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21 Cards in this Set
- Front
- Back
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1. What are the sources of one-carbon units for FH4?
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1. Serine
2. Glycine 3. Histidine (less abundant AA so contributes less) 4. Tryptophan |
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2. What products are commonly made after receiving carbons (from FH4-C1)?
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1. dTMP (precursor for DNA)
2. Purines 3. B12-CH3 4. Serine |
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3. What does FH4 require?
What happens if folate is absent from the diet? What can low folate in the first weeks of pregnancy cause? What is FH4 used to make? |
Folate
Megaloblastic anemia b/c can't make enough DNA Neural tube defects (spina bifida) 1. dTMP 2. Purines |
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4. What does FH4 do?
What is the ion in B12 that carries the carbon? |
Carries single Cs in various oxidation states
Central cobalt ion |
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5. What two reactions require vitamin B12?
What enzymes require it as a cofactor? |
1. Used to methylate homocysteine
**homocysteine methylase 2. Used to straighten out the C skeleton of methyl malonyl CoA to make succinyl CoA **methylmalonyl CoA mutase |
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6. What is important about the substrates that require vitamin B12?
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Both substrates are toxic
Homocysteine causes heart disease Methyl malonyl CoA (MMCoA) causes demyelination |
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7. What can adequate levels of B12 help prevent?
Without B12 what happens? |
Heart disease b/c converts homocysteine to methionine
Build up of toxic intermediates |
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8. What happens first in the metabolism of methionine?
What is SAM? What does SAM do? |
Methionine is converted to SAM
Single C carrier It always acts w/ acceptor molecule and methylates it |
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9. What eventually happens next in methionine metabolism?
What are the two fates of this product? |
Form homocysteine
1. Methylated B12 methylates it to reform methionine (no net generation of methionine though) 2. React w/ serine to form cysteine byproduct and eventually MMCoA |
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10. When will homocysteine not reform methionine?
What does the formation of cysteine from homocysteine require? What happens to the MMCoA? |
If lack either FH4-C1 or B12
PLP MMCoA forms succinyl CoA (need vit B12) which enters TCA cycle to form glucose |
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11. What three AA can form propionyl CoA (odd chain FA)?
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1. Methionine
2. Valine 3. Isoleucine |
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12. What three vitamins are required in methionine metabolism?
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1. B6 or pyridoxine (for PLP)
2. B12 3. FH4 from folate |
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13. What is SAM used to form?
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1. GA to Creatine
2. Norepinephrine to Epinephrine 3. Serotonin to Melatonin **Methylated products such as creatine and neurotransmitters |
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14. How are neurotransmitters and AA related?
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1. Tryptophan -> serotonin / melatonin
2. Phe/Tyr --> Catecholamines (dopa, dopamine, norepinephrine, epinephrine) 3. Arginine --> NO (nitric oxide) 4. Histidine --> Histamine 5. Glutamate --> GABA |
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15. What is GABA?
What is GABA sensitive to? Where is NO and what is its life span life? |
Inhibitor neurotransmitters of the CNS
Sensitive to low PLP (PLP is used to synthesis GABA) Smooth muscles and is inactivated rapidly (seconds) |
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16. What is required for both tyrosine and phenyalanine hydroxylase?
What is used to form epinephrine from norepinephrine? What two AA are needed then to make epinephrine? |
BH4
SAM (methionine provides methyl group for SAM) Tyrosine and Methionine |
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17. What three AA are used to create creatine?
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1. Arginine
2. Glycine 3. Methionine |
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18. How is creatine-phosphate synthesized?
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1. Glycine + Arginine --> intermediate
2. SAM methylates to form creatine 3. ATP phosphorylates creatine forming creatine-phosphate |
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19. What is creatine-phosphate?
What 2 things can happen to it? |
High energy compound that can phosphorylate ADP to ATP
1. Move to brain and muscles where it's an energy reserve 2. Break down non-enzymatically and irreversible to creatinine |
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20. What is creatinine again?
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Waste product
Key indicator molecule of how well kidney is functioning High levels in blood = poor kidney functioning |
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21. What is the major use of SAM in the body?
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Create creatine from glycine and arginine
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