Multiple ChoiceKinases 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.1746views7rank1comments
Multiple ChoiceWhat 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.3914views11rank
Multiple ChoicePhosphorylation 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.2618views3rank2comments
Multiple ChoiceIn liver cells, epinephrine stimulates the breakdown of glycogen. As the signal-transduction pathway progresses, __________. 724views
Multiple ChoiceA mutation in the active site of adenylyl cyclase that inactivates it would most likely lead to __________. 754views
Multiple ChoiceThe general name for an enzyme that transfers phosphate groups from ATP to a protein is __________. 908views
Multiple ChoiceATPgammaS is a form of ATP that cannot be hydrolyzed by enzymes. If this compound were introduced to cells so that it replaced the normal ATP present in the cell, which of the following would you predict? 664views
Multiple ChoiceSecond messengers tend to be water-soluble and small. This accounts for their ability to __________. 1093views
Multiple ChoiceDuring the transduction of a signal, one molecule or ion may be closely associated with the activity of another. Which of the following pairs correctly combines two associated molecules? 690views
Multiple ChoiceIn eukaryotic cells, which of the following is a second messenger that is produced as a response to an external signal such as a hormone? 738views1rank
Multiple ChoiceA difference between the mechanisms of cAMP and Ca2+ in signal transduction is that cAMP __________ and Ca2+ __________. 1078views
Textbook QuestionThe activation of receptor tyrosine kinases is characterized by a. dimerization and phosphorylation. b. dimerization and IP3 binding. c. a phosphorylation cascade. d. GTP hydrolysis.1256views
Textbook QuestionConsider this pathway: epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP. Identify the second messenger. a. cAMP b. G protein c. GTP d. adenylyl cyclase1654views
Textbook 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.887views
Textbook QuestionProtein phosphorylation is commonly involved with all of the following except a. 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.1998views
Textbook QuestionSuppose you were to model amplification by the phosphorylation cascade in Figure 11.16, using a penny for each kinase 1, a nickel for each kinase 2, and a dime for each kinase 3. Also suppose that Ras and each of the kinases can activate 10 proteins. How much money would you need to construct your model?714views
Textbook QuestionSuppose you were to model amplification by the phosphorylation cascade in Figure 11.16, using a penny for each kinase 1, a nickel for each kinase 2, and a dime for each kinase 3. Also suppose that Ras and each of the kinases can activate 10 proteins. How much money would you need to construct your model?333views
Textbook QuestionWhat is the significance of the observation that many signal transduction pathways create a network, where they intersect or overlap?475views
Textbook QuestionSteroid hormones, like most lipid-soluble signaling molecules, are processed directly. How does the absence of a signal transduction cascade in the processing of steroid hormones affect the cellular response that is possible?565views
Textbook QuestionSteroid hormones, like most lipid-soluble signaling molecules, are processed directly. How does the absence of a signal transduction cascade in the processing of steroid hormones affect (b) signal regulation?666views
Textbook QuestionSteroid hormones, like most lipid-soluble signaling molecules, are processed directly. How does the absence of a signal transduction cascade in the processing of steroid hormones affect (b) signal regulation?378views
Textbook QuestionSteroid hormones, like most lipid-soluble signaling molecules, are processed directly. How does the absence of a signal transduction cascade in the processing of steroid hormones affect (a) signal amplification?517views
Open QuestionProtein phosphorylation is commonly involved with which of the following?A. ligand binding by receptor tyrosine kinases.B. activation of G protein-coupled receptors.C. activation of protein kinase molecules.D. release of Ca2+ from the ER lumen.96views
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