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TLS Online TPP Program

#Question id: 12182

The cell cycle is controlled by protein kinases that comprise a catalytic subunit and a regulatory subunit. Which of the following statement is correct regarding to these subunits?

#Unit 2. Cellular Organization
  1. The catalytic subunits, the cyclin-dependent kinases (CDKs), have no kinase activity unless they are dissociated with a regulatory cyclin subunit. 
  2. Each CDK can associate with a small number of different cyclins, which determine the substrate specificity of the complex—that is, which proteins it phosphorylates.
  3. Cyclin-CDK complexes activate or inhibit hundreds of proteins involved in cell cycle progression by phosphorylating or dephosphorylating them at specific regulatory sites. 
  4. Proper progression through the cell cycle is governed by activation of the appropriate homodimeric protein kinase complex at the appropriate time.
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TLS Online TPP Program

#Question id: 1123

#Unit 4. Cell Communication and Cell Signaling

Epinephrine can be what kind of signaling molecule?

a. autocrine      b. direct contact  c. endocrine d. paracrine
TLS Online TPP Program

#Question id: 1124

#Unit 4. Cell Communication and Cell Signaling

Which of the following is (are) intracellular second messengers?

a. Ca2+                        b. cAMP          c. epinephrine             

d. protein kinase A      e. protein kinase C
TLS Online TPP Program

#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.
TLS Online TPP Program

#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.
TLS Online TPP Program

#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?
TLS Online TPP Program

#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