DNA Extraction from Kiwi fruit and Strawberry Essay Example

Introduction

The aim of this experiment was to extract DNA from Kiwi fruit and strawberry. The DNA was extracted using Youtube method and gel electrophoresis was performed on the extracted DNA. DNA is found in nearly all living organisms. The organisms range from the single-celled bacteria to multi-celled human beings. Different kinds of cells include prokaryotes and eukaryotes (Bachtrog, 2013). This experiment only considered eukaryotic cells, which make up both animals and plants. Eukaryotic cells have a distinctive, membrane-bound nucleus that separates the DNA from the other part of the cell. The structure of plant cells varies from the structure of animal cells as well as in cellular contents. This experiment only used plant cells, namely; strawberry and kiwi fruit cells.

DNA extraction Youtube method was used to extract the DNA from fruit (Kiwi fruit and strawberry). One piece of fruit sample was placed into a Ziplock bag and seal shut. The sample was then squished in the bag using fingers for 3 minutes. 10 mL of DNA extraction buffer was added using auto-pipette and squished for additional 2 minutes. The mixture was then filtered using a Chux cloth and funnel into a conical flask. After the dripping stopped, the Chux was discarded. An auto-pipette was used to transfer 3 mL of the sample into a 15 mL tube and the tube placed on ice and labeled appropriately. 10 ml of cold 100 percent ethanol was added in the sample and the sample was left on ice for at least 10 minutes. The reaction was observed and the white fluffy cloud appeared which was precipitation of proposed DNA was.

The DNA was removed carefully using a hook and placed into a labeled Microcentrifuge tube. This tube was then placed into the micro-centrifuge and spin at 12000 rpm for 3 minutes. After centrifugation, the supernatant was poured off. The tube was placed upside down on paper towel for drainage and left for 5 minutes. The appearance of the DNA pellet was recorded.

An auto-pipette was used to place 100 – 300 µL of distilled water into the tube and mixed thoroughly. After the DNA dissolved, the tube was then placed on the heat block at 55oC for 5 minutes. 10 µL of the sample in the micro-centrifuge tube was pipetted into the loading dye tube. The sample was then loaded into the agarose gel. The gel was then connected to the power-source and run. After the gel completed running, the image of the DNA was obtained.

The strawberry produced a higher amount of DNA when compared to the kiwi fruit. In spite of the kiwi fruit having had more juice than the strawberry, a small amount of DNA was extracted from the kiwi fruit after ethanol was added. It was very easy to extract DNA from the strawberry when compared to kiwi where DNA extraction was very difficult.

From the observations, DNA from the strawberry was formed much quicker when compared to DNA from the kiwi fruit after ethanol was added. Moreover, strawberry DNA was more visible because it stuck to the skewer and hence its observation was easy. DNA from strawberry was long, clearly colored and string like as observed in the figure below.

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Figure 1: observations of the appearance of the strawberry and kiwi DNA

On the other hand, even though the visibility of the kiwi DNA was evidence, the DNA did not stick to the skewer and was difficult to get it out to take its photo. The physical appearance of the kiwi DNA was clear, thin string-like pieces as shown by the figure below.

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Figure 2: observations of the appearance of the strawberry and kiwi DNA

Discussion

Extraction of DNA from strawberry was successful and visible DNA strands were observed. Squishing the strawberry and the kiwi fruit respectively opened their cells and hence released the nuclei where the DNA of these fruits is. The extraction buffer was important in breaking down the fatty membranes of the cells, breaking open the nuclear membrane and releasing the DNA into the solution (Goodman, 2007). The gauze retained strawberry/kiwi fruit cell debris and their respective DNAs were dissolved within the DNA extraction buffer, which passed through the gauze into the test tube (Collard et al, 2007).

After ethanol was added, ethanol allowed the DNA to be visible because insoluble molecules clump together and are visible and hence ethanol made the DNA visible ensuring its visibility. This is because ethanol collected between the layer of ethanol while kiwi and strawberry extracts remained beneath. As Tanaka and Ikeda (2002) explain, DNA is not soluble in alcohol and hence it undergoes precipitation. Therefore, the precipitate was the precipitation of kiwi DNA and strawberry DNA respectively. The DNAs were visible as thread-like molecules at interface of the ethanol and DNA solution. This is in line with Pirttilä et al (2001) who explain that precipitation of DNA into the non-polar layer facilitated the visibility of the long DNA strands with the naked eye. According to Pirttilä et al (2001) ethanol induces structural changes in DNA molecules and this causes aggregation and precipitation of the DNA molecules.

Generally, the extraction of DNA from strawberry was very successful and the DNA strands were satisfactorily visible. The DNA extraction from the strawberry was facilitated by the presence of 8 copies of every chromosome within the strawberry and this means that strawberry has octoploid genome. On the contrary, human beings have diploid genome and this means there are only two copies of every chromosome (Heslop-Harrison, 2000). Evidence indicates that extraction of DNA from cells with fewer copies of chromosomes is more difficult and hence the reason extraction of DNA from the kiwi fruit was difficult is because it has fewer copies of chromosomes when compared to the 8 copies of each chromosome in the strawberry (Rogers and Bendich, 1989).

Finally, the fact that the DNA from both the strawberry and the kiwi fruit were different shows that different types of food contain different types of DNAs and hence this shows that different types of food contain different types of genetic material (Choi et al, 2006). This aspect is important in genetic engineering because analysis of DNA from various type of food can assist in bioengineering of different types of foods.

As aforementioned, strawberry gave better quality DNA than kiwi fruit and this can be attributed to the fact that kiwi fruit has fewer copies of chromosomes and hence extraction of the DNA was more difficult. This therefore can be attributed to species difference and variation in genetic material (Bachtrog, 2013).

There are also lanes that did not appear to have DNA as indicated by the figure below.

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Figure 2: Figure showing some lanes lacking any DNA

The lacking lanes could have been as a result of severe degradation of the DNA and this can be prevented by proper storage of the starting material, maintaining the correct temperature where the DNA should be extracted at 4°C, on ice and the nuclease activity should be inhibited (Ghatak et al, 2013).

Limitations

Some limitations include that mashing both the strawberry and kiwi was difficult since some pieces could not be broken into the smallest possible sizes and this might have affected the amount of DNA that was extracted (Ghatak et al, 2013).

Conclusion

The DNA from Kiwi fruit and strawberry was different and this indicates that DNA from different foods is different. The strawberry DNA was more visible and thicker when compared to the kiwi fruit DNA. Being able to extract DNA from different foods is important in various ways. For instance, genetically modified foods are made by altering the genetic material and hence DNA extraction is useful in GMOs.

Bibliography

Bachtrog D, 2013. Y chromosome evolution: emerging insights into processes of Y chromosome degeneration, Nat Rev Genet, 14(2): 113–124.

Choi, K.H., Kumar, A. and Schweizer, H.P., 2006. A 10-min method for preparation of highly electrocompetent Pseudomonas aeruginosa cells: application for DNA fragment transfer between chromosomes and plasmid transformation. Journal of microbiological methods, 64(3), pp.391-397.

Collard, B.C.Y., Das, A., Virk, P.S. and Mackill, D.J., 2007. Evaluation of ‘quick and dirty’DNA extraction methods for marker‐assisted selection in rice (Oryza sativa L.). Plant Breeding, 126(1), pp.47-50.

Ghatak S, Bose M and Kumar., 2013. A Simple Method of Genomic DNA Extraction from Human Samples for PCR-RFLP Analysis, J Biomol Tech, 24(4): 224–231.

Goodman, S.R. ed., 2007. Medical cell biology. London: Academic Press.

Heslop-Harrison J, 2000, Comparative Genome Organization in Plants: From Sequence and Markers to Chromatin and Chromosomes, Plant Cell. 12(5): 617–636.

Pirttilä, A.M., Hirsikorpi, M., Kämäräinen, T., Jaakola, L. and Hohtola, A., 2001. DNA isolation methods for medicinal and aromatic plants. Plant Molecular Biology Reporter, 19(3), pp.273-273.

Rogers, S.O. and Bendich, A.J., 1989. Extraction of DNA from plant tissues. In Plant molecular biology manual (pp. 73-83). Springer Netherlands.

Tanaka, J. and Ikeda, S., 2002. Rapid and efficient DNA extraction method from various plant species using diatomaceous earth and a spin filter. Breeding science, 52(2), pp.151-155.