Biology » Cell Communication » Response to the Signal

Summarizing Response to the Signal


The initiation of a signaling pathway is a response to external stimuli. This response can take many different forms, including protein synthesis, a change in the cell’s metabolism, cell growth, or even cell death. Many pathways influence the cell by initiating gene expression, and the methods utilized are quite numerous.

Some pathways activate enzymes that interact with DNA transcription factors. Others modify proteins and induce them to change their location in the cell. Depending on the status of the organism, cells can respond by storing energy as glycogen or fat, or making it available in the form of glucose. A signal transduction pathway allows muscle cells to respond to immediate requirements for energy in the form of glucose.

Cell growth is almost always stimulated by external signals called growth factors. Uncontrolled cell growth leads to cancer, and mutations in the genes encoding protein components of signaling pathways are often found in tumor cells. Programmed cell death, or apoptosis, is important for removing damaged or unnecessary cells.

The use of cellular signaling to organize the dismantling of a cell ensures that harmful molecules from the cytoplasm are not released into the spaces between cells, as they are in uncontrolled death, necrosis. Apoptosis also ensures the efficient recycling of the components of the dead cell.

Termination of the cellular signaling cascade is very important so that the response to a signal is appropriate in both timing and intensity. Degradation of signaling molecules and dephosphorylation of phosphorylated intermediates of the pathway by phosphatases are two ways to terminate signals within the cell.



programmed cell death

growth factor

ligand that binds to cell-surface receptors and stimulates cell growth


molecule that binds to a protein (usually an enzyme) and keeps it from functioning


enzyme that removes the phosphate group from a molecule that has been previously phosphorylated


enzyme that degrades cAMP, producing AMP, to terminate signaling

[Attributions and Licenses]

This is a lesson from the tutorial, Cell Communication and you are encouraged to log in or register, so that you can track your progress.

Log In

Share Thoughts