| 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 |
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