B Vitamins

Question 1

Thiamin (B1)

Answer 1

Essential for ATP from glucose, and acetylcholine

Essential to the production of ATP from glucose
Required for the reaction that forms Acetyl CoA from pyruvate

Question 2

Thiamin (B1) Deficiency

Answer 2

Beriberi
Extreme weakness and fatigue
Occurs in alcoholics due to poor diet and decreased thiamin absorption

Question 3

Riboflavin (B2)

Answer 3

Forms FAD and FMN: so important for fat, carb, protein metabolism

Forms the active coenzymes flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN)

Question 4

Riboflavin (B2) Deficiency

Answer 4

Symptoms include inflammation of lips, mouth and tongue
Scaly, greasy skin eruptions
Deficiency is rarely seen alone-usually in conjunction with other B vitamins

Question 5

Niacin (B3)

Answer 5

Can be synthesized from tryptophan, required for NAD and NADP-so important in a lot of rxns

Can be synthesized in the body from the essential amino acid tryptophan if the diet is adequate in tryptophan
Required for synthesis of NAD and NADP so has key roles in virtually all aspects of metabolism
Important for reactions that synthesize other molecules

Question 6

Niacin (B3) Deficiency

Answer 6

Pellagra
Deficiency leads to 3Ds: Dermatitis, Dementia, Diarrhea
If untreated –> Death
GI symptoms include a bright-red tongue, vomiting, constipation or diarrhea
Mental symptoms include irritability, headaches, loss of memory, insomnia, psychosis and delirium

Question 7

Biotin (B7)

Answer 7

Functions in metabolism of fatty acids and amino acids and glucose synthesis

Question 8

Pantothenic Acid (B5)

Answer 8

Part of coenzyme A (CoA)

Coenzyme A is part of acetyl-CoA

Question 9

Vitamin B6

Answer 9

For aa acid, hemoglobin, neurotransmitters and myelin synthesis, converting tryptophan to niacin, glycogen metabolism and transamination and deamination rxns of amino acids

Need for conversion of tryptophan to niacin
Needed for metabolism of glycogen
Needed for synthesis of neurotransmitters and for lipids that are part of myelin coating in nerves
Needed for synthesis of hemoglobin, the oxygen carrier protein in red blood cells
Required by nonessential amino acids for synthesis

Question 10

B6 Deficiency

Answer 10

Symptoms include depression, headaches, confusion, numbness, tingling, anemia (microcytic), skin lesions, poor growth

Question 11

Folate/Folic Acid (B9)

Answer 11

DNA synthesis and metabolism of some AA

Folate coenzymes are needed for DNA synthesis and the metabolism of some amino acids

Question 12

Folate (B9) Deficiency

Answer 12

Symptoms include poor growth, problems in nerve development and function, diarrhea, inflammation of the tongue and anemia
Anemia - caused by inability of pre-red blood cells to divide because of lack of DNA (just grown bigger)
Results in megaloblastic anemia or macrocytic anemia
Low folate intake in early pregnancy is associated with an increased risk of neural tube defects

Question 13

Vitamin B12 (Cobalamin)

Answer 13

Myelin maintenance, breakdown of odd-chain fatty acids, synthesis of methioine from homocysteine

Necessary for the maintenance of myelin
Coenzymes function in breakdown of fatty acids with odd number of C in chain
If folate or Vitamin B12 is deficient, homocysteine cannot be converted to methionine

Necessary for the proper absorption of iron in the body

Question 14

Vitamin B12 (Cobalamin) Deficiency

Answer 14

Results in increase in blood homocysteine
Deficiency can be masked by excessive intake of folic acid
Macrocytic, megaloblastic anemia indistinguishable from anemia of folate deficiency
Neurological symptoms
Deficiencies rare because body stores and reuses
Pernicious anemia - caused by parietal cell destruction or by atrophic gastritis (therefore no intrinsic factor)

Question 15

B12 Absorption

Answer 15

Cells in the stomach release intrinsic factor
In the upper portion of the small intestine (duodenum), intrinsic factor binds to B12
In the lower part of the small intestine (ileum), B12-intrinsic factor complex binds to receptors on cells, allowing absorption
CANNOT be absorbed without intrinsic factor

Question 16

Choline

Answer 16

Formation of acetylcholine, provides one-carbon units for methylation, part of cellular membranes as phosphotidylcholine

Needed to form acetylcholine, a neurotransmitter
Provides one-carbon units for methylation
Choline metabolite phosphotidylcholine makes up cellular membranes
Deficiency can lead to fatty liver

Question 17

Vitamin C

Answer 17

Antioxidant in the body - can neutralize radicals before they can damage cell structures
Helps maintain the immune system
Important in the production of collagen - important coenzyme for the reaction that adds a hydroxyl group to proline (hydroxyproline) and to lysine (hydroxylysine)… these hydroxyl groups are necessary for cross-linking of collagen fibers *crosslinking will not occur in the absence of Vitamin C
Coenzyme in reactions that include production of some neurotransmitters, hormones, bile, acid, and carnation
Aids in iron absorption
Donates electrons in biochemical reactions
Used for synthesis and maintenance of connective tissue
(Only a vitamin for humans)

Question 18

Vitamin C Deficiency

Answer 18

Causes Scurvy - bleeding gums, poor wound healing, weakened connective tissue, decreased iron absorption, depression, mental problems