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| [[Image:Watson n crick.jpg|left|James Watson and Francis Crick]] [[Image:BASE PAIRS.png|right|199x253px|Figure 1.1 A-T and G-C base pairs]] | | See [[Watson-Crick_base_pairing|Watson-Crick base pairing]] |
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| DNA consists of two types of bases namely; [[Purine|purines]] and [[Pyrimidine|pyrimidines]]. There are two types of purines: [[Adenine|adenine]] and [[Guanine|guanine]] as well as two types of Pyrimidines: [[Cytosine|cytosine]] and [[Thymine|thymine]]. In the Watson-Crick DNA base pairing model a purine always binds with a pyrimidine, however, each purine binds to one particular type of pyrimidine.
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| Adenine (A) binds to thymine (T) whilst, guanine (G) binds to cytosine (C); although in RNA unracil (U) is substituted for thymine (T). This base pairing is referred to as complementary, hence the base pairs are called complementary [[Base pairs|base pairs]] <ref>Hartl D., Ruvolo M. (2012) Genetics; Analysis of Genes and Genomes, 8th edition, Burlington: Jones and Barlett.</ref>. The base pairs are bound by [[Hydrogen bonds|hydrogen bonds]], although the number of H-bonds differs between base pairs. G-C base pairs are bound by three (3) hydrogen bonds whilst, A-T base pairs are bound by two (2) hydrogen bonds as illustrated in the figure on the right.
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| === Importance ===
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| Watson-Crick base pairing is of very great importance as it is a deciding factor in [[Semi-conservative replication|DNA Replication]] <ref name="null">Genetic Science Learning Center (2011) Build a DNA Molecule. Learn.Genetics. Available at: http://learn.genetics.utah.edu/content/begin/dna/builddna/. [Last assessed: 26/11/2011] University of Utah</ref>. It ensures that pairs form between complementary bases only. The formation of base pairs between two non-complementary bases results in [[Mutations|gene mutations]] which can be detrimental to development of an organism.
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| === References ===
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| <references />
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Latest revision as of 10:02, 3 December 2011