Block 2: B Complex Vitamins Flashcards

1
Q

Vitamin B1

A

Thiamin

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2
Q

Vitamin B2

A

Riboflavin

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3
Q

Vitamin B3

A

Niacin

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4
Q

Vitamin B5

A

Pantothenic acid

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5
Q

Vitamin B6

A

Pyridoxine

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6
Q

Vitamin B7

A

Biotin

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7
Q

Vitamin B9

A

Folic Acid

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8
Q

Vitamin B12

A

Cyanocobolamin

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9
Q

What is the function of thiamin?

A
  1. Useful for the release of energy from carbs
  2. Appetitie and good health
  3. Normal function of NS
  4. Prevent the avitaminosis beriberi
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10
Q

What enzyme complexes require thiamin pyrophosphate as an essential cofactor?

A

Thiamin catalyzes oxidative decarboxylation reactions:
1. pyruvate dehydrogenase complex
2. Alpha-keoglutarate dehydrogenase complex
3. Branched chain ketoacid dehydrogenase complex

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11
Q

What is beriberi?

A

NS ailment caused by thiamin deficiency -> lethargy and fatigue

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12
Q

Vitamin B2 is a central component of what cofactors?

A

Riboflavin is a component of FMN and FAD

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13
Q

What are the coenzymes produced by B2?

A
  1. Flavin mononucleotide
  2. Flavin adenine dinucleotide
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14
Q

What is the major function of Riboflavin?

A

Electron carrier for the ETC

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15
Q

What are flavoproteins?

A

Enzymes that require FMN or FAD that serves as an electron carrier in the ETC: succinate dehydrogenase and xanthine oxidase

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16
Q

Why is FAD important?

A

Cofactor used in the conversion of succinate to fumarate in the CAC

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17
Q

What is B2 def?

A

Ariboflavinosis: mouth ulcers and inflammation

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18
Q

What is another name for Niacin?

A

Pellagra-preventing factor

Nicotinic acid + vitamin

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19
Q

How is niacin biosynthesized?

A

From L-tryptophan: 60 mg of tryptophan to 1 mg of niacin

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20
Q

What are the chief functions of B3?

A
  1. Part of coenzymes NAD and NADP used in energy metabolism
  2. Critical component of the CAC
  3. Part of the electron transport
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21
Q

What enzymes require NAD+ and NADP?

A

Lactate and malate dehydrogenase

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22
Q

What are the sx of pellegra and how is it treated?

A

Dour D’s of pellagra
1. Depression/dementia
2. Dermatitis
3. Diarrhea
4. Death

Alleviated by casein because it is rich in tryptophan

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23
Q

What is the most common source of Niacin?

A

Nuts for NADs

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24
Q

What is the function of B5?

A

Pantothenic acid is the precursor of CoA

25
Q

What is another name for Vitamin B5? Why?

A

the Greek pantothen meaning from everywhere because it is nearly found in every food

Reason why deficiencies are rare however can cause burning sensation in feet

26
Q

What is CoA?

A

From pantothenic acid and is a major acyl group in biological syntheses (carbon atom transporter)

  • Cellular respiration
  • Biosynthesis of fatty acids, cholesterol, and Ach
27
Q

What are the components of Pantothenic acid?

A

D-pantoate and beta alanine

28
Q

How is vitamin B5 absorbed into the body?

A
  1. In the form of CoA or acyl-carrier protein absorbed lumen and degraded from food to 4’-phosphopantetheine
  2. pantetheine is metabolized by pantetheinase to yield pantothenic acid
  3. Free acid is absorbed into intestinal cells by saturable, sodium dependent active transport system
29
Q

Therapeutic uses of B5?

A
  1. Hair care
  2. Acne
  3. Diabetic peripheral polyneuropathy
  4. Dream stimulant
30
Q

What is the metabolic function of B6?

A

3 forms of B6 are precursors of an activated compound (PLP) required for certain enzymatic activity:
* Transamination and decarboxylation of AA
* Gluconeogenesis
* Formation of niacin/serotonin from tryptophan

31
Q

What are the chemical forms of B6?

A
  1. Pyridoxine (plant)
  2. Pyridoxal (animal)
  3. Pyridoxamine

Active form Pyridoxal phosphate (PLP)

32
Q

What is transamination?

A

Transaminase enzymes breakdown amino acids are dependent on the presence of pyridoxal phosphate

33
Q

What is is transsulfuration?

A

Pyridoxal phosphate is a coenzyme needed for the proper function of enzymes cystathionine synthase and cystathionase (which are needed to transform methionine into cysteine)

34
Q

What is this?

A

Aminotransferase reaction with PLP cofactors

35
Q

Why is B6 essential?

A

Neurotransmitter synthesis of:
1. Tyrptophan to Serotonin
2. E
3. NE
4. Glutamate to GABA
5. Dihydroxyphenylalanine to dopamine

36
Q

What are the sx of B6 def?

A
  1. Atrophic glossitis with ulceration
  2. Angular cheilitis
  3. Somnolence
  4. Confusion
  5. Neuropathy
37
Q

Signs of B6 tox?

A

Sensory neuropathy

38
Q

What is the function of biotin?

A

CO2 transfer is carboxylase enzymes:
1. Acetyl-CoA carboxylase alpha and beta
2. Methylcrotonyl-CoA carboxylase
3. Propionyl-CoA carboxylase
4. Pyruvate carboxylase

39
Q

What is the composition of Biotin?

A

Ureido (tetrahydroimidizole) ring fused with a tetrahydrothiophene ring

40
Q

Describe the role of Malonyl CoA?

A

Derived from acetyl CoA used for chain elongation in FA biosynthesis by MCAT enzyme

41
Q

What are the Biotin sources?

A
  1. Royal jelly
  2. Brewers yeast
42
Q

How is Biotin absorbed

A

Absorption is selective based on food due to biotinidase releasing free biotin

43
Q

Signs of Biotin def?

A
  1. Dermatitis
  2. Alopecia
  3. FLKS
44
Q

Describe the primary function of Folic acid?

A

Serves as acceptors and donars of sungle carbon units in reactions requiring one-carbon transfer
1. Cell division (def leads to anemia)
2. dTMP synthesis

45
Q

What is the active form of Folate

A

Tetrahydrofolate (THF)

46
Q

Describe how B12 def affects B9?

A

Defects in homocysteine methyltransferase can lead to methyl-trap of THF and a subsequent deficiency fo B9

`

47
Q

What is the most common folate carbon carrier form?

A

N5, N10-Methylene H4 folate

48
Q

How does Folate contribute to dTMP synthesis?

A
  1. dUMP (uridine) surrounded by EWG and O2 -> electrophillic
  2. dUMP methylene is attacked by nucleophillic Cys
  3. dTMP (thymidine) is product
49
Q

In what ways is folate beneficial for human reproduction?

A
  1. Folate intake during periconceptual period provides protection against congenital defects (neural tube)
  2. Women who have experience NTD pregnancy and are planning to concieve is placed on 4mg/d of folic acid (10x the RDA)
50
Q

Folate food sources?

A

Liver

51
Q

How is B12 synthesized?

A

Accomplished by bacteria, fungi, and algae but conversion of forms occurs in the body

52
Q

Pernicious anemia is a def in what vitamin?

A

12

53
Q

Describe the structure of B12?

A

Organometallic:
1. Cobalt carbon bond
2. Corrin ring

54
Q

What is are the common forms of B12?

A
  1. Cyanocobalamin (Cyanide artifact after purification process)
  2. Hydroxocobalmin (Injection form)
  3. Methylcobalmin (activated form), cofactor of MTR
55
Q

Describe the process of methyl transfer?

A
56
Q

Decribe the relationship between B12 and 9 in regards to B12 def?

A

Due to folate def since it includes both pernicious anemia and megaloblastosis

Poor DNA synthesis reduces production of thymine

When sufficient folic acid is available, all known B-12 related deficiency syndromes normalize except MUT and MTR

57
Q

What is another name of B12?

A

Extrinsic facotr that binds to intrinsic in parietal gland enabling phagocytosis of the complex by distal ileum cells

58
Q

What are the sx of pernicious anemia?

A
  1. Gastrectomy
  2. IBD/IBS
  3. Defective secretion of intrinsic factor
  4. Chronic pancreatitis
59
Q
  1. Organ meats
  2. Seafood
  3. Eggs
  4. Hot dogs
  5. Milk

Are sources of what vit?

A

12