Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight, and mutations to the DNA in their skin cells are left uncorrected. Why are the mutations not corrected in individuals with this disorder?

#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.    

#Question id: 1131

#Unit 4. Cell Communication and Cell Signaling

Which of the following function(s) as an inhibitor of TGFβ signal transduction?

a. R-Smad       b. I-Smad        c. Co-Smad     d. Ski   e. SnoN

#Question id: 1132

#Unit 4. Cell Communication and Cell Signaling

Which of the following become(s) active as a kinase when an activation lip residue is phosphorylated?

a. EpoR                       b. JAK             c. STAT           d. Ras              e. MAPK

#Question id: 1133

#Unit 4. Cell Communication and Cell Signaling

What tertiary structure characterizes all cytokines?