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1 Jan 2026
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Understanding Carbohydrates in Biology
anna
@anna47
The Basics of Carbohydrates and Glucose
Carbohydrates are brilliant biological molecules that follow a simple pattern - they're made only from carbon, hydrogen, and oxygen in the formula Cx(H2O)y. Think of them as nature's building blocks that come in different sizes.
Single sugars like glucose are called monosaccharides, whilst long chains like starch are polysaccharides. Glucose is a hexose monosaccharide, meaning it's got six carbon atoms that are numbered clockwise from the oxygen when you draw its structure.
Here's where it gets interesting - glucose has two forms that look almost identical but behave differently. α-glucose has its hydroxyl group below the first carbon, while β-glucose has it above. This tiny difference makes a massive impact on what these molecules can do.
The magic happens through condensation reactions. When two glucose molecules get cosy, their hydroxyl groups react, releasing water and forming a glycosidic bond. A bond between carbon 1 and carbon 4 creates a 1-4 glycosidic bond, producing maltose - the sugar that makes your bread taste sweet.
Key Insight: Other sugars work similarly - fructose (from fruits) combines with glucose to make sucrose (table sugar), whilst galactose and glucose create lactose (milk sugar).
Starch and Glycogen - Nature's Storage Solutions
Plants are clever - they store glucose from photosynthesis as starch, which comes in two forms. Amylose is made entirely from 1-4 glycosidic bonds, creating a chain that coils up like a spring. This coiling, stabilised by hydrogen bonds, makes amylose compact and insoluble in water.
Amylopectin is more complex because it includes 1-6 glycosidic bonds roughly every 25 units. These bonds create branches, preventing the molecule from coiling but keeping it insoluble. Think of it like a tree with many branches spreading out.
Glycogen is the animal version - it's like amylopectin but with even more frequent branches. This branched structure is perfect for storage because your body can quickly add or remove glucose molecules from the branch ends when you need energy for that sprint to catch the bus.
Remember: To access stored glucose, your body uses hydrolysis reactions - basically the reverse of condensation, where enzymes help add water back to break the bonds.
Cellulose - The Structural Superhero
β-glucose creates something completely different from its α-glucose cousin. Because the hydroxyl groups are positioned differently, β-glucose molecules must flip every other one upside down to form bonds. This creates cellulose - long, straight chains that can't coil or branch.
These straight cellulose chains don't work alone. They bond together through hydrogen bonds to form microfibrils, which then bundle up into macrofibrils, and finally combine to create incredibly strong fibres. It's like making rope from individual threads - each step makes it stronger.
Cellulose fibres are brilliant for plant cell walls because they're strong and completely insoluble. They're so tough that your digestive system can barely break them down, which is why cellulose is crucial for healthy digestion - it's the fibre that keeps everything moving smoothly.
This structural strength explains why you can't digest grass like a cow can, and why eating vegetables gives you that satisfying crunch. Plants essentially build themselves from glucose in a way that creates natural reinforcement.
Fun Fact: The difference between energy-giving starch and structural cellulose all comes down to whether the glucose is in α or β form - amazing how one small change creates such different properties!
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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.
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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
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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
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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
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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 THE SCHOOLGPT. 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 THE SCHOOLGPT. 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 Carbohydrates in Biology
anna
@anna47
Ever wondered why pasta gives you energy or why plants are so tough? It's all down to carbohydrates - amazing molecules that fuel your body and give structure to plants. These biological superstars are made from just carbon, hydrogen, and... Show more
The Basics of Carbohydrates and Glucose
Carbohydrates are brilliant biological molecules that follow a simple pattern - they're made only from carbon, hydrogen, and oxygen in the formula Cx(H2O)y. Think of them as nature's building blocks that come in different sizes.
Single sugars like glucose are called monosaccharides, whilst long chains like starch are polysaccharides. Glucose is a hexose monosaccharide, meaning it's got six carbon atoms that are numbered clockwise from the oxygen when you draw its structure.
Here's where it gets interesting - glucose has two forms that look almost identical but behave differently. α-glucose has its hydroxyl group below the first carbon, while β-glucose has it above. This tiny difference makes a massive impact on what these molecules can do.
The magic happens through condensation reactions. When two glucose molecules get cosy, their hydroxyl groups react, releasing water and forming a glycosidic bond. A bond between carbon 1 and carbon 4 creates a 1-4 glycosidic bond, producing maltose - the sugar that makes your bread taste sweet.
Key Insight: Other sugars work similarly - fructose (from fruits) combines with glucose to make sucrose (table sugar), whilst galactose and glucose create lactose (milk sugar).
Starch and Glycogen - Nature's Storage Solutions
Plants are clever - they store glucose from photosynthesis as starch, which comes in two forms. Amylose is made entirely from 1-4 glycosidic bonds, creating a chain that coils up like a spring. This coiling, stabilised by hydrogen bonds, makes amylose compact and insoluble in water.
Amylopectin is more complex because it includes 1-6 glycosidic bonds roughly every 25 units. These bonds create branches, preventing the molecule from coiling but keeping it insoluble. Think of it like a tree with many branches spreading out.
Glycogen is the animal version - it's like amylopectin but with even more frequent branches. This branched structure is perfect for storage because your body can quickly add or remove glucose molecules from the branch ends when you need energy for that sprint to catch the bus.
Remember: To access stored glucose, your body uses hydrolysis reactions - basically the reverse of condensation, where enzymes help add water back to break the bonds.
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Cellulose - The Structural Superhero
β-glucose creates something completely different from its α-glucose cousin. Because the hydroxyl groups are positioned differently, β-glucose molecules must flip every other one upside down to form bonds. This creates cellulose - long, straight chains that can't coil or branch.
These straight cellulose chains don't work alone. They bond together through hydrogen bonds to form microfibrils, which then bundle up into macrofibrils, and finally combine to create incredibly strong fibres. It's like making rope from individual threads - each step makes it stronger.
Cellulose fibres are brilliant for plant cell walls because they're strong and completely insoluble. They're so tough that your digestive system can barely break them down, which is why cellulose is crucial for healthy digestion - it's the fibre that keeps everything moving smoothly.
This structural strength explains why you can't digest grass like a cow can, and why eating vegetables gives you that satisfying crunch. Plants essentially build themselves from glucose in a way that creates natural reinforcement.
Fun Fact: The difference between energy-giving starch and structural cellulose all comes down to whether the glucose is in α or β form - amazing how one small change creates such different properties!
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?
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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 THE SCHOOLGPT. 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 THE SCHOOLGPT. 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