February 25, 2010

Genetic Engineering - I

Since there is so much talk about GM foods, here is an attempt to demystify the technique and explain the process and methodology.

What is a gene? A gene is a part of the DNA that codes for a protein. The DNA of an organism (genome) is huge and only ~ 5% of the genome codes for proteins. The remaining part of the genome is still an enigma for scientists and there are only theories and conjectures on their possible roles.

What is DNA? DNA is the hereditary material that is passed on, each time a cell divides and makes new cells. The main role of DNA molecules is the long-term storage of information. DNA is often compared to a set of blueprints or a recipe, or a code, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules. DNA, is highly conserved and we share common genes and sequences across organisms, from bacteia to plants to animals. The simple dogma in genetics is - DNA contains genes, which in turn codes for protiens.

Through genetic engineering we clone one gene of interest, into the genome of the host cell and study the expression level of the cloned gene. For example, in my lab, we have cloned genes for conferring tolerance to salinity and drought. So, we have integrated these genes into local varieties of rice. We at first grow them in test tubes and then pot them and those plants having the desired genes, we collect seeds and monitor in subsequent generations.

I would like to emphasise here that plants that cannot grow normally and set seed are automatically weeded out in the laboratory itself.

That's it for now. Do let me know if this is in simple language or should I keep it more simple.. In my next post I will explain how we decide the more promising plants that we call transgenic plants, and screen them for gene expression.  

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