Introduction
In our genes, multiple different alleles determine whether one person will have a certain trait or not. Alleles are what make-up our genotypes and in this lab, we wanted to determine the genotypes of our class in the two loci: TAS2R38 and PV92. The TAS2R38 locus codes for a protein that involves the bitter taste of PTC; the gene determines whether or not a person will taste the PTC paper as very bitter or no taste at all. People with the “T” allele are tasters while those that are homozygous recessive (tt) are non-tasters. The taster locus can be found chromosome 7.3 The two different alleles present in the could be due to the effect of evolution and natural selection because the same can be found in chimps.4 The PV92 locus does not code for any protein but rather involves an Alu element that is 300-bp long. A person with the “+” allele would have the Alu element making that sequence longer while those with the “-“ allele don’t have the element and would have a shorter sequence. This locus can be found on chromosome 16.3 There are multiple Alu sequences found among primate genomes but there are human specific sequences such as the one found on the PV92 locus.1 In the experiment, student DNA was collected from cheek cells and PCR was used to target the loci and amplify the region of DNA. In the taster gene, after amplification, a restriction digest was performed to differentiate between the two alleles. The digest was able to show differentiation because those with the “T” allele would have two bands from gel electrophoresis and those with “t” will have one band because the restriction enzyme doesn’t cut it. For the PV92, we were able to distinguish between the alleles due to the added length of the Alu element. Those...
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...G.E., Ioannou P.A., Scheer W.D., Herrera R.J. et al. 1994. Africa origin of human-specific polymorphic Alu insertions. Evolution Vol. 91: pp 12288-12292
2Gómez-Pérez L, Alfonso-Sánchez M.A., Sánchez D, García-Obregón S, Espinosa I, Martínez-Jarreta B, De Pancorbo M.M., Peña J.A. 2011. Alu Polymorphisms in the Waorani Tribe from the Ecuadorian Amazon Reflect the Effects of Isolation and Genetic Drift. American Journal of Human Biology Vol 23(6): pp 790-795
3 Leicht B. G., McAllister B.F. 2014. Foundations of Biology 1411, 2nd edition. Southlake, TX: Fountainhead Press. Pp 137, 163-168, 177-180,
4 Wooding S. 2006. Phenylthiocarbamide: A 75-Year Adventure in Genetics and Natural Selection. In: James F. Crow, William F. Dove editors. Perspectives, Anecdotal Historical and Critical Commentaries on Genetics. Salt Lake City, Utah: Genetics Society of America. Pp 2015-2023
Modern human brain sizes are significantly smaller than Neanderthal’s and so are their brain cavities. TAS2R38 is the gene that controls taste. For Neanderthals, having a bitter taste “system” could have kept them from poisoning themselves by accident.
The study of Alu elements, such as the one found on the PV92 locus are of extreme importance for numerous reasons. Alu inserts have played a significant role in advancing the study of human evolution. For example, the analysis of specific polymorphic inserts has led some researchers to postulate that the divergence between primates and Homo sapiens was initiated in Africa, giving rise to the “Out of Africa” theory (Batzer, et al. 1994). Contrarily, others believe that the deviation arose from multiple regions from occurring mutations. Additionally, Alu elements are also speculated to have played a significant role in accelerating speciation in vertebrates by acting as a source of new mutations (Bohne, Brunet, Galiana-Arnoux, Schultheis & Volff, 2008), but further research is needed to confirm or refute these hypotheses.
Aside from the pedagogical implications of such a striking phenotype, many pioneering studies relating to PTC and the taster/non-taster phenotype have been conducted since its discovery (Wooding 2006). Directly after Fox presented his findings for the National Academy of Sciences, Blakeslee also presented his large-scale study of PTC inheritance within families and saw a similar phenomenon of taster and non-taster phenotypes. Furthermore, Blakeslee classified the tasters according to their taste acuity using dilutions at which the bitte...
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revealed that three of the fourteen samples were were homozygous while the other eleven were
In 1990, the first great stride of genetics took place. This was called the Human Genome Project, a large-scale operation that was designed to understand the human genome (genetic structure). Since its commencement, there have been many leaps and bounds that have taken place. For certain genetic issues that we once knew nothing about, we no...
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My research strives to answer the presence and degree of interbreeding between Neanderthal and Modern humans. Researchers use different comparisons of the fossil record, phylogenetic, morphological, and genetic methods to explore these questions in more detail. The literature provided many positive correlations to my hypothesis that Neandertals and Modern Humans interbred on a small-scale basis after the dispersal of modern humans from Africa. The literature also predicts a time frame of likely interbreeding. To explore this question it is important to research article’s explaining the statistical, genetic, and physical evidence associated with possible interbreeding.
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more than half the variation was found to be due to heredity. Among these traits were
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