Wk 2 Folate & B12

Question 1

What vitamin is folate?

Answer 1

B9

Question 2

What are dietary sources of folate?

Question 3

What must happen to folate in diet?

Answer 3

Must be reduced, twice to dihydrofolate then tetrahydrofolate (THF), which has 3 interconvertable forms

Question 4

How is folate part of DNA synthesis?

Answer 4

IMP for conversion of dUMP -> dTMP, which forms dTDP and dTTP

Question 5

thymidylate synthase

Answer 5

Converts dUMP to dTMP

Question 6

dihydrofolate reductase

Question 7

What is methotrexate?

Answer 7

Competitive inhibitor of dihydrofolate reductase (which is needed for conversion of dihydrofolate to tetrahydrofolate)

Question 8

What inactivates thymidylate synthase?

Question 9

How is B12 made?

Answer 9

Only by bacteria….which is in the colon
-autoimmune destruction of the parietal cells (destruction of intrinsic factor) is a common cause of B12 (pernicious anemia)

Question 10

Dietary sources of B12

Answer 10

primarily meat, eggs, dairy products

Question 11

What do folate and B12 deficiencies lead to?

Answer 11

Macrocytic anemias due to DNA replication defects
-lead to accumulation of homocysteine

Question 12

What symptoms does B12 deficiency cause?

Answer 12

pernicious anemia
neurological defects

Question 13

How can we determine a B12 deficiency and not folate?

Answer 13

Only B12 deficiency leads to increased methyl-malonic acid (MMA)