Written by the MBSA Executive Team
What are Genes?
DNA (deoxyribonucleic acid) is hereditary material in humans which is found in the nucleus of a cell. It takes the shape of a twisted ladder and the “rungs” are made up from 4 bases -adenine, guanine, cytosine and thymine – which are used as the basis of the genetic code. In humans it is the sequence and order of these bases which makes us all different.These sequences give rise to genes. Genes are segments of DNA that will code for a specific protein within cells in the human body. Genes are stored in chromosomes and inherited. Physical features are determined by your genes, so if a gene mutates, it may change the trait in codes for. These mutations are transferred from one generation to another, and thus can be used to provide a better understanding of past population processes.
Some Genes Facts and History
In the past, Europe’s royal families had a lot of inbreeding. This resulted in the rarer mutations found within the family itself being more common, thus increasing the chances of the future generations having that mutation. For example, Queen Victoria carried the gene for haemophilia, which is the prevention of effective blood clotting. She married her first cousin, who also carried this gene. As a result, their children had a high likelihood of also carrying the gene, causing it to spread to the rest of European royalty, namely Russia, Spain, and Germany.
What is Genetic Mutation?
Genetic mutations are often studied in the lab through bacteria. Bacteria are single-celled organisms that have their DNA roaming freely in their body. They are commonly used in the lab because they are easy to work with and their genes can easily be mutated . Their DNA is mutated through a specific type genetic material known as a plasmid. Plasmids are small pieces of circular DNA which do not form part of the cellular chromosome and hence performs independently of the chromosomal DNA allowing independent replication. These have been exploited through biotechnology whereby plasmids can be designed and created in the lab and hence be encoded specifically to contain certain proteins or antibacterial strains of interest.
This has been done for generations for the production of human insulin in bacteria and can be done to make bacteria glow.
How to Make your Genes Glow
Green Fluorescent Protein (GFP) is protein that, as the name suggests, glows green in visible and UV light and is taken from a species of jellyfish known as Aequorea Victoria. The gene coding for GFP can be included within a plasmid and inserted into bacterial cells to make it glow by reading the plasmid as its own and producing the protein.
The genetic mutations do not always take. To to eliminate the problem of separating glowing and non-glowing bacteria, the plasmid also typically contains a gene for antibiotic resistance. This antibiotic-resistance will only be characteristic of the successfully transformed bacterial cells, which have taken up the foreign DNA. Therefore, upon growing the bacterial culture in the presence of that particular antibiotic, only the plasmid-transformed cells survive, indicating the effectiveness or otherwise of the genetic modification process .
In addition to antibiotic resistance, the successfully transformed cells also exhibit fluorescence, as a result of GFP protein expression. Since the GFP protein exhibits green fluorescence in exposure to UV light, bacterial growth may be monitored by the number of visibly fluorescing colonies. Bacterial cells which have remained unmodified do not survive as they are not immune to the antibiotics present around them.
What’s the Use?
As fascinating as it may be to make bacteria glow, it wouldn’t be common lab practice if it didn’t have any further applications. The most common use is as a visual tagger. Many genes and proteins under research do not have visual indicators that they are present within a cell. By coupling the GFP gene on the plasmid with the gene of interest you can conclude that any bacteria that glow also has the other gene!