Chapter 11 Cell Communication

Single Transduction Pathway The process in which a signal on a cells surface is converted into a specific cellular response through a series of steps

Communicating Short Distances Local regulator: transmitting cell secretes these that influence cells in the vicinity – Growth factors Stimulate nearby target cells to grow and multiply – Panacrine signaling – Neurotransmitters Specific nerve cells are so close together, a signal can travel great distances without affecting the wrong parts Direct contact

Communicating Long Distances Hormones (endocrine signaling) – Specialized cells release hormone molecules into vessels of the circulatory system how they travel to their target cells

Three Stages of Cell Signaling 1.Reception – Target cell’s detection of a signal from outside the cell – It is detected when it binds to a cellular protein at the cell’s surface 2.Transduction – Binding of signal molecule initiates the process – Converts signal to a form that can bring about a response 3.Response – Transduced signal triggers a specific cellular response

Reception Signal molecule behaves as a ligand – Binding generally causes a receptor protein to undergo a change in shape – Shape change directly activates the receptor so that it can interact with another cellular molecule Most receptors are membrane proteins – G-Protein-linked receptor – Tyrosine-kinase receptors – Ion-channel receptors

G-Protein-Linked Receptors Plasma membrane receptor that works with help of G protein Vary in their binding sites for recognizing signal molecules and for recognizing different G proteins inside the cell G protein functions as a switch 1.Receptor is activated 2.Causes a protein change 3.Binds to another protein and alters its activity 4.Triggers the next step in the pathway

Tyrosine-Kinase Receptors Part of it functions as an enzyme 1.Ligand binds causing two receptor polypeptides to aggregate, forming a dimer