Term
| Pyrimidine Skelton (ring) is assembled first and attached to |
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Definition
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Term
| What is the major regulatory step? |
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Definition
| Formation of carbomyl phosphate |
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Term
| UTP can lead to formation of |
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Definition
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Term
| Carbamoyl phosphate synthase II takes place where? |
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Definition
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Term
| Where does the nitrogen come from in CPSII? |
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Definition
| Glutamine as opposed to ammonia in urea cycle. |
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Term
| orotate condenses with PRPPto form orodylate. A decarboxylation reaction leads to |
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Definition
| UMP, can eventually be used for RNA |
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Term
| UTP, glutamine, and ATP react to form |
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Definition
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Term
| Where does regulation occur? |
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Definition
| Carbamoyl phosphate synthetase II |
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Term
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Definition
| PRPP unregulates, ATP unregulated. UTP inhibits |
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Term
| UTP inhibits CPS II. What does UMP inhibit:? |
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Definition
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Term
| Pyrimidine salvage is catalyzed by? |
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Definition
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Term
| Pyrimidine catabolism is soluble which disease is caused by the soluble products of purine catabolism? |
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Definition
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Term
| What do oncologists monitor to see if tumors are being killed off? |
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Definition
| They monitor b-aminosobutyrate |
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Term
| What is the electron donor for deoxyribnonucleotide formation? |
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Definition
| NADPH the enzyme is ribonucleotide reductase. |
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Term
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Definition
| 2 Sulfhydryl groups turn ribose into deoxyribose |
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Term
| How do the electrons flow from NADPH to RR1? |
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Definition
| Indirectly flows thru Thioredoxin reductase, Thiordoxin and finally to RR1. |
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Term
| What inactivates/activates the activity of dntps biosynthesis? |
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Definition
| dATP binding to allosteric sites on ribonucleotide reductase. ATP activates it. |
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Term
| What is the one carbon donor in TMP formation? |
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Definition
| THF. Via the enzyme thymidylate synthase |
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Term
| What nucleotide production do you target to kill tumors? |
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Definition
| T, the first attempt was to block one carbon transfers |
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Term
| Fluorouracil is called the 'suicide substrate'. Why? |
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Definition
| It blocks the active site of Thymidine synthase 'killing' the enzyme |
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Term
| What folate analogue blocks the active site of dihydrofolate reductase |
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Definition
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Term
| What is it called when a tumor that has been destroyed returns? |
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Definition
| Relapse. Cells can become resistant to methotrexate by amplifying the gene for dihydrofolate |
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Term
| HOw does PRPP coordinate purine and pyrimidine biosynthesis? |
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Definition
| PRPP activates CPSII and limiters orotate phosphoribosyltrasnferase. PRPP activates amidophospribosaltransferae and is the substrate for HGPRT and APRT. |
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