Structure
Mitochondria
Convert energy from food into ATP, the cell's usable energy.
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.Source: NHGRISource: OpenStax, 2016
Organism or group
How Bacteria connects
Bacteria gave rise to
Structure
Chloroplasts
Capture light energy to make sugar by photosynthesis.
Bacteria is an example of
Level of life
Organism
An individual living thing, from a single bacterium to a tree or a person.
Bacteria is described by
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.
Bacteria is found in
Idea or model
Microbiome
The communities of microbes living in and on a body. A 2016 estimate put a reference adult's bacteria at about 38 trillion, similar to the number of human cells.
Bacteria is used by
Process
Nitrogen fixation
Some bacteria turn nitrogen gas into forms plants can use. Legumes house them in root nodules.
Process
Experimental evolution
Watching evolution in the lab: in a long-running E. coli experiment, one population evolved the ability to use citrate after about 31,500 generations.
Process
Chemosynthesis
Making food from chemical energy instead of light. At vents, bacteria inside tube worms oxidize hydrogen sulfide to feed their hosts.
Technology or method
Recombinant DNA
DNA joined from different sources, the starting point of genetic engineering and of medicines such as recombinant insulin.
Bacteria includes the example
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.
Bacteria is the source of
Technology or method
CRISPR
A bacterial immune system that researchers adapted into a programmable tool for cutting chosen DNA sequences.
Bacteria is related to
Technology or method
Antibiotics
Drugs that kill bacteria or stop their growth. Penicillin traces back to Fleming's 1929 report of a mold that stopped bacteria growing.
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
Innate immunity
The fast, built-in first line of defense. Toll-like receptors recognize features shared by many microbes.
Studied in
Your progress
Sources & further reading
The explanations on this page are our own summaries of these sources. Follow a link to read the original; if anything here disagrees with it, the original wins. How we choose and check sources.
Bacteria (opens the original in a new tab)
National Human Genome Research Institute. Talking Glossary of Genomic and Genetic Terms. National Human Genome Research Institute, NIH.
ReferenceGovernment sourceEducationalMicrobiology (opens the original in a new tab)
OpenStax (2016). OpenStax, Rice University.
TextbookEducationalLicence: CC BY-NC-SA 4.0 (linked, not reused)