biology

Topics: Signal transduction, Cell signaling, Protein Pages: 3 (729 words) Published: October 30, 2013
AP Biology Study Guide Chapter 11

1. Categorize chemical signals in terms of the proximity of the communicating cells.

Local signaling –
a. Paracrine signaling – a secreting cell acts on nearby target cells by discharging molecules of a local regulator (a growth factor, for example) into the extracellular 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 – transduced signal triggers a specific cellular response. May be any imaginable cellular activity.

3. Describe a ligand-receptor interaction and state how such interactions initiate a signal-transduction system.

Ligand – receptor interaction: when a signaling molecule specifically binds as a ligand 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-kinase receptors, and ligand-gated ion channels.

G-protein linked receptors are signal receptor proteins in the plasma membrane that respond to the binding of a signaling molecule by activating a G-protein. Tyrosine-kinase receptors are receptor proteins in the plasma membrane, the cytoplasmic (intracellular) part of which can catalyze the transfer of a phosphate group from ATP to a tyrosine on another protein;...
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