October 26, 2012 @ 1:39 pm
The wife and son went to see Frankenweenie a few weeks ago as a matinee. He liked it. He likes everything. Listen to his summary and review on next week’s special 50th episode of the podcast.
Speaking of reanimating the dead, I’ve had two really good class discussions on that during the past couple of weeks, specifically on why it doesn’t work. That’s a big question, the first one of the semester that really required some analysis, some breaking down into individual hypotheses. We treated it at a fairly abstract level in the 100 nonmajors class:
Why can’t we re-start these biochemical cascades like respiration or photosynthesis once the cell is dead? They thought about several answers.
Souls, which implies that soulless things could be restarted. That led to an argument about where to draw the line between souled and soulless things, which was a matter of opinion. “That’s your opinion” is generally a code phrase for agreeing to disagree, and the end of the argument.
Oxygen, which implies that replacing the oxygen could reboot life. We quickly agreed that won’t work, even if you inflate the lungs mechanically with a ventilator and pump the blood mechanically.
Energy, which implies that injecting ATP into a cell could do it. We agreed that won’t work, either.
Heat, noting that dead bodies cool off. After a moment’s reflection, we decided that no, heating up a dead body wouldn’t work. In fact, it would probably cause the rot to set in faster.
See the game? Basic experimental design. Thought experiments, “testing” one independent variable after another, always measuring the same dependent variable – life.
The Honors students in the majors class, 101, were less obviously spiritual (they might have thought souls, but they didn’t say it), more technical, and took the argument a little further. We had a fantastic unintentional visual aid in the form of a freshly dead bird which two of the young ladies had actually witnessed crashing into a building earlier that morning while they were out on our service project. He was still hot when they got to him. So this discussion had an immediacy and a personal element that as a teacher/performer I found really powerful. Based on the serious way they approached the question, I think they did too.
Energy, as in the electricity that powers a defibrillator. Interestingly, they weren’t clear on the fact that defibrillators only work on people who are dying but not yet dead.
Equilibrium, which is getting really really close, but it was a bit of a cheat because I had used the phrase “Equilibrium is death” earlier in the semester.
Time, as in the longer we wait, the less likely it is to reanimate a dead cell. True, but why?
They even recognized that frozen live cells are no longer metabolizing, that they are in a sense, paused. But what’s the essential difference between the paused state and the full-stop dead state? That was where they got stuck.
If I had been feeling really hard-core, pedagogically, I would have left the discussion right there for them to ponder over the four days of Fall Break. Sometimes I do, and ignore the howls of, “Just tell us the answer!” But to be perfectly honest, I had an epiphany about the topic the day before, and I was still a little high off that. So, like any geek with a secret, I was eager to show off.
So, in a word, reaching back a couple of chapters in the textbook, the secret of death is diffusion. We all know that if you put a drop of ink or food coloring into water, it will spread out until the color is even. Molecules move from areas of high concentration to areas of low concentration,
until that gradient is exhausted and the concentration is the same everywhere in the system, averaged over time, anyway. There will always be some empty boxes in the diagram above, because there’s not enough of the yellow solute to go around, but the average over time will always be 7/9 boxes occupied. That defines chemical equilibrium. I like to summarize that visually with right triangle icons, with the 90° angle being the side of high concentration.
Now there are a large number of chemical pathways inside a cell, most of them maintained far, far away from their equilibrium states by constant use of energy. A single injection of any random chemical could restore a single gradient in a single compartment of a dead cell, but to restart a dead cell you’d need to restore not just one gradient, but all of them. All the important ones at the head of a metabolic pathway, at least.
This is why Craig Venter and every other genetic engineer has to cheat, to use living cells for their creations, to simply replace the DNA of a living cell with constructed DNA. They can’t build cells from scratch. We as a species simply do not have the technology to manipulate all those gradients at the same time.
This problem sounds like what creationists call “irreducible complexity,” doesn’t it? That’s the idea that life could never start in the first place because our fancy modern cells are much too complicated to reanimate now. Evolutionary scientists don’t like that argument, because life obviously must have started somehow, because here we are. Scientists assume that there must be some minimum complexity that can self-organize reliably under an environment like the early Earth’s. We just don’t know what that minimum complexity is. There are good people working on that issue, and they’ll probably solve it eventually, but for now we have to just admit the limits of our knowledge.