How do we clone genes?



  1. 0 Votes

    What it means to clone a gene depends on who you’re talking to. One definition is to extract a gene from the genome of some organism and put it into a plasmid in a bacteria where it will be replicated indefinitely:

    If we already know the approximate sequence of the gene, we design primers (short pieces of DNA that are complementary to each end of the sequence of the gene itself), then we mix the primers together with a sample of DNA from the organism in question and several other chemicals and proteins and put it in a PCR machine (short for Polymerase Chain Reaction) which creates lots and lots of copies of the gene.

    After the sample comes out of the PCR machine, the DNA sequences can be inserted into a plasmid (a circle of DNA) which can be transformed into a bacteria by mixing the bacteria and DNA together and using an electrical shock (or sudden changes in temperature) to make the plasmid containing the gene we’re interested in enter the bacterial cell.

    Once the plasmid is inside a bacterial cell it will replicate and every time the bacteria divides, each of the two new cells will also carry the plasmid.

    In older literature, cloning a gene often meant simply identifying the sequence that coded for some interesting function. Lots of techniques could be used, from using a gene from a related species as a probe to screen a bacterial or phage library, to using mapping crosses to identify the location on a chromosomes of a gene which had been mutated to create an interesting phenotype. Once the location was known accurately enough a researcher could test whether they’d identified the correct gene by inserted a working copy of their candidate gene into the mutant plant, fungus or animal they were studying to see if it would turn their organism back into a wild type.

    In some contexts I’ve also seen “clone a gene” used to mean creating transgenic plants or animals.

    If you could comment back and let me know more specifically what you’re interested in I’d be happy to write you a more detailed answer.

Please signup or login to answer this question.

Sorry,At this time user registration is disabled. We will open registration soon!