10. Cell Signaling
Signal Amplification
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Practice this topic
- Multiple Choice
Kinases and phosphatases are essential to the cell because they:
a) Are enzymes that synthesize proteins.
b) Are enzymes that degrade proteins.
c) Are enzymes that can turn proteins 'on' and/or 'off' through changes in phosphorylation.
d) Are enzymes that can turn proteins 'on' and/or 'off' through changes in proton concentrations.
e) None of the above.
- Multiple Choice
What role do phosphatases play in signal transduction pathways?
a) They phosphorylate proteins involved in signal transduction or cellular response.
b) They activate protein kinases by phosphorylation.
c) They amplify the signal molecule.
d) They regulate the function of proteins involved in signal transduction pathways or cellular response.
- Multiple Choice
Phosphorylation cascades are useful signal transduction pathways because they ________.
a) Allow proteins to be easily activated by adding or removing a phosphate group.
b) Allow proteins to be easily deactivated by adding or removing a phosphate group.
c) Amplify the original signal many times.
d) All of the above.
- Multiple ChoiceIn liver cells, epinephrine stimulates the breakdown of glycogen. As the signal-transduction pathway progresses, __________.
- Open QuestionThe activation of receptor tyrosine kinases is characterized bya. dimerization and phosphorylation.b. dimerization and IP3 binding.c. a phosphorylation cascade.d. GTP hydrolysis.
- Open QuestionConsider this pathway: epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP. Identify the second messenger.a. cAMPb. G proteinc. GTPd. adenylyl cyclase
- Open QuestionWhich 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.
- Open QuestionProtein phosphorylation is commonly involved with all of the following excepta. 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.