AP Bio Study Guide

Big Idea 3.D

What is a signal transduction pathway?

A signal transduction pathway is a multistep process in which a small number of extra-cellular signal molecules produce a major cellular response, or cascade effect.

Things to know:

  • They are characterized by a signal, a transduction (conversion of the signal), and a response.
  • They are highly specific and regulated.
  • One signal molecule can cause a cascade effect, releasing thousands of molecules inside a cell.
  • They regulate cellular activity, altering gene expression, protein activity, or protein synthesis.
  • These pathways evolved millions of years ago in a common ancestor, which can be seen through the similarity of these pathways among diverse organisms.