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MBC - Lecture 53
Pyrimidine Metabolism (Mock)
| Question | Answer |
|---|---|
| Lecture 53 | Pyrimidine Metabolism |
| UMP is the parent nucleotide for ___ and ___. | CTP and dTMP |
| Formation of UMP is through ___ steps/reactions. | 6 |
| Not all reactions are ___ in formation of UMP. | cytosolic |
| UMP is not built on a PRPP donated ___. | ribosyl-5-phosphate |
| PRPP donating ribosyl-5-phosphate is the ___ step in making UMP. | last |
| UMP is forms to ___ before making CTP. | UTP |
| Biosynthesis of carbamoyl phosphate is by ___. | CPS II |
| CPS II works in the ___, and uses ___. | cytosol, glutamine |
| Regulated step in pyrimidine synthesis is ___. | CPS II |
| CPS II is actvated by ___. | PRPP |
| Synthesis of UMP uses two multifunctional ___. | enzymes |
| CAD is encoded by ___ gene(s). | 1 gene |
| Enzymes in CAD are ___, ___, and ___. | Carbamoyl phosphate synthase II, aspartate transcarbamoylase, and dihydroorotase. |
| Enzymes in UMP synthase are ___ and ___. | orotate phosphoribosyltransferase and OMP decarboxylase |
| ___ donates C4-6 and N1 to the pyrimidine structure. | Aspartate |
| ___ donates C2 to the pyrimidine structure. | HCO3- (Bicarbonate) |
| ___ donates N3 to the pyrimidine structure. | Glutamine amide |
| Hereditary orotic aciduria leads to anemia because of: | RBC synthesis’ high demand for DNA synthesis |
| Hereditary orotic aciduria causes anemia and ___. | growth retardation |
| UTP and CTP both negatively feedback to ___. | CPS II |
| ___ and ___ up-regulate CPS II. | ATP and PRPP |
| Orotic Aciduria, Type I | Defective UMP synthase (both), autosomal recessive, orotic acid crystalluria, FTT, megaloblastic anemia, immunodeficiency |
| Orotic Aciduria, Type II | Defective UMP synthase (orotidylate decarboxylase only), autosomal recessive, orotidinuria and orotic aciduria, megaloblastic anemia, treatable with oral uridine |
| Ornithine Transcarbamoylase Deficiency | Defective OTC, X-linked recessive, protein intolerance, hepatic encephalopathy, mild orotic acidura |
| UMP to UTP is through two ___ steps. | phosphorylation steps (ATP donor) |
| CTP Synthase | Catalyzes synthesis of CTP from UTP by substituting keto group for amino group |
| The nitrogen donor in CTP synthase is ___, releasing ___. | glutamine, releasing glutamate |
| The phosphate donor group in CTP synthase is ___. | ATP |
| Pyrimidine nucleosides can be salvaged by ___. | ATP-requiring kinases |
| Pyrimidine nucleoside salvaging kinases are: | uridine-cytidine kinase, thymidine kinase, deoxycytidine kinase |
| Nucleoside 5’-Diphosphate Reductase (Ribonucleotide Reductase) | Catalyzes synthesis of 2’-deoxyribonucleotide from ribonucleotide (DNA to RNA) |
| ___, ___, and ___ can be formed directly from its precursors by ribonucleotide reductase and phosphorylation. | dATP, dGTP, and dCTP |
| dTTP is not directly synthesized to prevent: | accidental incorporation of dUDP into DNA |
| Synthesis of dTTP can be from precursors ___ or ___. | CDP or UDP |
| CDP → ___ → ___ → ___ → ___ →→ dTTP | CDP →dCDP → dCMP → dUMP → dTMP →→ dTTP |
| UDP → ___ → ___ → ___ →→ DTTP | UDP → dUDP → dUMP → dTMP →→ dTTP |
| Thymidylate Synthase | Catalyzes synthesis dTMP from dUMP, requires tetrahydrofolate |
| Pyrimidine analogs can block ___. | DNA synthesis |
| Cytosine Arabinoside | Leukemia & non-Hodkin lymphoma therapy, AraC → AraCMP → AraCTP into DNA, inhibits strand elongation |
| 3’-azido-3’-deoxythymidine (AZT) | AZT triphosphate, inhibits HIV DNA polymerase |
| Methotrexate is a structural analog of ___. | folic acid |
| Methotrexate inhibits ___. | dihydrofolate reductase (synthesis of dihydrofolate from folate or regeneration of dihyrdofolate to tetrahydrofolate) |
| ___ cells are especially sensitive to dihyrdofolate reductase inhibitors (i.e. methotrexate). | Dividing |
| β-aminoisobutyrate excretion measures ___. | DNA breakdown |
Created by:
emyang
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