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Question 4 of 10 1.0/ 1.0 Points A common theme in many pathways is a cascade of similar enzymes acting on each other in sequence. For instance, MAP kinase kinase kinase adds a phosphate to MAP kinase kinase, which adds phosphate to MAP kinase, which adds phosphate to another substrate. What is the benefit of using a cascade of enzymes? •A. Extra genes provide backup in case the original became mutated. •B. A cascade amplifies output from the original signal. •
C. There is no benefit –“selfish genes” are often maintained in evolution for reasons unrelated to the function of their encoded proteins. •D. A cascade is used for timing since it delays the response. Feedback: Learning Objective: Analyze intercellular and intracellular communication Question 5 of 10 1.0/ 1.0 Points Cell surface receptors have three domains with different roles. Match each role to the domain that is responsible. A. Cytosolic domain B. Hydrophobic domain C. Extracellular domain 1. Binds the signaling molecule ________ 2. Sends conformational change through the plasma membrane ________ 3. Interacts with downstream signaling cascade ________ Feedback: Correct