The chromosomal theory of inheritance is a theory that defines the role of the chromosomes in the execution of the process of Mendelian inheritance (Waddington, 2016). The theory makes a maximum application of the Mendelian laws of inheritance based on various observations. Some of the observations affiliate to the laws includes; the migration of the homologous pairs of chromosomes as discrete structures independent of the other pairs that exist in the same strand.
In addition, the theory explains the random process of the pre-gamete occupation of each homologous pair of chromosomes (Waddington, 2016). The parent contributes half of the chromosomal complement in the gametes. Based on the theory, male and female gametes have different sizes and morphology, though they have an equal number of chromosomes and hence equal genetic contributions from both parents.
Additionally, though there exist diverse behaviors of chromosomes during the meiosis and the laws of Mendel, the proposition of the theory took place before the analysis of the traits associated with the chromosomes (Waddington, 2016). The theory has the support of the empirical evidence such as one of the experiments conducted in 1910 by Thomas Hunt Morgan, which in involved the Drosophila Melanogaster as the specimen.
Noteworthy is that the relationship between DNA and chromes exist because the chromosomes are the paired chains existing within the nucleus (Waddington, 2016). The same chromosomes comprise of the genes that are the ones responsible for the genetic makeup of an organism. The genes consist of a chemical material famous as DNA. Therefore, based on such relationship, it is evident that there cannot be an existence of the genes without the chromosomes, and the genes comprise of the DNA material (Milunsky & Milunsky, 2015). As a result, the chromosomes exist inside the DNA material.
Down syndrome is a hereditary chromosol disorder associated with chromosome 21, and it affects at least one person in a population of 800. The most susceptible group of people affected by the disorder is infants (Milunsky & Milunsky, 2015). The symptoms of the disorder include the difficulties in learning, poor muscle tone, the mental retardation, and a distinctive facial appearance. There are associated heart defects that most commonly affect the people who have Down's syndrome.
The disorder tends to lower the quality of life of an individual, because if one is having a problem in learning; it becomes difficult for them to go about most processes that are vital in life (Milunsky & Milunsky, 2015). The same child will have problems in school because they will not be able to grasp concepts in the same speed with their colleagues. Therefore, it is evident that ten quality of life of the victim will significantly deteriorate.
Finally, there is no reported instance of restriction of the disorder to a specific ethnic bloodiness. However, the disorder mainly materializes in infants. Additionally, it is common that disorders lower the life expectancy of an individual or a group of people in a country (Milunsky & Milunsky, 2015). Therefore, Downs’s syndrome will also lower the life expectancies of the people suffering from it, because they will have to struggle with most other associated challenges, as the stress associated with a mental slowness that causes one to be the odd one out in a class of individuals. Due to such stress or other associated challenges, the general life expectancy reduces.
References
Milunsky, A., & Milunsky, J. M. (2015). Genetic disorders and the fetus: diagnosis, prevention, and treatment. John Wiley & Sons.
Waddington, C. H. (2016). An introduction to modern genetics. Routledge.
