Monthly Archives: September 2015

Strawberry DNA

Today my lab group extracted the DNA from two delicious strawberries. Unfortunately, the strawberries didn’t remain delicious for long, but we’ll get to that in a moment. We started with two regular, washed, and dyed strawberries. 

First, we created a solution of water, detergent, and salt to mix with the strawberries. We then pipetted 10 mL of this into two plastic bags, each of which was also given a strawberry. We then closed the bags, and pounded them to a mush. The water helped the strawberries form a liquid with a few extra ingredients. The detergent dissolved the cell membranes, and the salt ions help separate out the DNA strands. The result:
 

As I mentioned, not quite as delicious anymore (we must make certain sacrifices for science). We slowly filtered this mixture through cheesecloth and a funnel, and were given 4 test tubes filled 1/4 with red strawberry goo. 
   

Next up was the alcohol. We pipetted an equal amount of ice cold alcohol  into the test tubes. Then, we watched as a gooey substance (DNA) rose into the alcohol (without being dissolved).  

Though we weren’t able to catch much of it with our wooden stick, we were able to observe the DNA in the rubbing alcohol. We even managed to pull a bit of it out on our pipette. And that’s how we extracted some strawberry DNA! 

 

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pH Indicator Lab Report

Last Thursday, during Biology class and the first half of lunch, I used red cabbage to create a veritable rainbow of colors. No, I did not use photoshop. Instead, I used acids and bases. My lab group used boiled, blended, filtered cabbage-water to help demonstrate levels of pH. First, we would add a dilute Acid or base drop by drop until our pH meter told us a change of one whole number had occurred. Then, we put 5 mL of the solution into a test tube to compare to the other steps. We ended up with a whole spectrum of colors, as seen below.  

This lab taught me a lot of things, both about acids and bases as well as the scientific method.

Firstly, I learned how to calculate the number of ions or molecules in a given substance. Firstly, you need to know the molar concentration of the substance (the number of ions present in 1 liter), and then you multiply his by the volume of your sample.

I also learned that a scientist is only as great as his or her measurements. Our pH meter did not give us consistent measurement of our samples, and  would often jump around by as much as .5 when reading the pH. 

   

Therefore, I’m not sure how accurate our data was, and I hope to see some of the data from the other groups. I was, however, able to use our data to make graphs of our findings. Here they are:

Effect of Sodium Hydroxide on pH of Indicator Solution  Effect of Hydrochloric Acid on pH of Indicator Solution

 Finally, I learned that doing homework earlier makes things easier for everyone. For the group portion of this project, I sent out a file with the lab group’s measurements last night. Or so I thought. Thankfully, I was able to resend the email today and it actually went through. I’m quite glad, though, that I didn’t save that piece of work for tonight. On the other hand, I saved the blog lab report for last, and it’s due tomorrow. So now I’m blogging