DNA.

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D.N.A is a polynucleotide - it's made up of lots of nucleotides joined together.

  • Each nucleotide is made up from a pentose sugar, a phosphate group and a nitrogenous base.
  • The sugar in D.N.A is a deoxyribose sugar.
  • Each nucleotide has the same sugar and phosphate, however the base on each nucleotide varies.
  • There are 4 bases: adenine....thymine....cytosine....guanine.

Two polynucleotide strands join together to form a double-helix.

  • The nucleotides join up between the phosphate group of one nucleotide and the sugar of another, creating a sugar-phosphate backbone.
  • Two D.N.A polynucleotide strands are joined by hydrogen bonds between corresponding bases. A and T. C and G.

The Structure of D.N.A.

  • D.N.A molecules are long and are coiled up very tightly, so a lot of genetic information…

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