W3-1: Folate/B12

Question 1

THF vitamin precursor

Answer 1

Folate (B9)

Question 2

Functional and storage forms of THF

Answer 2

Functional: monoglutamate

Question 3

Congenital defect caused by failure of the neural tube to close prenatally

Answer 3

Spina bifida

Question 4

Hereditary folate malabsorption

Answer 4

Defective intestinal (absorption) and liver (storage) proton-coupled folate transporters

–>megaloblastic anemia-dTMP cannot be synthsized from dUMP, RBCs grow but do not divide, WBCs also affected

Question 5

Reduction state-changing folate rxns

Answer 5

Question 6

DHF reductase inhibitors

Answer 6

methotrexate- cancer or RA

trimethoprim-antibacterial

pyrimethamine-antimalarial

Question 7

Action of 5-fluorouracil

Answer 7

inhibit thimidylate synthase

Question 8

THF-methyl group combinations

Answer 8

Question 9

dTMP synthesis

Answer 9

Question 10

Fate of 5-methyl THF

Answer 10

donates methyl to cobalamin

Question 11

2 amino acids that add methyls to THF

Answer 11

• Tryptophan (fumate)
• Serine (for methylene)

Question 12

2 useful forms of cobalamin

Answer 12

• methyl cobalamin
• adenosyl cobalamin

Question 13

methyl cobalamin rxn

Answer 13

homocysteine–>methionine

(to make cysteine)

Question 14

adenosyl cobalamin rxn

Answer 14

methylmalonyl-CoA —> succinyl-CoA (to TCA)

**from branched and odd chain fatty and amino acids

Question 15

What is the methyl trap?

Answer 15

when a lack of cobalamin traps all the THF as methyl-THF, unable to particiapte in other one-carbon transfers

(methylene form used to make thiamine)