Bisc 160 Ch 7 9 21 2015 o o o o o o o o o o o o o o o o o Signals can alter behavior or cell activity o Oxytocin female o Vasopressin male o o Physical light touch Chemical scent hormones Signal transduction pathways allow cells to respond to signals Communication Specificity receptor has to recognize specific molecule Form and function shape determines function Transducer another name for receptor Signal transduction Signal receptor response Figure 7 2 Short term change basic cell chemistry Long term change proteins Chemical signals can come from the environment or other cells External environment o o Autocrine when a cell produces a signal in response to its own signal o o o Juxtacrine the cell right next to you Cell next to it has receptors and can respond Paracrine a little further away from signaling cell Endocrine totally far away Secreting chemical compound signals into blood hormones Can transport all over body Use blood vessels To respond to signals cells must have a specific receptor Binding site specificity Reversible binding Stimulated Ligand signal Receptor number increase sensitivity increases Signal concentration Receptors undergo a change in shape after signal recognition Conformational change o o Active site o o o Ligand binding Phosphorylation Change in shape change in function Receptors can be in the cell membrane or in the cytoplasm Receptors in membrane are polar and large Transmembrane receptor Cytoplasmic receptor Receptor in cytoplasm that binds to nonpolar molecules that can simply diffuse through membrane 3 membrane receptor types Ion channels protein kinase g protein linked Gated ion channels are receptors that open in response to a signal Signal types Each channel haws own signal Each channel has own ion Figure 7 5 o o o o o o Protein kinase receptors phosphorylate proteins Kinase involved in transfer of phosphate group Enzyme Phosphorylation transfer of phosphate G protein linked receptors use G proteins as an intermediate Receptor o o G stands for GDP and GTP kinda like ATP o o Effector protein Figure 7 7 Cytoplasmic receptors are inside the cell and alter gene expression directly o Gene expression turning on or turning off a gene Transcription and translation o o Transcription factor Chaperone The same signals can result in completely different responses o Direct o o o Receptor and effector Indirect Receptor intermediate second messenger Signal transduction generates signaling cascades o Multiple interactions o Amplification o o Single signal molecule Protein kinase cascade Second messengers amplify signals o o o Signal cascades Rapid amplification Several examples Cyclic AMP cAMP Diaclyglyercol Inositol triphosphate Calcium ions Nitric oxide