. |
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Term
| What does an amino acid oxidase do to AA's? Where is it found? What is its cofactor? |
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Definition
| AA + H20 --> A-KA + NH3; Found in kidneys and liver; Flavins are cofactors |
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Term
| What does a dehydratase do to AA's? What is its cofactor? |
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Definition
| Remove NH3 and hydroxyl then replace with carboxylic group. (e.g. serine or threonine to pyruvate). Pyridoxal phosphate is its cofactor. |
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Term
| What does desulfhydrase do? |
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Definition
| Converts homocysteine to A-ketobutyrate which is then disposed of via the odd-chain FA pathway. |
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Term
| What's going on with that crazy urea cycle? |
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Definition
| It's making urea! Orn, Cit (+Asp), Argsucc, Arg (and Fum), Orn (and Urea) |
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Term
| What makes urea a good waste product? |
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Definition
| 1 C, 2 amino groups, can't be protonated, extremely soluble, not reactive |
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Term
| How do urea cycle enzymes fluctuate based on diet? |
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Definition
| As you'd expect: Levels decline in protein free diet (lower % urea in total urinary nitrogen). Opposite for high protein diet and early stages of fasting (ketone body metabolism). |
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