Nucleotides

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Nucleotides
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There are five different nitrogenous bases that
occur in DNA. These are adenine(A),
cytosine(C), guanine(G), thymine(T) and uracil.
Uracil is only found in RNA, and thymine can only
be found in DNA, one replaces the other. Adenine
will only form hydrogen bonds with itself and
thymine. Guanine will only bond with cytosine.
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There are two types of nitrogen containing
nucleotides Purines these are made up of a
double ring structure consisting of a six and
five sided ring, including adenine and
guanine. Pyrimidines are six sided ring
structures including thymine, cytosine and
uracil. A pyrimidine base will only bond with a
purine base.
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Nucleotides are the basic building blocks of
macromolecules, such as Deoxyribonucleic Acid
(DNA), and Ribonucleic Acid (RNA). Nucleotides
are built up by a condensation reaction between
the three components, (a pentose sugar, a base
and a phosphate). The pentose sugar is either
ribose, found in RNA, or deoxyribose, found in
DNA. Ribose contains one more oxygen atom than
deoxyribose.
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Two nucleotides join to form a dinucleotide.
This is the result of a further condensation
reaction between one pentose sugar and the
phosphate group attached to another pentose
sugar. This process can then be repeated many
times to form a polynucleotide molecule, which
could contain millions of individual
nucleotides. RNA molecules are made up of just
one polynucleotide chain, whereas DNA exists as
two chains, running in opposite directions and
twisted around each other in the form of a double
helix.
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Polynucleotides
Polynucleotides are polymers that are made from
nucleotides. These nucleotides are joined to each
other by condensation. Therefore, every time two
nucleotides are joined, a molecule of water is
lost. These nucleotides may be joined in any
order.
Phosphate Group
Base
Water Molecules which are lost.
Pentose Sugar
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End of Show
By Vikki Savage, Kerry Acheson and Tara Daze