Ch15_Lecture

Ch15_Lecture - 15 Cell Signaling and Communication 15 Cell...

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15 Cell Signaling and Communication
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15 Cell Signaling and Communication 15.1 What Are Signals, and How Do Cells Respond to Them? 15.2 How Do Signal Receptors Initiate a Cellular Response? 15.3 How Is a Response to a Signal Transduced through the Cell? 15.4 How Do Cells Change in Response to Signals? 15.5 How Do Cells Communicate Directly?
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15.1 What Are Signals, and How Do Cells Respond to Them? All cells process information from the environment. The information can be a physical stimulus, such as light; or chemical. Signals can come from outside the organism, or from neighboring cells.
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15.1 What Are Signals, and How Do Cells Respond to Them? To respond to a signal, a cell must have a specific receptor that can detect it. A signal transduction pathway is the series of steps involved in a cell’s response to a signal.
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15.1 What Are Signals, and How Do Cells Respond to Them? In a large multicellular organism, signals reach target cells by diffusion or by circulation in the blood. Autocrine signals affect the cells that made them. Paracrine signals affect nearby cells. Hormones travel to distant cells, usually via the circulatory system.
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Figure 15.1 Chemical Signaling Systems (Part 1)
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Figure 15.1 Chemical Signaling Systems (Part 2)
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15.1 What Are Signals, and How Do Cells Respond to Them? A signal transduction pathway is the entire signaling process, including the cell’s response. The pathway has two major components: a receptor and a responder . Example: E. coli and changes in solute concentration.
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15.1 What Are Signals, and How Do Cells Respond to Them? A signal transduction pathway: The signal causes receptor protein to change conformation. Conformation change gives it protein kinase activity. Phosphorylation alters function of a responder protein.
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15.1 What Are Signals, and How Do Cells Respond to Them? The signal is amplified. A transcription factor is activated. Synthesis of a specific protein is turned on. Action of the protein alters cell activity.
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15.2 How Do Signal Receptors Initiate a Cellular Response? Receptor proteins have very specific binding sites for chemical signal molecules, or ligands . Binding the ligand causes receptor protein to change shape. The binding is reversible.
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15.2 How Do Signal Receptors Initiate a Cellular Response? Inhibitors can also bind to the receptor proteins. Natural and artificial inhibitors are used in medicine.
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15.2 How Do Signal Receptors Initiate a Cellular Response? Ligands with cytoplasmic receptors : Small or nonpolar ligands can diffuse across plasma membrane (e.g., estrogen). Ligands with plasma membrane receptors : Large or polar ligands bind to plasma membrane receptors (e.g., insulin).
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Figure 15.4 Two Locations for Receptors
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Types of plasma membrane receptors:
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This note was uploaded on 05/10/2008 for the course BIOL 120 taught by Professor Hasek during the Spring '08 term at LSU.

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Ch15_Lecture - 15 Cell Signaling and Communication 15 Cell...

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