Extracting DNA

• You share 50% of your DNA with a banana
• All living cells contain genetic material in the form of DNA
• How much DNA is in each of your cells?

  Two meters
• DNA is about two nanometers wide because it is extremely narrow
• DNA is tightly wound around proteins to fit into cells
• What is the easiest way to extract DNA from cells?

  Using fruit
• Steps to extract DNA from fruit

  1️⃣ Blend or mash the fruit with salt water

  2️⃣ Pass the liquid through a sieve

  3️⃣ Add detergent to the fruit soup

  4️⃣ Add protease enzyme

  5️⃣ Pour ice-cold ethanol into the mixture

  6️⃣ Observe cloudy strings of DNA
• Why is salt water used in the first step of DNA extraction?

  Breaks down cell walls
• Salt water makes DNA more likely to clump together
• What does passing the fruit mixture through a sieve remove?

  Cell debris
• Detergent ruptures the cell and nucleus membranes
• Protease enzymes are used to break down proteins in DNA extraction
• What are three examples of substances containing protease enzymes?

  Pineapple juice, contact lens cleaner, meat tenderizer
• Ice-cold ethanol is used to make DNA insoluble
• Ice-cold ethanol slows down the action of DNA-degrading enzymes
• Why does ethanol form a separate layer on top of the fruit soup?

  It is less dense
• Cloudy strings of DNA appear at the boundary between the soup and the ethanol
• Extracted DNA can be observed under a microscope
• What tool can be used to remove the extracted DNA from the mixture?

  Wooden stick