Adenine and guanine are purines, and pyrimidines include cytosine and thymine. Transition: In this type of mutation, a purine base is replaced by another purine base or a pyrimidine base is replaced by another pyrimidine base.The purine bases are adenine and guanine. Depurination: This mutation occurs when there is loss of a purine base from a sequence, giving rise to an apurinic site.For example, deamination of cytosine would yield a uracil base and that of adenine will yield a hypoxanthine base. Deamination: This mutation arises when a base undergoes hydrolysis and the amine group is displaced from the base, transforming it into an atypical base with a keto group. There are 4 types of point mutations: deamination, depurination, transition, and transversion. Point mutations: These mutations are characterized by changes in a single nucleotide in a gene. The condition of heterochromia, where the two eyes have different coloration, is also due to the interaction of the OCA2 and HERC2 genes. A specific mutation in the HERC2 gene along with single nucleotide polymorphisms (SNPs) in the OCA2 gene causes the development of a spectrum of different eye colors in humans. The HERC2 gene regulates the expression of the OCA2 gene. The absence of this molecule leads to albinism. The OCA2 gene is responsible for production of melanin, a molecule that imparts color. However, the two main genes involved in this process are the OCA2 and the HERC2 genes located on chromosome 15. A research paper in the Journal of Human Genetics provides evidence that close to 16 genes may be responsible for eye color, and the way these interact with each other determine the specific shade of color. Since then, these mutations have been passed down through generations. Somewhere along the course of evolution, different eye colors emerged due to genetic mutations. The color of the eyes is a physical trait of humans that is determined by more than one gene. Some Common Genetic Mutations in Humans Hair Color In some cases, no change might be observed despite a genetic mutation. The alteration may sometimes lead to a desirable change or to an undesirable change. Any alteration in the set sequence of a gene can be called a genetic mutation. These bases, present in various combinations, are responsible for coding all the various molecules that form an organism and help it function. Each gene consists of a juxtaposition of the four basic building blocks of DNA: Adenine (A), Guanine (G), Thymine (T), and Cytosine (C). There are close to 30,000 genes in the human genome. A gene is a hereditary unit that consists of sequences of DNA that code for various molecules, which eventually help define an organism and regulate all processes associated with it. To understand what a genetic mutation is, one must first understand the concept of genes. The differences among the individuals arise due to variations in merely 0.1% of the whole genome. Others embrace them, taking them as a plus to their physical attributes.In humans, 99.9% of the genome is exactly the same in all individuals. In some instances, some term them as congenital disabilities, which is scientifically incorrect. In this regard, many people tend to overlook the occurrence of some rare natural hair colors. Mostly, the colour is more prevalent in Africa, Asia, and in some other parts of the globe, such as Eastern and Southern Europe, America, and Latin America. Science estimates that around 75 to 85% of the world’s population has black hair. Photo: UGCīlack hair is, arguably, one of the most common hair colours in the world. So, which are the rarest hair colors and eye combinations in the world? Female friends, with different natural hair colours, looking at their smartphones. Interestingly, the same applies to eye colours, and, at times, they can occur simultaneously. Mostly, the colours are a result of genetic mutation alongside other factors. However, some have unique hair colours, which are uncommon and unlikely to find. Many people around the world are naturally black-haired.
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