Enzymes 2.5

  2. 02 Molecular biology
  3. Enzymes 2.5
    4. 30'
Enzymes control almost everything which happens inside the cells of all living organisms.  In this topic we consider how enzymes make reactions faster as well as the effects of different environmental factors on the rate of enzyme controlled reactions. There are many industrial uses of enzymes, including washing powder, lactose free milk, and clear fruit juice.

Key concepts

Learn and test your biological vocabulary for 2.5 Enzymes using these flashcards 

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Essentials

These slides summarise the essential understanding and skills in this topic. 
They contain short explanations in text and images - good revision for all students.

These slides summarise the essential understanding and skills in this topic. 
They contain short explanations in text and images - great revision.

Read the slides and look up any words or details you find difficult to understand.

Summary

Summary list for 2.5 Enzymes

  • The role of the active site where specific substrates bind.
  • The effect of the motion of molecules and the collision of substrates with the active site.
  • The effect of Temperature, pH and substrate concentration on the rate of activity of enzymes. (including denaturing)
  • Enzymes (often immobilised) are extensively used in industry for the production of items including Lactose-free milk, fruit juice and washing powder.
  • Advantages of lactose-free milk, and ways of producing it, including immobilization in alginate beads.
  • Knowledge of possible designs of experiments to test the effect of temperature, pH and substrate concentration on enzyme activity.
  • Practical 3: Investigation of a factor affecting enzyme activity.
  • The skill of sketching a graph of expected results in enzymes experiments and the ability to explain reasons for their shapes.

Mindmaps

This diagram summaries the main sections of topic 2.5
Test if you can draw something like these concept maps yourself from memory.

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Exam style questions

Exam style question about enzyme experiments.

Understanding how to design experiments to test the rate of activity of enzymes is important in this topic.

Answer the question below on a piece of paper, then check your answer with the model answer.

Explain why it is important to keep factors such as; enzyme concentration, substrate concentration, and temperature constant when designing the method for an experiment to measure the effect of pH on the rate of an enzyme catalysed reaction. [4]

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Click the + icon to see a model answer.

Extra exam question on the lock and key model of enzymes

Exam style question about the lock and key model.

This question tests a student's knowledge of the lock and key model, and also their ability to use it to explain enzyme specificity.

Outline the lock and key model of enzyme function, including the reason why enzymes are usually substrate specific. [4]

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Click the + icon to see a model answer. 

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Test yourself

Multiple choice questions

This is a self marking quiz containing questions covering the topic outlined above.
Try the questions to check your understanding.


START QUIZ!

Drag and drop activities

Test your ability to construct biological explanations using the drag and drop questions below.

Enzyme functions and pH

Drag and drop the correct term into the gap to describe how pH can affect enzyme function.

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extremophiles stomach optimum above or below damaged (neutral) maximal active site denatured

An enzyme has an pH at which the reaction rate is , the rate drops when the pH is a little the optimum. At too high or low a pH, bonds in the protein are and the shape of the changes and the enzyme becomes .

Most enzymes have an optimum pH of around 7 but stomach pepsin has an optimum of pH 2 (the pH of the ).

There are organisms adapted to extreme pH and temperatures, , which have enzymes that are also adapted to that environment.

Examiner hint. You could include a graph in your response to this question.

Extra drag and drop explanation on controlling variables in ennzyme investigations click the '+' symbol to open it.

 

Enzyme investigation variables.

Drag and drop the correct term into the gap to describe the control of variables in enzyme investigations.

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controlled substrate decrease independent volumes concentration pH broken down concentrations drops

When carrying out an enzyme experiment, there are four variables to be considered which can either be the variable or the variables.

The four variables are enzyme , concentration, and temperature.

In practice, of enzyme and substrate solutions must also be kept constant as these affect .

During an enzyme-controlled reaction in vitro (laboratory conditions), as the substrate is , it’s concentration , and the reaction rate will gradually until all the substrate has been used up.

Examiner hint. You also need to be able to explain why these variables affect the rate of enzyme controlled reactions.

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Extra drag and drop explanation enzyme reaction rates  click the '+' symbol to open it.

Enzyme reaction rates and concentrations of enzyme and substrate.

Drag and drop the correct term into the gap to describe enzyme reaction rates.

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enzyme active sites constant plateau occupied fully increase substrate available

In a reaction in the laboratory between an enzyme and a substrate:

If the concentration is increased at a enzyme concentration, then the rate of the reaction will until all the enzyme are continually after which the rate will (stay the same).

If the concentration is increased at a constant substrate concentration, the reaction rate will increase due to their being more active sites until a plateau is reached when the active sites are occupied.

Explanation/Examiner hint. Substrate and enzyme concentration can affect the rate of an enzyme reaction in laboratory conditions (and in living organisms).

 

Just for fun

If you want to review key terminology and have some fun with your revision try this.

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MY PROGRESS

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