Topic List for Chapter 5 Control of Cells by Chemical Messengers Understand the importance of chemical messengers in the body and the kinds of processes they control Be able to give examples of situations where chemical messengers are important Chemical Messengers Lipid soluble Water soluble Hormones travel through blood distant places to target cells Paracrine close target cells in proximity to site of release so it doesn t travel far synthesized by cell and released in to extracellular fluid Autocrine released by one cell and acts upon same cell Neurotransmitters fast neuron or effector cell is in close proximity to site of neurotransmitter release Importance sending signals Understand the various signal transduction pathways for lipid soluble messengers and water soluble messengers What are the four main categories of water soluble messengers Where is the receptor located and what are the first few steps in the signal transduction pathway Lipid soluble messenger Non polar can go through plasma membrane passively Can bind to receptor inside target cell then acts on nucleus which acts on transcription DNA RNA Ex Steroid and Thyroid hormones Water soluble messenger bind to receptor in plasmas membrane polar they can t get through passively Ligand Gated Ion Channels channel opens because messenger binds to receptor cause response so it binds to and opens the channel Receptors that function as Enzymes receptor itself is an enzyme not active until messenger binds with it tyrosine kinase receptor pg 126 explain picture There is an exception gyanylyl cyclase Receptors that interact with Cytoplasmic Janus Kinases JAK s enzyme attached to receptor so messenger binds with receptor receptor changes shape which activates the JAK Topic List for Chapter 5 Control of Cells by Chemical Messengers G Protein Coupled Receptors GDP is bound to alpha subunit of G protein protein exists as an inactive trimetric molecule Bind GDP to alpha subunit which causes alpha subunit to disassociate which causes it to bind to the effector and that causes it to activate which then causes reaction Understand the following types of receptors receptors that act as ligand gated ion channels receptors that act as enzymes receptors that activate JAK s and receptors that activate G proteins See above Terms to know Receptor protein either on cell surface in cytosol or in the nucleus that binds a chemical messenger such as a hormone or neurotransmitter and mediates its actions in sensory system specialized peripheral ending of afferent neuron or separate cell intimately associated with it that detects changes in some aspect of environment Specificity selectively ability of binding site to react with only one or a limited number of types of molecules Affinity strength with which ligand binds to its binding site Saturation occupation of all available binding sites by their ligand Competition ability of similar molecules to combines with the same binding site or receptor Antagonist molecule that competes with another for a receptor and binds to the receptor but does not trigger the cells response Agonist chemical messenger that binds to receptor and triggers cell s response often refers to drug that mimics action of chemical normally in the body Signal transduction pathway sequence of mechanisms that relay information to plasma membrane receptor to cell s response mechanism Steroid hormone any of a family of hormones like progesterone whose structure is derived from cholesterol Transcription factor one of a class of proteins that act as gene switches regulating the transcription of a particular gene by activating or repressing the initiation process Transcription formation of RNA containing in linear sequence of its nucleotides the genetic information of a specific gene first stage of protein synthesis Protein kinase any enzyme that phosphorylates other proteins by transferring to them a phosphate group from ATP Topic List for Chapter 5 Control of Cells by Chemical Messengers Water soluble messenger cannot readily enter cells by diffusion through the lipid bilayer of plasma membrane Ligand gated ion channel membrane channel operated by the binding of specific molecules to channel proteins Receptors that function as enzymes receptors that have intrinsic enzyme activity G protein one protein from a family of regulatory proteins that reversibly bind guanosine nucleotides plasma membrane G proteins interact with membrane ion channels or enzymes G protein coupled receptors a cell membrane protein that binds an extracellular signal and then activates an associated G protein leading to activation of another protein such as adenylyl cyclase