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NUTR 3330 Midterm 2 Exam Questions
With Verified Answers
What type of vitamin k has a phytal side chain? - Answers✔Vitamin K1 (phylloquinone)
What type of vitamin k has a isoprene side chain? - Answers✔vitamin K2 (menaquinone)
What type of vitamin k has no side chain? - Answers✔vitamin K3 (menadione)
what are the 2 things GLA is important for? - Answers✔1) blood clotting
2) bone proteins
For what reaction is vitamin k required as a coenzyme - Answers✔carboxylation of glutamic
acid (GLU) to gamma carboxyglutamic acid (GLA)
what is GLAs sole purpose? - Answers✔to interact with calcium
how is vitamin k dependent carboxylation done? - Answers✔glutamic acid residue of vitamin k
dependent proteins
Blood clotting depends on what? - Answers✔- vitamin k
- >12 proteins and calcium
* 7 are vit k dependent proteins
- clotting cascade
How are clotting inactive factors converted to active factors? - Answers✔calcium
why are clotting factors left inactive till activated? - Answers✔Only want blood to clot at certain
times, could cause infarction through body and cause problems
where are vitamin k dependent blood coagulation proteins synthesized? - Answers✔liver
What do vitamin k dependent blood coagulation proteins have and why? - Answers✔- multiple
GLA residues
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- allows for binding of multiple calcium ions which chelates calcium and forms bridge on
membrane of injury site, allows clot to form (FIBRIN)
clotting cascade steps? - Answers✔- prothrombin to thrombin
- fibrinogen to fibrin
- cross linked CLOT
what is the prothrombin time test? - Answers✔- measures how long it tastes for blood to clot
- measures presence of 5 clotting factors
what would high (long) prothrombin time tell us about vitamin k status? - Answers✔low vitamin
k status
steps of the vitamin k cycle? - Answers✔- vit KH2 participates in carboxylation of GLU to GLA
and is converted to vit k epoxide
- vit k epoxide converted to vit k
- vitamin k reduced back to vit KH2
what kind of form is the process of vitamin k cycle - Answers✔cyclical
what are the 2 enzymes important to take vit k epoxide back to vit KH2? - Answers✔- vit k
epoxide reductase
- vit k (quinone) reductase
what is warfarin? - Answers✔- drug prescribed for people at risk for thrombotic events
- also used as a rodenticide
What does warfarin do? - Answers✔- blocks regeneration of vit KH2
- inhibits vit k cycle enzymes: vit k (quinone) reductase, vit k epoxide reductase
- decreases blood clotting
should patients taking warfarin decrease their vit k intake - Answers✔Don't want too much
vitamin k, consume less leafy greens, as its going against what warfarin is doing
what is bone GLA protein (BGP) OR osteocalcin synthesized by and what does it do? -
Answers✔- by osteoBLASTS
- promotes bone mineralization (^ in bone especially growing bone)
where is matrix GLA protein (MGP) found and what does it do? - Answers✔- found in bone &
blood vessels
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- reduces calcification of blood vessels (CVD implications)
how many GLA residues does BGP and MGP have? - Answers✔- BPG: 3
- GLA: 5
vitamin k food sources? - Answers✔- phylloquinone: green leafy vegs (collards, spinach, kale,
broccoli), soybean & canola oil
- menaquinone: fermented foods (natto japanese fermented soy)
Why is vitamin k deficiency uncommon in healthy adults? - Answers✔- widespread in food
- vit K cycle (conserves vit)
- microbiological flora of gut (menaquinone)
Vitamin K deficiency symptoms - Answers✔- prolonged blood clotting time
- easy bruising and bleeding
susceptible groups to vit K deficiency? - Answers✔- long antibiotic use
- newborns breastfed
> poor source
> lactating moms need supplement
hemorrhagic disease of newborn a.k.a vit k deficiency bleeding (VKDB) - Answers✔- bleeding
doesn't stop can cause fatal brain hemorrhage
- need prophylactic vit k (injection) at birth
how are vitamin k status and COVID 19 associated? - Answers✔- thromboembolism occurs in
COVID-19 patients (blood clot in vessel comes loose and blocks another vessel)
- vit k used to help blood clot & reduces amount of GLA protein
- patients had ^ inactive matrix GLA protein
how is vitamin k associated with cognition? - Answers✔- gut microbiota derived menaquinone
affects role of gut microbiota in cognition
how are iron status body pools studied? - Answers✔samples of blood and bone marrow easily
what is the most common worldwide nutritional deficiency? - Answers✔- iron
- >30% worldwide have this
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