| Term | Definition |
| virus | nonliving particle made up of nucleic acid and protein coat |
| capsid | protein coat |
| lytic cycle | virus invades a host, produces new viruses and lyses the cell |
| lyse | rupture or burst |
| lysogenic cycle | virus inserts nucleic acid into host DNA and hangs out |
| virulent | reproduce only by lytic cycle |
| vector | intermediate host that transfers a pathogen |
| pathology | study of pathogens |
| vaccine | solution contains harmless version of virus; causes an immune response |
| prokaryote | single-celled; no membrane bound organelles or nucleus |
| methanogen | archaea that produce methane gas |
| halophiles | archaea that love salt |
| thermoacidophiles | archaea that love hot, acidic environments |
| peptidoglycan | protein-carbohydrate compound found in cell wall |
| bacilli | rod-shaped bacteria |
| spirilla | spiral-shaped bacteria |
| coccus | sphere-shaped bacteria |
| antibiotics | chemical that inhibit growth or kill bacteria |
| capsule | outer covering of bacteria |
| pili | short, hair-like projections that allow bacteria to connect to other cells |
| endospore | resistant structure of bacteria, dormant |
| autotroph | obtains energy from sunlight or chemical compounds |
| heterotroph | obtains energy through consuming other organisms |
| aerobe | organism that lives in presence of oxygen |
| anaerobe | organism that lives in absence of oxygen |