Concept 5.1 Biological Membranes Have a Common Structure and Are Fluid

Transcription

1 Name Chapter 5 Reading Guide Cell Membranes and Signaling Concept 5.1 Biological Membranes Have a Common Structure and Are Fluid 1. What are the three components of a biological membrane? 2. Explain the difference between polar and nonpolar molecules. (This difference will be important in understanding the functioning of the cell membrane.) 3. Describe the chemical structure of a phospholipid. 4. The refers to the general design of a biological membrane. The serves as a fluid lake in which a variety of float. 5. What type of forces hold proteins within the membrane? 6. What are the three major functions of membrane proteins? 7. What is the role of carbohydrates associated with the cell membrane? 1

2 8. Label the following diagram to aid in understanding the structure of the phospholipid bilayer. 9. Explain the structure and role of cholesterol in the cell membrane. 10. Explain the 2 most important factors that affect membrane fluidity. 11. Why is it very rare for phospholipids to flip over in the bilayer? 2

3 12. What are the protein to lipid ratio in the following membranes; 13. What determines where a protein will insert into a membrane and how it will be positioned? 14. Explain the two general types of membrane proteins: 15. What are the chemical difference between peripheral and integral membrane proteins? 16. What is a transmembrane protein? 17. Explain the difference between glycolipids, glycoproteins and proteoglycans. 18. What is the role of the carbohydrates on the cell membrane? 3

4 Concept 5.2 Passive Transport across Membranes Required No Input of Energy 19. What does it mean to say that biological membranes are selectively permeable? 20. Define and distinguish between the 2 processes by which substances can cross biological membranes. 21. Define and describe diffusion. 22. What are the 3 factors that the rate of diffusion depends? 23. In a complex solution (one with many different solutes), the diffusion of each solute depends only on. 24. What substances can move through the membrane by simple diffusion? 25. How does water diffuse through the membrane? 26. What is osmotic pressure and how is it calculated? 4

5 27. Explain the following terms used to compare solute concentration of two solutions separated by a membrane: a. Hypertonic b. Isotonic c. Hypotonic 28. What is turgor pressure and why is it important to plants, archaea, bacteria, fungi and some protists? 29. List and explain the types of channel proteins. 30. What is the role of carrier proteins? What important molecule requires a carrier protein to diffuse into the cell? 31. Explain how the rate of diffusion via transport proteins is similar to the rate of enzyme catalyzed reactions. Concept 5.3 Active Transport Moves Solutes against Their Concentration Gradients 32. What molecule is often used as the energy source for the active transport of molecules across a membrane? 33. How is active transport different from simple and facilitated diffusion in terms of direction of movement? 5

6 34. What is the difference between primary and secondary active transport? 35. Use the figure below to describe the primary transport system known as the sodium-potassium pump. 36. Explain how sodium ions are involved in the secondary transport of glucose into cells in the digestive tract. Concept 5.4 Large Molecules Cross Membranes via Vesicles 37. Why can t macromolecules such as proteins, polysaccharides, and nucleic acids pass through the cell membrane? 38. Define the term secrete. 6

7 39. Compare and contrast exocytosis and endocytosis. 40. Describe the 3 broad types of endocytosis. Concept 5.5 The Membrane Plays a Key Role in a Cell s Response to Environmental Signals 41. Define the following terms: Ligand Signal Transduction Pathway 42. Explain the following signal sources and modes of delivery: Autocrine Signals Paracrine Signals Juxtacrine Signals Hormones External Signals 43. Only cells with the can respond to a signal. 7

8 44. Use the following illustration to explain the stages in signal transduction. 45. Define the following type of receptors: Intracellular Receptors Membrane Receptors 46. Why is it important for ligands to bind noncovalently? 47. What is an inhibitor and what type of substance in enzyme chemistry is it similar to?. 48. Explain the give an example of the 3 categories of cell membrane receptors: ******STOP NOW AND WATCH: *************** 8

9 Concept 5.6 Signal Transduction Allows the Cell to Respond to Its Environment 49. List 3 Possible Responses to a Signal: 50. Provide an example of how the same signal can lead to different responses in different types of cells. 51. What is a second messenger and what second messenger was discovered by Sutherland and his colleges. 52. Outline the steps in the amplification of signaling by epinephrine, resulting in the release of glucose to the bloodstream. At each step, is the amplification due to a covalent or noncovalent interaction? 53. Balance between the activities of regulating enzymes and the signaling enzyme is what determines the ultimate cellular response to a signal. Balance can be altered in which two ways? 9