Term
| Group II micronutrients are all involved in what biological function? |
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Definition
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Term
Place the following oxygen species in order of increasing reactivity:
H2O2, O2, OH, O2- |
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Definition
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Term
| Which form of vit E officially contributes to the RDA for this nutrient? |
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Definition
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Term
| alpha, beta, gamma and delta refer to what, when talking about vit E? |
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Definition
| the number & position of ring methyl groups |
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Term
| What are the two classifications of vit E and how do they differ? |
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Definition
Tocopherols: saturated side chains
Tocotrienols: unsaturated side chains |
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Term
| Which classification of vit E is most bioactive, and why? |
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Definition
| tocopherols because they are the best fit to Tocopherol Transfer Protein |
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Term
| What are some common food sources of Vit E? |
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Definition
| nuts, seeds, vegetable oils, leafy greens |
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Term
| What are some indicators of Vit E deficiency? |
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Definition
-lipid malabsorption (adults)
-hemolytic anemia, PNS & CNS damage (adults)
-rentinal degenration (premature infants) |
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Term
| What are some indicators of Vit E toxicity? |
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Definition
fatal cardiac endpoints in high risk CVD clinical trials
infants: heart conditions |
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Term
| Where is the tocopherol transfer protein synthesized? |
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Definition
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Term
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Definition
| sequesters RRA-alpha tocopherol & guides it to VLDL, for transport to various tissues |
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Term
| What would be the result of a mutation in the gene which encodes for TPP? |
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Definition
| -absence of or poorly formed TPP, will result in Vit E deficiency sydromes, neurological disorders |
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Term
| Why don't the beta, gamma and delta forms of tocopherols work well with TPP? |
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Definition
| position & number of their methyl groups mean they don't fit will in the active site |
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Term
| Why don't tocophtrienols work well with TPP |
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Definition
| unsaturated side chains don't fit in the active site |
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Term
| Can active Vit E be regenerated by Vit C? |
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Definition
| in vitro, but not very successful in vivo |
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Term
| Describe the metabolic paths of Vit E |
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Definition
1. Vit E reacts with PUFA peroxyradical, forms a stable vit E radical, then a vit E dimer, is incorporated into bile
2. Vit E reacts with PUFA peroxyradical, forms a stable vit E radical, then quinone and is excreted in the urine.
3. Vit E reacts with PUFA peroxyradical, forms a stable vit E radical,then MIGHT be regenerated by vit C to form active Vit E again. |
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Term
| What proportion of the metabolic product of Vit E is excreted in the urine, vs bile? |
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Definition
Approx 1/3 of vit E radical forms quinone & is excreted in urine
Approx 2/3 of vit E radical forms a vit E dimer & is incorporated into bile |
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Term
| What are some dietary sources of selenium? |
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Definition
-organ meats
-muscle meats
-cereals |
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Term
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Definition
| degeneration of the heart muscle resulting from a selenium deficiency |
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Term
| What are the dietary forms of selenium? |
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Definition
| selenomethionine & selenite |
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Term
| What are selenomethionine & selenite metabolized into in humans? |
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Definition
| both will form the metabolite selenocysteine |
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Term
| What is the 1st line of defense against lipid peroxidation? |
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Definition
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Term
| What is the 2nd line of defense against lipid peroxidation? |
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Definition
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Term
| What is the 3rd line of defense against lipid peroxidation? |
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Definition
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Term
| Why do only some species require Vit C? |
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Definition
| conversion of glucose to gulonolactone to ascorbic acid requires gulonolactone oxidase, some species don't have this enzyme |
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Term
| What are the biologically active forms of Vit C? |
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Definition
| ascorbic acid & dehydroascorbic acid |
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Term
| What are the functions of Vit C |
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Definition
Hyroxylation reactions
-e.g. postranslational modification of procollagen
-hydroxylation in steroid metabolism & neurotransmitters |
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Term
| What are some indicators of a Vit C deficiency? |
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Definition
-hemorrhage
-hair loss
-swollen joints
-poor wound healing |
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Term
True or False
In a Cochrane study, it was found that Vit C is not effective at preventing the common cold in the general adult population |
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Definition
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Term
True or False
Vit C is effective at preventing the common cold in athletes training in subarctic conditions, when consumed regularily |
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Definition
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Term
True or False
Vit E deficiency has been linked with CNS problems |
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Definition
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Term
| What are the biochemical functions of copper, zinc and manganese? |
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Definition
involved in superoxide dismutase reactions
(conversion of O2- to H2O2) |
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Term
| What is the biochemical function of Fe? |
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Definition
| required for hydroxylation reactions |
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Term
| What is the biochemical function of riboflavin? |
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Definition
| it is a prosthetic group for glutathione reductase, to regenerate GSH |
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Term
| What is the biochemical function of niacin? |
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Definition
| needed to form NADPH & required by glutathione reductase |
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Term
| What is the biochemical function of sulfur amino acids? |
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Definition
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Term
| What is the biochemical function of Vit C? |
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Definition
| major reducing agent in the blood |
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Term
| What is the biochemical function of selenium? |
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Definition
| reduces hydrogen peroxide & fatty acid peroxides to stable alcohols & water |
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Term
| What is the biochemical function of Vit E? |
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Definition
| scavenges PUFA peroxy radicals in membrane |
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Term
| How is hydrogen peroxide produced in the body? |
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Definition
1. O2 accepts a single electron to form a super oxide radical O2-
2. O2- is reduced by superoxide dismutase to form hydrogen peroxide |
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Term
| What is the idea means of dealing with hydrogen peroxide produced in the body? |
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Definition
1. Glutathione peroxidase takes 2 electrons from glutathione (GSH) & uses them to detoxify H2O2, forming H2O & GSSG instead.
2. Glutathione reductase uses electrons from NADPH to regenerate GSH from GSSG |
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Term
| What happens in the 'worst case scenario' if H2O2 is not detoxified? |
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Definition
1. H2O2 receives electrons from Cu or Fe to form a reactive hydroxyl radical (HO-)
2. HO- takes a hydrogen & electron from a PUFA ina membrane, forming a PUFA free radical.
3. PUFA free radical reacts with O2 to form PUFA peroxy radical
4. PUFA peroxy radical takes a hydrogen from another PUFA in the membrane, and a resulting chain reaction of lipid peroxidation ensues. |
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Term
| What is a slightly better outcome than propagation of lipid peroxidation, if H2O2 is not detoxified? |
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Definition
1. PUFA peroxy radical reacts with tocopherol to form tocopherol radical
2. PUFA hyroperoxide is still formed but the chain reaction of membrane oxidation is broken |
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Term
| What initiates lipid membrane peroxidation? |
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Definition
| HO- abstracting a H from a PUFA in the membrane |
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