Middle back pain is any type of pain or discomfort in the area between your upper and lower back. Health care professionals refer to this area as the lower thoracic area or lower thoracic spine. The upper thoracic area or upper thoracic spine makes up part of the upper back.
Amino Acids. Amino acids are the monomers of proteins. They have a positively-charged amino group on one side and a negatively-charged carboxyl group on the other. Attached to the central carbon is a variable group called the 'R' group. This group is different for each amino acid. There are 20 amino acids in human cells.
Amino acids are molecules containing an amine group, a carboxylic acid group, and a side-chain that is specific to each amino acid. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen. A dipeptide is a molecule consisting of two amino acids joined by a single peptide bond. Peptides are short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size, typically containing fewer than 50 monomer units.