1. Do you know how genetic engineering is performed?

2. Understand the details of how genetic engineering happens with information from a biochemistry professor in video on genetic engineering.

3. Listen to the professor again and complete this part of his presentation with a word or word combination

And from that point on, it's a part of the __________. So, every time the cell ________ or is even around it should read passed the DNA and _______ exactly what we wrote. Now, to do it on the _________ ________, it's pretty much the same thing except now they have tanks full of the __________ instead of little bottles of the enzymes, and they have _________ of ____________ growing or whatever cell growing instead of little bits of cells growing. The biggest thing issue comes into ____________ 'cos anytime __________ _________ __________ is what it reads the DNA, it's not going to do just create what you wrote. It's going to create everything else that's written on that ________ of ________, too.

1. Y

   Before you read

   ou are going to read an article about the basic genetic techniques and how a GMO is made. Before you read discuss with your group mate the following questions.

• Can you name the main methods in genetic engineering?

• Can you describe them?

2. Skim the text to check your ideas.

GENETIC ENGINEERING TECHNIQUES

Recently, we have begun to learn how to take evolution into our own hands through genetic engineering, which involves altering or manipulating an organism's genome to create a new and useful result. The methods often used by genetic engineers are many and varied, but generally fall under one of three categories: the plasmid method, the vector method, and the biolistic method.

The Plasmid Method

The first technique of genetic engineering, the plasmid method, is the most familiar technique of the three, and is generally used for altering microorganisms such as bacteria. In the plasmid method, a small ring of DNA called a plasmid (generally found in bacteria) is placed in a container with special restriction enzymes that cut the DNA at a certain recognizable sequence. The same enzyme is then used to treat the DNA sequence to be engineered into the bacteria; this procedure creates "sticky ends" that will fuse together if given the opportunity.

Next, the two separate cut-up DNA sequences are introduced into the same container, where the sticky ends allow them to fuse, thus forming a ring of DNA with additional content. New enzymes are added to help cement the new linkages, and the culture is then separated by molecular weight. Those molecules that weigh the most have successfully incorporated the new DNA, and they are to be preserved.

The next step involves adding the newly formed plasmids to a culture of live bacteria with known genomes, some of which will take up the free-floating plasmids and begin to express them. In general, the DNA introduced into the plasmid will include not only instructions for making a protein, but also antibiotic-resistance genes. These resistance genes can then be used to separate the bacteria which have taken up the plasmid from those that have not. The scientist simply adds the appropriate antibiotic, and the survivors are virtually guaranteed (barring spontaneous mutations) to possess the new genes.

Next, the scientist allows the successfully altered bacteria to grow and reproduce. They can now be used in experiments or put to work in industry. Furthermore, the bacteria can be allowed to evolve on their own, with a "selection pressure" provided by the scientist for producing more protein. Because of the power of natural selection, the bacteria produced after many generations will outperform the best of the early generations.

Many people strongly object to the plasmid method of genetic engineering because they fear that when the engineered plasmids are transferred into other bacteria it will cause problems if they express the gene. Lateral gene transfer of this type is indeed quite common in bacteria, but in general the bacteria engineered by this method do not come in contact with natural bacteria except in controlled laboratory conditions. Those bacteria that will be used in the wild - for example, those that could clean up oil spills - are generally released for a specific purpose and in a specific area, and they are carefully supervised by scientists.