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1 | |
If pSC102 had contained an EcoRI site in the middle of the kanr gene, how would this have affected the results? |
| | A) | The results would be the same. |
| | B) | It would have been less likely to get kanamycin resistant colonies because two fragments would need to be inserted into pSC101. |
| | C) | It would have been more likely to get kanamycin resistant colonies because two fragments would need to be inserted into pSC101. |
| | D) | None of the above |
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2 | |
In pSC101 had contained a single EcoRI site in the middle of the tetr gene, how would this have affected the results? |
| | A) | The results would be the same. |
| | B) | It would not be possible to insert the kanr gene and get colonies that are resistant to both antibiotics. |
| | C) | There would have been more colonies that were resistant to both antibiotics. |
| | D) | None of the above |
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3 | |
Near the end of this experiment, what is the purpose of gradient centrifugation? |
| | A) | To separate pSC101 and pSC102 |
| | B) | To separate pSC101, pSC102, and pSC105 |
| | C) | To denature pSC101, pSC102, and pSC105 |
| | D) | To determine the densities of pSC101, pSC102, and pSC105 |
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4 | |
Let's assume that the EcoRI digestion at the beginning of this experiment may not be 100% complete (i.e., some sites may not be cut). If so, the fact that a bacterial colony is resistant to both tetracycline and kanamycin could mean that |
| | A) | The kanr gene has been inserted into pSC101. |
| | B) | The pSC101 plasmid has been inserted into pSC102. |
| | C) | A bacterial cell has taken up both plasmids. |
| | D) | All of the above |
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5 | |
Let's suppose that the DNA fragment from pSC102 that carries the kanamycin resistance gene also has an origin of replication. If so, it could circularize to form a plasmid that would replicate in E. coli. Therefore, the strain called pSC105 could have contained two plasmids, pSC101 and a small plasmid derived from a fragment of pSC102 with the kanamycin resistance gene and an origin. Which results, namely the density gradient centrifugation and/or the gel electrophoresis, rule out this possibility? |
| | A) | Gel electrophoresis |
| | B) | Density gradient centrifugation |
| | C) | Both |
| | D) | Neither |
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