Friday, May 5, 2017

Recombinant DNA Technology [Biochemistry]

Because All organisms on Earth evolved from a common ancestor, so all organisms has a similar molecule of heredity - DNA. DNA has a double helix structure and contains a combination of the nitrogen bases: Adenine, guanine, cytosine and thymine. Although all the organism contain the same four bases, but there can be infinite number of ways to arrange them, so that each organism has a unique combination for their DNA strands. Due to the DNA structure of different organism having the same structure and bases, DNA can be “cut and past” which lead to recombinant DNA technology. Recombinant DNA Technology join the different strand of DNA, usually from two different species, and insert them into a host organism to produce new genetic combinations. The technology is beneficial to the understanding of DNA and the study of genetic engineering.
The first recombinant DNA molecule was produced in 1972 by Stanford researcher Paul Berg. Berg joined together DNA fragments from two different viruses with the help of restriction enzymes and ligase. Restriction enzymes are like “molecular scissors” that cut DNA at specific sequences. If the DNA from the different sources is cut with the same restriction enzyme, the cut ends can be joined together and then sealed into a continuous DNA strand by the enzyme ligase. In 1973, the first organism to contain recombinant DNA was engineered by Herb Boyer and Stanley Cohen. Together they introduced an antibiotic resistance gene into E.coli bacteria. Notably, they also produced bacteria that contained genes from the toad Xenopus laevis , which showed DNA from very different species could be spliced together. Paul Berg was awarded the 1980 Nobel Prize in Chemistry “for his fundamental studies of the biochemistry of nucleic acids, with particular regard to recombinant-DNA”.


The process of recombinant DNA technology: Step 1, Choosing the appropriate host organism and cloning vector. Step 2, Preparation of vector DNA and DNA to be cloned. Step 3, Creation of recombinant DNA. Step 4, Introduction of rDNA to host organism. Step 5, Screening for rDNA with specific properties sought from host organisms. Step 6, multiply or express the gene of interest.  
Now recombinant DNA technology is used in research laboratories worldwide to explore myriad questions about gene structure, expression pattern, regulation, function and much more. One of the widely used application is genetically engineer an animal to contain a particular gene of interest that is nonfunctional. The purpose of such experiments is to determine the function of the gene by analyzing the consequences of the missing gene. Another success in recombinant DNA techniques is the generation of genetically engineered plants to produce an insect toxin called Bt toxin. The toxin is derived from a bacterium called Bacillus thuringiensis that produces a toxin that disrupts gut function in the larvae of certain insects that eat crops. The gene of the toxin is introduced into plants by recombinant DNA technology, and it resulted in the killing of crop-feeding insects. It reduced the amount of pesticides used per year and has increased the longevity and success of several crops, it also has a major economic impact.

1 comment:

  1. I think that this is an interesting post because it combined part of what we learned about DNA in biology last year and what we learned this year about genetic chemicals as well as applying how medicine affects our bodies. As you demonstrated, science can benefit us not just individually, but economically and commercially as well.

    ReplyDelete