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26 Cards in this Set
- Front
- Back
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vitamin c is absorbed by what mechanism?
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active sodium dependent
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Vitamin C is a ____ agent.
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reducing
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Vitamin C is required for what function in collagen biosynthesis? Which other synthesis rxn closely resembles the architectural process of collagen biosynthesis?
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hydroxylation of proline and lysine --- these residuses stabilize the collagen triple helix and form sites for glucose attachment. carnitine synthesis is similar.
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Absorption of what metal is enhanced by vitaminC?
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iron
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How long does vitamin C store last?
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3-4 months
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Thiamin is vitamin B_. What are B2, B3, B5, and B6?
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1. Riboflavin, Niacin, Pantothenic Acid (sounds like pentothenic acid), Pyridoxal Phosphate
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Where is thiamin found?
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Starchy tubers, fortified cereals and grains
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How is thiamin absorbed?
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1) active sodium transport
2) passive transport Both occur - upper intestine |
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TPP is a coenzyme that acts in which two pathways?
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1. oxidative decarboxylation
2. transketolase in PPP |
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Thiamin deficiency is associated with what disease? What does it cause?
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alcoholism; Wernicke's encephalopathy
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How do you measure TPP function?
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erythrocyte TK assay
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Riboflavin is a fluorescent compound that can form which coenzyme?
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FMN. Addition of AMP forms FAD.
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Riboflavin is found where?
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Dairy products
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What are the clinical manifestations of riboflavin deficiency?
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Mild. ariboflavinosis - sores around the mouth; can cause retarded growth in children.
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How to assess riboflavin status?
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erythrocyte glutathione reductase assay (measure oximdation of NADPH to NADP, addition of FAD --- inversely proportional to urinary excretion of riboflavin.
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B3 is derived from what source? What is the cofactor produced from it?
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Tryptophan (meat). 60 mg of tryptophan produces 1 mg of B6 (which gets converted to nicotonic acid). NAD is produced from B3, requires B6.
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B3 production is inhibited by what amino acid?
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high leucine content inhibits transferase
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Lack of niacin causes what disease? What foods can precipate a deficiency?
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Pellagra - diarrhea, dermatitis, dementia. Sorghum can make a person deficient due to high leucine content.
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Pantothenic acid is required for what molecules?
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prosthetic group of both ACP (acyl carrier protein) and CoA (coenzyme A)
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Which reactions is pantothenic acid involved in?
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PDC reaction, TCA cycle, fatty acid oxidation and synthesis, cholesterol synthesis.
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pyridoxal phosphate (b6) is required for WHICH FOUR REACTIONS?
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1. transamination to keto acids (oxidative metabolism)
2. decarboxylation to amines (histamine, dopamine, GABA production 3. synthesis of b3 (niacin) and heme 4. glycogenolysis |
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Biotin is needed for what kinds of rxns?
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CARBOXYLASE reactions. pyruvate carboxylation (gluconeogenesis), acetyl coa carboxylate (fatty acid biosynthesis), propionyl coA carboxylase (propionyl to methylmalonyl to succinate to citric acid cycle)
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Biotin defiency results in...
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fatigue nausea, anorexia, muscle pains, anemia, dry scaly skin. biotin also synth by colonic bacteria.
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What happens to absorbed lipid molecules in enterocytes?
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Monoacylglycerols (long chain) are re-esterified into TAGs.
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What happens to short/medium chain fatty acids?
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Get absorbed in hepatic portal circulation
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B48 is used for?
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cholesterol clearance in the lumen.
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