Just prior to the onset of gastrulation in an embryo, the "organizer" cells are specified. If you were to experimentally block the specification of these cells, what would you expect the result to be in the developing embryo?

#Question id: 1125

#Unit 4. Cell Communication and Cell Signaling

Examples of G protein–coupled receptors include

a. rhodopsin receptor.             b. β-adrenergic receptor.

c. insulin receptor.                   d. acetylcholine receptor.

#Question id: 1126

#Unit 4. Cell Communication and Cell Signaling

Which of the following statement(s) is (are) true of the α subunit of a G protein?

a. It physically associates with the receptor.              

b. It binds GDP.

c. It binds GTP.                     

d. It is a transmembrane protein.

#Question id: 1127

#Unit 4. Cell Communication and Cell Signaling

Which of the following steps does not occur after acetylcholine binds to the muscarinic acetylcholine receptor in heart muscle cells?

#Question id: 1128

#Unit 4. Cell Communication and Cell Signaling

During the epinephrine stimulated conversion of glycogen to glucose 1-phosphate, which of the following steps involves protein phosphorylation?

a. inactivation of glycogen synthase               b. activation of protein kinase A

c. activation of adenylyl cyclise                      d. activation of glycogen phosphorylase

#Question id: 1129

#Unit 4. Cell Communication and Cell Signaling

Which of the following plays a role in the relaxation of smooth muscle cells by nitric oxide?

a. cGMP          b. protein kinase A      c. protein kinase G      d. guanylyl cyclise

#Question id: 1130

#Unit 4. Cell Communication and Cell Signaling

In muscle cells, glycogen phosphorylase kinase is activated by

a. Ca2+.           b. diacylglycerol.   c. nitric oxide.       d. protein kinase A.