| Term | Definition | |
| Epidemiology | Study of patterns of disease infection and spread | |
| Endemic | Diseases are present in a population all the time at low levels. | |
| Epidemic | Affects many individuals in a population in a short amount of time. | |
| Pandemic | Worldwide epidemic | |
| Differential Stain | Use of 2 or more dyes to differentiate among bacterial species or distinguish structures of an organism. Ex) gram stain | |
| Endospores | Unique to bacteria; tough dormant structures that allow bacteria to survive harmful environmental conditions; produced by vegetative cell. | |
| Aseptic technique | Set of procedure to minimize chances that cultures will be contaminated by organisms from environment (prevents cross contamination) | |
| Sterile | Free from bacteria or other living microorganisms | |
| Standard Plate Count | Technique used to determine the number of bacteria in a sample | |
| Selective Media | Enhances or inhibits the growth of some bacteria | |
| Differential Media | Distinguishes between bacteria on same medium based on physical changes in medium; visible change to medium | |
| Obligate aerobe | Requires oxygen to grow. | |
| Microaerophiles | Grows best in presence of a small amount of oxygen | |
| Obligate anaerobes | Killed by oxygen | |
| Faculty anaerobes | Carries aerobic metabolism in presence of oxygen and shifts to anaerobic metabolism in the absence of oxygen | |
| Psychrophile | Cold loving organisms grow best at
15C to 20C | |
| Mesophile | Organisms grows best at 25C and 40C including most bacteria | |
| Thermophile | Heat loving organisms 50 to 60C | |
| Hypertonic Solution | Concentration of dissolved materials is greater than that in a cell; water moves out of cell and cell shrinks | |
| Hypotonic solution | Concentration of dissolved materials is less than that of the cell; water moves in, cell lyses | |
| Halophile | Salt loving organisms | |
| Disinfectant | Chemicals used on the surface of an inanimate objects to kill microbes | |
| Antiseptic | | |
| Antibiotic | Chemicals that have ability to kill bacteria | |
| Photoreactivation | | |
| Repair of DNA divers by light activated enzyme | |
