Unformatted text preview: Bio 106 Cells Lecture 11 – Cell Signaling Cell Signaling Pathways
The conversion of an external signal to an amplified internal signal an amplified internal signal General Overview 2. Types of pathways 3. G-protein signaling cAMP/IP3 pathways
1. One Signal Type is Converted to Another
ECB3 16-2 Can you hear me now? Electrical signal into an amplified sound signal Extracellular signal (A) into an amplified intracellular signal (B) What do cell signaling pathways have in common with a cell phone?
A. B. Not a thing Both amplify an external signal amplify an external signal Different Types of Signaling Pathways ECB2 16-3 Example: Contact-dependent signaling Contactcontrols nerve-cell production nerveNerve cell (blue) begins to specialize while neighboring cells maintain the epithelial epithelial The structure. The Signal Responses contact signals prevent these cells from also becoming nerve cells. Movie 16-1 ECB3 16-4 Professor Owen Fall 2009 1 Bio 106 Cells Lecture 11 – Cell Signaling Cells depend on multiple extracellular signals
Signals work in combinations to combinations to regulate the behavior of the cell. Signaling Responses ECB3 16-6 ECB3 16-7 Based on what we have covered so far, which is the best description of cell signaling? Signals Bind Extracellularly or Intracellularly An electrical signal B. A weak external signal is amplified weak external signal is amplified C. A weak external signal is amplified internally as a second message D. A new ringtone for my cell phone
A. Signals unable to cross the plasma membrane bind to a surface receptor to then create in internal signal.
ECB3 16-8 Small hydrophobic signals diffuse across and act as a signal. Examples of Signaling Hormones Some Signals Alter Gene Expression
Cortisol, a hormone secreted in response to stress, diff diffuses across the th PM, binds to its receptor, enters the nucleus and alters gene expression. Cooper 15.2 ECB3 16-10 Professor Owen Fall 2009 2 Bio 106 Cells Lecture 11 – Cell Signaling Examples of Plant Hormones Auxin Signaling
Mattsson et al. (1999) Cooper 15.9 Cooper 15.10 Extracellular Signals Alter the Activity of Different Cell Proteins
In this example, the signal molecule binds to cell to a cell-surface receptor protein. Cellular Signaling Cascades “signal cascade” Modified from ECB3 16-12 ECB2 16-8 Intracellular Signaling Proteins
Intracellular signaling proteins can relay, amplify, relay, amplify, integrate and distribute the incoming signal. From the textbook reading for today, you learned that the largest family of cell surface receptors transmits signals via the intermediary action of:
A. B. C. D. E. hormones guanine nucleotide-binding proteins nucleotide proteins adenine nucleotide-binding proteins mammalian genes bacterial genes ECB3 16-13 Professor Owen Fall 2009 3 Bio 106 Cells Lecture 11 – Cell Signaling Many Signaling Proteins Act as Molecular Switches Three Classes of Cell-surface Receptors Cell- (We will focus on this pathway) ECB3 16-14 ECB2 16-14 Receptors On the plasma membrane; not abundant; hard to study Have saturation kinetics Analogs are useful to study receptors
= molecules with structural similarities to the natural ligand (hormone) Substances That Also Give a Signaling Response Agonists = mimic hormone function when binds to receptor Antagonists = binds to receptor but no response and competes with natural ligand Professor Owen Fall 2009 4 ...
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