Organism or group
Bacteria
Small single-celled organisms without a nucleus, found almost everywhere on Earth. Most bacteria in the human body are harmless, and some are helpful.
Microbe Lab
Compare bacteria, archaea, fungi, protists and viruses side by side, and model how a bacterial culture grows.
Step 6 of 7LabInteractive explorer
How this step works
- Open the Microbe Lab and work through it at your own pace.
- Come back here and mark the lab as done.
Lab XP is earned once per lab. If another path includes the same lab, finishing it here counts there too.
Concepts you will meet
Organism or group
Archaea
Single-celled organisms without a nucleus that form a separate domain of life from bacteria.
Organism or group
Virus
Nucleic acid in a protein coat. A virus cannot copy itself alone: it must infect a cell and use the cell's machinery.
Idea or model
Three domains of life
Comparing ribosomal RNA divides life into three domains: Bacteria, Archaea and Eukarya.
Process
Bacterial growth
In a closed culture, bacteria pass through lag, exponential, stationary and death phases.
Organism or group
Thermophiles
Microbes that thrive in heat, such as Thermus aquaticus from hot springs, the source of a heat-stable enzyme used in PCR.
Process
Nitrogen fixation
Some bacteria turn nitrogen gas into forms plants can use. Legumes house them in root nodules.
Organism or group
Prochlorococcus
The smallest known photosynthetic organism, about half a micrometer across. The ocean holds an estimated 2.9 × 10²⁷ of these cells.