Part A. A neutrophil is chasing a pathogenic bacterium. Explainhow it will detect and move toward its prey and how it will changecourse when necessary.
Part B. A mutation that destroys the GTPase function of Ras isan initiating event in many cancers. Describe how constantactivation of Ras will cause increased expression of Cyclin D and Sphase genes by the transcription factor E2F.
Part C. When the transcription factor E2F is activated, it canamplify its own gene expression and leads to the transcription ofCyclin E. Cyclin E with Cdk2 can phosphorylate Rb, removing theRb’s inhibitory effect on E2F. These are two positive feedbackloops that occur in E2F activation. What do you think is the effectand purpose of these two feedback loops? Â
