| Term | Definition |
| endospore | thick-walled, dormant spore inside a bacterial cell |
| eukaryote | an organism whose cell has a nucleus |
| cyanobacteria | bacteria that contains chlorophyll |
| Bacteria | the domain with the most organisms |
| Archaea | the domain whose members prefer extreme environments |
| binary fission | asexual reproduction in single-celled organisms in which it splits into two single-celled organisms |
| prokaryote | a single-celled organism with no nucleus |
| flagella | hair-like or whip-like parts used for locomotion |
| methane maker | a type of archaea that lives in swamps and animal intestines |
| heat lover | a type of archaea that lives in ocean vents and hot springs |
| decomposer | an organism that breaks down dead plant/animal matter |
| producer | an organism that uses the sun's energy to produce its own food |
| pathogenic bacteria | bacteria that cause harm |
| antibiotic | medicine used to treat many bacterial diseases |
| genetic engineering | changes in the genes of any organism |
| nitrogen fixation | the process by which bacteria change nitrogen in the air into a form that plants can use |
| lactose | milk sugar |
| bioremediation | the use of microorganisms to make hazardous material safe |
| lytic cycle | a cycle in which a virus attacks a host then causes it to make viruses |
| host | a living organism that a virus or parasite lives on/in |
| vaccination | a substance that helps prevent viral infections |
| antiviral medicine | a type of medicine that keeps viruses from reproducing |
| lysogenic cycle | a cycle in which a virus's genes live in a host but are inactive for a period of time |
| protein coat | protects the genetic information inside a virus and helps the virus enter its host |
| cocci | spherical shape of some bacteria |
| bacilli | rod-shape of some bacteria |
| spirilla | spiral shape of some bacteria |
| consumer | an organism that eats other organisms for its food/energy |