Enzyme Simulation

In our Human Body Systems course, students learn about the digestive system and enzymes that help break down various food macromolecules. As a bonus, most of my HBS students are also taking chemistry, so we have opportunity to share ideas across the disciplines.

In the past, we did a hands-on lab measuring the rate of reaction of catalase to break down hydrogen peroxide. We could vary the temperature, pH, agitation, concentration, or a number of other independent variables to determine their effect on the efficacy of the catalase enzyme. While I love doing hands-on labs with students, this one took several days to collect enough data, and the data we collected was often unreliable–students measured reaction rates using gas pressure sensors. Any leaks in the flasks, stoppers, or hoses would give us bad data, and then using the computer interface to find the slope of the pressure increase (our proxy for reaction rate) was a small hurdle as well.

A couple years ago, my class was running behind and I decided to forego the hands-on portion, but I still needed students to learn the effects of various conditions on enzymes. So, I found a great enzyme simulation at Biology Simulations. Very cool! I love how the collisions between molecules are clearly shown and how we can change so many variables to test their effect on the reaction.

However, for my purposes, this simulation incorporated a bit too much. There are multiple enzymes. There are multiple reactants and products. There are inhibitors! SO many things to play around with. Which is all good, but I needed my students to understand the basics. How do things like pH, temperature, and concentration affect an enzyme…

So, I set out to pare the biology simulations version down to just a few variables and a single enzyme.

Original (Biology Simulations) version

Simplified version

Click the button below to try it out. I also put together a very bare-bones ‘worksheet’ to go along with the simulation. Let me know if this is useful to you.

Reaction Time Applet (HBS 2.2.4)

During our PLTW Human Body Systems lesson on the nervous system, we study the speed at which signals travel through neurons, as well as the regions of the brain that control various functions. The curriculum points us to a cool little activity that measures our reaction time when doing tasks of increasing complexity. In Case 4, it becomes quite challenging to have to read a set of instructions and do the opposite as quickly as possible.

The applet used by PLTW is a Shockwave applet by Serendip, but Shockwave hasn’t been well-supported in a long time, and now that my students use Chromebooks, it definitely won’t work. It now appears that the shockwave app has been removed, and the PLTW curriculum now uses a much more basic reaction time app.

So, I set out to recreate this great applet in a more portable and cross-platform language (HTML and JavaScript). The functionality is similar. My attempt is definitely not as refined as the original, but it gets the job done. Also, students are responsible for recording their own times, because my version discards all times when changing between parts of the activity.

Reaction Time Applet