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Microbiology Study Questions

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11. Define restriction enzymes, and outline how they are used to make recombinant DNA.
12. Outline the PCR process and provide an example of its use.
13. Describe five ways of getting DNA into a cell.
14. Describe how a gene library is made.
15. Differentiate between cDNA and synthetic DNA.
16. Diagram the Southern blot procedure and provide an example of its use.
17. Discuss the advantages of the three-domain system.
18. List the characteristics of the Bacteria, Archaea, and Eukarya domains.
19. Differentiate among eukaryotic, prokaryotic, and viral species.
20. List the major characteristics used to differentiate the three kingdoms of multicellular Eukarya.

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Define restriction enzymes, and outline how they are used to make recombinant DNA.

Restriction enzymes recognize and cut DNA at specific sequences. DNA ends that have been cut with the same enzyme are complementary to each other and can then be ligated together with ligase. They are useful reagents in making recombinant DNA because it allows scientists to cut DNA pieces from one host DNA and to insert them into the complementary sites in a foreign piece of DNA. In other words, they allow scientists to recombine DNA pieces, so long as the ends of the DNA have been cut with the same restriction enzymes to generate complementary ends which can then be ligated together.

Outline the PCR process and provide an example of its use.

PCR typically involved:
Melting the template DNA to generate single stranded DNA
Annealing the complementary primers to the template DNA
Elongation of the DNA sequence from the primer by the polymerase
These steps are repeated for many cycles until the desired amount of DNA sequence has been amplified.

PCR is often used in cloning to isolate and amplify the desired sequence of DNA (a certain gene for example) from the larger genomic DNA.

Describe five ways of getting DNA into a cell.

Transformation - way by which a cells takes up naked DNA molecules
Electroporation - shocking the cells generates holes in the cell membrane to allow DNA uptake
Lipofection - when lipids are used to mediate the DNA entry into the cells
Tranduction - in bacterial, phage can mediate DNA uptake
Conjugation - conjugative plasmid mediates the DNA uptake
Transfection - infection of cells with a virus

Describe how a gene library is made.

The DNA molecules of an organism in interest are isolated. The DNA molecules are then partially digested by a endonuclease restriction enzyme. Sometimes, the ...

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Microbiology Study Questions

1. Clostridium and Streptococcus are both catalase-negative. Streptococcus grows by fermentation. Why is Clostridium killed by oxygen, whereas Streptococcus is not?

2. Assume that after washing your hands, you leave ten bacteria cells on a new bar of soap. You then decide to do a plate count of the soap after it was left in the soap dish for 24 hours. You dilute 1g of the soap 1:106 and plate it on standard plate count agar. After 24 hours of incubation, there are 168 colonies. How many bacteria were on the soap? How did they get there?

3. Why is each of the following bacteria often resistant to disinfectants?
1. Mycobacterium
2. Pseudomonas
3. Bacillus

4. Explain why gram-negative bacteria are more resistant to biocides than gram-positive bacteria. Be specific and descriptive in your response. A description of the differences between gram-negative and gram-positive bacteria should be included, along with an explanation of why any of those differences would have anything to do with the actions of biocides.

5. Ciprofloxacin, erythromycin, and acyclovir are used to treat microbial infections. Ciprofloxacin inhibits DNA gyrase. Erythromycin binds in front of the A site on the 50S subunit of a ribosome. Acyclovir is a guanine analog.
1. What steps in protein synthesis are inhibited by each drug?
2. Which drug is more effective against bacteria? Why?
3. Which drug is more effective against viruses? Why?
4. Which drugs will have effects on the host's cells? Why?
5. Use the index to identify the disease for which acyclovir is used. Why is it more effective than erythromycin for treating this disease?

6. Design an experiment using the vaccinia virus to make a vaccine against AIDS virus (HIV).

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