Podcast
Questions and Answers
Which of the following correctly defines a nucleoside?
Which of the following correctly defines a nucleoside?
What is true about adenosine-5’-monophosphate (AMP)?
What is true about adenosine-5’-monophosphate (AMP)?
Which molecule is the starting material for the synthesis of PRPP in purine nucleotide synthesis?
Which molecule is the starting material for the synthesis of PRPP in purine nucleotide synthesis?
In the de novo synthesis of purine nucleotides, which sources provide atoms necessary for purine base formation?
In the de novo synthesis of purine nucleotides, which sources provide atoms necessary for purine base formation?
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What is the first purine nucleotide formed in de novo synthesis?
What is the first purine nucleotide formed in de novo synthesis?
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Which component is NOT part of the initial steps in purine nucleotide synthesis?
Which component is NOT part of the initial steps in purine nucleotide synthesis?
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Which of the following is part of the structure of a nucleotide?
Which of the following is part of the structure of a nucleotide?
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When synthesize the purine ring structure, which position of sugar is initially modified?
When synthesize the purine ring structure, which position of sugar is initially modified?
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Which substance is considered a product of the pentose phosphate pathway that is used in nucleotide synthesis?
Which substance is considered a product of the pentose phosphate pathway that is used in nucleotide synthesis?
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What type of base is adenine classified as?
What type of base is adenine classified as?
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What is the initial substrate used in the de novo synthesis of pyrimidine nucleotides?
What is the initial substrate used in the de novo synthesis of pyrimidine nucleotides?
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Which enzyme is responsible for the formation of carbamoyl phosphate from bicarbonate, ATP, and glutamine?
Which enzyme is responsible for the formation of carbamoyl phosphate from bicarbonate, ATP, and glutamine?
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What compound is formed after the cyclization and modification of carbamoyl phosphate and aspartate?
What compound is formed after the cyclization and modification of carbamoyl phosphate and aspartate?
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How is orotate converted into OMP?
How is orotate converted into OMP?
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What is the consequence of mutations in the HGPRT enzyme?
What is the consequence of mutations in the HGPRT enzyme?
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What advantage does the salvage pathway provide in nucleotide synthesis?
What advantage does the salvage pathway provide in nucleotide synthesis?
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Which of the following is a product of the modification of OMP?
Which of the following is a product of the modification of OMP?
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Which substance does the salvage pathway recycle primarily?
Which substance does the salvage pathway recycle primarily?
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What is the final product of the de novo pyrimidine synthesis pathway?
What is the final product of the de novo pyrimidine synthesis pathway?
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Which of the following is a key difference between purine and pyrimidine nucleotide synthesis?
Which of the following is a key difference between purine and pyrimidine nucleotide synthesis?
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Study Notes
Bases, Nucleosides, and Nucleotides
- Adenine is a purine nitrogenous base.
- A nucleoside combines a nitrogenous base (like adenine) with a sugar (like ribose). Adenosine is an example.
- A nucleotide is a nucleoside with one or more phosphate groups attached to the sugar. Adenosine-5'-monophosphate (AMP) is an example.
De Novo Synthesis of Purine Nucleotides
- Ribose-5-phosphate, from the pentose phosphate pathway, is converted to PRPP (5-phospho-alpha-D-ribosyl-1-pyrophosphate).
- PRPP is the sugar substrate for purine synthesis.
- The purine base is synthesized on the C1 position of the sugar, using atoms from glutamine, THF, glycine, aspartate, and CO2.
- IMP is the first purine nucleotide formed.
- IMP is modified to form further nucleotides like AMP and GMP.
Pyrimidine Synthesis (De Novo Pathway)
- PRPP is the sugar substrate for pyrimidine synthesis.
- The pyrimidine ring is synthesized first and then attached to PRPP.
- Carbamoyl phosphate synthetase II catalyzes the formation of carbamoyl phosphate from HCO3-, ATP, and glutamine.
- Carbamoyl phosphate and aspartate are covalently linked, cyclized, and modified to generate orotate.
- Orotate is linked to PRPP to form OMP. OMP is modified to form UMP and CMP.
Salvage Pathway for Purine Nucleotides
- De novo synthesis of nucleotides is energetically costly.
- The salvage pathway recycles existing purines (like guanine) to avoid needing to synthesize everything from scratch.
- Degradation of nucleotides can release nitrogenous bases.
- PRPP is used in the salvage pathway.
- Hypoxanthine-guanine phosphoribosyltransferase (HGPRT) catalyzes the covalent linkage of guanine to PRPP to form guanosine-5'-monophosphate (GMP).
- Mutations in HGPRT cause Lesch-Nyhan Syndrome.
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Description
This quiz delves into the fundamental concepts of nucleobases, nucleosides, and nucleotides. Explore the processes of de novo synthesis of purine and pyrimidine nucleotides, highlighting key biochemical pathways. Test your knowledge on the biochemical building blocks crucial for DNA and RNA.
