Same Result Since The White 1 Gene example essay topic

Purpose: It is to perform Drosophila melanogaster genotyping using the method Polymerase Chain Reaction (PCR). Hypothesis: The specially designed primers are chosen to give 220 bp for the wild type and 4600 bp for the white eyes flies, to differentiate between the wild type and white-1 alleles. However, large products are not usually seen under normal conditions. Thus, our hypothesis is that the wild type will show a 220 bp while flies containing the white-1 allele will not show anything. Method: We followed the student instruction manual. However, there were several deviations made during the experiment.

- We did not do the control DNA PCR product - Day 1 step 5, for the incubation in water bath, it was only for 10 minutes rather than 30 minutes - Day 1 step 5, it was floated in 89 degrees water bath instead of 95 degrees Celsius - Day 2 step 3, the entire amount of samples contained is 25 ul rather than 30 ul. Conclusion Questions: 1) The smaller the DNA fragments the further it will travel along the agarose gel. Since we are using the 200 bp ladder as a guide, the last band presented on the marker lane is the 200 bp fragment. Therefore from this assumption, the length of the bands displayed on lane 2 and 4, above the 200 bp, is 220 bp. While the length of the fragments that is present in all three lanes is 1000 bp. 2) 4600 bp is the product in the white eyed flies, 220 bp is the product for the wild type and 1000 bp is the positive control of the unrelated locus 3) In order to produce a wild-type (red) eye color in the drosophila flies, the white gene, which is located in the X chromosome, is required.

This gene encodes the production of the pigments pteridines and ommochromes. As the "jumping gene", Doc Retro transposon, enter the promoter region of the white gene they are unable to signal the production of the two pigments, therefore the eyes of the flies are white color. 4) Since the Xw is recessive, then the resulting PCR will be the wild type PCR product. This is due to the XW being the dominant allele. We are unable to determine whether our female wild-type is either heterozygous or homozygous dominant because both genotypes above will show the same result since the white-1 gene is recessive. Errors: There are several errors that occurred during this experiment.

One of the errors that we observed is our failure to mash the "white-eyed" fly properly. As a result to this the fly is practically still intact, thus, the possibility that the PCR was not able to replicate the DNA effectively. Furthermore, because of the lengthy and complex procedure, we fail to follow each procedure carefully, for example, some alteration with the temperature for incubation, as well as the deviation in timing of incubation. These entire errors combine may cause the failure to obtain the optimal result.