Peptide bonds
A peptide bond is a kind of linkage between two amino acids. It is also known as an amide bond. A peptide bond connects two amino acids, forming a dipeptide, and is associated with the loss of a water molecule. This process is called a condensation reaction. One perhaps surprising fact about peptide bonds is that they are very kinetically stable, in fact a peptide bond in a solution will last 1000 years, if no catalyst is present to disrupt it.
Many amino acids can be connected via peptide bonds, making a polypeptide. Each amino acid is then called a residue as it forms part of the polypeptide [1]. The ends of a polypeptide chain will be different because an alpha amino group is present at one end and an alpha carboxyl group present at the other. This gives the polypeptide chain polarity [2].