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31 Cards in this Set
- Front
- Back
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Nucleotide and Nucleoside
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Phosphate group + pentose sugar + nitrogenous base
- Nucleoside without phosphate group |
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Precursor for Purines: De Novo
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Glycine
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Precursor for Pyrimidines: De Novo
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Aspartate
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Precursor for Purine/Pyrimidine: Salvage
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PRPP (derived from ribose-5-phosphate)
- in pyrimidines based of irritate which is then added to R-5-P |
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Glutamine-PRPP aminotransferase
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catalyzes the addition of the first nitrogen group from glutamine to PRPP in purines
- creates 5-phosphoribosylamine |
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GAR
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5-phosphoribosylamine + Glycine + ATP
- purines |
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FGAR
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GAR+ formyl
- cyclizes purines in this step |
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AIR
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FGAR+ ATP- H2O
- purines |
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CAIR
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AIR+ CO2 (via AIR caboxylase) in eukaryotes
or AIR+ HCO3 and ATP (intermediate step) in prokaryotes |
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SAICAR
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- Aspartate and ATP are added to CAIR
- purines |
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AICAR
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- fumarate leaves from SAICAR
- purines |
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FAICAR
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- formyl added to AICAR
- purine synthesis |
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IMP (Inosinate)
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- removal of H2O form FAICAR cyclizes the second ring
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IMP to XMP
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- interacts with water and generate NADH
- catalyzed by IMP dehydrogenase |
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XMP to GMP
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- interact with glutamine, ATP and water
- catalyzed by XMP-glutamine amidotransferase - an amino group on the second carbon makes it Guanylate (GMP) |
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IMP to AMP
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- Aspartate and GTP added
- catalyzed by adenylosuccinate synthetase - fumurate then leaves leaves the Nh2 on the 6th carbon - this is catalyzed by adenylosuccinate and form Adenylate (AMP) |
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Regulation of De-Novo Synthesis of Purines
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- PRPP from R-5-P inhibited by ADP
- PRPP to 5-phosphoribosylamine inhibitedby AMP, GMP and IMP - IMP to AMP inhibited by AMP - IMP to GMP inhibited by GMP |
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De- Novo Synthesis of Pyrimidines: Step 1
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Aspartate to N-Carbamoylaspartate
- catalyzed by aspartate trans-carbamoylase - addition of carbamoyl phosphate (mitochondrial; needs carbamoyl phosphate synthetase II) |
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De- Novo Synthesis of Pyrimidines: Step 2
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N-Carbamoylaspartate to Orotate
- removal of water and creation of NADH |
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De- Novo Synthesis of Pyrimidines: Step 3
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Orotate to Orotidylate
- attaches to PRPP - via orotate phosphoribosyl transferase |
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De- Novo Synthesis of Pyrimidines: Step 4
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Orotidylate to Uridylate (UMP)
- CO2 loss |
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De- Novo Synthesis of Pyrimidines: Step 5
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UMP via kinases and 2 ATP is converted to UTP
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De- Novo Synthesis of Pyrimidines: Step 6
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UTP plus the addition of a nitrogen group form glutamine to the 4th carbon (and ATP) becomes CTP
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Glutaredoxin reductase
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catalyzed the reduction of ribonucleotides to deoxyribonucleotides
- glutathione oxidizes into glutaredoxin |
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Thioredoxin reductase
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catalyzes the reduction of ribonucleotides to deoxyribonucleotides
- FAD to FADH2; goes to thioredoxin |
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Ribonucleotide reductase
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Takes glutaredoxin and thioredoxin and catalyzes the addition of HS groups
- creates ribonucleoside diphosphate from both |
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Thymine from dCDP
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dCDP --> dCTP via nucleoside diphosphate kinase
dCTP --> dUTP via deaminase |
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dUTP to Thymine
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(dUDP--> dUTP via deaminase)
- dUTP --> dUMP via dUTPase - dUMP --> dTMP via thymidylate synthase |
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Oxidative Phase PPPathway
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G-6-P to 6-phospho-glucono-lactate
o Via glucose-6-phosphatedehydrogenase o Makes NADPH Goes to 6-phosphogluconate o Via Lactonase Goes to Ribulose-5-Phosphate o Via 6-phosphogluconatedehydrogenase o Makes NADPH and CO2 To R-5-P o Needs phosphopentoseisomerase |
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Non-oxidative Phase PPPathway
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- Regenerates G-6-P from R-5-P
- Used in tissues requiring more NADPH than R-5-Plike liver and adipose - Enzymes transketolase,transaldolase (and isomerase andepimerase when coming fromxylulose-5-phosphate) |
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PPP Regulation
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- NADPH regulates how glucose is partitioned betweenglycolysis and PPP o G-6-P will go to glycolysis is there issufficient NADPH to stop it going down the PPPathway
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