Categorize chemical signals in terms of the proximity of the communicating cells. Local signaling – a. Appearance signaling – a secreting cell acts on nearby target cells by discharging molecules of a local regulator (a growth factor, for example) into the extracurricular fluid. B. Synaptic signaling – a nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cell. Long distance signaling- c. Hormonal signaling – specialized endocrine cells secrete hormones into body fluids, often the blood.
Hormones may reach virtually all body cells. 2. Describe the three main stages of cell signaling. A. Reception – target cell’s detection of signaling molecule coming from outside the cell; chemical signal is “detected” when the signaling molecule binds to a receptor protein located at the cell’s surface or inside the cell. B. Transduction – the signal is converted to a form that can bring about a specific cellular response. C. Response – transducer signal triggers a specific cellular response.
May be any imaginable cellular activity. 3. Describe a aligned-receptor interaction and state how such interactions initiate a signal-transduction system. Aligned – receptor interaction: when a signaling molecule specifically binds as a aligned to the receptor protein, the gate opens or closes, allowing or blocking the flow of specific ions; protein interaction is a unifying theme of cell regulation at the cellular level. 4. Compare and contrast G-protein-linked receptors, tyrosine-kinas receptors, and aligned-gated ion channels.
G-protein linked receptors are signal receptor proteins in the plasma membrane that suspend to the binding of a signaling molecule by activating a G-protein. Tyrosine- kinas receptors are receptor proteins in the plasma membrane, the cytoplasm (intracellular) part of which can catalyst the transfer of a phosphate group from TAP to a tyrosine on another protein; often respond to the binding of a signaling molecule by domineering and then phosphorescently a tyrosine on the cytoplasm portion of the other receptor in the dimmer.
The phosphorescently tyrosine on the receptors then activate other signal transduction proteins within the cell. Describe several advantages tot using a multiples pathway in stage of cell signaling. The possibility of greatly amplifying a signal Larger number of activated molecules the transduction More opportunities for coordination and regulation than simpler systems Allows fine- tuning of the response 6. What is usually passed along a signal-transduction pathway? The specific information of the signal (not the signal itself) 7.
Describe how phosphorescently propagates signal information. Phosphorescently transfers proteins that activate other proteins that eventually activate the cell’s response to the signal. The signal is propagated by forming a phosphorescently cascade containing 3 different protein kingies. The signal is transmitted by the cascade, each bringing with it a shape change. 8. Describe how cyclic AMP is formed and how it propagates signal information. An enzyme embedded in the plasma membrane, densely cycles, converts TAP to CAMP in response to an extracurricular signal.
When the signal molecule binds to the receptor site, the enzyme is activated, which can catalyst the synthesis of many molecules of CAMP. . Describe how cytoplasm concentration of Calcium ions can be altered and how this increased pool of calcium ions is involved in signal transduction. Ca concentration can be altered by the active transport out of the cell and active import into the cell of calcium ions; it can function as a second messenger because its concentration in the costly is normally lower than the concentration outside the cell. 10.
Describe how signal amplification is accomplished in target cells, At each catalytic step in the cascade, the number of activated products is much rater than in the preceding step. The amplification effect stems from the fact that these proteins persist in the active form long enough to process numerous molecules of substrate before they become inactive again. 1 1 . Explain how target cells discriminate among signals and how the same signal can elicit multiple cellular responses. The particular proteins a cell possesses determine what signaling molecules it responds to and the nature tot the response .
Deterrent kinds tot cells nave deterrent collections of proteins. This is because different kinds of cells turn on different sets of genes. 12. Explain how scaffolding proteins help to increase the efficiency of signal transduction. Scaffolding proteins simultaneously bind to a specific activated membrane receptor and three different protein kingies. This physical arrangement facilitates signal transduction by these molecules by increasing the speed and accuracy of signal transfer between cells, since the rate of protein-protein interaction is not limited by diffusion.