Exam 3 Review - Chapters 14 and 15 answers

Exam 3 Review - Chapters 14 and 15 answers - Kaiser Imam...

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Kaiser Imam November 18, 2007 BIOL 215 Exam 3 Review Chapters 14 and 15 Chapter 14: Signal Transduction 1. Receptor tyrosine kinases (RTKs) consist of __ one __ polypeptide chain(s) with __ one __ transmembrane segment(s) in the shape of a(n) __ α-helix __. 2. The cytosolic side of a receptor tyrosine kinase has two parts: a __ tyrosine kinase __ domain and a __ cytosolic tail __ that contains residues of the amino acid __ tyrosine __. 3. The extracellular side of the RTK has a __ ligand binding site __. 4. The binding of a ligand causes receptor tyrosine kinases to __ aggregate __. In situations in which two proteins do this the process is called __ dimerization __. The process by which the RTKs phosphorylate each other in a process called __ autophosphorylation __. 5. The ligand that binds to the RTK to start off the Ras pathway is __ epidermal growth factor (EGF) __. 6. Ras is a __ small monomeric __ G protein that is involved in regulating the __ growth __ and __ division __ of cells. Like many G proteins, Ras is in its active state when it is bound to __ GTP __ and inactive when bound to __ GDP __. The type of protein that makes the exchange of these molecules possible is called a __ guanine-nucleotide exchange factor __. 7. The guanine-nucleotide exchange factor (GEF) that activates Ras is called __ Sos __. This GEF forms a complex with a protein called __ GRB2 __ in order to bind to a receptor tyrosine kinase. 8. Ras can be deactivated by hydrolyzing the GTP molecule bound to it to GDP. This process is mediated by a __ GTPase activating protein (GAP) __. 9. Before its activation by Sos Ras is anchored to the plasma membrane by a __ covalent __ attachment to a __ lipid __ molecule. 10. What are SH2 domains? Give two examples of proteins with SH2 domains that were mentioned in class. SH2 stands for the Src homology domain 2 because its amino acid sequence resembles that of the Src protein. The SH2 domain is a portion of a protein that recognizes and binds to the phosphorylated tyrosine residues created as a result of the autophosphorylation of receptor tyrosine kinases. Specific examples of proteins with SH2 domains include GRB2 and PLC γ . 1
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11. What is the function of mitogen-activated protein kinases (MAPKs)? Describe their activity in the cell. MAPKs are activated when cells receive a stimulus to grow and divide. Such signals are often called mitogens because they prompt the cell to undergo mitosis. They are involved in the production of transcription factors that stimulate the transcription and expression of proteins needed for cells to grown and divide. MAPKs are activated as a result of the Ras pathway. 12. Give an outline of the Ras and MAP kinase pathway. How is this pathway turned off? The Ras pathway is involved in altering gene expression in cells to prepare them for division.
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This note was uploaded on 09/29/2009 for the course BIO 215 taught by Professor Diiulio during the Spring '09 term at Case Western.

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Exam 3 Review - Chapters 14 and 15 answers - Kaiser Imam...

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