Ptc Tasting

TESTING OF ALLELE DOMINACE IN GENES WHEN TASTING PHENYLTHIOCARBAMIDE
(BASED ON MEDELLIAN GENETICS)

ABSTRACT;
The hypothesis is that we will gain a 3:1 ratio, where the tasters show to have the dominant allele. We do not expect to see a difference between the observed and the expected data; therefore stating our hypothesis was supported, meaning the most dominant and outstanding allele is the one that allows people to the phenylthiocarbmide (PTC). Our hypothesis was supported.
INTRODUCTION;
The ability to taste phenylthiocarbamide has shown to be one of the most known Mendelian traits based on the human body (Wooding, 2006) and its use of alleles within genes to do so. Different varieties of the same gene are termed as alleles, (Brooker, 2012). Mendel’s law of segregation articulates that; “the two copies of a gene segregate (or separate) from each other during transmission from parent to offspring,” (Mendel) this means that just one copy of either mother or fathers’ gene is present in the gamete, (Brooker, 2012), these single choice genes are the alleles. During fertilization, the diverse combinations of two gametes can theorletically equate to many allelic combinations, (Brooker, 2012). Genetic alleles, like the ones which allow you to taste the PTC or not, are based on two factors they are; genotype and phenotype which are displayed both physically and genetically. The genotype is based of the genetic composition of a singular organism (Knox, Ladiges, Evans, & Saint, 2010), physical appearances in an organism that are determined by genetic inheritance (Knox et al., 2010).
Our expected hypothesis is that the, ‘tasters,’ will prove to have the dominant allele as, the trait will show to have the larger figure in the ratio of 3:1. We do not expect to see a difference between the observed and the expected, leading us to accept the hypothesis.
MATERIALS AND METHODS;
The materials we were given comprised of the explanation of a Chi Square and how to go about performing the mathematics when using said Chi Square. We were also given a sheet with raw data, which is shown in Figure Two. Through the use chi square table we were able to conduct our research, using the raw data to be able to calculate the answer and find out if the hypothesis would be supported or not, in answering the question, ‘Does the dominant allele allow people to taste the PTC?’
After we calculated the Chi Square results, the added the results of the taster and non-taster equations, (Figure Two.), were added together to give the deviation percentage. After we got the added result, (0.012), we looked up the number on the Chi Square probability table, by looking at this table we were told whether or not the hypothesis should be accepted by finding where the end result number 0.012 placed on this table. 0.012 showed to be >0.05, the table then states below it that any number >0.05 is to have the hypothesis accepted.
RESULTS;
After completing the Chi Square we contracted the answer of 0.012; this answer proves to support our hypothesis. This is known to be true because the table of X2 probability values tell us that any answer >0.05 proves to agree with our expectations as there was no deviation in the information we expected and the actual data that was observed in the test. We accepted our hypothesis from this as the results showed a 3:1 ratio, this is shown in Figure One, and the histogram clearly shows that both the dominant traits, TT and Tt, together are equivalent to three times the amount of the recessive trait tt.

Figure One. Number of PTC results from testing on third year students.
The Y axis displays the number of third year students tested, and placed into their genotypic category according to whether they could taste the PTC or not. The X-axis displays the genotypes in which the students fell into according to their ability to taste the PTC.
DISCUSSION;
The hypothesis was accepted as the results showed a 3:1 ratio, because the observed was not deviated, and the only cause of deviation would be due to chance. We found that the PTC, ‘tasting,’ allele was present in over three times the amount of students tested, in comparison to the amount of students who could not taste the PTC. In suggestion for people whom choose to out take this same experiment, I would say, to repeat the test more then five times, for greater accuracy, with a larger amount of students, for a broader spectrum. The large number of repeats, on such a large number of students is that, majority of the appeal PTC has is purely from the fact that it is practically impossible to tell whether the person is a taster or not until they are actually tested (Wooding, 2006).

REFERENCES;
Brooker, R.J. (2012). Genetics analysis and principles (4th edition), New York: McGraw-Hill.
Knox, B., Ladiges, P., Evans, B., & Saint, R. (2010). Biology an Australian Focus (4th edition), Australia: McGraw-Hill.

Wooding, S. (2006). Phenylthiocarbamide: A 75-year Adventure in Genetic and Natural Selection. Anecdotal, Historical and Critical Commentaries on Genetics, 1, 2015 – 2023.

APPENDIX;
Phenotypes and genotypes crosses | T | t | T | TT | Tt | t | Tt | tt |
Phenotype; Taster (T) x Non-taster (t)

Genotype; T x t

The Punnett Square gave us the predicted ratio for the results expected to be given to us from the Chi Square test calculations.

Chi Square table CLASS | OBSERVED (O) | EXPECTED (E) | DEVIATION (O – E) | (O – E)2E | TASTER | 83 | 82.5 | 0.5 | 0.003 | NON-TASTER | 27 | 27.5 | - 0.5 | 0.009 | | X12 | 0.012 |
X2 (n-1) = ∑ (0 – E)2 / E - O; is your observed value - E; is your expected value - n; is the number of independent class

Total = 26 + 57 + 27 = 110 110 / 4 = 27.5 x 3 = 82.5 (for the taster expected)
Deviation
Taster; T = 83 – 82.5 = 0.5 ∑ = (0.5)2 / 82.5 = 0.003 Non-taster; t = 27 – 27.5 = - 0.5 ∑ = (-0.5)2 / 27.5 = 0.009 X12 = 0.012 P ≥ 0.05 (accept hypothesis) Degrees of freedom; 1; P > 0.05, this means that there is no significant difference between the observed ratio and the expected 3:1 ratio.

Figure Two. The raw data given to us at the start of the experiment, and the results to the equations.

References: Brooker, R.J. (2012). Genetics analysis and principles (4th edition), New York: McGraw-Hill. Knox, B., Ladiges, P., Evans, B., & Saint, R. (2010). Biology an Australian Focus (4th edition), Australia: McGraw-Hill. Wooding, S. (2006). Phenylthiocarbamide: A 75-year Adventure in Genetic and Natural Selection. Anecdotal, Historical and Critical Commentaries on Genetics, 1, 2015 – 2023.