My AP Biology Thoughts  Unit 4 Cell Communication and Cell CycleWelcome to My AP Biology Thoughts podcast, my name is Victoria Villagran and I am your host for episode #90 called Unit 4 Cell Communication and Cell Cycle: Cellular Responses in Signaling Pathways. Today we will be discussing general cellular responses in signaling pathways. Segment 1: Introduction to Cellular Responses in Signaling Pathways Signaling pathway:Signaling begins with the recognition of a chemical messenger, a ligand, by a receptor protein in a target cellThe ligand-binding domain of a receptor recognizes a specific chemical messenger, which can be a peptide, a small chemical, or protein, in a specific one-to-one relationshipSignal reception, which is when the target cell receives a signaling molecule; transduction, which is a series of events that converts the signal to something the target cell can respond to; and cellular response, which is when the target cell responds to the signal. They are many varieties of ligands and receptors, and them binding can lead to many different responses May involved 2nd messengers or phosphorylation, and protein phosphorylation They all produce some kind of cellular responseThe same signal or ligand can lead to different responses Signal Pathways may influence how the cell responds to its environment Responses can be short or long termWe can see changes such as an increase in the transcription of certain genes or the activity of particular enzymes.We may be able to see changes in the outward behavior or appearance of the cell, such as cell growth or cell death, that are caused by the molecular changesThree Response Types1. Metabolism/Growth/Enzyme Activation/Open Ion ChannelAltering the activity of specific enzymes, metabolic enzymes in the cell become more or less active Activated G Protein binds to a molecule that starts the transduction pathway, we will go into more detail later Some signals bind to ligand-gated ion channels which either open or close in response to binding 2. Gene ExpressionThe process where information from a gene is used by the cell to produce a functional product, a protein. It involves two steps, transcription and...