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Enzyme Activity

Mr. Glickman's "Human Toothpickase" Activity


Starting out with 30 toothpicks, the human toothpickase would eventually have to stop. In the process, it would use up and break all of the toothpicks in half. Our guided hypothesis said that during the first time period the number of toothpick broken would be high. The second time period would have a lower number. The third time period an even lower number, and so on. Eventually the toothpicks would all be broken and we would have to stop. This graph looks the drawing in the PseudoGraph Box.

Our next step was to graph the speed of the enzyme versus the concentration. Our guided hypothesis said the curve would look like the graph in the PseudoGraph Box or something like it that would approach a value but never reach it, a horizontal asymptote. Our graph shows a mild resemblance to the hypothesized line.

The graph for the reactions per second versus substrate concentration makes sense. At first, the concentration is 30 out of 30, so the enzyme will run into a substrate. After it breaks one, it has a 29 out of 31 chance to run into a whole substrate. The probability goes to 28 out of 32 and 27 out of 33 and so on. Each time, it has less of a chance of running into a full substrate. Then enzyme runs into "waste" products more and more often. If running into a particle in the shoebox takes some constant amount of time, then as it runs into more and more "waste" it loses more time when it could have been doing work on some substrate. Thus, it slows down as the concentration goes down.

Well, even if the enzyme has all the substrate it will ever need in a highly concentrated solution, it still has the problem of time. It takes some amount of time to link up with the substrate and break it. This means that in a fixed amount of time, the substrate can only do a fixed amount of work, regardless of how swamped it is. Thus as the concentration rises, the speed of the enzyme must remain constant.