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. Proteins are polymers of amino acids joined together by peptide bonds. There are 20 different amino acids that make up essentially all proteins on earth. Each of these amino acids has a fundamental design composed of a central carbon (also called the alpha carbon) bonded to: 1  a hydrogen. 2  a carboxyl group. 3  an amino group. 4  a unique side chain or R-group.