Sewall  Wright's  metaphor  of  evolution  on  an  adaptive  landscape describes a  population  as  occupying  a  field  of genotypes  graded  by  contours  delimiting  gene  combinations  of  equal  fitness.  The  evolutionary  mechanism  most likely to move a population consistently "uphill"  toward adaptive peaks on this landscape is

#Question id: 1243

#Unit 4. Cell Communication and Cell Signaling

One form of receptor desensitization can be mediated by negative feedback involving phosphorylation of the receptor itself by a kinase activated downstream of a second messenger. The phosphorylated receptor likely:

#Question id: 1244

#Unit 4. Cell Communication and Cell Signaling

Which type of experimental evidence shows that the intrinsic GTPase activity of the Gα subunit is important for terminating effector activation?

#Question id: 1245

#Unit 4. Cell Communication and Cell Signaling

Many PTB-containing proteins act as docking sites for multiple proteins. If these proteins are involved in the RTK signal transduction pathway, they most likely:

#Question id: 1246

#Unit 4. Cell Communication and Cell Signaling

An SH2-containing protein contains a mutation that changes its binding pocket such that tyrosine and phosphotyrosine bind with equal affinity. As a result, MEK activity:

#Question id: 1247

#Unit 4. Cell Communication and Cell Signaling

Which of the following is NOT true about the role of adapter proteins in the activation of Ras by receptor tyrosine kinases?

#Question id: 1248

#Unit 4. Cell Communication and Cell Signaling

By what mechanism does PI-3 phosphate promote activation of protein kinase B (PKB)?

a. recruiting PKB to the plasma membrane

b. recruiting the activating kinase PDK1 to the plasma membrane

c. releasing inhibition of the catalytic site by the PH domain

d. by the activation of FOXO3A