A signal may reach a cell in the form of a single hormone molecule. Inside the cell, the signal must be amplified so that the response is carried out multiple times rather than just be a single molecule. Amplification is built into the system. Any molecule that catalyzes a reaction can do so multiple times producing more than one product molecule. So each step in the signaling chain has the potential for amplification. If a signaling chain is several steps long then there is a great potential for amplification of the signal. For example if the membrane receptor can produce 10 second messengers and each second messenger can generate the transcription of 10 mRNA chains then the signal has been amplified one thousand fold.