The Interactions of Genes with The Environment
- erudite .
- Apr 28, 2022
- 3 min read
By Anoushka Ghosh
Genes are the basic and functional unit that allows for heredity to occur. Our genes are smaller sections of something bigger known as the DNA, and the main role of these genes is to provide instructions to make molecules called proteins. Genetic diseases could result from a change in single or multiple genes. There is often a misconception regarding how genes are expressed. Genes are not set in stone, because the environment can also cause a different interaction with the genes that can either silence or activate the genes.
In order to further understand this phenomenon, it is vital to understand how genes are expressed. In our nucleus, we have chromosomes containing the genes that code for certain characteristics that are passed on to the next generation. Gene expression is the process by which the instructions in our DNA are converted into a functional product. This can occur through DNA methylation or histone modification. During DNA methylation, there is a transfer of the methyl group from S-adenosyl methionine to the fifth carbon of cytosine which occurs by the catalysis involving the enzyme, DNA methyltransferases. The addition of the methyl group (CH3) to the gene would lead to the deactivation of the gene and inhibit the transcription of DNA. Furthermore, there is histone modification involving the addition of the acetyl group to the lysine in histone and activating the gene to open up and allow proteins to bind to it, but the methyl group added to the lysine would deactivate the gene. The activation of the gene allows for transcription to occur and the protein being produced, but the deactivation of the gene leads to no protein being produced.
You may be wondering what transcription is? Well, DNA is significant in producing the instructions to construct proteins which would eventually be vital for different processes like metabolic reactions involving enzymes, antibodies, and other proteins. Hence, our DNA goes through a process of transcription and translation. Transcription is the process by which the information within the strand of DNA is converted into mRNA with the use of RNA polymerase to catalyse the joining of RNA nucleotides to the template strand. However, this would then lead to the translation of DNA into the amino acid sequence with the use of transfer RNA that would bind its anticodon to the respective codon on the mRNA and produce an amino acid sequence. This can only occur whether the gene is silent or activated.
Interestingly, gene expression can be seen through real-life events such as the Holocaust. In 1944, the Dutch were suffering during the Hongerwinter (hunger winter), which led to sparse food supplies across the northern and western regions of the Nazi-occupied Holland. Hence, the increased level of malnutrition occurred with children being small and underweight. Although the war had ended, the issues persisted well into their adulthood, leading to the increased risk of obesity for these children. The epigenetic markers weren’t removed, which led to the activation of the genes and the permanent modification of the genes.
After 60 years, Lambert Lumey, an epidemiologist at Columbia University, found that the isolated DNA from Hongerwinter survivors contained below-average methylation of insulin growth factor II gene (IGF2), which increased the expression of the hormone can possibly cause the formation of benign tumours and affect cholesterol transport, and ageing. It is unknown whether or not the changes persist into the next generation.
“These studies provide the first convincing evidence that early nutritional exposure causes a persistent change in epigenetic regulation in humans,” says Robert Waterland from Baylor College of Medicine in Texas. It’s too early to tell whether or not the disease persists into the next generations, but many professionals believe that it could possibly affect generations leading to an increased probability of the aforementioned symptoms.
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