Tweaking Lorenzo’s Oil

This year, AP Bio class time at my school was increased to four 80 minute blocks a week. This is up 40 minutes from last year. One of the benefits is that near Christmas we were at a good place in our curriculum and I was able to do the whole Lorenzo’s Oil movie unit in the three day week we had before Christmas break instead of splitting it before and after Break. (I blogged about this last year here.) This extra time allowed me to change things up a little. The first day, we just watched the movie. I do stop it on occasion to clarify and check for understanding. On the second day, we started with the demyelination activity. We used to do this before the very beginning of the movie, but after they’ve watched Lorenzo’s decline, the activity is more meaningful. We discussed the questions as a class and then went back to watching the movie. I was a little nervous because we only had about 30 minutes left of the movie for day 3, but we also had the competitive inhibition activity to do. I revised how we did it and loved it.

I wanted students to see how keeping the enzyme busy making unsaturated fatty acids increases the time the enzyme takes to build the C24 saturated fatty acids that were eating Lorenzo’s myelin. (Thus resulting in lower amounts of the bad saturated fatty acids in his blood.) This time, students started with a paper bag of jumbo silver paper clips (about 20 paper clips each representing 2 carbons), and a C14 fatty acid chain made of 7 joined jumbo paper clips. Each lab group timed two trials to see how long it took to build their saturated fatty acid into a C24 saturated fatty acid that was eating away at Lorenzo's myelin.

Then I gave them the original 7 paper clip chain and a 7 paper clip chain of neon paper clips to represent an unsaturated fatty acid and added about 10 neon (unsaturated) paper clips to the bag. Students timed two more trials, but this time, if they pulled a neon clip they added it to the neon chain. For the last trial, they were still timing how long it took to build a saturated C24 (silver jumbo clips), but we added another 15 neon clips to the bag. They averaged their times to build C24 for each scenario and then we looked at the class results. Maybe we'll eventually graph the means of each trial and add some errors bars.

Here are the numbers from the board.

Making Bad (C24)
	all bad (in seconds)	some good (in seconds)	more good (in seconds)
Group 1	27.2	78	78.7
Group 2	29	38	47
Group 3	34.4	87.5	63.2
Group 4	37	76	108
Averages (n=8)	31.9	69.9	74.2

Book-ending Christmas break with Lorenzo's Oil

Keeping students engaged on the last day before Christmas break can be a challenge, but I don't believe in wasting time.  We just finished our unit on Mendelian Genetics, and watching Lorenzo's Oil is a great complement to what we've done in AP Biology so far.  Last year I found a study unit on the movie here. We started with the activity demonstrating what happens to nerve signals as they become demyelinated. Students start with a "brain bucket full of signals (ping pong balls) and must pass them from one student to the next until it reaches the "body" bucket. We count how many signals (ping pong balls) make it into the body bucket in 10 seconds and then start again. But the second time
we do it, two students have to sit out and the remaining students may not move any closer to each other. We repeat one more time with two more students sitting out, to get a feel for how signal transmissions changes as more of the myelin is lost from nerve cells.

Then we get out the snacks and start watching the movie.  There are questions provided in the study unit to help them keep focused and delve deeper into the science of the movie.

When we get back from break we do the competitive inhibition activity with paper clips and finish the movie.  In the competitive inhibition activity we look at how providing more unsaturated fatty acids "competes" with the saturated fatty acids to hinder the production of very long chain saturated fatty acids (VLCSFA).

As we finish the movie, it leads naturally into a discussion of medical ethics, and is a great segue into our molecular genetics unit.