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hunt241 > Lecture 2-Flolate > Flashcards

Lecture 2-Flolate Flashcards

Folate

1
Q

What are key sources of folate in the diet?

A

Dark green leafy vegetables, orange juice, legumes, liver,

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2
Q

Folate is mediatory fortified into what ??

A

Bread
and cereals

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3
Q

What is the difference between folate and folic acid, and what is their relationship to each other?

A

Folate is methyltetrahydrofolate and differs from folic acid by a methyl group and 4 extra
carbons.

Folic acid is a pre vitamin - needs to be reduced to active form of folate = Tetrahydrofolate

They
have different carriers to cross cell walls and carry in blood.

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4
Q

What are the three main functions of folate in the body? For each, list at least three key
components of the relevant pathway

A

DNA synthesis
Purines
DNA methylation

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5
Q

why is liver such an important source of folate

A

mammals store 50% of their folate in their liver, so consuming liver from animals is a useful source

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6
Q

what part of the folate structure can we not make

A
  • Humans can not make the middle bit
  • We can also not combine all three so this is why it is an essential nutrient we get from our diet
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7
Q

what is folic acid

A

being added when the food is fortified

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8
Q

what is food folate

A

naturally present in food

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9
Q

where is folic acid usually found

A

supplements and food fortification

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10
Q

folic acid is in what form and why does this mean it is good to be used in fortification

A

fully oxidised form, it is quite stable and that is why it is used in fortification

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11
Q

which one of food folate of Folic acid either a polyglutatmate or monoglutamate

A

Food folate =polyglutamate
Folic acid = monoglutamate

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12
Q

absorption and cell retention order

A

Gut lumen
Enterocyte
Blood
Cell

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13
Q

when are polyglutamates in absorption of folate

A

when it has entered the enterocyte

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14
Q

what helps more food folate into the cell

A

reduced folate carrier

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15
Q

what helps move folic acid into the cell

A

folate receptor

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16
Q

what is DHFR (dihydrofolate reductase) do

A

add on hydrogens (reduction reaction) to get folate to the active form

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17
Q

add on hydrogens (reduction reaction) to get folate to the active form

A

hydrogens have been added

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18
Q

if converting from food folate to the active form what has changed

A

there has been removal of methyl group by enzymes

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19
Q

how is folate involved in DNA synthesis

A

when there is sufficient folate, dUMP is converted to dTMP and its thymine (one of the four nucleotide bases) is incorporated into DNA

20
Q

what happens to DNA synthesis when there is insufficient folate

A

dUMP is not converted to dTMP, and uracil is misincorperated into DNA

21
Q

purines are what nucleotide bases

A

A and G bases for nucleotides

22
Q

purines are also what

A

part of AMP and GMP, which are converted to ATP and GTP to use as energy currencies

23
Q

what does folate provide for DNA methylation and what is this used for

A

a methyl group which is used for epigenetic modification

24
Q

what is epigenetic modification

A

a critical process in control of gene expression and stabilisation of the genome

25
Q

how is folate linked to DNA methylation

A

tetrahydrofolate has a methyl group added to it

this gets converted to 5-methyltetrahydrofolate

then conversion to methionine, then to SAM

then number of steps to DNA methylation

26
Q

when is homocysteine formed

A

when the amino acid methionine is metabolised to cysteine

27
Q

what are the four possible fates of homocysteine

A
  1. reform s-adenosyl homocysteine (SAH)
  2. remethylation to form methionine
  3. degradation through transulfuration pathway
  4. leaks out of cell if intracellular concentration too high
28
Q

hyperhomocysteinemia is associated with increased risk of what

A

increased risk of CVD and thrombosis

29
Q

if there is not enough folic acid in the diet not enough what will be formed

A

not enough THF will be formed from folic acid

30
Q

if there is not enough 5-methyl THF then not enough what will be formed

A

not enough THF will be formed

31
Q

lacking 5-methyl THF means what for production of methionine

A

means you will not to be able to add on the methyl group to homocysteine to form methionine (stable compound)

32
Q

what is the stable compound that homocysteine is converted to

A

methionine

33
Q

if you are unable to form methionine because you are lacking in 5-methyl THF what will this mean

A

means you will have an increase in the homocysteine concentration and an increase in the SAH molecule as well

34
Q

why will homocysteine levels stay elevated if there is damage to the 5-methyl THF

A

you can not pump all of the homocysteine into SAH so will be left with higher levels of homocysteine

35
Q

a case study on 22 year old female student on a largely CHO diet but not vegetarian reported symptoms of tiredness and breathlessness on minimal exertion, what did she have and what was the reason

A

megaloblastic anaemia due to folate deficiency

36
Q

what are megaloblasts

A

really big compared to normal red blood cells, they are the immature form

37
Q

how is folate linked to meglaloblastic anaemia

A

you need folate to form the nucleotide bases to form DNA

without enough folate proper cell devision does not occur and there for formation of the red blood cell does not happen properly and it enters the circulation still containing its nucleus

38
Q

what is another effect of folate deficiency

A

neural tube defects

39
Q

what are the complications that come with neural tube defects

A

below the defect you will get abnormal nerve conduction, so you will have issues with motor and sensory control / function

40
Q

what are the two main types of neural tube defects and what are they

A

spina bifida (lesion on the spine)

anencephaly (not compatible with life)

41
Q

approximately how many cases of neural tube defects are there in NZ each year

A

approx 64

42
Q

what part of New Zealand has higher rates of neural tube defects

A

the north island

43
Q

what is the folate toxicity rates from naturally occurring folate in foods

A

no risk

44
Q

what is the upper limit of folate for fortified foods or supplements

A

1,000μg/day (adults)

45
Q

what is ministry of health recommendation of RDI and EAR of folate for adult men and women

A

EAR : 320μg/day

RDI : 400μg/day

46
Q

Q
what is ministry of health recommendation of RDI and EAR of folate during pregnancy

A

RDI : 600μg/day

47
Q

why is it important to have fortification of food with folate (pregnancy)

A

~53% of pregnancies are unplanned so they will not be taking a supplement which is why food sources need to be fortified

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