DNA, or deoxyribonucleic acid, is where genetic information is stored. Every living thing has DNA, and it acts as an instruction manual for life as it encodes cells with directions on how to grow, divide, and behave. Information is encoded in the double helical strands that are bound together by patterns of base pairs. These base pairs include adenine, guanine, thymine, and cytosine. The order that these base pairs line up provides the cell with directions for the production of amino acids that can be deciphered using the universal genetic code. These amino acids can then work to create the proteins that function in almost every aspect of life!
So, how do fruits come into play? Well, fruits are also living organisms. All plants, animals, and even microorganisms have DNA, and in this experiment the DNA will be extracted from bananas and strawberries. We specifically use fruits like strawberries and bananas because they are octoploid and triploid, respectively. This means that each strawberry cell has eight sets of DNA, and each banana cell has three sets, so there is a lot available for extraction. Here’s a fun fact too! Humans, DNA-wise, only differ from one another by 0.1%, so in that small 0.1% lies all of the human diversity on earth.
The structure of DNA also comes into play when discussing this experiment. In its natural state DNA is housed in the nucleus of the cell. When the detergent is added, the cells lyse, or break open, by dissolving the phospholipid bilayers that compose the membranes. As a result, the DNA is allowed to flow out of the cell and into the surrounding solution. Lastly, DNA is not soluble in isopropanol, or rubbing alcohol, and the colder the better in this case. So, once the DNA is out of the cell and into the rubbing alcohol mixture it can easily be extracted.