An Experiment to Extract and Isolate DNA present in Strawberry and Kiwi Fruits (Lab Report Sample)
Instruction for writing a scientific report
In the older times scientists used to communicate with each other by simply writing letters to each other. The letters would be compiled by scientific societies into journals (hence some journals still have the word "letters" in the title). Over time, instead of letters, researchers started to adopt a standard format for the reporting of their research. This format is often referred to as the IMRaD format which refers to the major sections of the report; introduction, methods, results and discussion. The IMRaD format is now the standard for written communication of scientific work hence we would like you to learn how write a report in this style. So how do you write an IMRaD paper?
First of all, remember you are not writing a practical manual. You are not writing a set of instructions for other students. You are writing a formal, professional document aimed at a professional, scientific audience. You can use other research article as a model for the style and structure and how to use scientific language. When writing you should imagine you are writing your report for a scientist who does not work at or care about Deakin. Someone who knows about science but does not know what experiment you did or why.
Your report must include a title, introduction, methods, results, discussion and reference list.
The results and possibly (but not necessarily) methods should include figures and/or tables. Every section should be written in fully-formed, well-structured paragraphs. Dot points, point form or question/answer format not acceptable.
• Should be as brief as possible but still specific to this experiment.
Eg an experiment that measured the growth of plants in different coloured lights should not be given the title “Plant Growth” but something like “The effect of wavelength of light on the growth of Arabidopsis thaliana”. Arabidopsis thaliana is the scientific name of the species of plant used in the study. Please note that scientific names for species are always typed in italic font.
Introduction should include;
• Opening sentence that clearly establishes the topic at the right level – not too general. Should include two or three keywords related to the study
• Background – what research has been done on this topic before?
• Research gap – what information is missing/what hasn't been done before?
• A clear statement of the aim/purpose/hypothesis
The introduction should only include enough information to understand the experiment that comes next. All the detailed explanation and analysis can be saved for the following sections. Since you are writing for a scientific audience you don't have to explain very basic scientific principles (eg it's not necessary to explain that DNA is comprised of nucleotides A, G, C, and T)
Method should include;
• Enough detail of the procedure for the experiment to be repeated by others (necessary)
• Details of any important solutions, equipment or conditions that could impact the outcome of the experiment (necessary)
• Justifications for why a particular method/equipment/reagent was chosen (not necessary for every detail) eg “ In order to prevent light from extraneous sources reaching the leaves, plants were placed in black-out boxes”
• Figures to display hard to explain procedures or experimental set-ups (not always necessary)
• Citations/references to other research from which methods have been taken (only necessary when you use another researcher's method)
The methods section is NOT a set of instructions. Therefor there should be no dot points, itemization or every sentence on a new line. You are writing a past tense account of what was done in the experiment in paragraph form. It should contain enough information for the experiment to replicable by others. However, avoid irrelevant details that would be meaningless to outsiders eg “After the experiment was complete equipment was cleaned and put away.” Referring to people (we, I, you, students, the demonstrator) should also be avoided (unless they are the actual subjects of the experiment). Instead use the passive form eg;
Don't write; ‘Students planted their seeds in seedling trays and then the demonstrator placed the trays in the incubator'
Instead write ‘Seeds were planted in seedling trays which were then placed in the incubator”
NOTE: we used two methods in this practical. For your report you should write in full the method that you used to isolate your sample and then refer to the prac manuals for the other method. For example, if you used the Youtube method in class then write the details of that method in full and then for the other method write “DNA was also extracted from strawberry and kiwi fruit using a salting out technique according to the method of the Cell and Genes Practical Manual (School of Life and Environmental Sciences (LES), 2016).”
I used YouTube method.
Results should include:
• A description of all the major features of results from each stage of the experiment
• In-text links to any results figures
Results should be a description of the main features, trends or points of interest of your data. In this case is will be a description of what was seen on the agarose gel image. In addition you may want to add what you observed at different stages of the experiment (what did the “DNA” look like during the ethanol precipitation step or after centrifugation). However, it should NOT be a rehashing of your graph/image in words. Eg.
Don't write something like: “Plants under red light grew 3 cm, plants under blue light grew 5 cm and plants under green light grew 1 cm (fig 1).” – this is just a list of all the data points in the graph
Write: “Plants that were grown under blue grew on average 5 cm higher than plants grown under other wavelengths of light (fig 1).” – this is focusing on a major difference between two groups
The Figures & tables:
• Be numbered in consecutive order throughout the report (figure 1, figure 2 & table 1, table 2)
• Have a caption (also called a legend) detailing what the figure/table is and what everything is within the figure or table (note: the figure caption is separate to and in addition to the results text)
• Figure captions should be below the figure
• Table captions should be above the table
• NOT be decorative – every figure must provide important information
• NOT be redundant – eg DON'T have exactly the same data in a table and graph
Depending on the experiment (and the journal the research is published in) figures or tables may occur in any section of the paper as needed (you, as the author, need to decide when they are needed) but there will most definitely be figures or tables in the results section. Your report must at leastinclude the results of the class gel electrophoresis.
Discussion should include;
• A clear statement of whether the aim/purpose/hypothesis was achieved or not
• Explanations of ALL the results –what did you see and WHY did you see it – you need to use evidence to support these explanations (evidence can be your own results or previous research?
• Comparison of results to previous research – are your results similar or different to previous research and why -
• Limitations – this is not “things that went wrong in my experiment” but “the conclusion made here can only be applied to X or in X circumstances because of Y”
• Applications/recommendations/suggestions for further research; Can the result of this study be used in the real world in some way? Can your results be used to provide advice about this topic? Has your research raised new research questions that should be investigated further? Any recommendation should relate directly back to the purpose/aim of your experiment.
• A concluding paragraph that summarizes the main points of the study (but doesn't introduce any new information).
The discussion will probably be the longest section of your paper. The discussion is the place where you link your data (results) back to all the points you wrote about in the introduction. In this way the discussion is a mirror image of your introduction; while the introduction starts with more general information about the topic and moves in to focus on the experiment the discussion starts with the experiment and moves out to relate the research to the wider world
The following points are prompts to help you think about what to write in your discussion. Please don't simply answer these points in a questions/answer format but incorporate them into the points into the structure outlined above.
• Was the aim achieved – were both methods used able to isolate DNA? How do the reagents used allow for extraction of DNA?
• How do DNA samples isolated by the two methods compare (compare quality, quantity and consistency between samples)? What differences in the method might account for this? How do the results of previous studies compare in terms of the methods and results?
• Was there any unexpected pattern to the results – did some fruits give more/better quality DNA than others? Why might this be? Is the difference due to a species difference or just these particular samples (ripeness?). What evidence can you find from the literature to support your assertions?
• Did there appear to be any correlation between the appearance of the pellet and the quality/quantity of DNA seen in the gel electrophoresis? What does this tell you?
• Did any lanes appear not to have any DNA? At which point in the process could DNA have been lost? What steps could be taken to minimise the losses or improve the process generally
• Are there any samples where it seems the DNA hasn't left the well? What factors effect movement of DNA through a gel? What factors specific to this experiment could affect movement of our DNA through the gel?
It is essential to acknowledge the sources of your information or you will be suspected of plagiarism (which will incur very harsh penalties). Any fact that was obtained from another source must be cited. Please paraphrase, that is, write the information in your own words followed by a citation.
Using the words of another author verbatim, surrounded by quotation marks followed by a citation, is referred to as a direct quote. Please DON'T use direct quotes in your report. The reasons for not using direct quotes are; a) paraphrasing (with a citation) is an important skill you need to practice, b) writing in your own words demonstrates your understanding (or lack thereof), c) quotes are only appropriate when it is necessary to preserve the original wording of the author and this is rarely the case in science reports.
We want you to become accustomed to using more scholarly sources for your information so for that reason, we ask that you to avoid unverified websites such as Wikipedia and stick to research articles and textbooks (ejournals and etextbooks are perfectly fine).
• Must all come from reliable/verifiable sources and should include other IMRaD articles
• Have an in-text citation AND a reference list entry
• Be consistently formatted using the Harvard
• NOT be direct quotes
 If you use the exact words of someone else without quotation marks and a citation (eg you ‘copy' and ‘paste' this is just plagiarism- DON'T DO IT!!
Good formatting is important. Make your report look professional
• Report must be typed
• Easy to read font eg Garamond, Times New Roman or Georgia.
• The body of the text should be 11-12 point font and justified (so it is straight down both sides).
• Title and section headings should be clearly differentiated from body of text
• Any figures should have typed labels (no hand written text).
• Line spacing 1.5 - 2.0
• File must be uploaded as a PDF file to ensure the file can be opened on any computer and the formatting in not altered when the file is opened on another computer.
Remember if you don't know how to format in Microsoft word you can find the solution easily on the internet. Just google “How do I …(whatever it is)….in Microsoft word”
DNA EXTRACTION LAB REPORT
By Student's Name
Date of submission
DNA Extraction Lab Report
An Experiment to Extract and Isolate DNA present in Strawberry and Kiwi Fruits
DNA or deoxyribonucleic acid refers to hereditary materials in all living organism. However, the DNA contents tend to vary between plants and animal, but both plants and animals cells contains contain double helix DNA and four chemical building blocks called Nucleotides (Brown & Davenport, 2015). Notably, the arrangement of nucleotides not only differ between plants and animals but also among the plants and animal cells. The sequence of DNA is the one responsible in determining, which proteins are manufactured and information they encode that decides the fate of an organism. To study the patterns and contents of DNA from a plant cell, scientist typically employ the suitable DNA extraction technique available. The process of DNA extraction is carried out using detergents to lyse the cells so that the DNA is squeezed to mix with the solution. (Brown & Davenport, 2015) The method is designed to extract DNA from strawberries and kiwifruits in abundance quantity to be visible and coiled. Since DNA exits inside a cell's, nucleus proteins, it must be denatured to locate the DNA. In a fruit plant, there are different vitamins that form organelles membranes, which permits DNA to spool to fit inside of the nucleus. For this reason a solvent of alcohol is added to precipitate out the DNA. Strawberry and kiwifruits are chosen because they more than five copies of genome making it easier to extract the DNA because they are many per cell whereas many organisms would have only a single copy of genome per cell.
Two studies by William S. Boyd (2009) and Goodwin, (2012) closely relates to this project. Boyd's experiments focuses on the extraction of DNA from fruits in stages of ripeness. The aim of Boyd's experiment was to investigate the whether the degree of ripeness in fruits effects the quantity and quality of extractable DNA. The study featured fruits such as bananas, strawberries and kiwifruits. The findings revealed that ripe strawberries and kiwis yielded more extractable DNA compared to the unripe ones. The results were different In the case of bananas as the unripe ones yielded released more quantity of extractable DNA than the ripe and overripe ones. Boyd concluded that ripen fruits possess already broken down nutrients that begins to decompose and destroying cells containing extractable DNA. Goodwin's experiment also seeks to determine whether the unripe, ripe, or overripe fruits would yield more extractable DNA or not. Goodwin used only strawberries and the results revealed that the ripe strawberries did yield more extractable DNA, which supported her hypothecation that strawberries would produce the most extractable DNA, as under-ripe strawberries than the unripe ones (Goodwin, 2012). The connection between this s experiment and the two studies is on how do DNA samples isolated by the YouTube method and the salting out compare in terms of quality, quantity and consistency between samples.
The literature on the extraction of DNA from fruits indicates that there are insufficient explanation regarding the appropriate degree temperature for solvents such as ethanol. This has led to erroneous cases in the experiment where the separation of DNA and the solutions in the inoculating loop (Kim, et al., 2010). Therefore, to improve the extraction efficiency, this experiment adopts a suitable method that uses toothpicks, or even the use of hands and a, a specific and constant temperature for th...
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