Proteins also contain nitrogen, and sometimes sulfur.
The building blocks of protein are amino acids, which is a carbon structure with an acid group and a side chain.
There are 20 acids that differ in the composition of the acid side chains.
Nine of the acids are considered essential, while the remaining 11 can be synthesized in the body and are therefore not essential.
The acid group of one acid can be joined to the group of another amino acid by peptide bonds to form a dipeptide.
If more acids are attached, tripeptides, polypeptides and proteins can be formed.
The order of amino acids in proteins is very important.
We can look at hemoglobin as an example.
Hemoglobin is an example of a polypeptide chain that contains a total of 574 acids.
The main function of hemoglobin is to carry oxygen in the red blood cells so that it may be transported throughout the body.
In sickle cell anemia patients, one amino acid and two of the polypeptide chains is incorrect.
Due to this defect, the structure of the hemoglobin is changed, and the hemoglobin can no longer carry oxygen, and sickle shaped cells can get caught in small blood vessels, resulting in impairment of circulation.
Thus, even very minor alterations in the acid sequence can alter the physiological properties of a protein and quite possibly make the protein nonfunctional.
Depending on the acid composition, proteins can be classified as either high quality proteins or low quality proteins.
High quality proteins contain all of the essential acids in the proportion needed by the body.
Low quality proteins lack one or more of the essential acids.