Nucleotides and ATP

• Provide the energy currency of cells in the form of adenosine triphophate (ATP).
• Also provide the building blocks for DNA and RNA.
• The most common types of nucleotides have either a purine base, which has two nitrogen containing rings, or a pyramidine base, which has only one.
• The most common purines are adenine (A) and guanine (G) and the most common pyrimidines are cytsosine (C), thymine (T) and uracil (U).
• These are the base pairings: A+T (U replaces T in RNA), C+G.

The structure:

About

• It is the universal energy supplier in cells.
• ATP is found in all living organisms in exactly the same form.
• Anything that interfers with the production or breakdown of ATP is fatal to the cell and ultimately destroys the whole multicellular organism.

How it works and 'makes' energy

When energy is needed in a cell, the third phosphate bond in the molecule is broken in a hydrolysis reaction. This is catalysed by the enzyme ATPase. The products of the reaction are adensodine diphosphate (ADP), another nucleotide and a free inorganic phosphate group (Pi).

One phosphate bond is broken as the ATP is spilt - this uses energy. Two further bodns are made to produce teh ADP and the stable phosphate group and this releases the energy that us needed to drive the other two reactions.