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Transcript
Agenda 11/16 • Signal Transduction Notes • Hormone Pairs • Homework: Signal transduction concept map • Turn in: Both Video Notes and Lab Endocrine & Cell Communication Part III: Hormonal Communication 3 • Enduring Understanding 3.D Cells communicate by generating, transmitting and receiving chemical signals. • EK 3D2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling c. Signals released by one cell type can travel long distances to target cells of another cell types. 1. Endocrine signals are produced by endocrine cells that release signaling molecules, which are specific and can travel long distances through the blood to reach all parts of the body. 4 The Process of Communication: Signal-Transduction Pathway Three stages of the SignalTransduction Pathway 1. reception 2. transduction 3. response Typical Signal Transduction Pathway Ligand = Chemical Messenger • Three major classes of molecules function as hormones in vertebrates (ligands) – Polypeptides (proteins and peptides) – Amines derived from amino acids – Steroid hormones 7 Ligands LIGAND: a molecule that binds to a larger molecule Typical Signal Transduction Pathway Phase 1: Reception The target cell detects the ligand • Membrane proteins –G-protein linked receptors –Ion channel receptors –Tyrosine Kinase • Intracellular receptor –Steroid hormone receptors Type of Receptor : G-protein linked Type of Receptor: Ion Channel Type of Receptor: Intracellular Receptor Action of G-Protein Linked Receptor Transduction • Binding changes the receptor protein. • Can set off a cascade reaction Response • Set any of a variety of cell activities in motion. –Activation of an enzyme –Rearrangement of cytoskeleton features –Activation of a specific gene Recap EXTRACELLULAR FLUID 1 Reception Receptor Signaling molecule CYTOPLASM Plasma membrane Recap EXTRACELLULAR FLUID 1 Reception CYTOPLASM Plasma membrane 2 Transduction Receptor Relay molecules in a signal transduction pathway Signaling molecule Recap EXTRACELLULAR FLUID 1 Reception CYTOPLASM Plasma membrane 2 Transduction 3 Response Receptor Activation of cellular response Relay molecules in a signal transduction pathway Signaling molecule Using this image, write your own set of steps for signal transduction Steps of Signal Transduction • 1. Reception occurs between a ligand and receptor. These bind through intermolecular forces • 2. After the ligand has bound to receptor, it begins the transduction process by setting off a cascade of events • 3. During transduction, proteins can activate or inhibit other proteins or enzymes and can activate secondary messengers that can relay another signal to another protein • 4. After the signal pathway is complete, a response is created such as activating an enzyme or promoting transcription of a specific gene 24 Exit Ticket • 1. Discuss the three components of cell communication on or within the cell • 2. Discuss two specific proteins that serve as an evolutionary advantage in cell communication in vertebrates • 3. Discuss the significance of the signal transduction pathway component of cell communication • 4. Draw, explain and label each phase of the signal transduction pathway 25 Agenda 11/17 • Hormone Pathway Lecture • Labeling a hormone pathway • Hormone Pairs Activity • Warm Up: Concept Map Review • Homework: Positive/Negative Feedback video and notes, homeostasis essay (due 11/20) • Turn in: Video Notes Only 26 Types of Receptors + 27 Which is the receptor? G-Protein? Ligand? Which Is A Receptor Through Which Ions Would Pass? Which Of These Acts As A Second Messenger? Water-soluble (hydrophilic) Lipid-soluble (hydrophobic) Polypeptides Steroids 0.8 nm Insulin Cortisol Amines Epinephrine Thyroxine • With your elbow partner, summarize what happens in the three steps of cellular communication – Reception – Transduction – Cellular response 32 Cellular Response Pathways • Water- and lipid-soluble hormones differ in their paths through a body • Water-soluble hormones are secreted by exocytosis, travel freely in the bloodstream, and bind to cellsurface receptors • Lipid-soluble hormones diffuse across cell membranes, travel in the bloodstream bound to transport proteins, and diffuse through the membrane of target cells SECRETORY CELL Lipidsoluble hormone Watersoluble hormone VIA BLOOD Signal receptor Transport protein TARGET CELL Signal receptor NUCLEUS (a) (b) SECRETORY CELL Lipidsoluble hormone Watersoluble hormone VIA BLOOD Signal receptor TARGET CELL Cytoplasmic response Transport protein OR Gene regulation Signal receptor Cytoplasmic response NUCLEUS (a) (b) Gene regulation Pathway for Water-Soluble Hormones • Binding of a hormone to its receptor initiates a signal transduction pathway leading to responses in the cytoplasm, enzyme activation, or a change in gene expression Specific Example Notice the presence of the second messenger Click here to view the animation Pathway for Lipid-Soluble Hormones • The response to a lipid-soluble hormone is usually a change in gene expression • Steroids, thyroid hormones, and the hormonal form of vitamin D enter target cells and bind to protein receptors in the cytoplasm or nucleus • Protein-receptor complexes then act as transcription factors in the nucleus, regulating transcription of specific genes Steroid Hormone Example: Testosterone Compare protein and steroid hormones by completing this T chart Characteristic Protein Hormone Steroid Hormone Speed of response Primary biomolecule composition Method of leaving secretory cell Location of receptor Example 41 Compare protein and steroid hormones by completing this T chart Characteristic Protein Hormone Steroid Hormone Speed of response Rapid response, cascade Response is slower, gene expression Primary biomolecule composition Amino acid cholesterol Method of leaving secretory Exocytosis cell diffusion Location of receptor Membrane bound Intracellular Example Epinephrine Testosterone 42 Multiple Effects of Hormones • The same hormone may have different effects on target cells that have – Different receptors for the hormone – Different signal transduction pathways Multiple Effects of Hormones • The hormone epinephrine has multiple effects in mediating the body’s response to short-term stress • Epinephrine binds to receptors on the plasma membrane of liver cells • This triggers the release of messenger molecules that activate enzymes and result in the release of glucose into the bloodstream 45 Same receptors but different Different receptors intracellular proteins (not shown) Different cellular responses Different cellular responses Epinephrine Epinephrine Epinephrine receptor receptor receptor Glycogen deposits Glycogen breaks down and glucose is released from cell. (a) Liver cell Vessel dilates. (b) Skeletal muscle blood vessel Vessel constricts. (c) Intestinal blood vessel Exit Ticket • Compare and contrast the pathways that water-soluble and lipid-soluble hormones take. You may draw a diagram or give a written explanation 47