Pyrimidine: Difference between revisions
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[[Nucleotide|Nucleotides]] can be divided into two catergories, [[Purine|purines]] and [[Pyrimidine|pyrimidines]]. [[Pyrimidine|Pyrimidines]] are named so as they are derived from the six membered ring [[Pyrimidine|pyrimidine]] | [[Nucleotide|Nucleotides]] can be divided into two catergories, [[Purine|purines]] and [[Pyrimidine|pyrimidines]]. [[Pyrimidine|Pyrimidines]] are named so as they are derived from the six membered ring [[Pyrimidine|pyrimidine]] <ref>Alberts <i>et al.</i>, Molecular Biology of the Cell 5th Edition</ref>. Examples of [[Pyrimidine|pyrimidines]] are [[Cytosine|cytosine]], [[Thymine|thymine]] and [[Uracil|uracil]] (which is only present in [[RNA|RNA]]). These bond via [[Hydrogen bonds|hydrogen bonds]] with there complementary [[Purine|purine]] [[Base|bases]] when in [[DNA|DNA]]'s double helix form. They also exist in [[RNA|RNA]], where [[Thymine|thymine]] is replaced by [[Uracil|uracil]]. | ||
These [[Base|bases]] are only refered to as [[Nucleotide|nucleotides]] when bonded to one or more [[Phosphate|phosphate]] groups by diester bonds, when separate they are known as [[Nucleoside|nucleosides]] | These [[Base|bases]] are only refered to as [[Nucleotide|nucleotides]] when bonded to one or more [[Phosphate|phosphate]] groups by diester bonds, when separate they are known as [[Nucleoside|nucleosides]] <ref>Stryer <i>et al.</i>, Biochemistry 6th Edition</ref>. | ||
=== References === | |||
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Revision as of 20:00, 3 January 2011
Nucleotides can be divided into two catergories, purines and pyrimidines. Pyrimidines are named so as they are derived from the six membered ring pyrimidine [1]. Examples of pyrimidines are cytosine, thymine and uracil (which is only present in RNA). These bond via hydrogen bonds with there complementary purine bases when in DNA's double helix form. They also exist in RNA, where thymine is replaced by uracil.
These bases are only refered to as nucleotides when bonded to one or more phosphate groups by diester bonds, when separate they are known as nucleosides [2].