CH16 Hw

What role does GAP play in the RTK pathway

GAP stimulates the hydrolysis of GTP to GDP in the Ras protein, and thus helps to inactivate the RTK pathway

The regulation of inflammatory responses at the site of an infection is an example of paracrine signaling

True

In the absence of a ligand binding to its receptor tyrosine kinase, which of the following scenarios would still result in a proliferation signal via the MAP kinase cascade?

a constitutively active MAP kinase and a defective GAP

The growth factor RGF stimulates proliferation of cultured rat cells. The receptor that binds RGF is a receptor tyrosine kinase called RGFR. Which of the following types of alteration would be most likely to prevent receptor dimerization

a mutation that prevents RGFR from binding to RGF

Match the class of cell-surface receptor (1-3) with the best description of its function (A-C). a. alter the membrane potential directly by changing the permeability of the plasma membrane b. all receptors of this class are polypeptides with seven transmembrane domains c. discovered for their role in responding to growth factors in animal cells

G-protein coupled receptors b. ion-channel coupled receptors a. enzyme-coupled receptors c.

The length of time that a G protein will signal is determined by the

GTPase activity of Gα

What happens when a G-protein-coupled receptor (GPCR) activates a G protein

The α subunit exchanges its bound GDP for GTP

Acetylcholine binds to a GPCR on heart muscle, making the heart beat slower. The activated receptor stimulates a G protein, which opens a K+ channel in the plasma membrane, as shown in in the figure below. Which of the following would enhance this effect of the acetylcholine

addition of a high concentration of a nonhydrolyzable analog of GTP

During nervous-system development in Drosophila, the membrane-bound protein Delta acts as an inhibitory signal to prevent neighboring cells from developing into neuronal cells. Delta is involved in __________ signaling

contact dependent

When a signal needs to be sent to most cells throughout a multicellular organism, the signal most suited for this is a __

hormone

Foreign substances like nicotine, morphine, and menthol exert their initial effects by __

interacting with cell-surface receptors, causing the receptors to transduce signals inappropriately in the absence of the normal stimulus

Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell to change its behavior

true