Homework
Instructions: On the answer form (download from Learn) write your answers in the space provided. For each question write the answer in one complete sentence and explain/support your answer with one or more additional supporting sentences.
1. Dopamine is a neurotransmitter that binds to a specific type of GPCR. Let’s say that one dopamine molecule can activate 20 G-proteins. In the absence of Ca2+ entry, activated adenylyl cyclase synthesizes 200 cAMP molecules. Two cAMP molecules are required to activate PKA and each molecule of PKA can phosphorylate 200 proteins. If 8 dopamine molecules bind to receptors, how many protein molecules can be phosphorylated?
Assume that there are loads of adenylyl cyclase and PKA molecules (they are not rate limiting).
Use the following information and graph to answer questions 2 and 3.
An animal lacking the gene for PKC-Mzeta (PKC Mzeta KO) is trained for two weeks. After training, the platform is removed and the animal is placed in the water maze and swims around for 10 minutes. The latency for a wild-type mouse and a mouse with a mutant form of adenylyl cyclase to reach the platform is shown in the figure to the right. Use this data to answer the following two questions.
2. If the mutant mouse were trained for another 10 days, what would be the time it would take for it to reach the
platform at the end of 20 days of training?
3. How much faster was the wild-type mouse at finding the platform at the end of training compared with the
mutant mouse at the end of training? Your answer should be in the form of a percentage relative to the control.
4. Different steps in the cellular signaling pathway of PKA can be blocked either during training (learning) of a
task, or after learning is complete the steps can be blocked after training. Blocking which step in the pathway
causes a decrease in learning under both of these two conditions?
5. How would up-regulation of a phosphodiesterase, which converts cAMP to AMP, affect learning?
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