AP Biology College Board

Cell Communication

Cell Communication Overview

• Communication between cells is crucial in coordinating and regulating complex processes in multicellular organisms.
• Cells use various methods to communicate with each other, from direct contact to heart-to-heart signalling.

Direct Contact

• Cells can communicate with each other through direct contact, also known as cell-cell interaction.
• This often occurs when surface molecules on one cell come into contact with surface molecules on another cell.
• This process is exceptionally crucial during immune responses, when immune cells identify and target infected or cancerous cells.

Local Signalling

• In local signalling, cells release messenger molecules or signals that affect nearby cells.
• This process is crucial in the healing of wounds and the coordinated responses of cells in the immune system.

Long-Distance Signalling

• Long-distance signalling is crucial for coordinating the functions of cells located in distinct parts of the organism.
• The endocrine system uses this form of cell communication by releasing hormones into the bloodstream, which then reach target cells located far from the hormone-producing cells.

Signal Transduction Pathways

• When a signalling molecule binds to a receptor on the surface of a cell, the cell undergoes a series of changes, a process known as a signal transduction pathway.
• This process ultimately leads to a response within the cell.

Cellular Responses

• The final consequence of cell-to-cell communication is a change in the receiving cell's behaviour, also known as a cellular response.
• Responses can include changes in gene expression, cell division, and activation or deactivation of particular cell functions.
• Crucially, a cell's response to a signal depends on its particular collection of proteins and the pathways activated.