Chapter 11 Lecture

Chapter 11 Lecture - CHAPTER 11 CELL COMMUNICATION Section...

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Unformatted text preview: CHAPTER 11 CELL COMMUNICATION Section A: An Overview of Cell Signaling 1. Cell signaling evolved early in the history of life 2. Communicating cells may be close together or far apart 3. The three stages of cell signaling are reception, transduction, and response 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 some universal mechanisms of cellular regulation, involving the same small set of cell-signaling mechanisms. Cells may receive a variety of signals, chemical signals, electromagnetic signals, and mechanical signals. Introduction One topic of cell conversation is sex. The yeast Saccharomyces cerevisiae , the yeast of bread, wine, and beer, identifies its mates by chemical signaling. There are two sexes, a and alpha , each of which secretes a specific signaling molecule, a factor and alpha factor respectively. These factors each bind to receptor proteins on the other mating type. 1. Cell signaling evolved early in the history of life Once the mating factors have bound to the receptors, the two cells grow toward each other and experience other cellular changes. Two opposite cells fuse, or mate. The a/ alpha cell contains the genes of both cells. The process by which a signal on a cells surface is converted into a specific cellular response involves several steps in a signal- transduction pathway . The molecular details in both yeast and animal cells are strikingly similar, even though their last common ancestor was over a billion years ago. Signaling molecules evolved first in ancient prokaryotes and were then adopted for new uses by single-celled eukaryotes and multicellular descendents. Cell signaling has remained important in the microbial world. Myxobacteria, soil-dwelling bacteria, use chemical signals to communicate nutrient availability. When food is scarce, cells secrete a signal to other cells leading them to aggregate and form thick- walled spores. Multicellular organisms also release signaling molecules that target other cells. Some transmitting cells release local regulators that influence cells in the local vicinity. Paracrine signaling occurs when numerous cells can simultaneously receive and respond to growth factors produced by a single cell in their vicinity. 2. Communicating cells may be close together or far apart In synaptic signaling, a nerve cell produces a neurotransmitter that diffuses to a single cell that is almost touching the sender. An electrical signal passing along the nerve cell triggers secretion of the neurotransmitter into the synapse....
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This note was uploaded on 01/30/2011 for the course BIO 113 taught by Professor Anderson during the Spring '10 term at Albright College.

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Chapter 11 Lecture - CHAPTER 11 CELL COMMUNICATION Section...

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