Exam 3 Biochem-Lecture 34 – Flashcards
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Unlock answers| What are purines and pyrimidines? |
Purines and pyrimidines, often called bases, are nitrogen-containing heterocyclic compounds. |
| Purine bases you will find in DNA are |
|
Pyrimidines have a single .......sided ring structure. |
Pyrimidines have a single six sided ring structure. |
| Example of Pyrimidines base |
Uracil is found in RNA. |
| The purine NSs end in |
| "-sine" |
| The pyrimidine NSs end in |
| "-dine" |
| To name the NTs: |
|
| NMP means |
Nucleotide monophosphate |
| NDP means |
Nucleotide diphosphate |
| NTP means |
Nucleotide triphosphate |
| Functions of Nucleotides |
nEnergy metabolism nMonomeric units of nucleic acids nPhysiological mediators nPrecursor function nComponents of coenzymes nActivated intermediates nAllosteric effectors
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| Nucleotides are components of coenzymes: |
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| Nucleotide activate intermediates like: |
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Why is purine salvage pathway of metabolism of purine important? |
|
| Synthesis of purines requires |
nAmino acids ¨Glycine ¨Glutamine (2) ¨Aspartate nCO2 nOne carbon units transferred via THF (2) |
| GOUT is a disorder characterized by: |
| high levels of uric acid in blood, as a result of either the overproduction or under excretion of uric acid. |
nGout is treated with drug such as |
| allopurinol that inhibit xanthineoxidase |
| CPS I has: |
|
CPS II |
•Cytosol •Pyrimidine Synthesis g-amide group of glutamine •Activator:–ATP •Inhibitor:–UTP |
| Source of carbon and nitrogen on pyrimidines are |
|
| Source of carbon and nitrogen atoms in purine ring |
1 from Asparate amine 2 from C1-H4folate 3 from Glutamine amide 4, 5,7 from Glycine 8 from C1 H4folate 9 from Glutamine amide |
In de novo synthesis, the pyrimidine ring is synthesized from |
|
| Synthesis of pyrimidines vs. purines. |
nFirst, the ring structure is assembled as a free base in pyrimidines, not built upon PRPP like purines. nSecond, there is no branch in the pyrimidine synthesis pathway. |
In Synthesis of Pyrimidine Nucleotides, what is regulated step? |
Carbamoyl phosphate Synthetase II |
In Synthesis of Pyrimidine Nucleotides, committed step involves which enzyme? |
| Carbamoylaspartate |
The regulatory step in Synthesis of Pyrimidine Nucleotides involves which enzyme? |
|
| Regulation of Purine Synthesis |
Inactivate Purine + PRPP----> Active Purine Activate Purine + IMP/GMP/IMP---> Inactivate Purine |
Inactivate Purine + ????----> Active Purine
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| PRPP |
| Activate Purine +????---> Inactivate Purine |
| IMP/GMP/IMP |
| Metabolism of Purine Nucleotides include: |
nSynthesis of purine nucleotides nPurine salvage nPurine nucleotide interconversions nGTP and tetrahydobiopterin nUric acid |
