My AP Biology Thoughts  Unit 4 Cell Communication and Cell Cycle

Welcome 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 cell
• The 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 relationship
• Signal 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 response
• The 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 term
• We 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 changes
• Three Response Types
• 1. Metabolism/Growth/Enzyme Activation/Open Ion Channel
• Altering 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 Expression
• The process where information from a gene is used by the cell to produce a functional product, a protein. It involves two steps, transcription and...