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chap11 studyguide - Chapter 11 Cell Communication Study...

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Chapter 11 Cell Communication Study Guide Overview: The Cellular Internet Cell-to-cell communication is absolutely essential for multicellular organisms. ° Cells must communicate to coordinate their activities. Communication between cells is also important for many unicellular organisms. Biologists have discovered universal mechanisms of cellular regulation involving the same small set of cell-signaling mechanisms. ° The ubiquity of these mechanisms provides additional evidence for the evolutionary relatedness of all life. Cells most often communicate by chemical signals, although signals may take other forms. Concept 11.1 External signals are converted into responses within the cell What messages are passed from cell to cell? How do cells respond to these messages? The process by which a signal on a cell’s surface is converted into a specific cellular response is a series of steps called a signal-transduction pathway. ° The molecular details of these pathways are strikingly similar in yeast and animal cells, even though their last common ancestor lived more than a billion years ago. ° Signaling systems of bacteria and plants also share similarities. These similarities suggest that ancestral signaling molecules evolved long ago in prokaryotes and have since been adopted for new uses by single-celled eukaryotes and multicellular descendents. Communicating cells may be close together or far apart. Multicellular organisms release signaling molecules that target other cells. Cells may communicate by direct contact. ° Both animals and plants have cell junctions that connect to the cytoplasm of adjacent cells. ° Signaling substances dissolved in the cytosol can pass freely between adjacent cells. ° Animal cells can communicate by direct contact between membrane-bound cell surface molecules. ° Such cell-cell recognition is important to such processes as embryonic development and the immune response. In other cases, messenger molecules are secreted by the signaling cell.
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° Some transmitting cells release local regulators that influence cells in the local vicinity. ° One class of local regulators in animals, growth factors, includes compounds that stimulate nearby target cells to grow and multiply. ° This is an example of paracrine signaling, which occurs when numerous cells simultaneously receive and respond to growth factors produced by a single cell in their vicinity. In synaptic signaling, a nerve cell produces a neurotransmitter that diffuses across a synapse to a single cell that is almost touching the sender. ° The neurotransmitter stimulates the target cell. ° The transmission of a signal through the nervous system can also be considered an example of long-distance signaling.
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This test prep was uploaded on 04/17/2008 for the course BSC 2010 taught by Professor Pf during the Spring '08 term at FSU.

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chap11 studyguide - Chapter 11 Cell Communication Study...

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