How Protein Molecules Are Formed

To form protein molecules, the amino ends of amino acid molecules link together with the acid ends of other molecules. The reaction is another example of a dehydration synthesis, similar to what we have already encountered when sugars link together to form starch and cellulose. The bond that forms is called a peptide bond. Each different kind of protein molecule is characterized by the particular amino acids of which it is composed as well as the sequence in which they appear. 

Our bodies are capable of manufacturing many of the amino acids we need from the protein in the food we eat. Certain substances called essential amino acids, however, cannot be manufactured by our bodies and must be present in the food we eat to prevent protein deficiencies. 

But how does an organism know what amino acids to use to synthesize a particular protein like insulin or hemoglobin, and what the necessary order of amino acids must be The answer lies in the organism s DNA, located in the nuclei of cells. DNA molecules are the genetic code that stores the information necessary for protein synthesis. 

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