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14 Jan 2026
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Understanding Enzymes: Active Sites, Induced Fit Model, and Temperature Effects - AQA Biology
Azelya Comak
@azelyacomak_
1 / 4
Factors Affecting Enzyme Activity
This page discusses various factors that influence enzyme activity, including temperature, pH, and substrate concentration.
Temperature Effects
Enzymes allow reactions to occur at lower temperatures than they would without the enzyme present. They do this by:
- Holding substrates close together, reducing repulsion and facilitating bonding.
- Putting strain on substrate bonds, making them easier to break.
Highlight: Understanding the effect of temperature on enzyme activity is crucial for AQA GCSE Biology enzymes exam questions.
However, excessive heat can lead to enzyme denaturation:
Definition: Denaturing occurs when hydrogen bonds break and the tertiary structure of the enzyme unfolds, rendering the active site non-complementary to the substrate.
pH Effects
The page includes graphs showing the relationship between enzyme activity and pH:
- A bell-shaped curve illustrating the optimum pH for enzyme activity.
- A logarithmic scale graph showing enzyme activity across a wider pH range.
Example: The effect of pH on enzyme activity can be demonstrated through practical experiments, often featured in AQA A Level Biology enzymes exam questions.
Enzyme and Substrate Concentration
Graphs illustrate how enzyme and substrate concentrations affect reaction rates:
- Enzyme concentration: Initially, increasing enzyme concentration increases reaction rate linearly until substrate becomes a limiting factor.
- Substrate concentration: Reaction rate increases with substrate concentration until enzyme saturation occurs.
Vocabulary: A limiting factor is a variable that constrains the rate of a reaction when other factors are in excess.
Enzyme Inhibitors
This page focuses on enzyme inhibitors, which are substances that reduce enzyme activity.
Types of Inhibitors
There are two main types of reversible inhibitors:
-
Competitive Inhibitors
- Have a similar shape to the substrate
- Can occupy the enzyme's active site
- Compete with the substrate for binding
- Inhibition depends on relative concentrations of substrate and inhibitor
-
Non-competitive Inhibitors
- Attach to enzymes away from the active site
- Alter the shape of the active site
- Not in direct competition with the substrate
- Adding more substrate does not decrease their effect
Highlight: Understanding enzyme inhibitors is crucial for AQA A Level Biology students, as it's often featured in exam questions and practical assessments.
Key Points About Enzymes
The page concludes with a summary of essential enzyme characteristics:
- Enzymes are biological catalysts made of globular proteins
- They lower activation energy without being consumed in the reaction
- Enzymes bind to substrates via their complementary active site
- This binding forms an enzyme-substrate complex
Example: The induced fit model vs lock and key comparison is a common topic in A Level Biology courses, illustrating different theories of enzyme-substrate interaction.
Vocabulary: The enzyme-substrate complex is the temporary structure formed when an enzyme binds to its specific substrate during a reaction.
Enzyme Structure and Function
Enzymes are biological catalysts made of globular proteins that play a crucial role in facilitating biochemical reactions. They maintain their highly specific shape through chemical bonds such as hydrogen bonds, ionic bonds, and disulphide bridges.
Definition: Enzymes are biological catalysts that speed up chemical reactions without being permanently changed in the process.
The active site of an enzyme is formed by a small number of amino acids in the polypeptide chains, but the overall shape is determined by the entire amino acid sequence and the bonds formed during protein folding.
Highlight: Enzymes can be found both intracellularly and extracellularly, participating in anabolic (building) and catabolic (breaking) reactions.
Collision Theory and Enzyme Action
Collision theory explains how enzymes work at the molecular level:
- Molecules move randomly due to kinetic energy.
- Reactions occur when molecules collide with sufficient energy to overcome the activation energy barrier.
- Enzymes lower this activation energy, making reactions more likely to occur.
Example: In the induced fit model of enzyme action, the enzyme's shape changes slightly to accommodate the substrate, forming an enzyme-substrate complex. This model is crucial for understanding enzyme active site interaction in AQA Biology GCSE and A-level.
Enzyme Action Diagram
The document includes a diagram illustrating enzyme action, comparing the energy profiles of reactions with and without enzymes. It shows how enzymes lower the activation energy required for a reaction to occur.
Vocabulary: Activation energy is the minimum energy required for a chemical reaction to take place.
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Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
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This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Understanding Enzymes: Active Sites, Induced Fit Model, and Temperature Effects - AQA Biology
Azelya Comak
@azelyacomak_
Enzymes are biological catalysts that speed up chemical reactions in living organisms without being consumed in the process. They play a vital role in essential life processes.
The induced fit model of enzyme actionexplains how enzymes work through a... Show more
Factors Affecting Enzyme Activity
This page discusses various factors that influence enzyme activity, including temperature, pH, and substrate concentration.
Temperature Effects
Enzymes allow reactions to occur at lower temperatures than they would without the enzyme present. They do this by:
- Holding substrates close together, reducing repulsion and facilitating bonding.
- Putting strain on substrate bonds, making them easier to break.
Highlight: Understanding the effect of temperature on enzyme activity is crucial for AQA GCSE Biology enzymes exam questions.
However, excessive heat can lead to enzyme denaturation:
Definition: Denaturing occurs when hydrogen bonds break and the tertiary structure of the enzyme unfolds, rendering the active site non-complementary to the substrate.
pH Effects
The page includes graphs showing the relationship between enzyme activity and pH:
- A bell-shaped curve illustrating the optimum pH for enzyme activity.
- A logarithmic scale graph showing enzyme activity across a wider pH range.
Example: The effect of pH on enzyme activity can be demonstrated through practical experiments, often featured in AQA A Level Biology enzymes exam questions.
Enzyme and Substrate Concentration
Graphs illustrate how enzyme and substrate concentrations affect reaction rates:
- Enzyme concentration: Initially, increasing enzyme concentration increases reaction rate linearly until substrate becomes a limiting factor.
- Substrate concentration: Reaction rate increases with substrate concentration until enzyme saturation occurs.
Vocabulary: A limiting factor is a variable that constrains the rate of a reaction when other factors are in excess.
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Enzyme Inhibitors
This page focuses on enzyme inhibitors, which are substances that reduce enzyme activity.
Types of Inhibitors
There are two main types of reversible inhibitors:
-
Competitive Inhibitors
- Have a similar shape to the substrate
- Can occupy the enzyme's active site
- Compete with the substrate for binding
- Inhibition depends on relative concentrations of substrate and inhibitor
-
Non-competitive Inhibitors
- Attach to enzymes away from the active site
- Alter the shape of the active site
- Not in direct competition with the substrate
- Adding more substrate does not decrease their effect
Highlight: Understanding enzyme inhibitors is crucial for AQA A Level Biology students, as it's often featured in exam questions and practical assessments.
Key Points About Enzymes
The page concludes with a summary of essential enzyme characteristics:
- Enzymes are biological catalysts made of globular proteins
- They lower activation energy without being consumed in the reaction
- Enzymes bind to substrates via their complementary active site
- This binding forms an enzyme-substrate complex
Example: The induced fit model vs lock and key comparison is a common topic in A Level Biology courses, illustrating different theories of enzyme-substrate interaction.
Vocabulary: The enzyme-substrate complex is the temporary structure formed when an enzyme binds to its specific substrate during a reaction.
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Enzyme Structure and Function
Enzymes are biological catalysts made of globular proteins that play a crucial role in facilitating biochemical reactions. They maintain their highly specific shape through chemical bonds such as hydrogen bonds, ionic bonds, and disulphide bridges.
Definition: Enzymes are biological catalysts that speed up chemical reactions without being permanently changed in the process.
The active site of an enzyme is formed by a small number of amino acids in the polypeptide chains, but the overall shape is determined by the entire amino acid sequence and the bonds formed during protein folding.
Highlight: Enzymes can be found both intracellularly and extracellularly, participating in anabolic (building) and catabolic (breaking) reactions.
Collision Theory and Enzyme Action
Collision theory explains how enzymes work at the molecular level:
- Molecules move randomly due to kinetic energy.
- Reactions occur when molecules collide with sufficient energy to overcome the activation energy barrier.
- Enzymes lower this activation energy, making reactions more likely to occur.
Example: In the induced fit model of enzyme action, the enzyme's shape changes slightly to accommodate the substrate, forming an enzyme-substrate complex. This model is crucial for understanding enzyme active site interaction in AQA Biology GCSE and A-level.
Enzyme Action Diagram
The document includes a diagram illustrating enzyme action, comparing the energy profiles of reactions with and without enzymes. It shows how enzymes lower the activation energy required for a reaction to occur.
Vocabulary: Activation energy is the minimum energy required for a chemical reaction to take place.
Sign up to see the contentIt's free!
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Improve your grades
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We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
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The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user