vitamins 2 Flashcards Preview

Boards microbio and biochem > vitamins 2 > Flashcards

Flashcards in vitamins 2 Deck (12):
1

What is the function of vitamin B5?

aka pantothenate ("pentothenate"). essential component of coenzyme A (cofactor for acyl transfers), and fatty acid synthase

2

What is seen in B5 deficiencies?

dermatitis, enteritis, alopecia, adrenal insufficiency

3

What is the function of B6?

aka pyridoxine. converted to pyridoxal phosphate- cofactor used in transamination (AST and ALT), decarboxylation, glycogen phosphylase. needed for synthesis of cystathionine, heme, niacin (B3), histamine, epinephrine, norepinephrine, dopamine, and GABA

4

B6 deficiency

convulsions, hyperirritability, peripheral neuropathy (deficiency inducible by isoniazid and OCPs), sideroblastic anemias d/t impaired hemoglobin synthesis and iron excess.

5

Vitamin B7 function

aka biotin. cofactor for carboxylation enzymes. pyruvate carboxylase (pyruvate to oxaloacetate), acetyl-CoA carboxylase (acetyl CoA to malonyl-CoA), propionyl-CoA carboxylase (propionyl CoA to methylmalonyl-CoA

6

B7 defiency

rare. dematitis, alopecia, and enteritis. caused by antibiotics or excessive ingestion of raw egg whites

7

B9 function

aka folic acid. converted to tetrahydrofolate (THF), a coenzyme for 1-carbon transfer/methylation rxns. important for synthesis of nitrogenous bases in DNA and RNA

8

B9 absorption, storage

small store in liver. absorbed in the jejunum

9

B9 deficiency. causes.

macrocytic, megaloblastic anemia, hypersegmented PMNs, no neuro symptoms. increased homocystine, but normal methylmalonic acid. most common vitamin deficiency in US. seen in alcoholism and pregnancy or by drugs like phenytoin, sulfonamides, and methotrexate.

10

B12 function

cofactor for homocystein methyltransferase (converts homocystein to methionine) and methylmalonyl-CoA mutase.

11

B12 deficiency

high levels of homocysteine (deficiency in homocystein methyltransferase) and high levels of methylmalonic acid. causes macrocytic, megaloblastic anemia, hypersegmented PMNs. Paresthesias, subacute combined degeneration (dorsal columns, lateral cotricospinal tracts, and spinocerebellar tracts) from abnormal myelin. may be irreversible

12

B12 abosorption

made by microorganisms. large reserve pool stored in iver. deficiency d/t insufficient intake, malabsorption, lack of intrinsic factor (pernicious anemia or gastric bypass), or absence of terminal ileum (Crohns).
to diagnose pernicious anemia, look for anti-intrinsic factor antibodies