Question

7. You perform the following microscopy experiments to measure the signaling output of two pathways and observe the following results. Experiment 1 - You genetically tag an M-cyclin with GFP. You add an upstream signal to a cell culture to activate the M-cyclin. Result 1 - GFP fluorescence intensity increases. Experiment 2 - You genetically tag adenylyl cyclase with RFP. You add an upstream signal to a cell culture to activate adenylyl cyclase. Result 2 - There is no change in the RFP fluorescence intensity. A. (4pts) Why would adding the respective upstream signals lead to changes in Cyclin A-GFP intensity but not adenylyl cyclase-RFP intensity? B. (4pts) For experiment 1, predict the timescale over which the GFP intensity ncreases

Answer 1

A) In the first case the addition of upstream signal unregulates M cycling production therefore showing higher GFP fluorescence.

In the second case addition of upstream singnal shows no upregulation of adenylyl cyclase and no high intensity of RFP is produced. The activation of adenylyl cyclase has not happened.

B) time scale varies among cell types. Normally m cyclins are produced at the end of G2 phase. So, it takes around 1 hour after G2 phase.