Multiple Choice Quiz Procaryotic Cell Structure and Function Eucaryotic Cell Structure and Function Choose the best answer 1. The significance of the plasma membrane is that it selectively allows some molecules to pass into the organism it prevents movement of molecules out of the organism it is the site of protein synthesis all of the above 2. The most commonly encountered bacteria are roughly spherical. The microbiological term describing this shape is coccus bacillus pleomorphic 3. Another common bacterial shape is that of a rod, often called coccus bacillus pleomorphic 4. In bacterial cells, ribosomes are packed into the cytoplasmic matrix and also loosely attached to the plasma membrane. What is the function of ribosomes? Site of energy production Site of protein synthesis Site of genetic reproduction 5. What is a plasmid? Self-replicating segment of double stranded DNA Self-replicating segment of single stranded RNA A bacterial chromosome 6. Plasmids are important to the genetics of many bacteria. This is because they are inherited from one generation to the next. they may carry genes that give their host a selective advantage. they can render bacteria drug-resistant. All of the above. 7. Bacteria do not always swim aimlessly but are attracted by such nutrients such as sugar and amino acids, and are repelled by harmful substances and bacterial waste products. Movement toward chemical attractants and away from repellents is called gliding motility. tumbling. chemotaxis. 1
8. Some bacteria are considered pleomorphic. This means they are shaped like bent rods. they have a corkscrew shape. they do not have just one shape. they are not either bacilli or cocci. 9. Poly-beta-hydroxybutyrate inclusion bodies protect bacteria from excessive drying. store carbon for energy and biosynthesis. turn reddish brown when stained with iodine. are composed of polymers of glucose. 10. Gas vesicles in bacteria help move cells to optimal nutrient levels. store oxygen for growth anaerobically. are bounded by a lipid bilayer membrane. are bounded by a membrane impervious to gas. 11. Magnetostomes in bacteria help cells attach to metal objects. help cells to magnetically attach to each other. help cells to float on the surface of fresh water ponds. help cells to orient in the earth's magnetic field. 12. The 70S procaryotic ribosomes consist of two 40S subunits. a 50S and a 30S subunit. a 40S and a 30S subunit. a 50S and a 20S subunit. 13. Gram positive cells have a second, outer membrane that helps retain the crystal violet stain. have multiple layers of peptidoglycan that help retain the crystal violet stain. have a thick capsule that traps the crystal violet stain. have a periplasmic space that traps the crystal violet. 14. The presence of D-amino acids in the crosslinks of the peptidoglycan layer is most likely because most peptidases can only cleave L-amino acids. D-amino acids fit the structural constrains of the cell wall better than L-amino acids. most L-amino acids have already been used for protein synthesis. D-amino acids are easier to crosslink in the absence of ribosomes. 2
15. The third amino acid in the peptidoglycan crosslinking chain is either diaminopimilic acid or lysine because this amino acid must be positively charged for a salt bridge to form. be hydrophillic. have a free amino group for peptide bond formation. have a large R-side chain to fill space in the cell wall. 16 Gram positive cells have thick, homogeneous cell walls. have large amounts of teichoic acids. do not have an outer membrane. all of the above are true. 17. The outer membrane of Gram negative cells is more permeable than the plasma membrane because LPS is larger than most membrane phospholipids. lipoproteins stretch the outer membrane. porin proteins establish holes in the outer membrane. the core polysaccharide spans the lipid bilayer. 18. The most important role of the prokaryotic cell wall is to maintain the shape of the cell. protect the cell from osmotic pressures. prevent ions from diffusing away from the cell. block the effects of antibiotics like penicillin. 19. Which of the following is not true about capsules and slime layers? 20. Fimbriae They consist of secreted material lying outside of the bacterial cell wall. They can prevent desiccation of bacteria cells. They are required for bacteria to grow normally in culture. They help bacteria resist phagocytosis by macrophages. attach bacteria to various surfaces. cause bacteria move through fluids. sense changes in nutrient concentration. are pathways for the secretion of exoenzymes. 21. A bacillus bacterium with a single flagellum at each end is described as Monotrichous Amphitrichous Lophotrichous Peritrichous 3
22. Which of the following is not true about bacterial flagella? Most of their length consists of a hollow, rigid protein tube. They are constructed largely of a single protein called flagellin. They spin like wheels, either clockwise or counterclockwise. They use cytoplasmic ATP as their primary energy source. 23. The flagellar filament grows by enzymatic addition of subunits to the tip of the flagellum. enzymatic addition of subunits to the base of the flagellum. self-assembly of subunits traveling through the hollow flagellum to the tip. self-insertion of subunits along the length of the filament. 24. How does a bacterium control the direction of swimming? The length of the flagellum acts as a rudder to steer the bacterium. The speed of rotation is faster when the bacterium is headed the correct way. The bacterium can stop and spin until it is pointed the correct way. The bacterium does not control the direction of its swimming. 25. The methyl-accepting chemotaxis proteins of bacteria are directly connected to the flagellar motor to guide the bacterium. can only sense conditions that are favorable for bacterial growth. integrate multiple signals through a two component phospho-relay system. tell the bacterium which way to go. 26. Bacteria accomplish chemotaxis by Steering toward better growth conditions. Making long, uninterrupted runs when conditions are good. Frequently stopping and tumbling to better sense good conditions. Stopping movement when conditions are good. 27. What is the purpose of bacterial endospores? Allow the bacterium to make hundreds of "seeds" to spread on the wind. Help the bacterium to differentiate into faster growing stages of bacteria. Allow the bacterium to survive the absence of oxygen. Allow the bacterium to survive extended periods of heat or dryness. 28. The diploid state of a microorganism refers to the times when cells contain copy (ies) of each chromosome and occurs after mitotic cell division. one two three 29. The mitochondria is the site of protein synthesis lipid synthesis energy production 4
30. The cytoplasmic matrix is best described as A dilute aqueous solution that fills most of the cell. A solution of inorganic salts intended to balance osmotic pressure in the cell. A semicrystalline mixture mostly of proteins and bound water molecules. Material in transit between membrane bound organelles. 31. Which of the following statements about Endoplasmic reticulum (ER) is not true? ER can transport proteins and lipids to the plasma membrane or for secretion. ER is the main site for cell membrane biosynthesis. ER is contiguous with the nuclear membrane. ER is the main site for synthesis of cytoplasmic proteins. 32. When Listeria monocytogenes invades a eucaryotic cell, it secretes the ActA protein that polymerizes actin filaments, causing the bacterium to move through the cytoplasm. depolymerizes microfilaments, allowing the bacterium to move more easily in the cytoplasm. degrades the cytoskeleton, allowing the bacterium to travel through the plasma membrane to adjacent cells. attaches to microtubules, allowing the bacterium to move along the fibers. 33. Colchicine treatment of cells to disrupt microtubules can result in loss of cell shape loss of directional movement. loss of nutrient transport. all of the above. 34. Which of the following is NOT a mechanism for a cell to degrade its own cytosolic proteins? Autophagic vacuoles Phagocytosis and secondary lysosome fusion. 26S Proteosome degradation. All the above are correct mechanisms. 35. Lysosomes of the cell are where lysozyme is synthesized. secretory proteins are transported to the surface. endocytosed material is degraded. glycogen is stored as an energy source. 36. Mitochondria are similar to bacteria in several ways. Which of the following is NOT a similarity? Both have peptidyl glycan in their cell wall. Both have circular, double stranded DNA. Both are about the same size. Both have 70S ribosomes. 5
37. The F1 particles of mitochondria are 38. Plastids are a type of ribosome that synthesizes mitochondrial proteins. a structural component of the mitochondrial inner membrane. an enzyme complex that synthesizes ATP during respiration. a storage complex for calcium phosphate in the mitochondria. protrusions of plasma membrane that bud off of plant cells. cytoplasmic organelles that often contain photosynthetic pigments. pieces of circular, double stranded DNA that can carry drug resistance. areas of the nucleus where rrna is transcribed. 39. The light reaction of photosynthesis is where carbohydrates are formed from CO 2 and water. polysaccharides are formed in the pyrenoid. proteins within the stroma are made to give off photons of light. photons from light are trapped to generate ATP and O 2. 40. The nucleus of the cell is where energy for cell division is generated. ribosomes translate mrna into proteins. chromatin is kept within a membrane delimited body. endocytic vacuoles fuse with lysosomes. 41. The nuclear pores are passageways between the nuclear matrix and the cytoplasm which allow DNA to reach the cytoplasm to be translated to RNA. allow ribosomes to enter the nuclear matrix. allow proteins synthesized in the cytoplasm to enter the nucleus. structurally reinforce the nuclear membrane. 42. DNA is the primary molecule for information storage in 43. Cell walls, when they exist, usually contain peptidoglycan in 44. When flagella exist, their movement is powered by ATP in 6
45. Membrane bound organelles such as mitochondria and Golgi are found in 46. Ribosomes are required for synthesis of proteins in 47. Exoenzymes are contained in the periplasmic space in 48. All the cells chromosomes are contained in the cell nucleus for 7