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