A hand with an extra finger, strangely overgrown bones, and red hair. What do all of these uncommon traits have in common? Simply put, these are all examples of genetic mutations. Genetic mutations are caused by gene disorders which are permanent alterations in an individual’s DNA sequence, the fundamental code for genetic information in nearly all living organisms, that result in a gene that is genetically different than that of other humans. Sickle-cell anemia, albinism, and down syndrome, are among some of the most common genetic disorders in humans today. Essentially a gene is a combination of nucleotides, which are the monomer unit molecules for forming the nucleic acid polymers required for deoxyribonucleic acid (DNA) and ribonucleic acid (RNA.) These genes are responsible for particular functions determining certain characteristics of an individual.
Genetic mutations occur as a result of irregular DNA replication and protein synthesis. As mentioned earlier, the code for genetic information carried by genes is used to make specialized molecules known as proteins. Proteins assist our body in many activities including the regulation of our bones and organs. DNA needs to replicate itself for a process known as cell division, in order for every cell in the human body to carry DNA and to be able to make proteins. The process whereby protein molecules are made is known as protein synthesis and different enzymes work together to facilitate this process. There are three major ones: Helicase, DNA Polymerase, and RNA polymerase. These three enzymes are linked closely with the nucleotides that make up the genes. Nucleotides are composed of a phosphate group, sugar, and a nitrogen base that pairs with other nitrogen bases to form DNA; adenine, a compound which is one of the four constituent bases of nucleic acids, pairs with thymine and guanine pairs with cytosine in a process known as base pairing. Base pairing is where the genetic mutations occur.
So how does base pairing mutate an individual? Helicase, DNA polymerase, and RNA polymerase work together to split DNA, match nitrogen bases correctly, check for errors in base pairing, and form RNA as a result. Often times, the enzyme DNA polymerase is unable to match every single nucleotide correctly and in fact, it rarely ever occurs where every enzyme is paired up accurately. The swapped up nitrogen bases create mutations because the pairing is not “normal.” There are also certain ways the gene can get mutated. Base substitutions occur when one nitrogen base is switched for another. This can change the gene as a whole or have no effect on it at all, which is referred to as a silent mutation. Genes can also be mutated through a process known as frameshift mutations. This is when genes are inserted or completely deleted, which causes the original gene to shift. Entire chromosome sets of genes can also be mutated in which they change positions, which is referred to as translocation. In all of these scenarios, genes are affected in a way that changes the way a trait expresses in an individual although the outcome may be insignificant where it goes unnoticed. The mutations can alter a single nucleotide of DNA resulting in a disorder such as down syndrome, or they can change an entire chromosome of DNA, in which case the mutation is likely to be more severe.
Gene mutations can be categorized in to two different types. There are hereditary mutations, which express themselves through virtually every cell in a human’s body because the mutation existed in the parents’ sperm or egg. There are also somatic mutations, which occur in only certain cells and are primarily a result of environmental factors.
Genetic mutations are not always bad. Some genetic mutations can even prove to be advantageous for humans. In Italy, there have been cases of genetic mutations where heart disease has been reversed and the mutation actually ends up protecting the heart. While mutations in the human body may seem bad, they are simply variations in the gene structures of an individual that may change the way that they express certain traits and they adds to the extreme diversity and variation in humans that we see in society today. For further information check out this link: https://ghr.nlm.nih.gov/primer/mutationsanddisorders/genemutation.