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47 Cards in this Set
- Front
- Back
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what is unique about Se incorporation into selenoproteins?
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selenium is inserted into the protein
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what are the functions of glutathione peroxidase, thioredoxin reductase?
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glutathione peroxidase converts peroxide to water and oxygen
if metals interact with peroxide we get hydroxy radical and thats bad thioredoxin reductase is an antioxidant dependent upon Se and it can regenerate Vit C reduce p53 reduce lipid hydroperoxides reduce lipoic acid |
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how is thioredoxin reductase related to vits E and C metabolism?
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thioredoxin reductase helps regenerate vit C
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what is the effect of host Se deficiency on the normally benign coxsackie virus?
** short answer question ** |
when host is Se deficient causes virus to mutate into more dangerous form which can be passed on-- even someone that has enough Se in their body
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what is the evidence for Se in cancer protection, what populations are most likely to benefit?
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shows its protective in early study
--may protect against prostate/colo-rectal cancers one study showed it did not people with low Se status tend to show best results of supplementation of Se if they have cancer-- like Se is most beneficial supplementation to fighting cancer |
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are Se contents of foods homogenous throughout the world? which areas of the world tend to have low amounts of Se in foods? what is the primary determinant for Se content in foods?
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no
washington/oregon, new york, massachusetts where it is grown |
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What might be a downfall of Se supplementation?
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increase risk in type 2 diabetes
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What is the primary bioactive form of Vit E?
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alpha-tocopherol
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What is the primary function of vit E, why is it a good antioxidant?
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antioxidant
very important in terms of lipid membranes good antioxidant because it doesnt become a radical itself afterwards regenerated through vit C |
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Besides direct antioxidant function, what other pathways can vit E influence?
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plays a role in inflammation thru NFKB (nuclear factor kappa-beta)
vit E can reduce activity of NFKB known to inhibit activity of protein kinase C, an important cell signaling molecule inhibit platelet aggregation and to enhance vasodilation |
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How is vit E absorbed?
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like a fat
all you need to know. no specific carrier proteins |
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is there concern for overt vit E deficiency?
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extremely rare
Americans seem to have a hard time getting sufficient amount unless you have a disease like cystic fibrosis or cholestatic liver disease that inhibits fat absorption |
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what have the latest studies suggested about vit E and cardiovascular disease/cancer?
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increase in prostate cancer
and CVD doesnt look any better--but there has been some data suggesting its association with decreased risk of heart attack try to get vit E through the diet as much as you can |
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what type of biological processes is Fe involved with?
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involved in several different enzymes
in heme that carries oxygen around electron transfer oxidative phosphorylation fenton chemistry-- leads to radicals |
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why is too much Fe dangerous?
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it can catalyze fenton chemistry in free radicals
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is Fe deficiency a problem?
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yes both in 3rd and 1st world
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what are some of the Fe overload diseases: what causes them?
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hemochromatosis- absorb too much
sickle cell anemia thalassemia anemia- low iron |
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how is Fe absorbed into enterocytes?
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LOOK at slide
two different transport proteins Heme carrier protein 1 HCP1 dependent divalent metal transporter DMT1 heme iron has its own transportern |
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How is total body Fe distributed, is there a dedicated Fe excretion pathway?
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losing a little through cells sluffing off
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what are the two types of dietary Fe, are they absorbed differently?
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Heme and nonHeme
yes. heme: absorbed as the stable porphyrin complex unaffected by other food nonheme: "free" or weak complexes. food components can trap iron from weak complexes and alters its bioavailability |
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how does hepcidin regulate Fe homeostasis, how is this relevant to: Fe deficiency/overload and infection/inflammation
***short essay answer question** |
..
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how does the IRE/IRP system work? what is the difference between IRP1 and 2? what genes regulated by this system and why are they important to Fe homeostasis?
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LOOK at SLIDE
stem loop structures ferritin gene- on 5 prime |
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what is the function of ferritin, how is ferritin transcriptionally regulated by heme?
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LOOK at SLIDE
to store iron heme causes increase transcription thru antioxidant response element increased transcription and increased translation |
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know some of the Cu dependent enzymes
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superoxide dismutase
cytochrome c oxidase tyrosinase lysyl oxidase hephaestin |
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is Cu deficiency a problem?
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no
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how is copper taken into enterocytes?
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by a protein called CTR1
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what are the chaperones that direct copper in liver cells?
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know them just by looking at them
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what is metallothionein, how is it involved in Cu metabolism?
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protein that binds Cu, Zn
much like ferritin negatively regulates its own self |
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what mutations cause Wilson's disease? Menke's disease? how do these mutations influence Cu homeostasis?
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look at slide
Wilsons- Cu overload -autosomal recessive mutation in gene ATP7B happening in hepatocyte Menke's- Cu deficiency X linked recessive leads to neurological defects mutation in the ATP7A gene happening in enterocyte |
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why is Zn important in biology?
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need for several transcription factors
zinc fingers |
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what are the general functions of ZnT and ZIP proteins?
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ZnT proteins lower intracellular zinc
Zip proteins increase intracellular zinc |
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what is the ZIP protein that imports Zn into enterocytes, what turns this gene off/on?
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Zip 4
expression is increased when dietary zinc is low adequate zinc-- increased MTs |
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is Zn deficiency a problem?
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it can be
especially in elderly populations |
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how is Zn deficiency related to cancer risk?
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Zn needed for P53 which is a tumor suppressor protein
Zn deficiency- p53 not active, not good This binding region (p53) contains zinc, and to coordinate the events related to DNA repair, p53 must be able to bind to specific DNA-binding domains to transcriptionally activate downstream targets involved in DNA repair |
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what populations could benefit from Zn supplements in terms of immune function?
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elderly
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what is epigenetics?
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when we methylate DNA it causes changes in expression
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what nutrients are considered methyl donors?
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be able to recognize them
choline methionine folate alcohol zinc |
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where does DNA methylation normally occur?
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at CpG island
methylation of cytosines is a heritable modification of DNA |
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what is the significance of the agouti mouse experiments?
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your grandmother's diet has an effect on your gene expression
exposed to her diet as an egg inside of your mom |
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what is gene imprinting?
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silence one copy of a gene
epigenetic modification that inactivates one allele of a gene |
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why are dietary methyl donors important in cancer? what are the mechanisms?
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IGF2 loss can result in cancer
(Dutch Hunger winter study -- not enough food, led to genomic imprinting with IGF2 which led to increased cancer) The prevailing hypothesis is that hypermethylation of promoter-associated CpG islands of tumor suppressor genes leads to inactivation of these genes and development or progression of cancer |
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what are the purported health benefits of the anthocyanins? what are good dietary sources?
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anti cancer benefit
ie. colon cancer berries for the most part |
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what is the most convincing health benefit of proanthocyanidins?
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reduced blood pressure when people ate dark chocolate
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what are the main health benefits of reseveratrol? how is resveratrol related to aging?
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anti aging- hasnt been shown in humans
turns on the Sirtuin genes which increase lifespan |
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why are isoflavones biologically active?
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they mimic estrogen
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what does the most current literature say about isoflavones and osteoporosis?
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mixed.
some say yes some say no |
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why might high isoflavone intakes be inappropriate for some?
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because your flooding body with way more "estrogen like" compounds than you should be
so like babies. |
