Answers to lab report for enzyme activity
Graphs: All graphs were done in class on Friday. Please get information if you were
absent. You will be expected to explain the processes going on that generated each
graph.
Data: Due to an overwhelming number of students who believe that rate is time
divided by distance, there will be data calculations on the test. Be able to explain
what happens to a data point if the time goes up or down relative to the same
distance travelled.
Answers to questions: Due to an overwhelming number of students who calculated
the rate to be time divided by distance, the answers to the questions were mostly
wrong for those students. Therefore, the correct answers are posted below.
Questions:
1. What is the effect of enzyme concentration on enzyme activity?
As the concentration goes up, so does the activity of the enzyme because
more and more enzyme molecules are coming in contact with the substrate.
At some point the enzyme activity will reach a maximum due to the limited
number of substrate molecules available to react.
Explain how enzyme activity changes as enzyme concentration decreases,
and discuss why this occurs (on a molecular level).
As the number of enzymes decrease, the rate of reaction will decrease as well
due there being less and less enzymes available to perform the reaction.
Fewer enzyme molecules mean the fewer places for the substrate to react
with.
2. What is the effect of substrate concentration on enzyme activity?
As the substrate level increases, so does the reaction rate due to there being
more substrate for the enzyme present to work with. At some point the level
of substrate will exceed the ability for the available enzyme to react and the
reaction rate will level out.
Explain how enzyme activity changes as the substrate concentration level
decreases?
As the concentration of substrate decreases throughout the reaction, the
activity of the enzyme will also decrease as the number of substrate
molecules to react with is reduced until there is no enzyme left and the
reaction will cease.
3. How does temperature affect the activity of catalase? Explain your
observations by discussing the effect of temperature on protein structure.
Discuss both high and low temperatures.
Temperature affects the activity of an enzyme by disrupting hydrogen bonds.
There is an optimal temperature for the enzyme to work as shown by a peak
at 22 degrees on the graph.
Low temperatures: Below 22 degrees, the movement of the substrate and
enzyme is reduced which reduces the number of reactions that are occurring.
If the temperature is reduced too far, the reaction rate will cease due to the
energy of the molecule being insufficient to proceed with the reaction.
High temperatures: As the temperature goes up, the molecule’s hydrogen
bonds start to denature and the enzyme becomes less and less effective until
the active site is no longer able to perform the reaction. If the temperature
gets too high, the enzyme may be permanently denatured.
4. How does pH affect the activity of catalase? Consider both high and low pH,
and explain your observations by discussing the effect of pH on protein
structure.
There is an optimal pH for enzyme activity. Most enzymes of any biological
organism have optimal pH activity around a pH of 7 (neutral). As the pH
decreases (acidic) OR increases (basic), the hydrogen bonds are disrupted.
Instead of forming hydrogen bonds within the molecule, the hydrogen bonds
start forming with the hydrogen or hydroxide ions instead. This causes the
protein to denature. If the hydrogen bonds are disrupted enough, the
enzyme may be permanently denatured.
5. Ectothermic organisms have body temperatures that vary with the
temperature of their surroundings. Discuss the effect this variation might
have on the functioning of enzymes in these organisms. Suggest some ways
ectothermic organisms might cope with this problem.
Ectothermic organisms have an optimal body temperature. If the
temperature is too low, the organism might move to a sunny location, a warm
road surface, inside your house, or begin to vibrate their muscles to increase
the heat generated by their muscles to reach this temperature even if the
environment does not.
Snakes sun themselves on rocks as well as turtles to warm up. Snakes and
many other organisms have adapted to crawling onto a warm road to absorb
the heat from the asphalt. Stinkbugs and lady bugs invade your home to
reach their optimal temperature when the outside temperatures are going
down. Butterflies, moths, and bees will vibrate their wing muscles to
generate the heat they need to achieve their optimal temperatures. Honey
bee hives need to maintain 72 degrees Fahrenheit all 365 days a year. To
heat their hive throughout the winter, they close it off and workers vibrate
their wings to keep the temperatures warm inside.
Many organisms will hide during the heat of the day in the shade or below
ground. In the hot summer months, honey bees bring water into the hive and
fan it across the entire hive to absorb the heat.