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23 Jan 2026
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Understanding Enzymes in Biology
Hannah
@hannah_studys1012
1 / 3
Enzyme Structure and Function
Ever wondered why enzymes are so picky about what they work with? It's all about shape and complementary binding. Enzymes have a specific active site where substrates bind, and this shape determines exactly which reactions they can catalyse.
You'll find intracellular enzymes working inside organelles like chloroplasts and mitochondria, whilst extracellular enzymes like lipase and amylase get secreted outside cells to break down food during digestion.
The induced fit hypothesis explains how enzymes actually change shape slightly when substrates approach, ensuring the perfect fit. This is much more accurate than the old lock-and-key model because the enzyme (unlike a lock) gets altered during the process.
Cofactors are enzyme helpers you need to know about. Prosthetic groups like iron, zinc, and copper stay permanently attached, whilst coenzymes such as ATP and NAD bind temporarily to help reactions happen.
💡 Remember: Haemoglobin contains iron in its haem group - a perfect example of a prosthetic group in action!
Factors Affecting Enzyme Activity
Temperature dramatically affects enzyme performance, and there's a neat pattern to remember. As temperature increases, so does the reaction rate until you hit the optimum temperature - this happens because higher kinetic energy means more successful collisions.
The Q₁₀ coefficient shows that reaction rates typically double every 10°C rise. However, beyond the optimum, enzymes denature as bonds in their protein structure break, causing the active site to lose its shape.
Enzyme concentration and substrate concentration follow similar patterns - increasing either boosts the reaction rate until one becomes the limiting factor. When the graph flattens out, you've found your bottleneck.
pH changes can be deadly for enzymes since extreme conditions break protein bonds. Different enzymes have wildly different optima - pepsin loves acidic conditions (pH 3) whilst amylase prefers neutral to slightly alkaline .
Competitive inhibition occurs when inhibitor molecules race substrates for the active site, whilst non-competitive inhibition involves inhibitors binding elsewhere and changing the active site's shape. The key difference? You can overcome competitive inhibition by adding more substrate, but non-competitive inhibition reduces the maximum possible reaction rate.
💡 Exam tip: If increasing substrate concentration doesn't help, you're dealing with non-competitive inhibition!
Enzyme Inhibition in Action
Real-world enzyme inhibition can be absolutely lethal, making this topic more relevant than you might think. Cyanide poisoning demonstrates irreversible inhibition at its most dangerous.
Potassium cyanide (KCN) blocks cytochrome c oxidase, the final enzyme in aerobic respiration's electron transport chain. It also inhibits catalase, effectively shutting down cellular energy production and causing rapid death.
Snake venom works differently by targeting neurotransmission. It inhibits chemicals that normally diffuse across nerve synapses, leading to constant muscle contraction and eventual paralysis of breathing muscles.
⚠️ Real-world connection: Understanding enzyme inhibition helps explain how many poisons and medicines actually work in the body!
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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
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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
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Best app on earth! no words because it’s too good
Thomas R
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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.
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
Understanding Enzymes in Biology
Hannah
@hannah_studys1012
Enzymes are biological catalysts that speed up chemical reactions by lowering activation energy, and they're absolutely crucial for life processes. Understanding how their shape determines function and what affects their activity will help you tackle those tricky A-level Biology exam... Show more
Enzyme Structure and Function
Ever wondered why enzymes are so picky about what they work with? It's all about shape and complementary binding. Enzymes have a specific active site where substrates bind, and this shape determines exactly which reactions they can catalyse.
You'll find intracellular enzymes working inside organelles like chloroplasts and mitochondria, whilst extracellular enzymes like lipase and amylase get secreted outside cells to break down food during digestion.
The induced fit hypothesis explains how enzymes actually change shape slightly when substrates approach, ensuring the perfect fit. This is much more accurate than the old lock-and-key model because the enzyme (unlike a lock) gets altered during the process.
Cofactors are enzyme helpers you need to know about. Prosthetic groups like iron, zinc, and copper stay permanently attached, whilst coenzymes such as ATP and NAD bind temporarily to help reactions happen.
💡 Remember: Haemoglobin contains iron in its haem group - a perfect example of a prosthetic group in action!
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Factors Affecting Enzyme Activity
Temperature dramatically affects enzyme performance, and there's a neat pattern to remember. As temperature increases, so does the reaction rate until you hit the optimum temperature - this happens because higher kinetic energy means more successful collisions.
The Q₁₀ coefficient shows that reaction rates typically double every 10°C rise. However, beyond the optimum, enzymes denature as bonds in their protein structure break, causing the active site to lose its shape.
Enzyme concentration and substrate concentration follow similar patterns - increasing either boosts the reaction rate until one becomes the limiting factor. When the graph flattens out, you've found your bottleneck.
pH changes can be deadly for enzymes since extreme conditions break protein bonds. Different enzymes have wildly different optima - pepsin loves acidic conditions (pH 3) whilst amylase prefers neutral to slightly alkaline .
Competitive inhibition occurs when inhibitor molecules race substrates for the active site, whilst non-competitive inhibition involves inhibitors binding elsewhere and changing the active site's shape. The key difference? You can overcome competitive inhibition by adding more substrate, but non-competitive inhibition reduces the maximum possible reaction rate.
💡 Exam tip: If increasing substrate concentration doesn't help, you're dealing with non-competitive inhibition!
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Enzyme Inhibition in Action
Real-world enzyme inhibition can be absolutely lethal, making this topic more relevant than you might think. Cyanide poisoning demonstrates irreversible inhibition at its most dangerous.
Potassium cyanide (KCN) blocks cytochrome c oxidase, the final enzyme in aerobic respiration's electron transport chain. It also inhibits catalase, effectively shutting down cellular energy production and causing rapid death.
Snake venom works differently by targeting neurotransmission. It inhibits chemicals that normally diffuse across nerve synapses, leading to constant muscle contraction and eventual paralysis of breathing muscles.
⚠️ Real-world connection: Understanding enzyme inhibition helps explain how many poisons and medicines actually work in the body!
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?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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Most popular content: Enzymes
Most popular content in Biology
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Can't find what you're looking for? Explore other subjects.
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4.9/5
App Store
4.8/5
Google Play
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