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WVSOM -- biochem

WVSOM -- Tetrahydrofolate, Vit B12 and S-Adenosym Metabolism

QuestionAnswer
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: Todd Jamrose Todd Jamrose on 2008-12-03



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