Nucleic Acids

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  • Created by: Becky
  • Created on: 18-04-13 11:40

Nucleic Acids

Built up from units called nucleotides.

Nucleotides are made up of three parts that are combined by condensation reactions.

  • Phosphate ion – has same structure in all nucleotides
  • Pentose sugar – in RNA it is ribose, in DNA it is deoxyribose
  • Organic base which contains nitrogen

Five different types of bases divided into two groups

  • Pyrimidine bases (single ring) – thymine, cytosine, uracil
  • Purine bases (double ring) – adenine and guanine

DNA 

DNA is always made up of 50% purines and 50% pyrimidines. There is always the same amount of thymine as adenine. Always the same amount of cytosine as guanine.

  • Double stranded polymer of nucleotides or polynucleotide
  • Polynucleotides may contain many million nucleotides
  • Is a double helix – maintained by hydrogen bonding
  • Pentose sugar is deoxyribose
  •  Contains adenine, guanine, cytosine, thymine
  • Strands linked by pairs of organic bases
  • Cytosine with guanine, adenine with thymine – link by H-bonds (complimentary base pairs)

Well suited to carry out its function because:

  • It’s a very stable molecule, can pass from generation to…

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