In multicellular organisms, cells work together in teams. Multiple cell types, each specialized for a certain function, team up to form tissues. And multiple tissue types are organized into organs.
This virtual card sort has some tricky examples. Do you know which ones are alive and which are not?
See the parts of a cell in action.
How big are cells compared with other objects, molecules, and atoms?
Cells do endless jobs, often using structures your textbook never dreamed of.
Learn how cells work together in tissues, organs, and organ systems.
In 1665, Robert Hooke coined the term cell to describe the structures he could see in cork with some of the first microscopes. Since then, technology has given us an increasingly complex view of the basic unit of life.
Small compartments called vesicles carry materials throughout the cell.
Membranes are critical for organized and efficient cell function.
The endosymbiotic theory explains how relatives of ancient bacteria ended up in modern-day cells.
Explore links to videos and images starring real cells.
Cells communicate through signals, aided by pathways made mostly of proteins. A cell's response depends on the signal itself, as well as the cell type.
When the brain detects danger or a threat, cell signaling machinery springs into action, producing a variety of responses throughout the body.
Take an in-depth look at one axis of cell communication during the fight or flight response.
Cell signals travel through the body, coming in contact with many cell types. The response depends on the type of cell the signal reaches.
Cell communication can be disrupted in a number of ways, sometimes resulting in disease.
See how signals travel into and through cells.