9. Is the rate of product production constant over time? Hint: Is the slope of the line constant or does it change?
The slope of the line is constant for earlier time points, which means that the rate of product production is constant during this time. At later time points, the rate of product production should decrease some. If the reaction is carried out to completion, then the rate will eventually go to zero.
Activity 2 Analysis Questions 1. How can you determine the initial rate of the reaction for each temperature?
The initial rate is equal to the amount of absorbance between the 0 and 2 minute time point divided by 2 minutes. This is also the initial slope of the line of product produced vs. time. 2. At what temperature do you think this enzyme works best? How did you come up with your answer?
This enzyme seems to work best at 37°C. I know this because the rate of product production was the highest at this temperature. Note: if the rate continued to increase, then the student would not be able to guess the optimal temperature but only be able to predict that it would be at a somewhat higher temperature than what was tested. 3. Why do chemical reactions occur faster at higher temperatures?
4. Why do chemical reactions occur more slowly at low temperatures?
Molecules are moving slower at lower temperatures. Therefore, there are fewer collisions and the molecules may not have enough energy to reach the transition state. 5. Why do most enzymatic reactions slow down at extremely high temperatures?
Most enzymes are proteins. Proteins denature at high temperatures. This is because the weak bonds between amino acids break, and the protein can lose its three dimensional structure. At higher temperatures, bonds such as hydrogen, ionic, and Van der Waal’s interactions can break. This will unravel the protein’s tertiary and secondary structures. Any covalent bonds will remain. The only covalent bonds involved in tertiary structure are the disulfide bonds between cysteine amino acids. 6. If you were a scientist who wanted to use this enzyme to produce glucose, at what temperature should you run the reaction?
For the experiments run, the enzyme works fastest at about 37°C. In order to save energy, however, it may be more efficient to run the reaction at lower temperatures.
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APPENDIX G
Molecules move more quickly (have more kinetic energy) which increases the number of collisions between molecules. The average kinetic energy of the substrates is higher and therefore more substrate molecules have the required activation energy in order to reach the transition state.