SolutionProblemSetE

SolutionProblemSetE - Problem Set E 1) Based on the...

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Problem Set E 1) Based on the following diagram, explain how the yeast Saccharomyces cerevisiae uses cell signaling in its mating process. In step 1, each cell type secretes a specific mating factor. The alpha cells secrete the alpha mating factor and the a cells secrete the a mating factor. These mating factors bind to receptors on the other type of cell. In step 2, the result of the signal transduction pathway involving the binding of mating factors is that the alpha and a cells undergo changes that allow them to fuse together. In step 3, a new alpha/a cell is produced which has genes from the two cells that fused to form it. 2) Both animal cells and plant cells have types of cell junctions that connect the cytoplasm of adjacent cells and allow signaling molecule to pass between cells without having to diffuse across the plasma membrane. In animal cells these are __ gap junctions __ and in plant cells they are __ plasmodesmata ___. In addition, animal cells may communicate via the interaction of _ membrane proteins __, which protrude from their surfaces. A cell secretes a specific type of local regulator, a growth factor, to influence cells in the nearby vicinity. This is an example of __ Paracrine_ _ signaling. Another type of local signaling involves an electrical signal triggering the release of a neurotransmitter which diffuses across a synapse and acts on another nerve cell. This is an example of __Synaptic ___ signaling. Animals and plant cells use __ hormones __ for long distance signaling. Examples of these include the hydrocarbon __ Ethylene_, which signals fruit to ripen in plants, and __ Insulin _, which regulates blood sugar levels. 1
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The first stage of cell signaling is _ Reception_ . This involves the binding of a _signaling molecule/ligand _ _ to a specific receptor protein. Upon binding, the receptor will undergo a _ conformational change_ which will change its activity. This initiates the second stage of cell signaling: _transduction _. The second step usually involves multiple molecules or proteins activating each other in sequential steps. The final stage of cell signaling is Response. Give 3 examples of responses. Activation or deactivation of a gene, catalysis by a specific enzyme, or rearrangement of the cytoskeleton. 3) 2
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Step 1: Because Testosterone is a hydrophobic molecule it is able to diffuse across the plasma membrane. Step 2: Testosterone will bind to a specific receptor protein in the cytoplasm, forming a hormone-receptor complex. Step 3: The hormone-receptor complex enters the nucleus and binds to s specific gene. Step 4: The gene is transcribed into mRNA which can then travel to the ribosome for translation. Step 5: The mRNA is translated into a specific protein. 4a). G protein coupled receptors tend to have seven transmembrane alpha helices as part of their
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This note was uploaded on 12/17/2009 for the course BIOL 1 taught by Professor Patrick during the Fall '09 term at CSU Northridge.

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SolutionProblemSetE - Problem Set E 1) Based on the...

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