Vocabulary If you are a little unsure about what all of these strange words mean, or just need a quick reminder, this page should provide a list of all the vocabulary that you might find difficult to grasp. Along with their defin itions of course. Capsid The protein coat of a virus, which is made up of units called capsomeres. The chemical nature of the capsid is important in stimulating the body’s immune response against the invading virus. Capsomere Any of the protein units that make up the regularly organized outer coat of the viruses. The capsid of most viruses contains more than one type of protein molecule. Virion The virus as a whole. Bacteriophages Viruses which infect bacteria. Icosahedrons 20-sided polygons. Nanometers One-millionth of a millimeter. Lipoprotein One of a group of compounds consisting of a lipid combined with a protein. Glycoprotein A carbohydrate linked covalently to a protein. Retrovirus An RNA-containing virus that converts its RNA into DNA by means of the enzyme reverse transcriptase; this enables it to become integrated into its host’s DNA.