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Nucleotides

  • Nucleic Acids (DNA and RNA) are polymers and their monomers are Nucleotides. Each nucleotide is composed of
    • a Pentose Sugar (Deoxyribose in DNA and Ribose in RNA)
    • an Organic Nitrogenous Base
    • a Phosphate Group
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  • Nucleotides are joined together by a Condensation Reaction between the Phosphate Group of one and the Sugar Group of another. The bond between the two monomers is called a Phosphodiester Bond. Many nucleotides joined together in this way make a repeating Sugar-Phosphate 'backbone' out of which the organic bases project.
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  • There are five possible organic bases that can form nucleotides, and as two mean the same in terms of genetic code, there are only really four different nucleotides that code for DNA.
  • The organic bases are grouped into Pyrimidines and Purines. Pyrimidines are smaller as they contain a single ringed structure, whereas Purines are larger as they contain a double ring structure. The Pyrimidines are:
    • Thymine
    • Uracil
    • Cytosine

    The Purines are:
    • Adenine
    • Guanine
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  • If one has too much Nucleic Acid, especially in one's extremities, one may develop a condition known as Gout. In the liver, excess Purines are broken down in Uric Acid, which is then excreted in the urine. However, if one's blood contains too much of this Uric Acid, it may form crystals that are deposited in the joints, which can be particularly painful.