What is the significance of the observation that many signal transduction pathways create a network, where they intersect or overlap?

Which observation suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells?

a. Enzymatic activity was proportional to the amount of calcium added to a cell-free extract.

b. Receptor studies indicated that epinephrine was a ligand.

c. Glycogen breakdown was observed only when epinephrine was administered to intact cells.

d. Glycogen breakdown was observed only when epinephrine and glycogen phosphorylase were mixed.

Protein phosphorylation is commonly involved with all of the following except

a. Activation of receptor tyrosine kinases

b. Activation of protein kinase molecules

c. Activation of G protein-coupled receptors

d. Regulation of transcription by signaling molecules

Suppose you were to model amplification by the phosphorylation cascade in Figure 11.16, using a penny for each kinase 1, a nickel for each kinase 2, and a dime for each kinase 3. Also suppose that Ras and each of the kinases can activate 10 proteins. How much money would you need to construct your model?

Steroid hormones, like most lipid-soluble signaling molecules, are processed directly. How does the absence of a signal transduction cascade in the processing of steroid hormones affect (c) the cellular response that is possible?

Steroid hormones, like most lipid-soluble signaling molecules, are processed directly. How does the absence of a signal transduction cascade in the processing of steroid hormones affect (b) signal regulation?

Steroid hormones, like most lipid-soluble signaling molecules, are processed directly. How does the absence of a signal transduction cascade in the processing of steroid hormones affect (a) signal amplification?