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WVSOM -- biochem
WVSOM -- Tetrahydrofolate, Vit B12 and S-Adenosym Metabolism
| Question | Answer |
|---|---|
| Why is one carbon metabolism important? | some reactions require the addition of one group, carbons don’t always want to move and usually need a little help, folates and SAM can carry carbon groups and force them elsewhere |
| What is one carbon metabolism? | movement of one carbon group |
| What is on the end of folic acid? | folate with glutamate on the end |
| What synthesizes folate? | plants and bacteria |
| Supplements have how much glutamate at the end? | just one |
| How much glutamate is found on folate in plants? | chains |
| What enzyme is required to reduce and activate folate? | dihydroflate reductase |
| Where are the glutamate cleaved? | intestines |
| What form of folate is absorbed? | monoglutamate form |
| What is folate reduced to? | FH2 and then FH4 |
| What is the primary carbon source to FH4? | serine |
| Where are carbon groups usually attached? | N5 or N10 |
| What are one carbon pools? | folates with carbon groups attached |
| What processes require folates with carbons attached? | purine and dTMP synthesis, serine synthesis and methylcobalmin synthesis |
| Folate is required for? | DNA synthesis and cell division |
| What is the most reduced and stable form of folate? | FH4 |
| What does N5-methyl-FH4 donate its carbon to? | Vitamin B12 |
| What is B12 also called? | cobalamin |
| What is the structure of B12? | corrin ring + cobalt |
| How do we get B12? | by eating something that has ingested bacteria (meat) |
| What synthesized B12? | bacteria |
| What is the most common B12 found in supplements? | cyanocobalamin |
| What is B12 converted to after ingestion? | methyl cobalamin or deoxyadenosylcobalamin |
| What does B12 absorption and transport require? | protein carriers |
| What protein is B12 gerenally bound to in the small intestine? | haptocorrin |
| Reduced acid production by Bea’s gastric mucosa would do what to B12 absorption? | Only dietary protein because acid is not needed to break the B12 from the acid |
| What are crystalline B12? | not bound to proteins |
| How is B12 absorbed? | Proteases release the B12 and then it binds to IF. The IF-B12 complex enters the ileal cells |
| What 2 reactions require B12? | Methione metabolism process; to form methionine and coversion of methylmalonyl-CoA to succinyl CoA |
| Why is methionine essential when we make it? | becuase it requires homocyteine for production and it can only be obtained by diet |
| What reactions are SAM needed for? | nor epi -> epi, guanidinoacetate -> creatine, nucleotides -> methylated nucleotides, phosphatidylenthanolamine -> phosphatidylcholine, acetylserotonin -> melatonin |
| What is required for DNA and histone methylation? | SAM |
| What is SAM? | s-adenosylmethionine |
| What is hyperhomocysteinemia? | High levels of homocysteine |
| What could cause hyperhomocysteinemia? | B6, B12, Folate deficiencies |
| What disease risk factors are associated with hyperholmocysteinemia? | cadriovascular, miscarriage, neurological disorders, cancer |
| What is PLP? | Vitamin B6 |
| How can homocystein levels be reduced? | betaine and choline supplementation as well as b12, B6 and folate supplementation. |
| What causes macrocytic anemia? | B12 or folate deficiencies |
| What is marcocytic anemia? | RBC are larger than normal but fewer in number |
| What causes the larger RBC? | enlarged hematopoietic precursor cells |
| What happens to these larger RBC? | most destroyed in the bone marrow |
| Why does B12 deficiency cause macrocytic anemia? | You need B12 to recycle the N55-methyl-FH4 and folate is needed for methylcobalamin |
| What does folate deficiency during pregnancy result in? | neural tube defects |
| Why does B12 and folate deficiency results in so many problems? | needed for DNA replication!!!! |
| What are the causes of B12 and folate deficiency? | dietary insufficiency, chronic alcoholism, abdominal surgery resulting in dec. IF production, GI disease, intestinal parasites, certain drugs, IF deficiency |
| How is B12 and folate deficiency diagnosed? | measurement of serum B12 and folate, CBC/Diff, Homocysteine and methylmalonic acid serum levels and schilling test |
| What is Schilling test? | Radiolabeled crystalline B12 is ingested then followed with IM B12 injection, urine is collected over time, difference between oral input and secreted amount incidcates how much is absorbed. |
| How is B12 and folate deficiency treated? | supplements. In pernicious anemia, injection or nasal spray must be used. |
| Where is B12 deficiency more common? | elderly |
Created by:
tjamrose
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