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GI > The "One Carbon Metabolism" B-vitamins (B6, B9, B12) > Flashcards

The "One Carbon Metabolism" B-vitamins (B6, B9, B12) Flashcards

1
Q

Vitamin B6 is

A

Pyridoxine

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2
Q

The supplement form of B6

A

Pyridoxine

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3
Q

The active cofactor form of B6

A

Pyridoxal 5’-phosphate (PLP)

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4
Q

What are the 5 types (more than 100 individual) PLP-dependent reactions?

A

Transaminations, Decarboxylations, 1st step in heme synthesis, one-carbon metabolism, lipid and carb metabolism

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5
Q

Converstion of amino acids to respective ketoacids

-Ex. Glutamate to α ketoglutarate

A

Transamination

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6
Q

Elimination of CO2

-Ex. L-dopa to dopamine

A

Decarboxylations

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7
Q

The first step of heme synthesis, which requires B6 is

A

Succinyl CoA + Glycine = δ Aminolevulinate

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8
Q

Functions in serine-glycine conversion and homocysteine catabolism

A

B6

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9
Q

Functions in sphingolipid synthesis and in muscle glycogen phosphorylase

A

B6

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10
Q

Which 4 things can be caused by vitamin B6 deficiency?

A

Microcytic anemia, convulsions and EEG abnormalities, Hyperhomocysteinemia, and inflammatory disease

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11
Q

Classified as inhibited heme synthesis

A

Microcytic anemia

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12
Q

Cause by inhibited neurotransmitter synthesis (e.g. serotonin, dopamine) and the accumulation of toxic products of tryptophan metabolism

A

convulsions and EEG abnormalities in B6 deficiency

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13
Q

Vitamin B6 deficiency results in inhibited catabolism of

A

Homocysteine

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14
Q

This hyperhomocysteinemia icreases the risk of

A

Vascular disease

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15
Q

Inflammatory bowel disease and rheumatoid arthritis can be caused by

A

PLP deficiency

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16
Q

As inflammation increases, B6 status

A

Decreases

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17
Q

Vitamin B9 is

A

Folate/folic acid

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18
Q

The synthetic, supplement form of folate

A

Folic acid

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19
Q

How many active forms of folate are there?

A

6

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20
Q

Folate functions predominantly in

A

One-carbon metabolism

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21
Q

What are the three types of one-carbon metabolism that folate function in?

A
  1. ) DNA/RNA synthesis
  2. ) Methionine recycling
  3. ) S-adenosylmethionine (SAM) synthesis
22
Q

Folate functions to convert homocysteine to

A

Methionine

23
Q

Folate functions to produce which 3 nucleic acids?

A

Thymidine, Adeniene, and Guanine

24
Q

What are three common pathologies associated with folate deficiency?

A
  1. ) Macrocytic (megalolastic) anemia
  2. ) Hyperhomocysteinemia
  3. ) Neural tube defects
25
Q

Which two neural tube defects can be caused by folate deficiency?

A

Spina bifida and Anencephaly

26
Q

Folic acid reduces

A

Neonatal Deaths

27
Q

Folic acid has also been show to help in primary prevention of

28
Q

Folic acid toxicity may mask

A

B12 deficiency

29
Q

May promote cancer growth

A

Folic acid toxicity

30
Q

What is vitamin B12?

31
Q

The synthetic, supplemental form of Vitamin B12 (cobalamin)

A

Cyanocobalamin

32
Q

There are 4 different forms of B12, which are characterized by their R groups. What are the 4 types of R groups for vitamin B12?

A

CN, OH, CH3, and Deoxyadenosyl

33
Q

The CN and OH forms are the

A

Supplement forms

34
Q

Vitamin B12 requires which three transport proteins for absorption and bioavailability?

A
  1. ) Haptocorrin (HC)
  2. ) Intrinsic Facotr (IF)
  3. ) Transcobalamin (TC)
35
Q

Found in saliva

36
Q

Produced by the parietal cells of the stomach

37
Q

Found in intestinal cells

38
Q

B12 absorption also requires

A

Stomach acid (HCl)

39
Q

What are the two main functions of Vitamin B12?

A

One-carbon metabolism and odd-chain FA metabolism

40
Q

Functions in the same 3 one-carbon metabolism reactions as Folate

41
Q

Functions in the conversion of methylmalonyl CoA to Succinyl CoA in the Krebs cycle

42
Q

What are the three pathologies associated with B12 deficiency?

A

Macrocytic (megaloblastic) Anemia, Hyperhomocysteinemia, and Neurological diseases

43
Q

Can lead to degeneration of the spinal cord

A

B12 deficiency

44
Q

B12 deficiency can also lead to the degeneration of nerves in the

A

Hands and Feet (peripheral neuropathy)

45
Q

Can lead to degeneration of the brain (cognitive impairment and dementia)

A

B12 deficiency

46
Q

What are the two causes of B12 deficiency?

A
  1. ) Dietary deficiency

2. ) Malabsorption

47
Q

Vegans and vegetarians with low intake of animal source foods are at risk for

A

B12 deficiency

48
Q

An autoimmune disorder characterized by a loss of IF in the stomach

-B12 deficiency occurs fast and can be fatal

A

Pernicious anemia

49
Q

The loss of stomach acid which prevents B12 from being absorbed in food

-B12 can be absorbed by pill

A

Atrophic gastritis

50
Q

In Pernicius anemia, patients can not absorb B12 from

A

Food or Pills

51
Q

Vitamin B supplementation helps to slow

A

Brain atrophy

GI (59 decks)

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