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Vitamins - Water Soluble > Water Soluble Vitamins - Gropper Ch 9 > Flashcards

Water Soluble Vitamins - Gropper Ch 9 Flashcards

1
Q

*

A

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2
Q

B vitamins are divided into which two functional groups?

A
  1. energy releasing
    (thiamin, riboflavin, niacin, pantothenic acid, biotin, pyridoxine)
  2. Hemtopoietic
    (folate, B12, B6, pantothenic acid)
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3
Q

Which B vitamins are required for energy releasing activities? (6)

A 
Thiamin
Riboflavin (FAD)
Niacin (NAD)
Pantothenic acid (acetyl-CoA)
biotin
B6 Pyridoxine
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4
Q

What B vitamins are hematopoietic?

A

folate
B12
B6
pantothenic acid

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5
Q

What is the main coenzyme form of thiamin?

A

thiamin diphosphate (TDP, which is also called thiamin pyrophosphate TPP)

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6
Q

What is the main coenzyme form of riboflavin?

A

flavin adenine dinucleotide (FAD)

and

flavin mononucleotide (FMN)

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7
Q

What is the main coenzyme form of niacin?

A

nicotinamide adenine dinucleotide (NAD)

and

nicotinamide adenine dinucleotide phosphate (NADP)

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8
Q

What is the main coenzyme form of pantothenic acid?

A

Coenzyme A

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9
Q

What is the main coenzyme form of biotin?

A

carboxybiotinyl lysine

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10
Q

What is the main coenzyme form of B6?

A

pyridoxal phosphate (PLP)

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11
Q

What are the main coenzyme forms of folate?

A

tetahydrofolate derivitives

5,10-methylene THF
10-formyl THF
5-formimino THF
5,10-methylenyl THF
5-methyl THF (folate trap - gets stuck in this form if B12 deficient)
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12
Q

What are the coenzyme forms of B12?

A

methylcobalamin

adenosylcobalamin

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13
Q

What are the main biochemical reaction that requires thiamin?

A
  1. oxidative decarboxylation of alpha-ketoacids

(pyruvate dehydrogenase, branched chain keto acid dehydrogenase, alpha-ketoglutarate dehydrogenase

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14
Q

What are the main physiological functions of thaimin? (2 as a coenzyme, 1 non-coenzyme)

A
  1. energy transformation (oxidative decarboxylation of pyruvate, alpha-ketoglutarate, branched chain amino acids)
  2. Synthesis of NADPH and pentoses in the Pentose Phosphate Pathway
  3. membrane and nerve conduction (in a noncoenzyme capacity)
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15
Q

What is the main biochemical function of riboflavin?

A

Flavins act as oxidizing agents because of their ability to accept hydrogen atoms

Their main biochemical function is in electron (hydrogen) transfer reactions

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16
Q

Flavoproteins are required for synthesis or metabolism of which nutrients? (3)

A
  1. B6 (synthesis of the coenzyme form PLP)
  2. folate (synthesis 5-methyl THF)
  3. choline catabolism
17
Q

What is the main biochemical function of niacin?

A

the coenzymes NAD and NADP act as hydrogen donors or acceptors (in redox reactions)

18
Q

What energy producing pathways require NAD as a cofactor? (5)

A
  1. glycolysis
  2. TCA cycle (oxidation of acetyl-CoA)
  3. beta-oxidation of fatty acids
  4. oxidation of ethanol
  5. oxidative decarboxylation of pyruvate to acetyl-CoA (pyruvate dehydrogenase)
19
Q

What biosynthetic pathways require NADPH as a cofactor? (6)

A
  1. fatty acid synthesis
  2. cholesterol and steroid hormone synthesis
  3. deoxyribonucleotide synthesis (precursors to DNA)
  4. glutathione, vitamin C, and thioredoxin regeneration
  5. folate coenzyme synthesis
  6. proline synthesis
20
Q

What is the main biochemical function of pantothenic acid?

A

acyl transfer reactions

21
Q

What are the main functions of pantothenic acid as Coenzyme A? (5)

A
  1. as acetyl-CoA holds the central position in the transformation of energy
  2. pyruvate dehydrogenase requires CoA for the production of acetyl-CoA
  3. Synthesis of cholesterol, bile salts, ketone bodies, fatty acids and steroid hormones requires CoA (HMG-CoA is the key intermediate in these pathways)
  4. phospholipid and sphingomyelin production require CoA
  5. acetylation of some proteins, sugars, and drugs (choline is acetylated to form the neurotransmitter acetylcholine)
22
Q

What is the biochemical function of biotin?

A

CO2 transfer / carboxylation reactions

23
Q

What enzymes (4) require biotin as a cofactor?

A
  1. pyruvate carboxylase (converts pyruvate to oxaloacetate. Replenishes oxaloacetate for TCA cycle and needed for gluconeogenesis)
  2. acetyl-CoA carboxylase (forms malonyl-CoA from acetate. Commits acetate for fatty acid synthesis.)
  3. propionyl-CoA carboxylase (converts propionyl-CoA to methmalonyl-CoA. Metabolism of some amino acids and odd chain fatty acids.)
  4. beta-methlcrotonyl-CoA carboxylase
24
Q

What non-coenzyme roles does biotin play?

A

biotinylation of proteins involved in gene expression (nonhistone and histone proteins)

25
Q

What is the biochemical role of B6?

A
  1. transamination reactions
  2. decarboxylation reactions
    - formation of GABA from glutamate
    - production of serotonin from 5-hydroxy-tryptophan
    - synthesis of histamine from histidine
    - synthesis of dopamine from tyrosine (phenylalanine)

The PLP coenzyme form of B6, PLP, is associated with >100 enzymes, the majority of which are involved in amino acid metabolism

26
Q

What is the main storage site for B6?

A

muscle

75-80% of vitamin B6 stores are found in muscle

5% to 10% are found in the liver

27
Q

Vitamin B6 functions importantly in all of the following except?

transamination of amino acids
modulation of gene expression
synthesis of fatty acids
glycogen breakdown
heme synthesis
A

fatty acid synthesis

28
Q

What is the biochemical role of folate?

A

one-carbon transfer reactions

29
Q

What is the dietary folate equivalent (DFE) of folate from food and folic acid from supplement or enriched foods consumed with a meal?

A

folic acid from supplements is more easily absorbed than natural folate from food.

1 DFE folate = 0.5 DFE from folate taken with meals

30
Q

What are the physiological functions of B12?

A
  1. methylation of homocysteine to methionine
  2. conversion of methlmalonyl-CoA to succinyl-CoA (metabolism of methionine, isoleucine, threonine, and odd chain fatty acids)
31
Q

Intakes of about _________ of vitamin C per day have been shown to maximize the body pool?

A

100 to 200 mg

32
Q

Vitamin C has positive effects on?

frequency of colds
cardiovascular disease
eye health
prevention of skin cancer

A

prevention of skin cancer

Vitamins - Water Soluble (8 decks)

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