Question

1. Obtain a fresh strawberry. If the green leaves (sepals) on the strawberry have not yet been removed; remove them. 2. Place the strawberry in a zip seal plastic bag. Press the air out and seal it. 3. Gently mash the bagged strawberry with your fingers for 5 minutes. Don't break the bag. 4. Add 10 ml of lysis buffer to the bag. Press the air out carefully and seal the bag. 5. Mash the bagged strawberry with the lysis buffer for 2 minutes. CAUTION: Mix carefully, the fewer bubbles created the better your results. 6. Cut one of the bottom corners of your baggie off and squeeze the strawberry pulp along with the liquid into a small cup covered with cheesecloth. 7. Rinse the pulp with water to ensure you obtain as much DNA as possible. 8. Discard the baggie, cheesecloth and the strawberry pulp into the trash can. 9. Place the filtrate into a test tube, but leave room to add the alcohol. 10. Slowly drizzle ice-cold ethanol along the side of the test tube until DNA begins to appear. It will look somewhat like cotton candy fibers. 11. Keep the test tube at eye level so you can see what is happening! Pay attention to the characteristics of the DNA as it precipitates. Analysis 1. What did the DNA look like? 2. In order to study our genes, scientists must extract the DNA from human tissue. Would you expect the method of DNA extraction we used for the strawberry to be the same for human DNA? Explain? 3. Is the DNA in any cell in the human body the same? Explain your answer. 4. If you wanted to extract DNA from a living person, which cells would you use and why? 5. Please list two reasons why a scientist might want to study the DNA of strawberries.

What are the independent, dependent and controlled variables for this experiment?

Answer 1

If you look up the definition of independent vs dependent variables you will see that all inputs into an experiment are "independent variables". Meaning that each input, so in your case, the strawberry, the lysis buffer, the alcohol all can have a separate impact to the final result. Meaning, if any one of those materials are faulty it could impact your final outcome of the experiment. So all these are independent variables.

DNA of the experiment is the "dependent variable" because how the result turns out depends on whether the inputs work correctly.

Since you have done this experiment only one time and with one strawberry only, there Is no controllable variable. But some people consider lysis buffer as control variable due to its constant volume. But still it's controversial to use it or not.

So it's totally up to you

If you need anything else, just comment on the answer.

Thanks