| Further to capuchins answer, this is a biological reaction. Biological reactions are made to sustain life, so each and every one is unique to the fact that are a condensation reaction (expelling water). As you can see in the above answer, the bottom left hydroxide molecule bonds with the lone hydrogen on the right to form water, which allows the 2 separate sections of each Amino Acid to bond together.
The R is a variable and can contain numerous amounts of materials, namely long chain fatty acids and in rare occurrences phosoplipids.
Enough of these reactions will form a peptide bond and eventually a protein... - I seem to have forgotten what a nucleotide base is made of... | 
Linear Mode
