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nutr 3330 midterm > folate > Flashcards

folate Flashcards

1
Q

which is found in the body, folate or folic acid?

A

folate

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2
Q

which form is found in supplements and fortified foods, folate or folic acid?

A

folic acid

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3
Q

pteroylglutamate or pteroylglutamic acid is the chemical name for what vitamin?

A

folate

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4
Q

the number of forms of folate corresponds to the number of _____

A

glutamates (5-8)

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5
Q

where does the “action” happen in a folate molecule?

A

at the nitrogens

C units attach at N-5 and N-10 to form coenzyme forms

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6
Q

what needs to happen to folate in order for it to be in its coenzyme form

A

needs to be reduced (hydrogens get added to it)

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7
Q

what is needed in order to convert folate to its coenzyme form?

A

an enzyme (dihydrofolate reductase)

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8
Q

what is the coenzyme form of folate

A

THF (TETRAhydrofolate)

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9
Q

Tetrahydrofolate is the fully ______ state of folate

A

reduced

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10
Q

majority of food folates are _____

A

polyglutamates

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11
Q

since the majority of food folates are polyglutamates, what must happen to it before it can be absorbed?
What is the enzyme involved in this?

A

must be cleaved to mono-glutamate (one glutamate)

Folyl conjugase

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12
Q

list two ways drugs can compete with folate

A
  1. inhibit absorption

2. compete for transport

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13
Q

how is folate transported

A

using folate binding proteins identified in plasma and other tissues

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14
Q

where does folate get transported to?

A

to liver and other cells

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15
Q

how do cells store folate?

A

by adding back glutamates (POLY)

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16
Q

Folate metabolic role

A
  • calling card of folate (THF)
  • acceptor and donor of 1-carbon units
  • important in :
    • AA metabolism
    • nucleotide metabolism
17
Q

amino acid metablism WRT folate

A

1) methionine synthesis
- involves homocysteine (hcy to met)
- folate deficiency will build up homocsyteine
- also needs Vit B12

2) histidine metabolism
- basis for a folate deficiency test; FIGLU

3) interconversion of serine and glycerine
- serine-OH-methyltranferase
- also needs vit B6

all involve transfer of one carbon units

18
Q

Folate and nucleotide metabolism

A

1) synthesis of purines and pyrimidines
- folate is needed
- DNA bases
- Purine: adenine, guanine
- Pyrimidine: uracil, thymine, cytosine

2) DNA synthesis
- crucial for cell division and growth
- folate acts as a coenzyme for enzyme involved in DNA synthesis

19
Q

methotrexate

A
  • chemotherapy drug
  • inhibits dihydrofolate reductase

reduction in dihydrofolate means less THF, less nucelotide synthesis, less DNA , less cancer cell replication

20
Q

folate food sources

A
  • dark green vegetables
  • corn, dried peas, beans, and lentils
  • fortified products
    • white flour, enriched pastas, corn meal
21
Q

Folate deficiency

A
  • usually due to diet
  • could be due to drugs or malabsorption
  • same anemia as Vit B12 deficiency
    • megablastic/ macrolcytic anemia
    • decreaed oxygen carrying capacity of blood
  • weakeness, depression, increased homocysteine
  • neural tube defects ..this is really remarkable about folate and very casia;
22
Q

folate can mask a Vit B12 deficiency

A

if you have either a B12 or a folate deficiency, you will have macrocytic anemia
either will correct the anemia
so if u have inadequate B12 with adequate folate, you will NOT see the anemia

23
Q

what test would you use to diagnose a folate deficiency

A

FIGLU test

also called a histidine load test

24
Q

what is the process of a FIGLU test

A

-give excess histidine
-24hr urine collection
-measure FIGLU in the urine
-if high, then folate deficiency
refer to OH 16

25
Q

what factors should you consider for folate requirements

A
  • Vit B12 deficiency
  • drug interactions
  • women of child-bearing age; supplementation
  • pregnancy
26
Q

dietary folate equivalents

A

DFE=dietary folate equivalent

  • food not the same as supplements
  • food folate LESS bioavailable than supplemental folic acid because it is bound to other food components
  • amount of folate depends on the source
  • cant just say you need ___g folate…depends on source
27
Q

Folic acid supplements and Neural tube defects

A

folic acid supplementation reduces risk of NTDs

28
Q

who should supplement with folic acid

A

all women of child-bearing age…many pregnancies are unplanned

29
Q

Folate can decrease cancer risk

A

DECREASE

  • cancer; DNA damage»>DNA repair
  • folate key role in DNA and RNA synthesis and methylation
  • folate can contribute to genetic stability
  • most evidence for colorectal cancer
30
Q

what is the general relationships found in studies between folate and cancer

A

high folate, lower cancer

low folate, higher cancer

31
Q

folate can increase cancer risk

A

folate can facilitate multiplication of cancer and pre-cancerous cells

-paradoxical acceleration of carcinogenesis

  • core issues:
    • timing of exposure
    • level of exposure
    • folate vs folic acid
32
Q

Homocysteine is an intermediate of what AA metabolism?

A

methionine

33
Q

homocysteine

A

is not present in diet
not incorporated into protein

associated with CVD

possible role in dementia/alzheimers

34
Q

what are the 3 possible fates of homocysteine

A
  1. remethylation to methionine
  2. transsulfuration to cysteine
  3. release into circulation
35
Q

what 3 vitamins are needed to metabolise homocysteine

A

folate
B6
B12

nutr 3330 midterm (13 decks)

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