Question

Read the passage and answer the following question.

A group of students tried to insert a small gene into a plasmid that was $4,500bp$ in size. They then attempted to insert the plasmids into bacteria by the transformation. Several days later, they chose four small colonies and grew them up in broth culture. They extracted the DNA from the bacteria in each tube and loaded them onto a gel (lanes 1 to 4).
The plasmids shown in lanes 2 and 3 are the same size as the original plasmid.

Select the correct statement.

• A. The plasmids in lane 1 could be the result of cutting the original plasmid with restriction enzymes
• B. The plasmids in lane 1 can be the same size but different configurations
• C. The plasmids in lane 4 are smaller than the original plasmids
• D. The students were probably successful in their genetic engineering attempt
• E. Both B and D

Answer 1

Answer: (D)

The students were probably successful in their genetic engineering attempt

The transformation experiment was successful - this we can say after having a look at the gel (diagram).

The plasmids, as told in the question, in lane 2 and lane 3 are of the original size. When there is an insert (successful transformation), the molecular weight of the plasmid with insert will increase and this can be seen in lane 4 as well as one band in lane 1, which is corresponding to mol wt. 5,000.

Thus, the students were successful in their genertic engineering attempt.