Question

4. The DNA profiles to the right below represent four different individuals. o 111 Which of the following statements is consistent with the results? A. B is the child of A and C. B. C is the child of A and B. C. D is the child of B and C. D. A is the child of B and C. E. A is the child of C and D. <ULTE ILI UTILIT THITI TIL ILI 5. A eukaryotic gene with EcoRI sites at its ends has been cloned into 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. 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 contain the plasmid, but not the eukaryotic gene, would grow A. in the nutrient broth plus ampicillin, but not in the broth containing tetracycline. B. only in the broth containing both antibiotics. C. in the broth containing tetracycline, but not in the broth containing ampicillin. D. in all four types of broth. E. in the nutrient broth without antibiotics only.

Answer 1

4. The DNA bands of the parents should be almost dissimilar and their recombinants DNA bands will be found in their progeny. If you examine the gel picture given in the question, the DNA bands in lane A and B have little similarities to each other and the bands in the lane C and D have similarities with both DNA bands in the lane A and B. Hence the DNA bands in C and D are the progeny of the DNA bands present in A and B. Hence C and D are the progeny of A and B. Hence the correct answer is: B. C is the child of A and B.

5. There is an EcoRI site in the tetracycline gene and hence if there is a eukaryotic gene inserted into the plasmid, the tetracycline resistant gene will be lost and the bacteria will become sensitive to tetracycline if the gene is inserted. Hence the bacteria which does not have gene inserted in it will grow on both media containing ampicillin and tetracycline because the tetracycline gene hasn't been interrupted due to insertion. Hence the correct answer is: D. In all four types of broth.

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