? Viruses Virus - an infectious agent made up of a core of nucleic acid and a protein coat. viruses are not cells, they are non-living does not have a nucleus, a membrane, or cellular organelles. do have organized structural parts All viruses have at least 2 parts: core of nucleic acid (DNA/RNA) capsid - protective protein coat around the core of nucleic acid. The capsid protects the nucleic acid core from its environment. Additional parts may include: an envelope is an additional protective coating usually made of lipids, proteins, and carbohydrates. spiked projections that bind to the membrane of the cell being infected. **envelopes are only found in viruses that infect animal cells (i.e. flu virus). IV. Vaccines