| Pathogen | An organism that causes disease. |
| Saprophyte | An organism that feeds on dead matter. |
| Parasite | An organism that feeds on a living host. |
| Aerobic Organism | An organism that requires oxygen. |
| Steady State | A state in which members of a population die as quickly as new members are born. |
| Exponential Growth | Populations growth that is unhindered because of the abundance of resources for an ever-increasing population. |
| Logistic Growth | Populations growth that is controlled by limited resources. |
| Conjugation | A temporary union of two organisms for the purpose of DNA transfer. |
| Plasmid | A small, circular section of extra DNA that confers one or more traits to a bacterium and can be reproduced separately from the main bacterial genetic code. |
| Transformation | The transfer of a DNA segment from a nonfunctional donor cell to that of a functional recipient cell. |
| Transduction | The process by which infection by a virus results in DNA being transferred from one bacterium to another. |
| Endospore | The DNA and other essential parts of a bacterium coated with several hard layers. |
| Strains | Organisms from the same species that have markedly different traits. |
| Anaerobic Organism | An organism that does not require oxygen. |
