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Questions and Answers
What is the primary role of nucleotides in cellular biology?
Which of the following correctly describes deoxyribose?
What type of bond forms between a nitrogenous base and a sugar in a nucleoside?
Which nitrogenous base is found only in DNA?
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Which of the following statements about purine and pyrimidine bases is true?
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Which of the following is a nucleotide composed of deoxyadenosine?
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What role does Cyclic AMP (cAMP) primarily serve in biological systems?
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Which nucleotide acts as a source of energy in cellular processes?
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Which of the following nucleotides is known for its role as a methyl donor?
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Which of the following statements is true regarding the function of nucleotides?
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Study Notes
Nucleic Acids
- Nucleic acids, DNA and RNA, are composed of repeating subunits called nucleotides.
- Nucleotides are the building blocks of DNA and RNA.
- Nucleotides exist as polynucleotide chains (in DNA and RNA) or as free nucleotides.
Nucleotide Structure
- Nucleotides are composed of three components:
- Nitrogenous base: Adenine (A), Guanine (G), Cytosine (C), Thymine (T) or Uracil (U)
- Pentose sugar: Ribose (in RNA) or Deoxyribose (in DNA)
- Phosphate group (Phosphoric acid)
Pentose Sugar
- Ribose is the sugar present in ribonucleic acid (RNA).
- Deoxyribose is the sugar in deoxyribonucleic acid (DNA), it is essentially a ribose sugar with the removal of an oxygen atom from the 2-carbon atom.
Phosphate
- Phosphoric acid attaches to the 5-carbon of ribose by an ester bond.
Nitrogenous Bases
- Two families of nitrogenous bases exist:
- Purine bases (two rings): Adenine (A) and Guanine (G)
- Pyrimidine bases (one ring): Cytosine (C), Thymine (T) (DNA), and Uracil (U) (RNA)
Minor Nitrogenous Bases
- Other purine metabolites like Xanthine, Hypoxanthine, and uric acid are not usually found in nucleic acids.
Nucleosides
- Nucleosides are formed by covalently linking a nitrogenous base to the 1-carbon of a sugar via an N-glycosidic bond.
- The base is attached to the 1-carbon of the sugar.
Nucleotides
- Nucleotides are formed when one or more phosphate groups are attached to the 5-carbon of the nucleoside.
- Nucleoside di- and triphosphates are high-energy compounds
Nomenclature of Ribonucleotides
- Base | Nucleoside | Nucleotide | Diphosphate | Triphosphate
- Adenine | Adenosine | Adenylic Acid (AMP) | Adenosine Diphosphate (ADP) | Adenosine Triphosphate (ATP)
- Guanine | Guanosine | Guanylic Acid (GMP) | Guanosine Diphosphate (GDP) | Guanosine Triphosphate (GTP)
- Cytosine | Cytidine | Cytidylic Acid (CMP) | Cytidine Diphosphate (CDP) | Cytidine Triphosphate (CTP)
- Uracil | Uridine | Uridylic Acid (UMP) | Uridine Diphosphate (UDP) | Uridine Triphosphate (UTP)
Nomenclature of Deoxyribonucleotides
- Base | Nucleoside | Nucleotide | Diphosphate | Triphosphate
- Adenine | Deoxyadenosine | Deoxyadenylic Acid (dAMP) | Deoxyadenosine Diphosphate (dADP) | Deoxyadenosine Triphosphate (dATP)
- Guanine | Deoxyguanosine | Deoxyguanylic Acid (dGMP) | Deoxyguanosine Diphosphate (dGDP) | Deoxyguanosine Triphosphate (dGTP)
- Cytosine | Deoxycytidine | Deoxycytidylic Acid (dCMP)| Deoxycytidine Diphosphate (dCDP) | Deoxycytidine Triphosphate (dCTP)
- Thymine | Deoxythymidine | Deoxythymidylic Acid (dTMP) | Deoxythymidine Diphosphate (dTMP) | Deoxythymidine Triphosphate (dTTP)
Other Important Nucleotides
- S-adenosyl methionine (SAM): A methyl group donor
- Phosphoadenosine-phospho-sulfate (PAPS): A sulfate donor
- Cyclic AMP (c.AMP): A second messenger for hormone action
Functions of Nucleotides
- Building blocks of RNA and DNA
- Energy source: ATP and GTP act as energy carriers.
- Mediation of hormone action: c.AMP and c.GMP are second messengers.
- Co-enzymes: NAD, FAD, and Co-enzyme A.
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Description
Dive into the world of nucleic acids with this quiz focused on DNA and RNA. Explore the structures of nucleotides, their components, and the types of nitrogenous bases. Test your knowledge of how these basic units build the foundation of genetic material.
