Cell Signaling Homework

Instructions

Answer the following questions based on the lecture videos and textbook reading.

1. What is the difference between autocrine, paracrine, and endocrine? What is similar about all three of them? 
2. What is the difference between a secondary messenger and a phosphorylation cascade? 
3. What does crosstalk between signaling pathways mean? 
4. Predict what would happen if there was an insertion at the carboxy end of a GPCR – list the steps through the GPCR pathway you could go through before you ran into a problem. 
5. Predict what would happen if there was a mutation in a GPCR leading to loss of serine in the cytoplasmic domain of the GPCR – list the steps through the GPCR pathway you could go through before you ran into a problem. 
6. What are three possible options for re-setting cell surface GPCRs? 
7. How do cAMP and PKA lead to amplification of the signal transduction pathway?

Cell Signaling Homework Answer

What is the difference between a secondary messenger and a phosphorylation cascade?

• A secondary messenger is just a small molecule or ion that relay signals to the next step of the signalling pathway. It is created when the first messenger binds to the receptor to activate the effector (usually an enzyme). The secondary messenger is involved in signal amplification and can affect a variety of molecule and trigger different reactions, depending on the pathway.