Welcome back. If you missed the first part, click here to read part one. Today we will be going through the details on how genetic engineering is accomplished.
The first step to understanding genetic engineering is to understand DNA. DNA (or deoxyribonucleic acid) can be found in the nucleus of every cell. DNA molecules are the blueprints for creating functional molecules in cells called proteins. DNA is double stranded in a helix spiral. It is made up of four nucleotides on a sugar-phosphate backbone. These nucleotides are in pairs, adenine with thymine and guanine with cytosine. Genes are sections of DNA that code for a certain characteristic such as eye/hair colour. The way genes are decided is through the placement of the nucleotides through that section of DNA.
In genetic engineering we need to extract the genes that we want to use and then find a way to replicate that gene so that we can insert it into the DNA of the subject we want to change. Firstly in this process we need to find the gene we actually want to replicate. After we’ve found where the gene starts and finishes in the DNA we can then extract the gene samples by using very specific enzymes designed to link up with that section only and separate it from the rest of the DNA. In DNA the pairs of nucleotides line up across from each other. In the genes the coding is decided by three nucleotide pairs called codons. These codons are associated to the specific enzyme required for the gene. For a more complex detail on how we separate the gene from the DNA look here. Once we have our gene we need a way to replicate the gene quickly and efficiently as we have just taken it out of the cell. The way we do this is by the use of bacterial cells. We use the plasmids found in the cells as ways to transfer across section of DNA from our original sample to be replicated by the bacteria. Plasmids are circular DNA molecules found in Bacterial cells. Because they are circular you could theoretically keep adding genes as long as it doesn’t break. Because we insert the desired gene straight into the bacteria’s DNA the gene will be replicated whenever the bacteria cell reproduces and due to the large speed of which some bacterial cells reproduce we can get large quantities of the gene in a small amount of time compared to the time taken to extract it from eukaryotic cells. We then essentially complete the same process with the initial DNA with the DNA from the bacteria so that we can take the replicated forms and put it into the target cell where we want our gene to be.
For our final part we will be looking into the ethical issues and the problems that can come from genetic engineering