Chapter 3 HW - mastering homework PDF

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Chapter 3

1. Peptidoglycan is a polymer of millions of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) sugars based on glucose molecules linked together in long chains cross-braced with four amino acids that link individual polymer chains together in a chain-link fence pattern. Layers of cross-braced NAG and NAM sheets are stacked vertically and held together by proteins with lipid anchors attached to the cell’s cytoplasmic membrane to form a scaffold of sugars and proteins that is able to hold the bacterial cell’s shape, even in response to extreme osmotic pressures. How would you expect a microbiology student to be able to describe the composition of peptidoglycan? What is the composition of the peptidoglycan layers found in the cell wall of bacteria? short amino acid chains, NAG, NAM, and some lipid proteins 2. A cell wall is a requirement for all living bacteria. FALSE 3. What structural part of a bacterial flagellum is composed of flagellin? Filament 4. How are Gram-positive and Gram-negative flagella different? A Gram-positive flagellum has only two rings in its basal body; Gram-negatives each have four. 5. The rings; anchor the flagellum to the cell membrane. 6. The basal body is comprised of which structural component(s) of flagella? Rod and Rings 7. Pathogenic bacteria; can be identified and classified by differences in their flagellar proteins. 8. When comparing size, how would you describe prokaryotes versus eukaryotes? Prokaryotes are smaller. 9. Lipid A is a component of; the outer membrane of Gram-negative bacteria or Lipopolysaccharide (LPS). 10. Which of the following may be a component of bacterial cell walls? both lipoteichoic and mycolic acids 11. Using a microscope, you observe an amoeba moving toward a food source. This is an example of responsiveness. 12. Which of the following is a nonmembranous organelle found only in eukaryotic cells? Ribosome. 13. Which of the following molecules would be blocked by a cell membrane? Ions 14. Hydrophobic molecules move across a membrane; by passive transport directly across the membrane. 15. What is a hallmark of passive transport across cell membranes? It occurs along an electrochemical gradient, and may involve the use of transport proteins. 16. A positively charged sodium ion; would require the use of integral protein channels to pass through a cell membrane. 17. Which of the following scenarios is an example of bacterial motility? A bacterium moving towards a food source 18. Axial filaments are found on; spirochetes 19. What term describes the flagellar arrangement where flagella cover the entire surface of a bacterial cell? Peritrichous 20. What feature is missing in prokaryotes but commonly found in eukaryotes, as hinted at by their names? Nucleus 21. Which of the following statements about bacterial flagella is true? Flagella can rotate 360 degrees.

22. Taxis is. movement towards or away from a stimulus. 23. Which of the following terms refers to a bacterium moving towards a light source? Positive phototaxis 24. as a bacterium approaches a food source, one would expect; runs to become more frequent. 25. Which of the following would contain teichoic acids? Gam positive cell wall 26. Some bacteria have an outer layer called a ______ which allows them to adhere to surfaces and contributes to their ability to cause disease. capsule. 27. Some ______ use group translocation as a means of transport. bacteria. 28. One distinction between Gram-positive and Gram-negative cells is the relative thickness of peptidoglycan. Which group has a thicker layer of peptidoglycan? Gram positive 29. What makes phospholipid membranes good at keeping some molecules out, and allowing others to freely pass? They have both hydrophilic and hydrophobic regions. 30. Integral proteins are mostly involved in; transport function 31. How does water enter and exit a cell? By simple diffusion or by use of an integral transport protein 32. A glycoprotein; is a type of peripheral protein above that can be used as a receptor or in enzymatic functions. 33. How do axial filaments differ from regular bacterial flagella? The axial filament is located between the cell membrane and the outer membrane. 34. What is the advantage to spirochetes of the corkscrew movement provided by axial filaments? It allows the cells to move more easily through viscous human tissues and fluids, such as mucus. 35. Axial filaments are composed of.... endoflagella 36. Which of the following statements concerning pili is FALSE? Pili are longer than fimbriae and flagella. 37. The filament and basal body are associated with which of the following external structures found in some bacterial cells? flagella. 38. In a hypotonic environment, the vacuole of a plant cell enlarges and pushes the cytoplasm against the cell wall. Which organelles are most likely able to store that extra water? Vacuoles 39. Which of the following is NOT a function of the eukaryotic cytoskeleton? Packages cellular secretions. 40. Why is using antimicrobial drugs to kill large numbers of Gram-negative bacteria in a short period of time a cause for medical concern? Dead Gram-negative cells release lipid A, which causes fever and other medical problems. 41. How is osmosis different from simple diffusion? Water movement is driven by the concentration of solutes rather than its own concentration. 42. Nonspecific permeases; allow a variety of molecules to cross the cytoplasm membrane 43. What will happen to a cell that is placed in a solution containing a high concentration of sugar, a molecule that cannot pass across the cell membrane? the cell will lose its interior water, causing it to shrivel up and possibly die 44. How is simple diffusion different from other types of passive transport? Simple diffusion does not require a permease...