What is the process of making a genetically modified organism in a lab?

Answer 1

Contrary to the common understanding of the word, the process which we use to create transgenic organisms is called "cloning". This doesn't refer to copying an organism as often believed. Cloning as scientists mean it refers to creating DNA which does not naturally occur in any organisms. This is also called transgenic DNA.

To make a genetically modified organism, we need:

1. transgenic DNA - made by cloning
2. an organism

The transgenic DNA of course needs to be made for a specific purpose. Depending on how big it needs to be, it can be made in different ways. Very small stretches of DNA can be synthesised chemically. Larger bits of DNA are usually made by extracting a cell's DNA and then using a technique called polymerase chain reaction (PCR) to take only one particular bit of the DNA out. We then use restriction enzymes and ligase to cut and paste different bits of DNA together. Usually, the end product will be a plasmid.

The finished plasmid (transgenic DNA) then needs to be introduced into the target organism - and there are different ways of doing it for every type of organisms. Some bacteria for example will simply take up plasmids and integrate them into their own DNA without a complicated process around it being necessary. For bigger organisms like animals, it's very difficult - usually impossible - to modify an already living organism. For these, the only option is usually to take an oocyte (egg cell, e.g. a flower seed) and introduce the plasmid into it. If the egg survives this procedure and develops (which is very difficult to achieve), the resulting organism will be transgenic, or genetically modified.