Cell Signaling Lecture 9

Cell Signaling Lecture 9 - Cell Communication How organisms...

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Unformatted text preview: Cell Communication How organisms translate extracellular signals into a cellular response Cell Communication The central problem in communication is that the cell membrane acts as a barrier to information the cell needs for function or survival. Extracellular signals from the environment Glucose Light Hormones Nucleus Cell membrane Organisms must be able to sense the environment around them, and respond appropriately. Single-celled organisms move toward food sources, locate compatible partners for mating, or form complex structures such as Single celled organisms communicate with each other The budding yeast, Saccharomyces cerevisiae, sends a signal to cells of the opposite mating type to stop dividing and prepare to mate. http://upload.wikimedia.org/wikipedia/commons/thumb/1/12/Yeast_mating_scheme.svg Single celled organisms communicate with each other www.dentistry.usc.edu/ research.aspx?id=1152 If bacteria sense that they are surrounded by a dense population of other pathogens, they can join together on essentially any surface and form a protective matrix around their group. A vast number of the pathogens we harbor are grouped into communities called biofilms. Multicellular organisms with many different types of cells sense their environment Smell, taste and sight allow us to sense our environment Multicellular organisms with many different types of cells coordinate development Communication among cells facilitates the formation of complex patterns during development. Above right: Drosophila wing that is malformed due to inadequate signaling Below right: Normal Drosophila wing www.the-scientist.com/ article/display/18086 Cell Communication Cells have to be able to communicate with one another for the benefit of the organism as a whole. Communication depends on: 1. Extracellular signaling molecules 2. Cell surface receptor proteins 3. Intracellular signaling proteins 4. Target proteins Six basic principles of cell signaling Higher eukaryotes have hundreds of different kinds of signaling molecules ; signals bind to cell surface receptors or intracellular receptors on a target cell; most signaling falls into four general categories : contact-dependent, paracrine, autocrine, synaptic; extracellular signals can induce a rapid or slow cell response (change in cell behavior); the same signaling molecule can induce different responses , based on the target cell type; There are many different kinds of signaling molecules Signaling systems in higher eukaryotes include hundreds of different kinds of signaling molecules : proteins, small peptides, amino acids, nucleotides, steroids, retinoids, fatty acid derivatives, and Signaling may involve cell-surface receptors… …or intracellular receptors Nuclear receptors (Steroid hormones) Cytoplasmic receptors (gases: NO, CO, H2S) There are 4 kinds of signaling: Signal molecules may remain bound to the surface of the target cell Contact-dependent signaling, also known as juxtacrine signaling Example: Drosophila...
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This note was uploaded on 11/24/2011 for the course BIOLOGY 310 taught by Professor Mueller during the Fall '11 term at Drexel.

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Cell Signaling Lecture 9 - Cell Communication How organisms...

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