Definitively, cancer is a medical condition in which cells abnormally divide uncontrollably and can result in tumors that could invade nearby normal cells. According to the National Cancer Institute (2018), there are different forms of cancer including carcinoma, sarcoma, leukemia, lymphoma and multiple myeloma, as well as the CNS cancers. Regarding the normal cell growth, the cancerous cells multiply or grow abnormally and could be spread by invading nearby normal cells. On the other hand, genetic variation is defined as the difference in DNA sequences between individuals within a population. Variation occurs within germ cells such as the sperm and egg (gametes) as well as in somatic cells.
However, Griffiths et al. (2000) provide a deeper insight by asserting that genetic variations in a population accrue from alleles. However, since a single cell contains one to two chromosome sets, a single individual can carry one or two alleles per gene. To this end, the authors conclude that allelic variation is the basis for hereditary variation. Nevertheless, certain factors influence genetic variation. In any single species, the prevalent factor that causes genetic variation is a mutation which can create entirely new alleles in the population. Genetic variation can as well result from random fertilization, random mating, as well as recombination between homologous chromosomes during meiosis that causes a reshuffling in the alleles of an orgasm’s offspring.
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Other factors could be external. For instance, in a new or changed environment that provides the organism with only two options of either adapt or die, genetic variation occurs giving rise to phenotypic variation. In other situations, in the bid to survive, the alleles provide the organism with the ability to multiply or reproduce quickly allowing the survival of the allele in the population. Gene duplication is yet another factor underpinning genetic variation in a population through the production of new alleles and genes thus increasing genetic variation. Also, according to Lumen (2018), the genetic drift which is the change in the frequency of an allele in a population due to random events and sampling can as well cause variations. The random events and sampling lead to the reproduction and survival of those individuals.
Other factors include the bottleneck effect as a result of natural disasters that wipe out a large proportion of the population thereby leaving individuals with different allele frequencies than the previous population (Amos & Harwood, 1998). An additional factor is the founder effect that occurs when a part of the population breaks off from the old population to form a new population with different allele frequencies. All in all, genetic variation is important as it helps individuals of the population to adapt to new environments while at the same time maintain the survival of the species.
References
Amos, W., & Harwood, J. (1998). Factors affecting levels of genetic diversity in natural populations. Philosophical Transactions of the Royal Society B: Biological Sciences, 353 (1366), 177–186. DOI: 10.1098/rstb.1998.0200
Griffiths, A.J.F., Miller, J.H., Suzuki, D.T. et al. (2000). An Introduction to Genetic Analysis. 7th edition. New York: W. H. Freeman. Genetic variation. Retrieved from: https://www.ncbi.nlm.nih.gov/books/NBK22007/
Lumen. (2018). Population Genetics: Genetic Variation. Retrieved from https://courses.lumenlearning.com/boundless-biology/chapter/population-genetics/
National Cancer Institute. (2018). NCI Dictionary of Cancer Terms. Retrieved from https://www.cancer.gov/publications/dictionaries/cancer-terms/def/cancer
