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Questions and Answers
Which of the following is the first committed step in purine nucleotide biosynthesis?
Which of the following is the first committed step in purine nucleotide biosynthesis?
- Conversion of GMP to XMP
- Formation of 5-phosphoribosylamine (correct)
- Conversion of IMP to AMP
- Formation of PRPP
Which enzyme catalyzes the formation of 5-phosphoribosylamine in purine biosynthesis?
Which enzyme catalyzes the formation of 5-phosphoribosylamine in purine biosynthesis?
- Amidophosphoribosyltransferase (correct)
- IMP dehydrogenase
- PRPP synthetase
- Adenylosuccinate synthetase
Which molecule serves as the precursor for the ribose sugar in purine biosynthesis?
Which molecule serves as the precursor for the ribose sugar in purine biosynthesis?
- Fructose-6-phosphate
- PRPP
- Ribose-5-phosphate (correct)
- XMP
What is the source of the nitrogen in the formation of 5-phosphoribosylamine?
What is the source of the nitrogen in the formation of 5-phosphoribosylamine?
Which purine base is formed first during de novo synthesis?
Which purine base is formed first during de novo synthesis?
What is the function of PRPP in purine biosynthesis?
What is the function of PRPP in purine biosynthesis?
Which amino acid contributes both nitrogen and carbon atoms to the purine ring?
Which amino acid contributes both nitrogen and carbon atoms to the purine ring?
The enzyme IMP dehydrogenase is responsible for the conversion of IMP to which compound?
The enzyme IMP dehydrogenase is responsible for the conversion of IMP to which compound?
GMP is synthesized from which intermediate in the purine biosynthesis pathway?
GMP is synthesized from which intermediate in the purine biosynthesis pathway?
Which enzyme catalyzes the conversion of adenosine to inosine in purine catabolism?
Which enzyme catalyzes the conversion of adenosine to inosine in purine catabolism?
What is the final product of purine catabolism in humans?
What is the final product of purine catabolism in humans?
Xanthine oxidase is involved in the conversion of xanthine to which compound?
Xanthine oxidase is involved in the conversion of xanthine to which compound?
What is the major clinical condition associated with excess uric acid production?
What is the major clinical condition associated with excess uric acid production?
The conversion of AMP to IMP during purine degradation is catalyzed by which enzyme?
The conversion of AMP to IMP during purine degradation is catalyzed by which enzyme?
Which compound is a substrate for the enzyme purine nucleoside phosphorylase?
Which compound is a substrate for the enzyme purine nucleoside phosphorylase?
Hypoxanthine is converted to xanthine by which enzyme?
Hypoxanthine is converted to xanthine by which enzyme?
Which of the following is NOT an intermediate in purine catabolism?
Which of the following is NOT an intermediate in purine catabolism?
Which molecule acts as a feedback inhibitor of PRPP synthetase?
Which molecule acts as a feedback inhibitor of PRPP synthetase?
What is the salvage pathway for purine nucleotides?
What is the salvage pathway for purine nucleotides?
A key feature of purine nucleotide synthesis is that it occurs mainly in:
A key feature of purine nucleotide synthesis is that it occurs mainly in:
The purine ring is assembled on which molecule?
The purine ring is assembled on which molecule?
Which of the following is true about purine catabolism in humans?
Which of the following is true about purine catabolism in humans?
Purine nucleotides consist of which nitrogenous bases?
Purine nucleotides consist of which nitrogenous bases?
What does PRPP stand for in purine metabolism?
What does PRPP stand for in purine metabolism?
Which amino acid is the primary nitrogen donor in purine biosynthesis?
Which amino acid is the primary nitrogen donor in purine biosynthesis?
The purine ring structure is built on which sugar molecule?
The purine ring structure is built on which sugar molecule?
Which of the following is a precursor for both purine and pyrimidine synthesis?
Which of the following is a precursor for both purine and pyrimidine synthesis?
Which of the following is NOT involved in purine biosynthesis?
Which of the following is NOT involved in purine biosynthesis?
Which organ in humans is primarily responsible for purine synthesis?
Which organ in humans is primarily responsible for purine synthesis?
What is the main purpose of the salvage pathway in purine metabolism?
What is the main purpose of the salvage pathway in purine metabolism?
Flashcards
What is the first committed step in purine biosynthesis?
What is the first committed step in purine biosynthesis?
The committed step in purine biosynthesis marks the point where the pathway is dedicated to the synthesis of purines. This step involves the formation of 5-phosphoribosylamine.
Which enzyme catalyzes the formation of 5-phosphoribosylamine?
Which enzyme catalyzes the formation of 5-phosphoribosylamine?
Amidophosphoribosyltransferase is the crucial enzyme responsible for catalyzing the formation of 5-phosphoribosylamine from PRPP and glutamine.
What is the precursor for the ribose sugar in purine biosynthesis?
What is the precursor for the ribose sugar in purine biosynthesis?
Ribose-5-phosphate, a molecule derived from the pentose phosphate pathway, is the precursor for the ribose sugar that forms the backbone of purine nucleotides.
What is the source of nitrogen in 5-phosphoribosylamine formation?
What is the source of nitrogen in 5-phosphoribosylamine formation?
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Which purine base is formed first during de novo synthesis?
Which purine base is formed first during de novo synthesis?
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What is the function of PRPP in purine biosynthesis?
What is the function of PRPP in purine biosynthesis?
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Which amino acid contributes nitrogen and carbon atoms to the purine ring?
Which amino acid contributes nitrogen and carbon atoms to the purine ring?
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What does IMP dehydrogenase convert IMP to?
What does IMP dehydrogenase convert IMP to?
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What is the intermediate in the synthesis of GMP?
What is the intermediate in the synthesis of GMP?
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Which enzyme catalyzes the conversion of adenosine to inosine?
Which enzyme catalyzes the conversion of adenosine to inosine?
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What is the final product of purine catabolism in humans?
What is the final product of purine catabolism in humans?
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What does xanthine oxidase convert xanthine to?
What does xanthine oxidase convert xanthine to?
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What is the major clinical condition associated with excess uric acid?
What is the major clinical condition associated with excess uric acid?
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Which enzyme catalyzes the conversion of AMP to IMP?
Which enzyme catalyzes the conversion of AMP to IMP?
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Which compound is a substrate for purine nucleoside phosphorylase?
Which compound is a substrate for purine nucleoside phosphorylase?
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Which enzyme converts hypoxanthine to xanthine?
Which enzyme converts hypoxanthine to xanthine?
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Which is NOT an intermediate in purine catabolism?
Which is NOT an intermediate in purine catabolism?
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Which molecules act as feedback inhibitors of PRPP synthetase?
Which molecules act as feedback inhibitors of PRPP synthetase?
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What is the salvage pathway for purine nucleotides?
What is the salvage pathway for purine nucleotides?
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Where does purine nucleotide synthesis mainly occur?
Where does purine nucleotide synthesis mainly occur?
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The purine ring is assembled on which molecule?
The purine ring is assembled on which molecule?
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What is true about purine catabolism in humans?
What is true about purine catabolism in humans?
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Purine nucleotides consist of which nitrogenous bases?
Purine nucleotides consist of which nitrogenous bases?
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What does PRPP stand for in purine metabolism?
What does PRPP stand for in purine metabolism?
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Which amino acid is the primary nitrogen donor in purine biosynthesis?
Which amino acid is the primary nitrogen donor in purine biosynthesis?
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The purine ring structure is built on which sugar molecule?
The purine ring structure is built on which sugar molecule?
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Which of the following is a precursor for both purine and pyrimidine synthesis?
Which of the following is a precursor for both purine and pyrimidine synthesis?
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Which is NOT involved in purine biosynthesis?
Which is NOT involved in purine biosynthesis?
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Which organ in humans is primarily responsible for purine synthesis?
Which organ in humans is primarily responsible for purine synthesis?
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What is the main purpose of the salvage pathway in purine metabolism?
What is the main purpose of the salvage pathway in purine metabolism?
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Study Notes
Purine Anabolism (Synthesis)
- First committed step: Formation of 5-phosphoribosylamine
- Enzyme catalyzing 5-phosphoribosylamin formation: Amidophosphoribosyltransferase
- Precursor for ribose sugar: Ribose-5-phosphate
- Nitrogen source for 5-phosphoribosylamine: Glutamine
- Enzyme converting IMP to AMP: Adenylosuccinate synthetase
- Enzyme converting IMP to GMP: IMP dehydrogenase
Purine Catabolism (Breakdown)
- Final product in humans: Uric acid
- Enzyme converting xanthine to uric acid: Xanthine oxidase
- Enzyme converting AMP to IMP: AMP deaminase
- Enzyme converting adenosine to inosine: Adenosine deaminase
- Intermediate in purine catabolism (besides hyoxanthine, xanthine and uric acid): IMP
- Enzyme that converts Hypoxanthine to Xanthine: Hypoxanthine-guanine phosphoribosyltransferase
Purine Salvage Pathway
- Purpose: Recycling free purine bases into nucleotides
- Role of PRPP: Essential molecule in the salvage pathway
Regulation and Disorders
- Feedback inhibitor of PRPP synthetase: ATP, GMP, IMP
Other Questions
- Purine nucleotide components: Adenine and Guanine
- Primary nitrogen donor in purine biosynthesis: Glutamine
- Primary organ for purine synthesis: Liver
- Major clinical condition associated with excess uric acid production: Gout
- Sugar molecule on which purine ring is built: Ribose
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Description
This quiz focuses on the processes of purine anabolism, catabolism, and the salvage pathway. It covers essential enzymes and intermediates involved in the synthesis and breakdown of purines. Test your understanding of how these biochemical pathways function and their significance in human metabolism.
