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Questions and Answers
Which molecule is the major energy source in cells?
Which molecule is the major energy source in cells?
Which enzyme is required for the de novo synthesis of nucleotides?
Which enzyme is required for the de novo synthesis of nucleotides?
Which molecule is the precursor for the synthesis of pyrimidine nucleotides?
Which molecule is the precursor for the synthesis of pyrimidine nucleotides?
Which enzyme converts UMP to UDP and then UTP?
Which enzyme converts UMP to UDP and then UTP?
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Which enzyme is involved in the de novo synthesis of purine nucleotides?
Which enzyme is involved in the de novo synthesis of purine nucleotides?
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Which enzyme is negatively regulated by feedback inhibition from AMP and GMP?
Which enzyme is negatively regulated by feedback inhibition from AMP and GMP?
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How do we convert RNA nucleotides to DNA nucleotides?
How do we convert RNA nucleotides to DNA nucleotides?
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Which of the following is classified as a purine nucleobase commonly found in DNA and RNA?
Which of the following is classified as a purine nucleobase commonly found in DNA and RNA?
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Which of the following is classified as a pyrimidine nucleobase commonly found in DNA and RNA?
Which of the following is classified as a pyrimidine nucleobase commonly found in DNA and RNA?
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What is the difference between a nucleoside and a nucleotide?
What is the difference between a nucleoside and a nucleotide?
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Which of the following is an example of a deoxyribonucleoside?
Which of the following is an example of a deoxyribonucleoside?
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What is the role of the enzyme Ribonucleotide Reductase?
What is the role of the enzyme Ribonucleotide Reductase?
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Which of the following is true about the salvage pathway for purines?
Which of the following is true about the salvage pathway for purines?
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What are the building blocks of DNA and RNA?
What are the building blocks of DNA and RNA?
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During purine degradation, what is the end product?
During purine degradation, what is the end product?
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What is the starting material for purine degradation?
What is the starting material for purine degradation?
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What are the important enzymes involved in purine degradation?
What are the important enzymes involved in purine degradation?
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What are the steps involved in pyrimidine synthesis?
What are the steps involved in pyrimidine synthesis?
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What is the end product of pyrimidine degradation?
What is the end product of pyrimidine degradation?
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What is the starting material for pyrimidine degradation?
What is the starting material for pyrimidine degradation?
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What are the important enzymes involved in pyrimidine synthesis?
What are the important enzymes involved in pyrimidine synthesis?
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What is ribonucleotide reductase and what role does it play in nucleotide synthesis?
What is ribonucleotide reductase and what role does it play in nucleotide synthesis?
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What are the rate limiting steps in purine synthesis?
What are the rate limiting steps in purine synthesis?
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Which pyrimidine is found in RNA only?
Which pyrimidine is found in RNA only?
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Which of the following pairs are both pyrimidines?
Which of the following pairs are both pyrimidines?
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Which of the following is a purine base?
Which of the following is a purine base?
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What are nucleotides made of?
What are nucleotides made of?
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Which of the following is not a precursor for de novo purine biosynthesis?
Which of the following is not a precursor for de novo purine biosynthesis?
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What is an activator of the enzyme 'Glutamine: Phosphoribosylpyrophosphate amidotransferase' (GPAT)?
What is an activator of the enzyme 'Glutamine: Phosphoribosylpyrophosphate amidotransferase' (GPAT)?
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Are all deoxyribonucleotides synthesized from ribonucleotides?
Are all deoxyribonucleotides synthesized from ribonucleotides?
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Which pyrimidine is found in RNA only?
Which pyrimidine is found in RNA only?
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Which of the following pairs are both pyrimidines?
Which of the following pairs are both pyrimidines?
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Which of the following is a purine base?
Which of the following is a purine base?
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What are nucleotides made of?
What are nucleotides made of?
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Which of the following is not the precursor for de novo purine biosynthesis?
Which of the following is not the precursor for de novo purine biosynthesis?
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What is an activator of the enzyme 'Glutamine: Phosphoribosylpyrophosphate amidotransferase' (GPAT)?
What is an activator of the enzyme 'Glutamine: Phosphoribosylpyrophosphate amidotransferase' (GPAT)?
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All deoxyribonucleotides are synthesized from the ribonucleotides.
All deoxyribonucleotides are synthesized from the ribonucleotides.
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Which of the following is not the precursor for de novo purine biosynthesis?
Which of the following is not the precursor for de novo purine biosynthesis?
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Which of the following is not the precursor for de novo purine biosynthesis?
Which of the following is not the precursor for de novo purine biosynthesis?
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Which of the following is not the precursor for de novo purine biosynthesis?
Which of the following is not the precursor for de novo purine biosynthesis?
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Which of the following is NOT a precursor of a purine ring?
Which of the following is NOT a precursor of a purine ring?
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What is the final product of purine degradation in mammals?
What is the final product of purine degradation in mammals?
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A 42-year-old male patient undergoing radiation therapy for prostate cancer develops severe pain in the metatarsal phalangeal joint of his right big toe. Monosodium urate crystals are detected by polarized light microscopy in fluid obtained from this joint by arthrocentesis. This patient’s pain is directly caused by the overproduction of the end product of which of the following metabolic pathways?
A 42-year-old male patient undergoing radiation therapy for prostate cancer develops severe pain in the metatarsal phalangeal joint of his right big toe. Monosodium urate crystals are detected by polarized light microscopy in fluid obtained from this joint by arthrocentesis. This patient’s pain is directly caused by the overproduction of the end product of which of the following metabolic pathways?
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What is the catabolic end product of pyrimidine nucleotides?
What is the catabolic end product of pyrimidine nucleotides?
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Which of the following is NOT a precursor for de novo purine biosynthesis?
Which of the following is NOT a precursor for de novo purine biosynthesis?
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Which molecule is the major energy source in cells?
Which molecule is the major energy source in cells?
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Which pyrimidine is found in RNA only?
Which pyrimidine is found in RNA only?
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What are nucleotides made of?
What are nucleotides made of?
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Which enzyme is required for the de novo synthesis of nucleotides?
Which enzyme is required for the de novo synthesis of nucleotides?
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Which enzyme converts UMP to UDP and then UTP?
Which enzyme converts UMP to UDP and then UTP?
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Study Notes
Major Energy Source and Molecules
- ATP (adenosine triphosphate) is the primary energy source in cells.
- Nucleotides are composed of a nitrogenous base, a sugar (ribose or deoxyribose), and phosphate groups.
Enzymes in Nucleotide Synthesis
- De novo nucleotide synthesis requires ribose-5-phosphate and is catalyzed by various enzymes.
- UMP (uridine monophosphate) is converted to UDP (uridine diphosphate) and then to UTP (uridine triphosphate) by the enzyme UMP kinase.
- Purine nucleotide synthesis involves Glutamine: Phosphoribosylpyrophosphate amidotransferase (GPAT), negatively regulated by AMP and GMP.
Precursor Molecules
- Carbamoyl phosphate is the precursor for the synthesis of pyrimidine nucleotides.
- Inosine monophosphate (IMP) is the critical precursor in the de novo synthesis of purine nucleotides.
- The starting material for purine degradation is AMP (adenosine monophosphate).
Regulation and Feedback Inhibition
- Enzymes in purine synthesis are subject to feedback inhibition by end products like AMP and GMP.
- Ribonucleotide reductase plays a crucial role in converting RNA nucleotides to DNA nucleotides by reducing ribonucleotides to deoxyribonucleotides.
Nucleobases and Nucleosides
- Adenine and guanine are purine nucleobases, found in both DNA and RNA.
- Cytosine, thymine, and uracil are classified as pyrimidine nucleobases.
- A nucleoside consists of a nitrogenous base and a sugar, while a nucleotide includes the phosphate group as well.
Degradation Pathways
- The end product of purine degradation is primarily uric acid in mammals.
- Pyrimidine degradation results in the generation of beta-alanine and ammonia as catabolic products.
Key Enzymes in Synthesis and Degradation
- Important enzymes involved in purine degradation include xanthine oxidase.
- Pyrimidine synthesis involves enzymes like carbamoyl phosphate synthetase II (CPS II).
Notable Observations
- The only pyrimidine found uniquely in RNA is uracil.
- Cytosine and uracil are both classified as pyrimidines.
- Hypoxanthine is a notable purine base.
Clinical Correlation
- A case of gout, characterized by the deposition of monosodium urate crystals, is directly linked to the overproduction of uric acid, the end product of purine metabolism.
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Description
Test your knowledge on nucleotide synthesis and the role of enzymes involved in the process. Explore topics like purine degradation, HGPRT, Lesch-Nyhan syndrome, pyrimidine nucleotide synthesis, CTP synthetase, and deoxynucleotide synthesis.
