Bill asked in Science & MathematicsBiology · 10 years ago

# ap bio free response?

i need help with this question

1988: LABORATORY #2 ENZYME CATALYSIS

After an enzyme is mixed with its substrate, the amount of product

formed is determined at 10-second intervals for 1 minute. Data from this

experiment are shown below.

Time (sec) 0 10 20 30 40 50 60

Product formed (mg) 0.00 0.25 0.50 0.70 0.80 0.85 0.85

Draw a graph of these data and answer the following questions.

a. What is the initial rate of this enzymatic reaction?

b. What is the rate after 50 seconds? Why is it different from the

initial rate?

c. What would be the effect on product formation if the enzyme were

heated to a temperature of 100 oC for 10 minutes before repeating

the experiment? Why?

d. How might altering the substrate concentration affect the rate of

the reaction? Why?

e. How might altering the pH affect the rate of reaction? Why?

im really stuck and i dont understand, could you please explain each of them

Relevance
• Anonymous
10 years ago

I'm stuck too, because when I drew the graph the marker just defaced my monitor and didn't put the picture onto Yahoo Answers.

a. The initial rate is 0.025 mg / sec.

This is just the amount formed at time t=10 seconds divided by 10 seconds.

b. The rate at 50 seconds is 0.005 mg / sec.

This is the amount formed at time t=50 - the amount formed at time t=40 divided by 10 seconds.

It is different from the initial rate due to depletion of substrate -- there's a much lower substrate concentration remaining, so substrate is, at t=50, much less likely to bump into the enzyme.

c. I would expect there to be virtually no product formed if the enzyme had been heated to 100 degrees celsius first, depending on these factors:

1) How well the reaction proceeds without the enzyme. I have assumed that it doesn't proceed at all at experimental temperatures.

2) I have assumed that the enzyme will be denatured by heating to 100 degrees celsius (i.e. it is not an thermophile extremophile's enzyme).

==

Denaturing the enzyme changes its 3D configuration. I have assumed that the enzyme will have been irreversibly denatured, i.e. unable to return to an active configuration following the period of heating and cooling. Without the proper 3D configuration the enzyme's active site area will no longer be of the proper shape to interact with the substrate.

d. Increasing the concentration of the substrate will have the reaction retain the initial rate for a longer period.

I have assumed that the enzyme concentration is at a level where in our original experiment, all the enzyme molecules were "in use" at time t=10.

So, increasing the concentration of substrate will keep all the enzyme molecules busy for a longer period of time.

Decreasing the amount of substrate will cause the reaction to have a lower rate of product formation. With a lower concentration of substrate, it's less likely for substrate molecule to bump into enzyme molecule.

e. Changing the pH will probably decrease the rate of reaction. Enzymes operate within an optimal pH range. I have assumed that we're changing to the pH to be outside the optimal pH range for this particular enzyme.

• 4 years ago

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