Tag: DNA

DNA Extraction

Hello readers,

Aim:

For term 1 biology we are looking at DNA. For today’s experiment we will be extracting DNA from a banana. We do this experiment to mainly investigate how it looks and feels. A fact about this is that this information can be used to improve crops so that they are more resistant to diseases.

Equipment used:

  • Peeled banana
  • Salt
  • Dish soap
  • Ethanol
  • Test tube
  • 250mL Beaker
  • Metal spatula

Method:

  1. Mush some peeled bananas in a zip-lock bag with a splash of water and a small teaspoon of salt.
  2. Get the biggest beaker you have in your tray and strain the sample through a cloth into your beaker.
  3. Add a squirt of dish washing liquid into your sample.
  4. Pour your sample into a test tube.
  5. Place the test tube into a beaker filled with warm water.
  6. Let your sample warm up for 10 minutes.
  7. Slowly pour 5mL of ethanol down the inside of your test tube.

DNA Extraction is used for:

  • Finding genetic causes of diseases
  • Development of diagnostic tools (finding out what’s wrong with people)
  • Development of drugs/treatments
  • Also essential for, forensic science, sequencing genomes, detecting bacteria and viruses in the environment, and determining paternity.

How we can extract DNA from fruits:

As you can see from my method I will be explaining WHY we do this.

Firstly we put salt into our mashed fruit in order to separate the cells, this also breaks down the cells walls. Then we sieve our sample to extract our fruit soup, that soup will contain all (your fruit of choice) cells with the DNA inside the nucleus. To break apart the membranes surrounding the cell and the nucleus and release the DNA, we add our dish detergent such as washing up liquid to the soup, this will help rupture the cell membranes. Adding a pinch of protease enzyme will help break down the proteins the DNA is wound tightly around. The DNA will then uncoil and will now be present in the mixture as long strings, you can use pineapple juice, contact solution, cleaner or a pinch of meat tenderizer. All those products contain protease enzymes. You won’t be able to see the DNA just yet because it is dissolved in the mixture, to see the DNA you have to make it insoluble, to do this you use cold ethanol. The cold ethanol will slow down the actions present in the cell. You then dip your popsicle stick into the mixture and you will see a cloudy string wrapped around your popsicle stick. That is the DNA you have extracted from your fruit.

Result:

I know my group and I did something wrong with the experiment, maybe we added something that’s extra. But when we put the popsicle stick into our sample, we couldn’t extract DNA from the fruit soup, the long strings that were supposed to twist around our stick wasn’t there. But for the rest it worked perfectly fine.