University:
Northwest College
Course:
MOLB-2210 | General Microbiology
Academic year:

2021
Views:

153

Pages:

2
Author:

rehinhea0c

1. Alcohol works as a disinfectant by a) denaturing proteins. b) denaturing nucleic acids. c) dissolving and disrupting cell membranes. d) disrupting carbohydrate function. 2. The most effective way to sterilize most bacterial media is by a) filtration. UV radiation. b) c) boiling. d) autoclaving. 3. Colonies visible on an agar plate are a) composed of a single bacterial cell. b) are clones, the result of repeated cell division, starting with a single cell. c) the result of repeated cell division, starting with multiple cells. d) all dead cells. 4. In the medical Laboratory, bacterial characteristics such as size and shape are usually determined by a ______ stain. A. Negative B. Differential C. Structural 5. Which one of the following statements about the Gram stain is false? A. In the Gram stain, a dye called crystal violet is used to stain the cells purple. B. Gram negative cells have thinner cell walls than Gram positive bacteria. C. In the Gram stain, alcohol is used to kill the bacteria. D. Gram positive cells end up being stained purple. E. Gram negative cells end up being stained pink or red. 6. The Gram stain divides microorganisms into two groups, purple vs. red, on the basis of differences in the: A. presence of a capsule. B. presence of an outer membrane. C. thickness of the peptidoglycan layer of the cell wall. D. presence of waxy mycolic acids in the cell wall. E. presence of endospores. 7. Which of the following is true of restriction enzymes? Select all that apply. a) Restriction enzymes are exonucleases. b) Restriction enzymes are endonucleases. c) Restriction enzymes always cut to leave DNA 'sticky' ends. d) Restriction enzymes are part of the defense system of bacteria against attack by bacteriophages. 8. A eukaryotic gene has "sticky ends" produced by the restriction endonuclease EcoRI. The gene is added to a mixture containing EcoRI and a bacterial plasmid that carries two genes conferring resistance to ampicillin and tetracycline. The plasmid has one recognition site for EcoRI located in the tetracycline resistance gene. This mixture is incubated for several hours, exposed to DNA ligase, and then added to bacteria growing in nutrient broth. The bacteria are allowed to grow overnight and are streaked on a plate using a technique that produces isolated colonies that are clones of the original. Samples of these colonies are then grown in four different media: nutrient broth plus ampicillin, nutrient broth plus tetracycline, nutrient broth plus ampicillin and tetracycline, and nutrient broth without antibiotics. Bacteria that do not take up any plasmids would grow on which media? a. the nutrient broth only b. the nutrient broth and the tetracycline broth c. the nutrient broth and the ampicillin broth d. the tetracycline broth and the ampicillin broth