1. What is the process of bacterial transformation? Why is it difficult to get f
ID: 60601 • Letter: 1
Question
1. What is the process of bacterial transformation? Why is it difficult to get foreign DNA into bacterial cells? How are bacterial cells made “competent” to receive DNA?
2. Describe how restriction enzymes are used in the process of making recombinant DNA molecules. Why is ligase needed to make recombinant DNA molecules?
3. How are “selectable markers” such as antibiotic resistance genes used in cloning and specifically bacterial transformations?
4. What are some of the challenges in using recombinant DNA technology to make human therapeutics? Use the example of insulin production described on the DNA interactive web site and describe 2 major problems experienced when producing insulin in bacteria.
5. What were some of the ethical issues surrounding the use of recombinant DNA molecules that confronted scientists at the time and do they still exist? This discussion can be found again in the DNA interactive site and the module “putting it together.”
Explanation / Answer
1. Bacterial transformation is the genetic mechanism by which a cell directly uptake and incorporate exogenous genetic material from its surrounding that is taken up through the cell membrane. Transformation occurs naturally in some species of bacteria.
It is difficult to get foreign DNA into bacterial cells. Bacterial cell membrane does not allow large molecules directly into the cell, they do need special channel proteins allow the entry of foreign DNA.
2. In rDNA technology, restriction enzymes are used to cut the cloning vector, and the same enzyme is used to cut the desired DNA segment. Cutting both the DNA molecules with the same enzyme provides cohesive ends that are easily stick together using ligase.
Ligase is the enzyme used to seal the two DNA fragments. Ligase forms bond between 3’-OH group and 5’-P group.
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