Chapter 11 Notes

Chapter 11 Notes - Chapter 11 Notes Cell Communication 11.1...

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Chapter 11 Notes – Cell Communication 11.1 External signals are converted to responses within the cell 1. Evolution of Cell Signaling a. Signal transduction pathway is the process by which signal on a cell’s surface is converted to a specific cellular response. Ex. Yeast reproduction b. Signaling mechanisms first evolved in ancient prokaryotes and single-celled eukaryotes. c. Quorum sensing is the phenomenon where the concentration of signaling (small molecules) allows bacteria to sense the local density of bacterial cells. d. Biofilms are aggregations of bacteria that often form recognizable structures containing regions of specialized function. 2. Local and Long- Distance Signaling a. Embryonic development and immune response – cell-cell recognition b. Messenger molecules secreted by signaling cells travel short distance, are called local regulators , and influence cells in the vicinity. c. Growth factors consist of compounds that stimulate nearby target cells to grow and divide. Paracrine signaling is the type of local signaling in animals where numerous cells simultaneously receive and respond to the growth facror produced by a single cell. Synaptic signaling occurs in the animal nervous system. An electrical signal along a nerve cell triggers the secretion of a chemical signal carried by neurotransmitter molecules. These diffuse across the synapse, the narrow space between the nerve cell and its target cell. The neurotransmitter stimulates the target cell. d. Hormones are used for long-distance signaling. Specialized cells release hormone molecules into vessels of the circulatory system. Plant hormones ( plant growth regulators) sometimes travel in vessels but more often reach their target by moving through cells or diffusing through air as a gas. e. The transmission of a signal through the nervous system can also be considered an example of long-distance signaling. 3.
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Chapter 11 Notes - Chapter 11 Notes Cell Communication 11.1...

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