New
New
Year 10
OCR
Foundation

The effect of pH on the rate of an enzyme reaction: data analysis

I can analyse and explain data from an investigation into the effect of changing pH on the rate of an enzyme reaction.

New
New
Year 10
OCR
Foundation

The effect of pH on the rate of an enzyme reaction: data analysis

I can analyse and explain data from an investigation into the effect of changing pH on the rate of an enzyme reaction.

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Lesson details

Key learning points

  1. Interpretation of graphs showing data from an investigation of the effect of pH on the rate of an enzyme reaction.
  2. Consideration of whether the data increase or decrease confidence in the original prediction or hypothesis.
  3. Enzyme reaction rate is highest at an optimum pH, at which all active sites are full.
  4. Enzyme reaction rate decreases at pH values below and above the optimum as the active site becomes denatured.

Common misconception

As pH increases above the optimum, enzymes denature and reaction rate falls, but this is not what happens at pHs below the optimum, so the graph and explanation resemble temperature.

The process of denaturing an enzyme is explored in detail, and a graph of reaction rate is explained carefully to make it clear that the changes to rate occur above and below the optimum pH.

Keywords

  • Rate of reaction - How fast a chemical reaction occurs.

  • PH - A measure of how acidic or alkaline a solution is.

  • End point - The point at which the chemical reaction has finished.

  • Active site - The part of an enzyme where the substrate binds.

  • Denatured - A permanent change in the shape of an enzyme which stops it from working.

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Video

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6 Questions

Q1.
What is iodine used to test for the presence of?
Correct Answer: Starch
Q2.
Which piece of equipment would you use in this practical to heat the test tubes of starch and amylase to a specific temperature?
Bunsen burner
autoclave
kettle
Correct answer: water bath
microwave
Q3.
Which of these are examples of continuous sampling?
Taking a before and after sample.
Taking a sample when something changes.
Correct answer: Taking a sample every minute.
Correct answer: Taking a sample every 30 seconds.
Taking a sample at 10 100 and 1000 seconds.
Q4.
What does amylase break starch down into?
lactose
fructose
Correct answer: maltose
maltase
amylose
Q5.
What is this piece of equipment called?
An image in a quiz
Correct Answer: Spotting tile
Q6.
Which numbered dimple(s) shows that all the starch has been digested?
An image in a quiz
1
8
9
Correct answer: 10

6 Questions

Q1.
Which statement defines the term ‘rate of reaction’?
How much substrate is converted into product.
How long a chemical reaction takes.
Correct answer: How fast a chemical reaction occurs.
How much enzyme is used.
Q2.
Calculate the missing rate of reaction.
An image in a quiz
Correct Answer: 0.2
Q3.
On which axis would you plot the rate of a reaction, when it is plotted against pH?
x-axis
Correct answer: y-axis
Q4.
In the graph below which letter shows when an enzyme is at its optimum temperature?
An image in a quiz
a
Correct answer: b
c
Q5.
When enzyme reaction rate is at its highest all the sites are full.
An image in a quiz
Correct Answer: active
Q6.
What word describes an enzyme whose active site has changed shape due to being placed in unfavourable conditions?
Correct Answer: denature, denatured