A Look Into: Mutations

Contrary to popular media, mutations are not always as great as they are made out to be. They do not constitute to super powers as many would like to believe, although sometimes they provide beneficial traits that can help out a species. For example, an organism may develop a mutation that codes for a certain color that allows it to camouflage from its predators. This will then give the organism a better chance to reproduce and the potential for a resulting new population of its species thanks to its particular trait. Though, most of the time mutations lead to hindrances that affect survival because changes are more likely to cause a problem to the intricate system of nucleotide translation. Mutations result from damage in an organism's DNA. They can occur either spontaneously during DNA replication or through exposure to factors that increase the chances of acquiring mutations, mutagens. An example of a mutagen is the UV light radiation from the sun's rays, which is why you hear that you should not sunbathe constantly because doing so will continuously expose the skin to this type of radiation and can result in a mutation that causes adjacent thymine bases in DNA to dimerize and potentially lead to skin cancer.

As mentioned before though, mutations are not entirely bad and can increase the rate of an organism's survival. In fact, mutations (mainly the spontaneous kind) are a major contributor to evolution. It is through changes in DNA that variety among species is possible but these events are actually uncommon because cells contain sophisticated repair mechanisms that check the DNA before replication takes place and correct any errors that they detect. These repair mechanisms are not perfect though and DNA errors will sometimes go unchecked. There are different types of mutations that can result and the DNA's function will be affected depending on the type of mutation. A single point mutation results when one base on a codon is either deleted or added. In this case, there could be a synonymous mutation, resulting in the translation of the same amino acid. This does not harm an organism, unlike the possibility from missense mutations and nonsense mutations. Missense mutations produce changes in codons that translate to amino acids that are different from the ones originally translated, and nonsense mutations change a codon translation to a terminal signal. At the DNA level, indel mutations add or delete DNA base pairs.

The worst kinds of mutations are double-stranded breaks because they are difficult to repair and can lead to cancer. As you may have guessed, UV light radiation can cause double-stranded breaks, but it is not until the base excision repair process takes place on UV damaged DNA that double stranded breaks form. The repair process removes the damaged bases on each of the two DNA strands and breaks are formed in the locations of the removal sites. If two complimentary points on each DNA strand are damaged then neither of the strands can be used as templates to fix each other.

One other important point to note is that not all mutations are passed on to progeny. In order for a mutation to be passed on, the parents must have this mutation present in germ line cells because these are the cells that are used to form the offspring. There is no concern about the mutations present in the parents' somatic cells since these are simply body cells that do not get inherited during sexual reproduction.

Article Source: Salvador Barajas

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