Antibodies to common microorganisms have been developed by infancy. <span>An </span>antibody<span> (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein produced mainly by plasma cells that is used by the immune system to identify and neutralize pathogens such as bacteria and viruses.</span>
...require a living host cell to survive.
Coenzymes
Coenzymes are small organic molecules that, themselves, do not function as catalysts (i.e. enzymes) but aid the latter in carrying out their functions. Enzymes are biological catalysts, which means that they allow reactions to occur at lower activation energies. In a way, enzymes help to "speed up" chemical reactions.
Coenzymes are mostly derived from vitamins. Examples include TPP from Vitamin B1 (thiamine), FAD from Vitamin B2 (Riboflavin), and NAD+ from Niacin.
Long chains of amino acids used for building, repair, and maintenance.
