BIO 173 Quiz 1 UMich Actual Exam/ 114 Q&A/ . Terms like:
Cofactor - Answer: Organic molecules or metal ions attached to the active site; extra substances that are necessary for the reaction catalyzed by the enzyme
Logarithmic Graph - Answer: A logarithmic graph depicts decreasing returns. In...
BIO 173 Quiz 1 UMich Actual Exam/ 114 Q&A/
2024-2025
Cofactor - Answer: Organic molecules or metal ions attached to the active site; extra substances
that are necessary for the reaction catalyzed by the enzyme
Logarithmic Graph - Answer: A logarithmic graph depicts decreasing returns. In a
Vmax/substrate concentration graph, as substrate concentration increases, the velocity
continues to increase by a smaller amount until the velocity increase is negligible. This velocity
"halt" is Vmax.
Non-competitive inhibitor - Answer: A substance that reduces the activity of an enzyme by
binding to a location remote from the active site, changing its conformation so that it no longer
binds to the substrate
Catalyst - Answer: Something that causes or accelerates a chemical reaction without being
affected itself.
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,Reaction Rate - Answer: The rate at which reactants change into products over time. For our
experiments, rate can be found by absorbance over time
Spectrophotometer - Answer: An instrument that measures the proportions of light of different
wavelengths absorbed and transmitted by a pigment solution. Used to measure the color of the
solutions in the experiments because the color change indicates the concentration of the
quinones and therefore the rate the reaction was occurring
Absorbance - Answer: The amount of light absorbed by a sample. Used to measure reaction
rate, found by spectrophotometer
Catechol - Answer: The substrate used in the experiment, meant to react with PPO to produce
benzoquinone
PPO (polyphenol oxidase) - Answer: -The enzyme we used in the experiment, found in plants
and animals.
- an enzyme found in potatoes (and others), which may protect plants against predators
-converts catechol to orthoquinone
-orthoquinone breaks down into a series of other products, which happen to be colored
red/brown.
-the appearance of color suggests a way to measure reaction rate- spectrophotometry
-the amount of light absorbed is proportional to the amount of product present
Benzoquinone - Answer: Byproduct of PPO reaction; appears to be broadly toxic to a variety of
microbes and insects (protects the plant/fruit); turns brown/orange color
Percent inhibition - Answer: Percent drop in enzyme activity in the presence of the inhibitor.
***
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, Cellular Homogenization (in the centrifuge) - Answer: By homogenizing the potato in the
centrifuge we are able to release and extract the PPO enzyme, used as the enzyme in our
experiment
Centrifugation - Answer: A separation process which uses the action of centrifugal force to
promote accelerated settling of particles in a solid-liquid mixture. Used to get a supernatant
which contains the enzyme
Serial Dilution - Answer: the process of diluting a sample several times
Pipetting - Answer: Used to transport a small measured volume of liquid. Used for preparing
cuvettes in the experiments and dilution
Enzyme concentration - Answer: The greater concentration of the enzyme the greater the rate
of reaction until all of the substrate is being used and it plateaus
Allosteric Site - Answer: Site that activates or inactivates the enzyme, cofactors can bind here
Vector/Plasmid - Answer: Double stranded circular DNA fragment used to insert DNA into
bacteria
Enzyme-substrate complex - Answer: The binding of the enzyme with the substrate used to
affect the reaction rate
Experiment 4: 0, 20, 45 and 65 degrees - Answer: -Higher temperature = higher reaction rate
-Too high of a temperature = enzyme will start to denature
-There is an optimal temperature where the reaction is the highest
-Lower temperature = slower reaction rate bc the molecules aren't moving around as much
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