DNA contains all the genetic information for any living organism.
A1. Demonstrate scientific investigation skills in the four areas of skills
D2. Investigate through laboratory activities, the structures of cell components and their roles in processes that occur within the cell
A1.5 Conduct inquiries, controlling relevant variables, adapting or extending procedures as required, and using appropriate materials and equipment safely, accurately, and effectively, to collect observations and data
A1.6 compile accurate data from laboratory and other sources, and organize and record the data, using appropriate formats, including tables, flow charts, graphs, and/or diagrams
A1.8 Synthesize, analyse, interpret, and evaluate qualitative and/or quantitative data to determine whether the evidence supports or refutes the initial prediction or hypothesis and whether it is consistent with scientific theory; identify sources of bias and/or error; and suggest improvements to the inquiry to reduce the likelihood of error
A1.11 Communicate ideas, plans, procedures, results, and conclusions orally, in writing and/or in electronic presentations, using appropriate language and a variety of formats
D2.3 Conduct an investigation to extract DNA from a specimen of plant or animal protein [PR]
www.scihigh.ca www.tedu556jyam.com/Documents/Banana%20DNA%20Extraction.doc
This wet lab can be carried out after students have been introduced to the concepts of biotechnology and DNA cloning. This will help students consolidate their knowledge of how DNA is extracted for inserting into plasmids, however it should be known that the procedure for this wet lab does not produce purified DNA.
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DNA is found in all living organisms
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Proteins and enzymes may obscure the DNA
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Extraction: A procedure to obtain a substance by chemical or mechanical action
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Precipitate: Solid material that comes out of solution as a result of a chemical or physical change
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Understand the basic procedure used to extract DNA
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Investigate how different molecular variables can affect DNA extraction
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Analyse the method used to extract DNA and provide suggestions for further improvement
1.
What is the full name of DNA and what is its function?

2.
Where is DNA located in prokaryotes and eukaryotes?
3.
What is the purpose of the following reagents and how do they interact with DNA? i.
Dishwashing liquid ii.
Isopropanol iii.
Salt
4.
What is the purpose of crushing the banana into a pulp?
5.
Would this protocol work on food samples that are cooked or heated? Why or why not?
6.
Why do we need to separate the DNA from the proteins and lipids?
7.
What is the purpose of having a control?
1.
DNA, deoxyribonucleic acid is the hereditary material in living organisms and contains the genetic instructions needed for the development of living things.
2.
In prokaryotes DNA is found in the cytoplasm. In eukaryotes DNA is found in the nucleus.
3.
i. The dishwashing soap contains sodium laurel sulfate which is responsible for breaking up the fats and proteins. ii. The isopropanol is used to precipitate the DNA out of the solution because isopropanol separates DNA from the other cell components which are left behind in the water solution. iii. The salt is used to enable the DNA strands to come together and aggregate.
4.
The banana needs to be crushed into a pulp to separate the cells so that they will be exposed to the detergent and salt.
5.
No this protocol would not work on cooked or heated samples because the DNA will be denatured (broken into bits and pieces) due to the heat.
6.
The cell membrane is composed of layers of lipids and fats and in order to extract the
DNA the lipids and proteins that make up the membranes surround the cell and nucleus need to be broken so that the DNA can be released from the cell.
7.
The control allows a comparison with the experiment results and validates that the results obtained were a result of the factors tested in the experiment and not a natural occurrence. In other words you need to ensure that the changes/results are occurring because of the variable you are altering and not because of any other factors. With the use of control the experiment is validated itself.
1.
Describe and draw the appearance of the DNA you extracted. Make sure to include colour, shape, size, and consistency.
2.
How do the results of your experimental sample compare with your prediction? Does your data support or refute your initial prediction?
3.
What could you do differently to increase the yield and purity of the DNA sample? What other reagents might be of use?
4.
What were some sources of procedural error?
5.
If you try to extract DNA from the same amount (by weight) of grapes, would you obtain more or less DNA? Explain.
6.
Compare and analyse the results of your graph. Explain, on a molecular level, how the amounts used for each of these variables affected the amount of DNA extracted.

1.
The DNA appears white and will form a clump made of string-like strands that wrap onto the glass rod.
2.
The students would answer this questions based on their individual experimental variable and their prediction.
3.
Knowing how all of the variables that were tested affect the amount of DNA extracted I would redesign the protocol possibly using more detergent, cold alcohol and less salt.
Another change that I would make would be to use 90% isopropyl alcohol as opposed to the
70% that were used in this lab that would be able to precipitate more DNA out of solution. I would also allow the solute to collect for a longer period of time to make sure to collect all the solution with the DNA dissolved in it. After precipitating the DNA with cold alcohol I would then filter the solution to collect the solid DNA in a filter paper as opposed to trying to catch it with a stirring rod. I would then just let the DNA air dry on the filter paper and collect and weigh the dried DNA a few days later.
The sample of DNA collected is probably not very pure as other cell components such as protein or RNA could be bound to it. To increase the DNA purity I would add ribonucleases such as RNase A to degrade RNA molecules and proteases to cleave the proteins into their individual amino acid subunits. These components would then just be solubilized in water and not be collected in the final DNA extract.
4.
A source of experimental error could be inaccurate measurements of the amounts of ingredients used. An inability to collect all of the DNA that had precipitated out of solution was also an issue as it was quite hard to pick up the DNA with a stirring rod. Another possible source of error could be not collecting equal amount of solutions for the experimental and control samples. Also if the DNA is to be weight to quantify it, the solution must be left long enough to completely dry it so as not to overestimate its weight by also measuring the weight of water.
5.
You would likely extract less DNA. Grapes contain a lot of water and there will likely be fewer cells to extract DNA from.
6.
Since we do not have a pooled classroom data we can just talk in general about how these three different variables affect the amount of DNA extracted compared to the control. Using more detergent resulted in a larger amount of DNA extracted. This could be so because the purpose of the detergent is to lyse the cells and using more detergent could have resulted in more of the DNA to be released into the solution that was later extracted. Using cold ethanol resulted in the extraction of more DNA than when room temperature alcohol was used. Cold solutions are able to precipitate the DNA more easily as it is less soluble in them.
In the case of salt, using more salt resulted in less DNA extracted. While salt is required to allow the negatively charged DNA backbone to bind to the positively charged sodium cations and aggregate, too much salt might disrupt this process as there would also be a lot of negatively charged chloride ions in solution that could compete with DNA for the sodium ions and repel and not allow the DNA to bind it.

Categories 50-59% (Level 1)
Knowledge of content
Understanding of content
Demonstrates limited knowledge of
DNA, its function, and variables that affect DNA extraction
Demonstrates limited understanding of
DNA, its function, and how variables affect DNA extraction
Use of processing skills
Use of critical thinking processes
Uses processing skills with limited effectiveness and observation notes are not clear or detailed in any way
Uses critical thinking processes with limited effectiveness in the post-lab questions
Expression and organization of ideas and information
Use of conventions, vocabulary, and terminology
Expresses and organizes ideas and information with limited effectiveness in the pre-lab, observation notes, and post-lab
Uses conventions, vocabulary, and scientific terminology with limited effectiveness
Application of knowledge and skills
Applies knowledge and skills in familiar contexts with limited effectiveness and post-lab questions show little understanding of theory
60-69% (Level 2)
Demonstrates some knowledge of DNA, its function, and variables that affect
DNA extraction
Demonstrates some understanding of
DNA, its function, and how variables affect
DNA extraction
Uses processing skills with some effectiveness and observation notes are clear but with little detail
Uses critical thinking processes with some effectiveness in the post-lab questions
Expresses and organizes ideas and information with some effectiveness in the pre-lab, observation notes, and post-lab
Uses conventions, vocabulary, and scientific terminology with some effectiveness
Applies knowledge and skills in familiar contexts with some effectiveness and post-lab questions show some understanding of theory
70-79% (Level 3)
Demonstrates considerable knowledge of DNA, its function, and variables that affect DNA extraction
Demonstrates considerable understanding of DNA, its function, and how variables affect DNA extraction
Uses processing skills with considerable effectiveness and observation notes are clear with considerable amount of detail
Uses critical thinking processes with considerable effectiveness in the post-lab questions
Expresses and organizes ideas and information with considerable effectiveness in the pre-lab, observation notes, and post-lab
Uses conventions, vocabulary, and scientific terminology with considerable effectiveness
Applies knowledge and skills in familiar contexts with considerable effectiveness and postlab questions show thorough understanding of
80-100% (Level 4)
Demonstrates thorough knowledge of DNA, its function, and variables that affect DNA extraction
Demonstrates thorough understanding of DNA, its function, and how variables affect DNA extraction
Uses processing skills with a high degree of effectiveness and observation notes are very clear with a lot of detail
Uses critical thinking processes with a high degree of effectiveness in the post-lab questions
Expresses and organizes ideas and information with a high degree of effectiveness in the prelab, observation notes, and post-lab
Uses conventions, vocabulary, and scientific terminology with a high degree of effectiveness
Applies knowledge and skills in familiar contexts with a high degree of effectiveness and postlab questions show detailed understanding of theory

Making connections within and between various contexts
Makes connections within and between the results obtained in the lab and theory learned in class with limited effectiveness
Makes connections within and between the results obtained in the lab and theory learned in class with some effectiveness theory
Makes connections within and between the results obtained in the lab and theory learned in class with considerable effectiveness
Makes connections within and between the results obtained in the lab and theory learned in class with a high degree of effectiveness