Cloning Genes

Making Copies The final step is to use E. coli bacteria to make copies of the gene for you. All of this work in the test tube has made perhaps a few thousands copies of the plasmid with the gene. With E. coli , you can make millions of copies. You need this many copies for most experiments with cloned genes. First, the E. coli are treated so that they will absorb DNA into their cells. Next, the E. coli are mixed with the DNA and given time to take the plasmid into their cells. The E. coli are then added to a large test tube filled with nutrients to allow them to grow. E. coli reproduce very quickly, and in less than 24 hours you can have millions of E. coli in the test tube, each one with a copy of the plasmid with the NLB-1 gene. Each one of these E. coli is a clone because they all started from the same test tube, have the same plasmid, and have the same NLB-1 gene. You can now do many different experiments with the bacteria. You can study what the NLB-1 gene does to the E. coli . You can isolate the protein from the bacteria and study its structure. You can even cause the gene to mutate and learn what happens to the polypeptide when a different amino acid is present. Whatever experiment you do, you are on the cutting edge of science. Summary Cloning is used commonly in the laboratory and consists of taking a piece of DNA and putting it into E. coli for experimental purposes. PCR is the most common lab technique used for cloning DNA. Concept Reinforcement 1. Explain the difference between how the word “clone” is usually used in movies, and what biologists mean. 2. What could happen if you aren’t careful and somehow cut more than just the gene NLB-1 to from your gel? How could this effect the rest of your experiment? 3. Explain why E. coli with the NLB-1 gene are considered to be recombinant bacteria.