Unit 4:  How Do Cells Sense Their Environment?

Cells may be self-sustaining units of life, but they don't live in isolation. Their survival depends on receiving and processing information from the outside environment, whether that information pertains to the availability of nutrients, changes in temperature, or variations in light levels.

Cells also can communicate with one another — and change their own internal workings in response — by way of a variety of chemical and mechanical signals. In multicellular organisms, cell signaling allows for specialization of groups of cells. Multiple cell types can then join together to form tissues, such as muscle, blood, and brain tissue. In single-celled organisms, signaling allows populations of cells to coordinate with one another and work as a team to accomplish tasks no single cell could carry out on its own.