DNA Extraction From Strawberries - The Technical Report

                 There were four main procedural elements that were present in the DNA extraction process. The first was the maceration and manipulation of the strawberry in the presence of a DNA extraction buffer. The second was the separation of the resultant mixture in an attempt to isolate the filtrate from the rest of the components in the mixture. The third procedural element was the agitation of a mixture containing a 1:1 ratio of the filtrate developed earlier and Ethanol in an attempt to separate DNA from the filtrate. The final procedural element of the extraction process is the separation of the DNA from the Ethanol in which it was stored. This is done through the use of a centrifuge rotating at an extremely high rate of speed.

                The first procedural element of the lab focuses on the maceration of strawberries in the presence of an extraction buffer. The use of strawberries is based upon the nature of their DNA, or more specifically, their chromosomes. Strawberries possess octoploid chromosomes. The possession of eight sets of chromosomes allows for a large amount of DNA to be contained in a very small source sample. i.e. One small strawberry can contain enough DNA for many good sized samples. The maceration and the use of a mortar and pestle on the strawberries is paramount to the success of the extraction. By manipulating the strawberries the cell membrane and nuclear membranes of the cell are destroyed. This releases the genetic material of the strawberry so that it can be harvested later on in the process. The extraction buffer is a safety measure that is put in place to suspend the DNA and keep it from being dissolved by nuclease. The buffer is a "soapy" that contains EDTA. The detergent and salt in the buffer will ionize the cell membrane which makes the DNA extraction process even easier. EDTA acts against nucleases to keep the genetic material intact and able to be extracted. It inhibits the occurrence of DNAsis.

                Once the strawberry mixture has been manipulated such that it is homogeneous in appearance the next step is filtering the solution. By placing the mixture in a funnel lined with cheesecloth the solid components of the mixture will be removed. The porous nature of the cheesecloth allows only liquid to pass through it. The liquid that passes through the cheesecloth and is gathered in the beaker underneath the funnel is known as the filtrate. The filtrate is a solution that does not contain any solids of the strawberry. Contained in the filtrate is the DNA of the strawberry, the extraction buffer, and the molecules which make up the scent and colour of strawberries. The important factor of this procedural element is the removal of all the solutes found in the initial mixture. By having a completely homogeneous solution when the ethanol is introduced the actual task of extracting the DNA will be much easier.

                The third procedural element of the DNA extraction process is the introduction of ethanol to the filtrate. By placing ethanol in the same containment device (a test tube) as the filtrate, DNA can be openly extracted from the solution. The ratio of filtrate to alcohol is 1:1. Nucleic acids, specifically DNA, are water soluble. The introduction of ethanol removes the water from around the DNA. In the absence of water the DNA clumps and precipitates. This process will result in the visible separation of DNA from the filtrate. The DNA will remain suspended in the ethanol and the process can be aided through the agitation of the test tube. This entire process is called DNA Extraction by Ethanol Precipitation.

                When the DNA is finally separated from the test tube it will be stored in a micro centrifuge tube along with some of the ethanol. To separate the DNA and the ethanol the tube must be placed in a centrifuge which will spin at extremely high speeds. This spinning motion will force the DNA, a solid precipitate, into the bottom of the tube where it will form a pellet. This pellet is formed at the bottom of the tube because the DNA is denser than the ethanol. The density of the DNA when exposed to high rotational speeds forces it to the bottom of the tube. The DNA will then be stuck there and the ethanol can be removed with the help of a pipette. Once the ethanol is removed all that remains is the DNA which can be stored and analyzed at a different date.

                The goal of this lab was to extract the DNA from a strawberry using ethanol precipitation. By utilizing all of the procedural elements and the theories behind them the lab was successful in nature. DNA was properly extracted and stored in a micro centrifuge tube for later analysis.