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MBC - Lecture 49

Water Soluble Vitamins II (Mock)

QuestionAnswer
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