Definition z Protein from the Greek proteios, meaning primary. z Proteins are the work horses of biological systems. – They play key roles in constructing and maintaining living cells z Our genes code for proteins z Proteins are polymers of amino acidsDefinition z Protein from the Greek proteios, meaning primary. z Proteins are the work horses of biological systems. – They play key roles in constructing and maintaining living cells z Our genes code for proteins z Proteins are polymers of amino acids