I dilute it until I get a change of about mmHg over the three minutes. This may sound confusing but I simply inform my students that the bottle of H2O2 is stock and our dilutions are measured from that. I use potato or liver usually potato. I always start with a new bottle.
The lab takes about 10 minutes and then could be repeated at different temperatures or substrate concentrations.
In scrounging around our filter paper supply, I found lots of different grades and have been testing different ones. It was most satisfying to watch them float at varying times, exactly as the lab said they would. I have used it for the last several years and find it to be excellent.
The directions were pretty bad. I have never tried yeast, but yeast and I have never gotten along very well! The oxygen evolved can be measured as it displaces the water in the graduated cylinder.
It seems that the person in the company that designed the lab left several years ago and no one there could give me any sample data. As a stopper for the bottle, use a one-hole stopper with the glass part of an eye dropper inserted in the hole.
We ran the lab twice more, changing the temperature of the enzyme just for fun, and because we had time minute classes and seven students. Sometimes the students have trouble getting the discs in place in the bottle—curved forceps work best for this.
It has always worked very well for me as long as I use fresh peroxide I use 3 percent straight out of the bottle and liver homogenate I have used small pieces of Ap biology enzyme same slice now for five years—I keep it in the freezer and blend a small piece of it for a few seconds in cold water, then filter through cheesecloth and keep on ice.
Therefore, I usually test various dilutions before letting the students do them. In doing a test run of the lab this morning, I found that the discs floated immediately. Is this because the amount that decomposes is so small that it is not accurately measurable by this method?
Bell, Science Teacher, St. The amount of H2O2 consumed is usually equal to or less than the baseline. Be sure to caution students on the use of chicken liver and salmonella.
Does anyone have experience with these? This can be compared at different temperatures and substrate concentrations. And kept on ice. They actually have to investigate a variable of this protocol at home since everything is so cheap and safe.
It is far superior to the KMNO4 titration, which, frankly, calls for too many measurements six considering the small differences the kids are supposed to find in the end.
I ended up spending a lot of time rewriting that lab so that students could follow directions. We peeled and cubed the potato, put it into a blender with chilled distilled H2O almost to the top, and pureed it.
For some reason, the dehydrated catalase that I had from Sigma was inactive. I attach a pipette and pump directly to the rubber stopper so that I can add the enzyme at a set time and then select the first 15 seconds of readings for measuring the velocity rate of the reaction.
I called the company with some questions and they could not answer them. Equipment and Supply Modifications Question: Carefully turn the bottle degrees to expose the discs to the peroxide, and start timing I usually have them take measurements every 30 seconds for 10 minutes, but have shortened the total time to 6 minutes before also.
Keep the enzyme cold by leaving it in an ice bath once it is made. I first used undiluted 3 percent peroxide and found I had to dilute it many times to get the disc to stay on the bottom for any time at all. Then I have the kids design their own experiments. It was very weak when I purchased some a few years ago.
Over the years my students have investigated this protocol ad nausea—partly this is because I make this a take-home lab.AP Biology Lab 2 - Enzyme Catalysis Paul Andersen starts with a brief description of enzymes and substrates. He then explains how you can measure the rate of an enzyme mediated reaction.
Keep the enzyme cold by leaving it in an ice bath once it is made. We ran the lab twice more, changing the temperature of the enzyme just for fun, and because we. 6. Enzymes a. Biological catalysts (made of protein) that speed up rate of chemical reactions by lowering activation energy required for reaction to occur b.
Enzyme has active site (exposed R groups) where reaction occurs c. Enzymes can break down substance (catabolic reaction) or build up substances (anabolic) d.
Enzyme/substrate complex is formed e. Learn ap biology enzymes with free interactive flashcards. Choose from different sets of ap biology enzymes flashcards on Quizlet. enZYMe aCtivitY* How do abiotic or biotic factors influence the rates of enzymatic reactions?
BACKGROUND Enzymes speed up chemical reactions by lowering activation energy (that is, the energy needed for a reaction to begin). In every chemical reaction, the starting materials (the * Transitioned from the AP Biology Lab Manual (). LAPs are enzymes that remove N-terminal amino acids from proteins and release the free amino acids into the cytosol.
To investigate the evolution of. LAPs in wild. Free-Response Questions from the AP Biology Exam Keywords: Biology; Free-Response Questions; ; exam resources; exam information; teaching resources; exam practice.Download