Nucleotides are monomers consisting of a phosphate group, a five carbon sugar(either ribose or deoxyribose) and a one or two ring nitrogen containing base.
Nucleotides are important for several reasons. First the genetic material (DNA) is a polymer of four different nucleotides. The genetic information is coded in the sequence of nucleotides in a DNA molecule. Polymers of nucleotides such as DNA and the several types of RNA in the body are called nucleic acids.
In nucleotides there may any one of a number of nitrogen bases. Nitrogen bases are functional groups consisting of one or two rings containing both carbon and nitrogen. Adenine monophosphate, AMP and cytosine monophosphate, CMP illustrate the two basic types of nucleotide nitrogen bases.
Purines are nitrogen containing bases consisting of two rings. AMP's
nitrogen base has two nitrogen bearing rings(Nitrogens=blue, Phosphorus=yellow,
Carbon = grey, Oxygen = red) and is thus a purine
called adenine. The two purines you will encounter as part of the structure
of nucleotides are called adenine and guanine.
NADH is an important electron acceptor in cellular respiration. Note that it consists of a purine containing nucleotide and a pyrimidine containing nucleotide.
Nucleic acids are polymers of nucleotides joined together to make large macromolecules. The important nucleic acids are deoxyribonucleic acid(DNA) and various types of ribonucleic acids(RNA).
DNA: This model represents part of a strand of DNA, the genetic material. Notice the double helix, the backbones of which are formed by joined phosphate groups(yellow). DNA is the genetic material found in cells and contains instructions that help determine the structure and function of cells.
Below is a type of RNA called transfer RNA. This molecule is involved in protein synthesis. It is not a double helix but actually more of a clover looped shape. In both DNA and the RNA's, hydrogen bonds are important in determining the molecule's shape and which nucleotide pairs with which.
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pgd. revised 6/24/02