1. Suppose that to become activated, an inactive protein in a cell must be phosphorylated. Explain how a chemical signal from outside the cell can trigger this internal change?

2. Describe each of the following receptors and choose which of the following receptors that could be trigger as well as the pathway to activation of the protein and explain your reasoning.

1. An ion channel receptor:
2. An active transport protein:
3. A G protein-linked receptor:
4. A protein kinase receptor :
5. An intracellular receptor: