Biology 101 Practice Questions Set 7 PDF

© 2024 City College of New York Biology 101: Biological Foundations I Practice Questions Set 7 Cell Communication 1. In bacteria, to what does “quorum sensing” refer? See p. 244 in the textbook and slide 4 from class and the introductory video. 2. What...

© 2024 City College of New York Biology 101: Biological Foundations I Practice Questions Set 7 Cell Communication 1. In bacteria, to what does “quorum sensing” refer? See p. 244 in the textbook and slide 4 from class and the introductory video. 2. What is the difference between endocrine and neuroendocrine signaling? See slide 6 from class. 3. Is chemical synaptic signaling an example of autocrine or paracrine signaling? Explain. Compare slides 6 and 7. 4. What are connexins and connexons? See p. 121 in the textbook and Slide 8. 5. Signaling molecules can move directly between cells in both plant and animal cells. Compare and contrast the structure of Gap Junctions and Plasmodesmata, and how they both allow this to happen. See slides 8-9 and the introductory video. 6. How is it possible for us to enjoy apples in NYC in the spring when apples are harvested in early fall? How are apples stored? How is that related to ethylene synthesis? See slide 12. 7. Oral secretion products from chewing insects have been suggested as triggers that augment the release of plant green leaf volatiles. Caterpillars of Pieris brassicae species have a - glucosidase enzyme present in their oral secretions that might trigger volatile emissions in cabbage plants. Design an experiment to determine whether the protein -glucosidase is as effective as a chewing caterpillar of Pieris brassicae in eliciting a defense response from cabbage plants through release of plant volatiles. Include all elements of experimental design in your answer. 8. Chewing by insects has been suggested as a trigger for the release of plant volatiles to warn neighboring plants that an herbivore attack is imminent. However, since plants can sense sound (yes, they can “hear”), some have argued that the sound of chewing on a nearby plant is the warning to the nearby plants. Design an experiment to determine whether the signal that warns the neighboring plants about the imminent herbivore attack is a) the plant volatiles released from the plants that are being chewed by the insects, or b) the sound of chewing. Include all elements of experimental design in your answer. 9. According to Sutherland, when a cell receives an external signal, it goes through three processes. List them. See slide 14. 10. Consider a steroid hormone. Why is there no receptor in the plasma membrane for a steroid 1 © 2024 City College of New York Biology 101: Biological Foundations I hormone? Explain what is happening in Figure 9.4 in the textbook. 11. Refer to the figure showing the ligand-gated ion channel receptor. Explain what is happening. Review your notes from slide 19 from class and Figure 9.5 in the textbook. 12. Refer to the figure showing activation of receptor tyrosine kinases. For a receptor tyrosine kinase to carry out its function in a cell, list the steps in order from reception of the external signal to activation of signaling proteins that lead to the cellular response. See Figure 9.8 in the textbook and your notes from slide 21 from class. 13. Review Figure 9.6 from the textbook. Explain what is happening. Why is it important for the alpha subunit of the G protein to function as a GTPase enzyme to hydrolyze its bound GTP to GDP? See slides 23-24 from class and p. 232 in the textbook. 14. Define what a first messenger and a second messenger are. See slide 26. 15. Explain why it is important for the Ca2+ pumps to reduce the concentration of Ca2+ in the cytosol. See class notes on slide 28. Important for the gradient for the ion, sensitivity to the 2nd messenger if any enter, and termination phase. 16. Which one of the following is a common second messenger? a. cGTP b. cMHC c. cATP d. cAMP e. cGDP 17. Explain what kinases and phosphatases do. See p. 238 in the textbook and slides 33-34. 18. Review the reaction carried out by phospholipase C. Where is the substrate for the reaction coming from? What are the products of the reaction and what do they act as? See Figure 9.13 in the textbook and slide 30. 19. Review the figure showing the attachment of a hormone to a receptor leading to activation of PKC. Identify the first and second messengers in this pathway. Li+ can be used as a drug to inhibit phospholipase C. What will be the consequence of using Li+ on this pathway? See p. 239 in the textbook and class notes on slide 31. 20. When a ligand binds to a receptor, the receptor is activated. During the termination process, what are two possible ways to deactivate this receptor? See slide 36. 2 © 2024 City College of New York Biology 101: Biological Foundations I 21. Review the slide showing the synthesis of cAMP. During the termination phase how is this secondary messenger “removed”? What carries this out? See slide 32, which shows both synthesis of cAMP and “removing” it. 22. Ca2+ ions can act as secondary messengers. During the termination phase, how are they removed from the cell? See slide 28. 23. Review the slide showing the response to epinephrine. Identify the first and second messengers. Explain how epinephrine leads to the final response. Explain the role of the relay proteins in the process. Explain what termination will mean for the 1st messenger, the G-protein, the relay proteins, and the 2nd messenger. 24. Arrange the following steps in the pathway activated by G protein-coupled receptors. A. Activation of effector B. Activation of protein kinases C. Receptor binds first messenger D. Production of second messenger E. Activation of G protein See slides 31 and 35 as examples. 25. Amplification is an important characteristic of signal transduction pathways involving surface receptors. What is amplification and how is it accomplished in the cell? See slide 35 as an example. 26. Explain what Figure 9-10 in the textbook is showing (do not memorize the figure). What would happen if the ligand is not removed from the receptor? What if the G protein RAS does not hydrolyze its GTP back to GDP and remains active? See slides 39-40. 27. Why is it important for activated ERK to enter the nucleus? See slide 40. 28. Review the last slide. Compare the top two figures. How is the same signal leading to different responses in these two cells? Same signaling molecule and same receptor. What is different? 29. What is meant by “cross-talk”? See last slide bottom left. Review the questions related to the article reviewed in class discussion. 3