Science Club

Year 7 and 8 scientists are exploring new scientific concepts and techniques this term. They extracted DNA from Kiwi fruit and did flame tests with different metal ions. They will be doing more fun experiments like King Kong’s hands, Creating crystals, Rainbow fizz and Dying an egg this term. Science club is open to all Year 7 & 8 students.

-Dr N Marya

Kiwi DNA extraction

This is one of the experiments we did in science club, and we are going to share what this kiwi experiment is all about.

What is DNA?

Deoxyribonucleic acid, commonly known as DNA, is a complex molecule found in every living organism, from humans to plants and even bacteria. It serves as the fundamental blueprint of life, carrying the genetic instructions required for the growth, development, functioning, and reproduction of an organism. Structurally, DNA is made up of two long strands that form a double helix, held together by complementary base pairs: adenine (A) with thymine (T) and cytosine (C) with guanine (G).

These sequences of bases encode the information that determines an organism's unique traits, much like how letters form words in a book. DNA is organized into genes, which act as specific instructions for building proteins, the molecules that perform most of the work within cells. Found in the nucleus of cells, DNA can also be extracted from various biological materials, such as hair, blood, and even fruits, showcasing its universality across living beings. This remarkable molecule not only defines what we are but also connects all forms of life through its shared structure and function.

Why DNA is important

DNA is incredibly important because it carries genetic information that dictates an organism's traits, such as eye color, height, and susceptibility to certain diseases. Through a process called protein synthesis, DNA provides the instructions needed to build and maintain the proteins essential for cell structure, function, and overall life processes. Additionally, DNA plays a critical role in heredity, ensuring that genetic information is passed down from one generation to the next, allowing for reproduction and the continuation of species. Without DNA, life as we know it would not be possible, as it is the key to growth, development, and adaptation.

What we did in the lab

In the lab, we started by mashing slices of kiwi in a mortar with a pestle until we obtained a liquid extract. Next, we used filter paper and a funnel to separate the solid residue from the liquid, collecting the filtrate (kiwi extract) in a beaker.

To this filtered kiwi extract, we added the same volume of a prepared kiwi solution, effectively doubling the original amount of liquid. After mixing thoroughly, we carefully poured an equal volume of cold ethanol down the side of the container to form a distinct layer on top of the kiwi mixture.

Within a few moments, we observed white, stringy threads forming at the interface of the two layers. These were strands of DNA, precipitated out of the solution by the alcohol. Using a wooden stick or pipette, we gently spoiled the DNA for observation.

This process demonstrated how DNA can be extracted from living tissue using simple steps like mashing, filtering, combining, and precipitating with alcohol.

- By Smrithi V (7SZA), Anuki A (7SZA), Amelie H (7MMH)