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26 Cards in this Set
- Front
- Back
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What are the five major functions of nucleotides?
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Building blocks of nucleic acids
energy storage for muscle contraction activated intermediates in biosynthesis Components of co-enzymes Metabolic regulators |
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What are the functions for the high energy phosphate nucleotides?
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ATP – central to energy metabolism
GTP – drives protein synthesis CTP – drives lipid synthesis UTP – drives carbohydrate metabolism |
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What is adenosine?
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Adenosine controls coronary blood flow
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how is adenosine formed?
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It is a break down product of ATP found in all cells
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how does adenosine alter cellular metabolism?
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released into the bloodstream
binds to receptors on another cell and initiates changes in the target cell |
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what plant chemical blocks the action of adenosine in the human body?
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Caffeine inactivates the adenosine receptor and blocks phosphodiesterase and prevents it from converting cAMP to ATP
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Where do nucleotides come from and how do we process them?
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Nucleotides come from ingested food
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know the names for the 4 enzymes that we use to process nucleotides coming from food or inside cells?
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Deoxyribonuclease
Ribonuclease 5-nucleotidase Nucleosidase |
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How do we synthesize nucleotides?
Purines |
build purine ring onto the sugar
AMP or GMP that is reacted with AMP or GMP kinase to become ADP or GDP |
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How do we synthesize nucleotides?
Pyramidines |
Start with simple metabolites and build the free pyramidine ring
OMP becomes UMP which is reacted with UMP kinase to make UDP |
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Name the first purine nucleotide and pyrimidine nucleotide formed during the de novo synthesis of nucleotides?
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IMP is the 1st purine nucleotide
OMP is the 1st pyramiding nucleotide |
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What is the rate-limiting step for purine nucleotide synthesis?
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Amidophosphoribosyl transferase
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How is Purine Necleotide Synthesis regulated?
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Through feedback inhibition from inosinic acid, adenylic acid, and guanylic acid
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What is the rate-limiting step for pyrimidine nucleotide synthesis?
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Carbomoyl phosphate synthetase
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How is Pyrimidine Necleotide Synthesis regulated?
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It is regulated by feedback inhibition and stimulation:
-UTP and CTP (-) -PRPP and HCO3 (+) |
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What are the two end products of pyrimidine base degradation?
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β-alanine
β-amnioisobutyric acid |
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What is the end product of purine base degradation and why is this compound specific to primates?
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Uric acid – toxic waste product
Primate specific because other species further metabolize uric acid |
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What are the salvage pathways for the purines and the pyrimidines?
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Type I (purines and pyramidines)
-Base + 5’PRPP --> nucleotide MP Type II (pyrimidines only) -Base + ribose-1-P --> nucleoside -->nucleotide |
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why are the salvage pathways important?
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Used to create GMP and AMP
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What is gout and how is it treated?
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Excess uric acid is deposited in joints and causes acute arthritic joint inflammation
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What other disorders of purine metabolism besides gout occur in humans and what causes these other disorders?
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Lesh-Nyan syndrome
SCIDs -Defect in adenosine deaminase (ADA) -Bubble boy disease – patients extrememly susceptible to infection -Defect in B-cell and T-cell |
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List the two nucleotides that are used to form deoxythymidine monophosphate?
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dCTP and dUTP
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What are aminopterin and methotrexate?
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They are competitive inhibitors of dihydrofolate reductase that converts dihydrofolate to THFA
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What is 5-flurouracil, what does it do and what is it used for?
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It is a suicide inhibitor of thymidylate synthase
Used in Ribose-5-P salvage pathway to create deoxyribose P |
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Name the enzyme needed to form deoxyribonucleotides?
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Ribonucleotide reductase
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how the activity of Ribonucleotide reductase regulated?
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Inhibits:
-dATP – overall -TTP – substrate specific Stimulates: -ATP - overall -ATP, dGTP, TTP – substrate specific |
