Chapter 7: Membrane Structure and Function

Transcription

1 Chapter 7: Membrane Structure and Function 7.1 Cellular membranes are fluid mosaics of lipids and proteins 1. The large molecules of all living things fall into just four main classes. Name them. 2. Explain what is meant when we say a molecule is amphipathic. 3. Who proposed the fluid mosaic model of membrane structure? When? Describe this model. 4. What is meant by membrane fluidity? Describe the movements seen in the fluid membrane. 5. Describe how each of the following can affect membrane fluidity: a) decreasing temperature b) phospholipids with unsaturated hydrocarbon chains c) cholesterol Pannone Biol 101 Page 1

2 6. Membrane proteins are the mosaic part of the model. Describe each main categories: integral proteins peripheral proteins transmembrane proteins 7. Use Figure 7.9 to briefly describe major functions of membrane proteins. Function Description Transport Enzymatic activity Signal Transduction Cell Cell recognition Intercellular joining Attachment to cytoskeleton and ECM 8. Distinguish between glycolipids and glycoproteins 9. Label the following structures: glycolipid cholesterol glycoprotein phospholipid integral protein peripheral protein ECM fibers cytoskeleton microfilaments Pannone Biol 101 Page 2

3 7.2 Membrane structure results in selective permeability 10. Distinguish between channel proteins and carrier proteins. 11. Are transport proteins specific? Cite an example that supports your response. 12. Peter Agre received the Nobel Prize in 2003 for the discovery of aquaporins. What are they? 13. Consider the following materials that must cross the membrane. For each, tell how it is accomplished. Material Method CO2 glucose H+ O2 H2O 14. Define the following terms: diffusion concentration gradient passive transport osmosis isotonic hypertonic hypotonic turgid flaccid plasmolysis Pannone Biol 101 Page 3

4 15. Use as many words from the list in number 14 to describe why a carrot left on the counter overnight would become limp. Underline each word you use. 16. What is facilitated diffusion? Is it active or passive? Cite two examples. 17. Label the hypotonic solution, isotonic solution, and hypertonic solution. What is indicated by the blue arrows? Label them. Which cell is lysed? Turgid? Flaccid? Plasmolyzed? Apply all these labels. 18. Why doesn t the plant cell burst? 7.4 Active transport uses energy to move solutes against their gradients 19. Describe active transport. What type of transport proteins are involved, and what is the role of ATP in the process? Pannone Biol 101 Page 4

5 20. The sodium-potassium pump is an important system for you to know. Use the following diagram to understand how it works. Use the following terms to label these figures, and briefly summarize what is occurring in each figure: extracellular fluid, cytoplasm, Na+, K+, ATP, ADP, P, transport protein. Summary On the diagram below, add these labels: facilitated diffusion with a carrier protein, facilitated diffusion with a channel protein, active transport with a carrier protein, simple diffusion. For each type of transport, give an example of a material that is moved in this manner. 22. What is membrane potential? 23. What is cotransport? 7.5 Bulk transport: Exocytosis, Endocytosis (phagocytosis and pinocytosis) 24. Define each of the following, and give a specific cellular example. Pannone Biol 101 Page 5

6 Endocytosis phagocytosis pinocytosis exocytosis receptor-mediated endocytosis 25. What is a ligand? What do ligands have to do with receptor-mediated endocytosis? 26. Are the processes you described in question 21 active or passive transport? Explain your response. Testing Your Knowledge: Self-Quiz Answers Now you should be ready to test your knowledge. Place your answers here: Reproduce the diagram for question 6, and draw arrows as instructed. 6b. 6c. 6d. 6e. Chapter 12: The Cell Cycle 12.1 Cell division results in genetically identical daughter cells 1. What is meant by the cell cycle? 2. What is the meaning of genome? Compare your genome to that of a prokaryotic cell. 3. How many chromosomes are in a human somatic cell? 4. Name two types of somatic cells in your body. Pannone Biol 101 Page 6

7 5. What is a gamete? 6. Name the two types of gametes. 7. How many chromosomes in a human gamete? 8. Define chromatin. 9. How many DNA molecules are in each of your somatic cells? 10. You are going to have to learn the difference between a number of similar-sounding terms. Draw a sketch that looks like an X. This X represents a replicated chromosome that has two sister chromatids. The narrow waist represents the location of the centromere. Label the indicated areas of the figure and then define each of the terms below. chromosome chromatid centromere chromatin 11. Study Figure Label the figure, and summarize what occurs at the DNA level in each stage. Pannone Biol 101 Page 7

8 12. What is mitosis? How is it different from cytokinesis? 13. What occurs in meiosis? How is the chromosome number of daughter cells different? 14. Select either mitosis or meiosis to answer the following questions. By what process are the damaged cells in a wound replaced? By what process are eggs formed? By what process does a zygote develop into a multicellular organism? In which process are identical daughter cells produced? Which process reduces chromosome number of daughter cells? 12.2 The mitotic phase alternates with interphase in the cell cycle 15. Label each of the parts of the cell cycle listed below, and give a brief explanation of what happens in each phase. G1 S G2 M 16. What are the components of the mitotic spindle? What is the source of these components? 17. In animal cells, the assembly of spindle microtubules starts at the centrosome. What is another name for the centrosome? 18. Describe what happens to the centrosome during interphase and then prophase. 19. What is a kinetochore? Pannone Biol 101 Page 8

9 20. You will need to spend some serious time with Figure Use it to help you label this figure. Label each phase by name; then label the smaller structures. Finally, make 2 or 3 summary statements that indicate important features to note about the phase. 21. Explain the difference between kinetochore and nonkinetechore microtubules. What is the function of each? Pannone Biol 101 Page 9

10 22. Describe cytokinesis in an animal cell. Use a labeled sketch that shows the cleavage furrow. 23. Describe cytokinesis in a plant cell. Use a labeled sketch that shows the cell plate. 24. Prokaryote reproduction does not involve mitosis, but instead occurs by binary fission. This process involves an origin of replication. Describe binary fission The eukaryotic cell cycle is regulated by a molecular control system 25. What controls the cell cycle? Study the Inquiry Figure to help you answer this question. 26. What is a cell cycle checkpoint? 27. Summarize what happens at each checkpoint. You may add to this chart as you study this section. Checkpoint What happens? How is it controlled? G1 G2 M Pannone Biol 101 Page 10

11 28. What is the Go phase? Describe this phase. 29. What is a protein kinase? 30. Kinases drive the cell cycle, but they must be activated by attachment of a. 31. The activity of cyclin-dependent kinases (CDks) rises and falls. Why? 32. What does MPF trigger? What are some specific activities that it triggers? 33. What happens if all the chromosome kinetochores are not attached to spindle fibers? When this occurs, which checkpoint is not passed? 34. Cancer cells exhibit different behaviors than normal cells. Here are two normal behaviors they no longer show. Explain each behavior. density-dependent inhibition anchorage dependence 35. What is transformation? metastasis? Testing Your Knowledge: Self-Quiz Answers Pannone Biol 101 Page 11