CHAPTER 11 CELL COMMUNICATION Overview: The cellular internet I. Evolution of cell signaling A. Most, but not all, communication universal 1. Further evidence for evolutionary relatedness of all life 11.1 External signals=internal cellular response I. Evolution of cell signaling A. Signal transduction pathway 1. The process of converting a signal on the cell’s surface to a specific cellular response 2. May require several steps

II. Local & long distance signaling A. Local 1. Cell Junctions a. Gap juctions b. Plasmodesmata 2. Direct contact via membrane proteins a. Cell-cell recognition

3. Local regulators a. Chemicals secreted by signaling cells into extracellular matrix & influence cells in the vicinity b. Paracrine signaling 1. Growth factors c. Synaptic signaling

B. Long distance 1. Hormones a. Endocrine signaling b. Plant growth regulators c. Vary in size & type 1. Ethylene & insulin C. In order for cell communication to work chemical signal must be detected, changes/interpreted, & target cell must respond

III. 3 stages of cell signaling A. Reception 1. Target cell’s detection of signaling molecule (ligand) a. Signaling molecule binds to receptor protein on target cell 1. Receptor molecule is complimentary to ligand B. Transduction 1. Converting signal to a form that brings about a specific response in target cell 2. Signal transduction pathway a. Mechanism linking a mechanical or chemical stimulus to a specific cellular response b. Alter & amplifies the change

C. Response 1. Transduced signal triggers a specific cellular response

IV. G Protein-Coupled Receptors

V. Ion Channel Receptors