Mutation and Polymorphism - Essay Example

In the heart of the Genetic Mutation article lies the hypothesis that a change in the base chain of a specie’s deoxyribonucleic acid may result into one of these three effects. Either, the base change would result in a genetic disorder making the organism to be predisposed to certain diseases or it would result in a beneficial adaptation or in some instances, it may have no change at all. Therefore, this article questions how these base changes or mutation occurs and how they may influence the wellbeing of species with regards to its functionality both at the present and in the future. The article provides a background, which precedes its main body that provides explanations of how mutations occur. Mutation and polymorphism are two terminologies that are often used by biologists and appear to share a similar meaning but are slightly differentiated. According to Suzanne, mutation is a broad term, which encompasses the alteration of the deoxyribonucleic acid (DNA). On the other hand, she describes a single nucleotide polymorphism (SNP) to be the alteration of a single base pair that occurs frequently among the populace (Suzanne). Therefore, from Suzanne’s definition, it is clear that polymorphism is a genetic location where two or more sequences are found with the occurrence of a variation of at least 1 percent of the populace. A variation that is lower than 1 percent of the populace means that it is a typical mutation (Suzanne). Every human function is a result of genetic instructions. These genetic instructions or information is the human genome. Two genome is stored as DNA sequences. These are the haploid human genome and diploid human genome. The haploid human genome is found in the reproductive tissues (germ-line cell) while the diploid is found in the non-reproductive tissues (Somatic cells). The haploid human genome, which is the focus of this essay, has 3 billion nucleotides. Although there is a presence of a large number of nucleotides, any change that occurs in, for instance, a single base pair may lead to a malfunction. Most of the changes (mutations), which occur, have a deleterious effect in terms of diseases. Some mutations are known to be silent, as they do not express themselves unless detected by a DNA sequence analysis test. It is important to point out that not all mutations are deleterious. Some mutations are beneficial in that when they occur, they strengthen the organism. For instance, an individual with the sickle-cell mutation is not predisposed to be infected with malaria. Sickle-cell anemia is one example of a disease that occurs because of a base change. It comes about when a single nucleotide changes an amino acid n the protein chain. The nucleotide is located in the beta chain. The change brings about devastating results. The mutation changes a normal hemoglobin gene into a sickle cell gene (The hemoglobin gene is the protein that carries oxygen in the body and gives the blood its red color). This change occurs when the sixth amino acid in the hemoglobin gene becomes valine instead of the usual glutamic acid. As a result of the mutation, the sickle cells aggregate and form rods, which clog blood vessels and make it hard for the cells to transport oxygen around the body. A person who suffers from sickle cell has a high chance of clogged capillaries, which would lead to the death of body tissues such as heart or even the brain. From these effects, it is evident that even the smallest mutation that occurs in a nucleotide will result in a serious medical condition. Ironically, not all mutations are dangerous or harmful. Mutation is the force behind evolution. Mutation enables an organism to adapt and develop new characteristics that will help and organism to cope better with its environment. Such mutation is passed down from the parent to the offspring and thereby increasing their rate of survival (Suzanne). Types of changes in the DNA A mutation can occur in either of two major ways in any cell. A mutation may occur in the reproductive cells of an organism, such that during sexual reproduction the mutation will be passed on to the offspring. This means that every offspring will have the mutation in its DNA. This mutation is known as the germ-line mutation. The second mutation occurs in the non-reproductive cells of an organism, and it may only be passed to the daughter cells through mitosis. The somatic mutation will not express itself in an organism’s offspring. A DNA change mutation can occur in three major ways. These type of classes are point mutation, chromosomal mutations, and copy number variations (Suzanne). Point mutation The point mutation class has three types of mutations. These are the substitution, insertion, and deletion mutations. Substitution has been discussed above results in sickle-cell anemia. Substitution Under the substitution, a single base pair substitutes a pair that is in a corresponding position along the complementary stand. This class of substitution results into an individual suffering from anemia. Insertion This class is associated with the beta-thalassemia disease. A frame shift occurs in the replicating DNA due to the nucleotides inserted into it. Deletion It also results into a frame shift that is brought about by skipping of nucleotides in the process of replication. The disease that is associated with the deletion of the nucleotides is the cystic fibrosis. Chromosomal mutation The chromosomal mutation as its name suggest occurs at the chromosome level. Parts or in some circumstances large portions of the chromosomes undergo mutations. The types of mutations that occur under the class of chromosomal mutation are deletion, duplication, inversion, and translocation. The main effects associated with chromosomal mutations are the modified gene dosage, missing genes or in some instances, the gene sequence is completely rearranged. The diseases associated with the chromosomal mutations are some types of cancers such as the leukemia, which is a blood cancer. Copy number variation The copy number variation also occurs when complete areas that form parts of a chromosome are entirely undergo duplication or are lost. The types of mutation that occur under the class (Copy number variations) are the amplified genes and the expansion of the trinucleotide repeats. Trinucleotide repeats refer to the repeat of a three-nucleotide sequence a number of times. The diseases associated with the copy number variation are breast cancers and the Huntington’s disease. Areas of a genome such as the trinucleotide repeats are known as hot spots. They are considered hot spots because they are the regions, which are most prone to mutations. A key characteristic of the so-called characteristic regions is the frequent repetitions that occur in them. As such, a polymerase slips leading to mistakes when it dissociates and reassociates itself to a strand of DNA. The frame shift mutations are as a result of the insertion or deletion. When a single base is inserted or deleted, it causes a shift in the nucleotides. Hence, any reading done by the ribosomes, which is usually done in groups of three, will shift and result in a different reading frame. Suzanne shows that mutations can throw off the reading frame of a protein. For instance, the sentence below provides an analogy for the three series nucleotides: THE MAD MAN HAD ONE RED AND BLU CAR. If a mutation occurs and eliminates the first D, then the rest of the sentence will become: THE MAM ANH ADO NER EDA NDB LUC AR. The resulting nucleotide or protein will thus be read incorrectly from the original sentence. The factors that course mutations to occur Many factors that exist can cause the alteration of DNA. Some of these factors are discussed below (Suzanne). Influence by the environment Often the environment has a great effect on the DNA. Environmental factors such as the sun can cause the alteration of DNA. For instance, the Ultra Violet (UV) rays emanating from the sun can cause mutations of the skin cells. Suzanne opines that UV rays can cause the hydrolysis of bases causing them to mispair. Mispairing of the cytosine and adenine and the resultant replacement by thymine often causes skin cancers. Therefore, the UV light in the environment affects the social life of people who suffer from skin cancer. Such individuals can only go outdoors during the night when the sun down. Furthermore, the sun as environment possesses other rays with varying wavelengths such as the X-rays, gamma rays that possess the ionizing radiation. This form of radiation is worse that the UV since it penetrates deep into the body tissues as well. In light of this, any part of the body is susceptible to mutations caused by ionizing radiations. Chemicals Free radicals have the capacity of modifying nucleotides in such a way that it affects their capacity to base pair. The presence of such chemicals often increases the susceptibility of DNA to insertions or deletions. Some known oxidizing agents (Dioxin) and carcinogens (such as benzopyrene) can cause mutations, which lead to diseases such as lung cancer. Such chemicals are known to induce mutations. Spontaneous mutations Not all mutations that occur in the body of an organism are a result of agents. Some mutations occur spontaneously. Some spontaneous mutations known to man include deamination and depruniation. Deamination is the removal of an amine group while depruniation is the loss of purine base from a nucleotide. Deamination causes substitution of a cytosine to uracil. DNA replication errors DNA replication is an important process that occurs in organisms. However, this important process in some instances also becomes the Achilles heel by facilitating some mutations. For instance, it has been shown that during the trinucleotide repeat expansions, that deletion or insertion of a single base would result into a shift. During replication, if DNA polymerase slips, then it would repeat the replication of a preceding segment. Such repeat will cause a mutation that will be expressed in offspring of affected the parent. The inheritance of the disease occurring from the mutation of a trinucleotide is normally sex-specific. Mutation has different classes and each of these classes have their causes. It is important to note that mutations can also occur naturally. The natural occurrence of mutation is not a common occurrence. When it occurs, this error rate is because of the halting of cell division. The DNA repair machinery is the one that is charged with overseeing cell division. When cell division is halted before a nucleotide sets in place, a mismatch occurs. The mismatch in an established cell leads to a mutation. The mutation is inherited by the offspring. When it occurs in an organism, mutation places the organism at risk of acquiring disease. However, mutations also lead serves as a base material on which the evolution process can spring form. Mutation allows evolution of organisms to better adapt with their surroundings. Hence, Suzanne opines that although mutation is seen to be having a negative effect on an individual, it also provides variation in the populace as it is a source of diversification in the general population. The article General Mutation has incorporated a number of visual images such as tables, pictures, and figures. The images help the reader to become interactive with the subject. As the article progresses, it is periodically broken by figures that are further used as a visual medium to explain the topics it is covering. I believe the article has adequately utilized visuals to make any person who is reading it understand the topics in them. The reader can identify and form mental pictures regarding mutation. My interest in this article is aroused particularly with the mutation as a raw material of evolution. Mutation allows the perpetuation of species and organisms to adapt and live in their environments. For instance, the giraffe in the animal kingdom amazes me. The giraffes mutated and developed a longer neck, which enabled them to reach higher leaves and survive while other giraffes with shorter necks starved and died. Mutation could be the key to a better future not for animals alone but also human beings, as we adapt to the changes in the environment like global warming. Works Cited Suzanne, Clancy. "Genetic Mutation." Nature Eucation (2008): 187. Web. . 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