CHAPTER 11 CELL COMMUNICATION

CHAPTER 11 CELL COMMUNICATION - CHAPTER 11 CELL...

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Regulation is an essential feature of life. It unifies the various levels of biological organization by embracing the fields of molecular and cell biology, organismal biology, and population biology and ecology. It provides the necessary coordination for all aspects of life, including metabolism, growth, development, and reproduction. Chemical substances are the principal agents of biological regulation and they exert their effects on cells through signaling systems. This chapter describes the fundamental components of cell signaling systems. I. An Overview of Cell Signaling A. Communicating cells may be close together or far apart A chemical signal that communicates between two nearby cells is called a local regulator . Examples: - nearby cells can produce growth factors, a group of factors which stimulate cells to divide and grow. - a nerve cell releases a signal (e.g., neurotransmitter) into a synapse, the narrow space between the transmitting cell and a target cell, such as another nerve cell or muscle cell. A chemical signal which communicates between cells some distance apart is called a hormone . Hormones have been described in both plants (e.g., ethylene, a gas which promotes growth and fruit ripening) and animals (e.g., insulin, a protein which controls various aspects of metabolism, including the regulation of blood glucose levels). The distinction between local regulators and hormones is for convenience. A particular chemical signal may act both as a local regulator and as a hormone. Insulin, for example, may act as a local regulator on adjacent cells (e.g., other
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CHAPTER 11 CELL COMMUNICATION - CHAPTER 11 CELL...

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