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MBC - Lecture 49
Water Soluble Vitamins II (Mock)
| Question | Answer |
|---|---|
| Lecture 49 | Water Soluble Vitamins II |
| Active form of pyridoxine is ___. | pyridoxine phosphate |
| Manifestations of pyridoxine deficiency are: | irritability, depression, neuropathy, and convulsions |
| Pyridoxine deficiency symptoms arise from interference of ___ synthesis. | neurotransmitter |
| B6 dependent synthesis processes are: | dopamine/norepinephrine/epinephrine, serotonin/melatonin, GABA |
| B6 dependent step in synthesis of dopamine, norepinephrine, and epinephrine is ___. | DOPA decarboxylase |
| B6 dependent step in synthesis of GABA is ___ | glutamate decarboxylase |
| Pyridoxine responsive anemia is caused by defective ___. | ALAS2 (gene coding for an aminolevulinic acid synthase) |
| AST/SGOT | Catalyzes the reversible transamination of L-aspartate and α-ketoglutarate to oxaloacetate and L-glutamate |
| High prevalence of low B6 in young women was assessed by ___. | tryptophan load test |
| Tryptophan load test measures ___ in the urine, the B6 dependent step. | kynurenine |
| Activation Coefficient | [Activity after B6] / [Activity before B6] |
| Normal activation coefficient is ___. | stable (goes up only a small amount after supplement) |
| Abnormal activation coefficient has a ___ coefficient. | high (drastically increased activity after supplement) |
| Folic acid is a ___ donor. | methyl |
| Tetrahydrofolate is a ___ carrier. | 1-carbon |
| Methylene Tetrahydrofolate Reductase | Catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5-methyltetradehydrofolate |
| Formation of cysteine from homocysteine is a ___ dependent step. | vitamin b12 |
| Folate deficiency causes: | inadequate intake, impaired absorption (alcoholism, GI disease), impaired metabolism (B12 deficiency, methotrexate), increased requirement (lactation, pregnancy, neural tube defects), anticonvulsants/OCP, |
| Vitamin B12 Structure | Cobalamin (corrin ring with central cobalt), deoxyadenosylcobalamin, methylcobalamin |
| Binding of B12 to ___ is essential for absorption in the ___. | intrinsic factor, distal ileum |
| Pernicious Anemia | Megaloblastic anemia, fatal degeneration of spinal cord, treated with EF from liver |
| B12 binds to ___. | R protein |
| ___ digests R, releasing B12 for binding to IF. | Pancreatic proteases |
| The B12 enzymes are: | MMCoA mutase and methionine synthase |
| Methionine Synthase | Catalyzes the formation of methyl B12 from hydroxy B12 |
| MMCoA Mutase deficiency leads to ___. | methylmalonic aciduria |
| Folate and B12 deficiency both cause ___. | megaloblastic anemia |
| Folate Trap Hypothesis | Folate is trapped in the N5-MTHF form if B12 deficient, unable to regenerate tetrahydrofolate |
| Folate treatment without B12 treatment can ___ or ___ B12 neurologic damage. | precipitate or mask |
| The only source of cobalamin are foods of ___ origin. | animal |
| Strict vegan diets will eventually lead to ___ deficiency, but takes years (10-12). | B12 |
| Gulonolactone Oxidase | Catalyzes the synthesis of ascorbic acid from gulonolactone |
| Vitamin C (ascorbic acid) is an ___ vitamin in humans, derived from ___ sources. | essential, exogenous |
| Ascorbate is important in: | collagen biosynthesis, tyrosine degradation, epinephrine/carnitine synthesis, bile acid synthesis, iron absorption, bone mineral metabolism, antioxidant |
| Scurvy | Vitamin C deficiency, failure in matrix and collagen, heavily mineralized bones, bleeding underneath the bone (“bone-in-a-bone”) |
| Ecchymosis, purpura, and petechia are ___, most likely due to ___ synthesis. | sub-dermal bleedings, collagen |
Created by:
emyang
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