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| A nucleotide consists of a Phosphate group, a deoxyribose five-carbon sugar (also known as a Pentose sugar) and a nitrogenous organic base. Many nucleotides join together to form a chain called a polynucleotide. This is what forms the basis of a DNA molecule.
| | See [[nucleotide|nucleotide]] |
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| The nitrogenous organic bases can be either Adenine or Guanine (Purine bases), Cytosine or Thymine (Pyrimidine bases). The nucleotides themselves are linked together by phosphodiester bonds (a covalent bond between the phosphate and the pentose sugar). In this case the 5th Carbon of the Pentose sugar and 3rd Carbon of the Pentose sugar join to the Phosphate groups.
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| Two nucleotides then join together to form an antiparallel double helix by hydrogen bonds between the bases. The bases have specific pairing - A always joins to T by 2 hydrogen bonds, C to G by 3 hydrogen bonds. This is complementary base pairing and ensures that replication of DNA is easier and the DNA sequence can be passed from generation to generation.
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Revision as of 19:28, 23 November 2011