Laboratory report on experimental procedures and results

Extracting DNA from strawberries

In my experiment, I attempted to extract the DNA from strawberries; in order to fulfill my purpose, I have followed the stages presented in the example: I blended the strawberries together with salt and cold water, I put the mixture through a strainer into a cup, then I added liquid detergent and then I moved the liquid into a glass container, after that I added pineapple juice, I stirred and in the end I poured ethyl alcohol. In the end I was able to see the DNA raising to the surface of the container. It looked like a small White Sea jelly.

"Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of living organisms. All living things contain DNA, with the exception of some viruses with RNA genomes. The main role of DNA in the cell is the long-term storage of information. It is often compared to a blueprint, since it contains the instructions to construct other components of the cell, such as proteins and RNA molecules. The DNA segments that carry genetic information are called genes."

History: DNA was first discovered Friedrich Miescher, an Austrian monk, who found out in 1869 that human traits are determined by some minimal factors, which he called "nuclein." In 1937, William Astbury was the one who produced the first X-ray diffraction patterns that proved that DNA had a regular structure. "In 1943, Oswald Theodore Avery discovered that traits of the "smooth" form of the Pneumococcus could be transferred to the "rough" form of the same bacteria by mixing killed "smooth" bacteria with the live "rough" form. Avery identified DNA as this transforming principle DNA's role in heredity was confirmed in 1953, when Alfred Hershey and Martha Chase in the Hershey-Chase experiment, showed that DNA is the genetic material of the T2 phage."

However, the first adequate DNA model was produced in 1953 by James D. Watson and Francis Crick, the Watson winning the Nobel Prize 9 years later for his discovery..

Importance:

nowadays, we highly benefit from these previous discoveries, since the role of the DNA is of valuable importance, since it contains genetic information that lead to living, growing and reproducing of the living organisms. These processes are made possible by the sub-divisions of the DNA, called genes.

DNA is also used in the forensic identification:

it helps finding potential suspects by the evidences from the crime place which contain DNA; reduces the possibility of a wrong crime accusation; identifies the victims of a crime, establishes family relationships, especially paternity.

3. Materials and Methods: Since I have read in the example given that I could extract DNA from anything living, and among the stipulated examples were the strawberries, I decided to use these fruits as material for my experiment. Therefore, I have chosen four medium-sized strawberries and I put them in the blender from my kitchen (I guided myself with the help of the example given for choosing this measurement, trying to approximate the quantity used there). I also added approximately 1 ml table salt and 200 ml cold water. I pushed the blender's "high" button and I blended it for 15 seconds. The result was looking similar to a smoothie, and I was able to see the strawberries' small cores, so I thought that I had succeeded to separate their cells through blending them.

Afterwards I poured the liquid through a strainer, just as it had been done with the peas in the given demonstration and I noticed that the poor substance was even thinner than the one obtained at the blender. I added 35 ml of liquid detergent and then I swirled. I waited around 9 minutes and then I moved the object of my research into three test tubes, being aware of the fact that the detergent had continued the task of the blender and has broken the sacks of the cells, allowing the DNA to be found. I poured the substance in such a way that only 1/3 of each test tube would be filled, and then I added pineapple juice, which played the role of the enzymes cutting the proteins.

After that I started to stir the mixture, making sure that my action would detain the success of my experiment by stirring it too hard. The content of the test tubes started to look rather pink, taking the color of the pineapple juice. Afterwards I gently poured the ethyl alcohol down the side, in order for it to be able to form a layer on top of the substance. Since half of the test tubes' space was already occupied with the previously-obtained mixture, I filled the other half with alcohol. From this moment I paid attention only to one of the test tubes, since I was aware of the fact that I had to keep one of them in my hand in order to be able to see the entire process.

4. The result was the one I was expecting: I succeeded to separate the prepared mixture and the alcohol, and only after a few minutes the DNA slowly rose from the yellow down part to the upper half of the container, looking like a small White Sea jelly. I succeeded to take it out from the test tube by using a small wood stick. I took it in the light of the sun and tried to observe its small parts. Moreover, after fulfilling my experiment, I was able to understand the DNA structure: