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Unformatted text preview: 1 April 17, 2008 April 17, 2008 Biology 113, Lecture 7 Biology 113, Lecture 7 Concepts: 11.1 and 11.2 Part 1 Part 1 - Overview Overview • An overview of cell signaling • External signals are converted into cellular responses • Signal reception and the initiation of transduction • Types of signal receptors Cell Communication - Chapter 11 Cells need to Cells need to “talk talk ” to each other to each other • Critical in multicellular organisms to co-ordinate development of the embryo and function of the adult • Also important in unicellular organisms ( example: mating in yeast) • Components of cell-cell communication are highly conserved in evolution • Multi-step process: – Reception – Transduction (signal propagation through the cell) – Response General types of cell communication General types of cell communication • Exchange of factors between different cell types during mating (yeast) • Communication through direct cell contact and cell junctions • Local and distant signaling between cells: – Paracrine – Synaptic – Hormonal Communication between mating yeast cells Communication between mating yeast cells • type a cells release a-factor • a-factor binds receptors on α cells • type α cells release α-factor • α-factor binds receptors on a cells • binding of the mating factors to their receptors induces fusion (mating) • the resulting a/ α cell has all the genes from the a and α cells (diploid) Saccharomyces cerevisiae Figure 11.2 Types of intercellular junctions in animals Types of intercellular junctions in animals Tight junctions prevent fluid from moving across a layer of cel s Tight junction 0.5 μm 1 μm Space between cel s Plasma membranes of adjacent cel s Extracel ular matrix Gap junction Tight junctions 0.1 μm Intermediate filaments Desmosome Gap junctions TIGHT JUNCTIONS DESMOSOMES GAP JUNCTIONS Figure 6.31 Communication by direct contact between cells Communication by direct contact between cells • Cell junctions – direct passage of molecules through cell junctions – not crossing the plasma membrane • Interaction of surface- bound molecules – a transmembrane signal and its receptor Figure 11.3 2 Local and distant cell communication in animals Local and distant cell communication in animals Figure 11.4 1. Paracrine signaling (local) 2. Synaptic signaling (local) 3. Hormonal signaling (long distance ) Paracrine Paracrine signaling signaling • signaling between neighboring cells • one cell secretes a factor into the extracellular space • the target cell receives the signal and responds • Example: Growth factors that stimulate nearby target cells to grow and multiply Synaptic signaling Synaptic signaling • a signal moves along the axon of a nerve cell • at the junction between two nerve cells (or a nerve and some other cell type, e.g . muscle) a neurotransmitter is released across the synapse • the signal is propagated in the second nerve cell • hormones signal cells at...
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This note was uploaded on 04/29/2008 for the course BIO 113 taught by Professor Swenson during the Spring '08 term at Ohio State.
- Spring '08