Open main menu

Wikipedia β

The blue lobster is an example of a mutant.
Wild-type Physcomitrella and knockout mosses: Deviating phenotypes induced in gene-disruption library transformants. Physcomitrella wild-type and transformed plants were grown on minimal Knop medium to induce differentiation and development of gametophores. For each plant, an overview (upper row, scale bar corresponds to 1 mm) and a close-up (bottom row, scale bar equals 0.5 mm) is shown. A, Haploid wild-type moss plant completely covered with leafy gametophores and close-up of wild-type leaf. B-D, Different Mutants.[1]

In biology and especially genetics, a mutant is an organism or a new genetic character arising or resulting from an instance of mutation, which is an alteration of the DNA sequence of a gene or chromosome of an organism. The natural occurrence of genetic mutations is integral to the process of evolution. The study of mutants is an integral part of biology; by understanding the effect that a mutation in a gene has, it is possible to establish the normal function of that gene.[2]

Contents

EtymologyEdit

Although not all mutations have a noticeable phenotypic effect, the common usage of the word "mutant" is generally a pejorative term only used for noticeable mutations.[3] Previously, people used the word "sport" (related to spurt) to refer to abnormal specimens. The scientific usage is broader, referring to any organism differing from the wild type.

Mutants should not be confused with organisms born with developmental abnormalities, which are caused by errors during morphogenesis. In a developmental abnormality, the DNA of the organism is unchanged and the abnormality cannot be passed on to progeny. Conjoined twins are the result of developmental abnormalities.

Chemicals that cause developmental abnormalities are called teratogens; these may also cause mutations, but their effect on development is not related to mutations. Chemicals that induce mutations are called mutagens. Most mutagens are also considered to be carcinogens.

Benefits of Mutant speciesEdit

Mutants spawn from an increase in mutations within a given species that allow them to adapt a physiological difference that provides them with either subtle, or important traits, thereby affecting the new species fitness. Within any given environment, a certain species has a variety of different competitors for resources, and predators to be wary of. Darwin emphasized a phenomenon, natural selection, which referenced how only the best suited species in a given environment will out-last, and out-compete their competition[4]

Beneficial mutations can increase the odds that a species will prevail within that environment, allowing it to survive a longer time and increase its fitness. This applies to truly realistic environments, which are ephemeral. They are dynamic and constitute a multitude different aspects especially as seasons change. This means for a species to exist within this ecosystem, they must be able to adapt to whatever environmental cues they are given[4]. This gives rise to some species having special advantages over others. A difference between species is prevalent in this manner. For example, If there are two very closely linked organisms, but one has the ability to survive with less amounts of food (organism A) and an organism who needs a regular amount of nutrients (organism B), and if there was an environmental shift in their ecosystem that caused their prey to leave, then organism A could have a higher rate of survival than compared to organism B. This is an example of a beneficial mutation that caused a mutant who can live within their harsh environment.[5] This success will cause organism A to have a higher fitness rate, thereby rapidly expanding the mutations which helped organism A to survive, to other future generations. This creates a whole new mutant of the original species.[6][7]

Another example of this is during the industrial revolution. During this massive increase in factories and other facilities, there was an influx in air pollution within many different environments. This influx caused a massive change in many ecosystems. The peppered-moth, shown here, had a body color of white, which aided it in blending well within its environment to avoid predators. Unfortunately because of the influx of air pollution, the trees it would hide in started turning darker and darker because of the black smock coming from the factories. A mutant species spawned of the peppered-moth, bearing a black-skin phenotype that allowed the new moths to hide in the darker environment better than the white moths could. This allowed for a higher survival rate of the black-skin moths, and a dwindling of the white-skin moths.[8][5][6][7][4][8][5]

Disadvantages of Mutant speciesEdit

Although mutations can serve as benefits to many organisms, these alterations in genetic sequences can also cause detrimental effects to survival[disambiguation needed], fitness, and other biological factors important to life. Genetic mutations changing the effects of specific proteins can cause conditions that can be life-threatening to organisms. For example, genetic mutations can be so acute that they could prevent an embryo from surviving until birth. These affects can occur throughout any stage of an organisms embryonic development.[9] These types of modifications do not occur because of a specific gene, but due to a specific mutation to that gene. Some examples of gene mutated disease that can cause phenotypic or genotypic drawbacks are: Epidermolysis bullosa, Sickle-cell disease, Phenylketonuria, and Neurofibromatosis type I. Some of these genetic disorders may or may not show an early onset of expressed traits. For example, an individual (human baby) affected by MSUD may not show symptoms immediately, but after a few days they can arise. The examples provided are just a couple of the various types of disorders and diseases that can act as a disadvantage upon the livelihood of an organism.

See alsoEdit

ReferencesEdit

  1. ^ Egener et al. BMC Plant Biology 2002 2:6 doi:10.1186/1471-2229-2-6
  2. ^ Clock Mutants of Drosophila melanogaster
  3. ^ Mutant. (n.d.). The American Heritage Dictionary of the English Language, Fourth Edition. Retrieved March 05, 2008, from Dictionary.com
  4. ^ a b Sauna, Zuban; Chava, Kimchi-Sarfaty (October 2011). "Understanding the contribution of synonymous mutations to human disease". Nature Reviews Genetics (12): 683–691. doi:10.1038/nrg3051. Retrieved 29 March 2017. 
  5. ^ a b c Cook, L.M.; Grant, B.S.; Saccheri, I.J.; Mallet, J. (2012). "Selective bird predation on the peppered moth: the last experiment of Michael Majerus". Biology Letters. doi:10.1098/rsbl.2011.1136. 
  6. ^ a b Miller, Lisa (7 September 2015). "Misfolded opsin mutants display elevatedβ‐sheet structure". FEBS letters. 589 (20b): 3119–3125. doi:10.1016/j.febslet.2015.08.042. Retrieved 28 March 2017. 
  7. ^ a b Knickelbein, Kyle (2015). "Mutant KRAS as a critical determinant of the therapeutic response of colorectal cancer". Genes and Diseases. 2 (1): 4. doi:10.1016/j.gendis.2014.10.002. Retrieved 28 March 2017. 
  8. ^ a b Sabeti, P.C.; Schaffner, B. Fry; Lohmueller, J.; Varrily, P.; Shamosky, O.; Palma, A.; Mikkelsen, T.S. (16 January 2006). "Positive Natural Selection in the Human Lineage". Science. 312 (5780): 1614–1620. doi:10.1126/science.1124309. Retrieved 29 March 2017. 
  9. ^ https://ghr.nlm.nih.gov/primer/mutationsanddisorders/mutationscausedisease

External linksEdit