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9 Dec 2025
•
Understanding Cell Structure in Biology
A
amena.msbegum
@amena.msbegum
1 / 10
Course Overview and Specification
This AQA Biology unit dives into the fascinating world of cell structure, covering everything you need to ace your exams. You'll explore three main areas: eukaryotic cells (like yours), prokaryotic cells (bacteria), and how scientists study cells using microscopes.
The course breaks down into manageable chunks with specific lesson targets and exam questions. Each section builds on the previous one, starting with complex eukaryotic cells before moving to simpler prokaryotic structures and viruses.
You'll also master practical skills like using microscopes and calculating magnification - essential techniques that often appear in exam questions. The final section covers advanced laboratory methods like ultracentrifugation, showing how scientists separate different cell components.
Quick Tip: Pay attention to the lesson structure - each section has specific mark allocations that hint at exam importance.
Key Cell Types and Structures
Eukaryotic cells are the complex cells found in plants, animals, and fungi. They're packed with membrane-bound organelles like the nucleus, mitochondria, and Golgi apparatus. In plants, you'll also find chloroplasts and cell walls made of cellulose.
These cells can become highly specialised for specific jobs - think muscle cells for movement or red blood cells for oxygen transport. This specialisation follows a hierarchy: cells form tissues, tissues form organs, and organs form complete systems.
Prokaryotic cells (bacteria) are much simpler and smaller. Instead of a nucleus, their DNA floats freely in the cytoplasm as a circular molecule. They have smaller ribosomes and cell walls made of murein rather than cellulose.
Viruses aren't even proper cells - they're just genetic material wrapped in a protein coat called a capsid. They can't survive on their own and need to hijack other cells to reproduce.
Remember: The key difference is membrane-bound organelles - eukaryotes have them, prokaryotes don't!
Microscopy and Key Terms
Understanding magnification versus resolution is crucial for your exams. Magnification is how much bigger something appears, whilst resolution is how much detail you can actually see.
Optical microscopes use light and can magnify up to about 1500x, but they're limited by light wavelengths. Electron microscopes use electron beams instead, giving much higher magnification and resolution - perfect for seeing organelles in detail.
There are two types of electron microscopes: transmission electron microscopes (TEM) show internal structures, whilst scanning electron microscopes (SEM) create detailed 3D surface images.
Cell fractionation and ultracentrifugation allow scientists to separate different cell components by spinning them at incredibly high speeds. Heavier organelles settle out first, followed by lighter ones.
Exam Focus: You must know the magnification formula: Magnification = Image size ÷ Actual size
Essential Vocabulary
This comprehensive key word list covers all the technical terms you'll encounter in cell structure topics. Master these definitions and you'll handle any exam question with confidence.
Key transport terms include carrier proteins for facilitated diffusion and ion channels that allow specific particles through membranes. Understanding isotonic solutions helps explain why cells maintain their shape.
Differentiation explains how cells become specialised, whilst mitosis and meiosis describe different types of cell division. Metabolism encompasses all chemical processes in living organisms.
Plant-specific terms like phloem, xylem, and stomata relate to transport and gas exchange. Chloroplasts contain thylakoids and grana where photosynthesis occurs.
Study Tip: Don't just memorise - understand how these terms connect to create living systems.
Eukaryotic Cell Organelles
Eukaryotic cells contain numerous organelles, each with specific functions that keep the cell alive and working efficiently. Learning these structures and their jobs is essential for understanding how complex life forms operate.
The nucleus controls the cell and contains DNA organised into chromosomes. Mitochondria are the powerhouses, producing energy through respiration with their folded inner membranes called cristae.
Ribosomes make proteins either freely in the cytoplasm or attached to the rough endoplasmic reticulum (RER). The smooth endoplasmic reticulum (SER) lacks ribosomes and handles lipid synthesis instead.
The Golgi apparatus modifies and packages proteins from the ER, whilst lysosomes digest waste materials. Plant cells additionally have chloroplasts for photosynthesis and cell walls made of cellulose for support.
Memory Trick: Think of the cell as a factory - each organelle has a specific job in the production line!
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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
Understanding Cell Structure in Biology
A
amena.msbegum
@amena.msbegum
Ever wondered what goes on inside every cell in your body? Cell structure is fundamental to understanding how life works, from the tiniest bacteria to complex organisms like yourself. This topic covers the key differences between cell types and how... Show more
Course Overview and Specification
This AQA Biology unit dives into the fascinating world of cell structure, covering everything you need to ace your exams. You'll explore three main areas: eukaryotic cells (like yours), prokaryotic cells (bacteria), and how scientists study cells using microscopes.
The course breaks down into manageable chunks with specific lesson targets and exam questions. Each section builds on the previous one, starting with complex eukaryotic cells before moving to simpler prokaryotic structures and viruses.
You'll also master practical skills like using microscopes and calculating magnification - essential techniques that often appear in exam questions. The final section covers advanced laboratory methods like ultracentrifugation, showing how scientists separate different cell components.
Quick Tip: Pay attention to the lesson structure - each section has specific mark allocations that hint at exam importance.
Sign up to see the contentIt's free!
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Key Cell Types and Structures
Eukaryotic cells are the complex cells found in plants, animals, and fungi. They're packed with membrane-bound organelles like the nucleus, mitochondria, and Golgi apparatus. In plants, you'll also find chloroplasts and cell walls made of cellulose.
These cells can become highly specialised for specific jobs - think muscle cells for movement or red blood cells for oxygen transport. This specialisation follows a hierarchy: cells form tissues, tissues form organs, and organs form complete systems.
Prokaryotic cells (bacteria) are much simpler and smaller. Instead of a nucleus, their DNA floats freely in the cytoplasm as a circular molecule. They have smaller ribosomes and cell walls made of murein rather than cellulose.
Viruses aren't even proper cells - they're just genetic material wrapped in a protein coat called a capsid. They can't survive on their own and need to hijack other cells to reproduce.
Remember: The key difference is membrane-bound organelles - eukaryotes have them, prokaryotes don't!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Microscopy and Key Terms
Understanding magnification versus resolution is crucial for your exams. Magnification is how much bigger something appears, whilst resolution is how much detail you can actually see.
Optical microscopes use light and can magnify up to about 1500x, but they're limited by light wavelengths. Electron microscopes use electron beams instead, giving much higher magnification and resolution - perfect for seeing organelles in detail.
There are two types of electron microscopes: transmission electron microscopes (TEM) show internal structures, whilst scanning electron microscopes (SEM) create detailed 3D surface images.
Cell fractionation and ultracentrifugation allow scientists to separate different cell components by spinning them at incredibly high speeds. Heavier organelles settle out first, followed by lighter ones.
Exam Focus: You must know the magnification formula: Magnification = Image size ÷ Actual size
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Essential Vocabulary
This comprehensive key word list covers all the technical terms you'll encounter in cell structure topics. Master these definitions and you'll handle any exam question with confidence.
Key transport terms include carrier proteins for facilitated diffusion and ion channels that allow specific particles through membranes. Understanding isotonic solutions helps explain why cells maintain their shape.
Differentiation explains how cells become specialised, whilst mitosis and meiosis describe different types of cell division. Metabolism encompasses all chemical processes in living organisms.
Plant-specific terms like phloem, xylem, and stomata relate to transport and gas exchange. Chloroplasts contain thylakoids and grana where photosynthesis occurs.
Study Tip: Don't just memorise - understand how these terms connect to create living systems.
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By signing up you accept Terms of Service and Privacy Policy
Eukaryotic Cell Organelles
Eukaryotic cells contain numerous organelles, each with specific functions that keep the cell alive and working efficiently. Learning these structures and their jobs is essential for understanding how complex life forms operate.
The nucleus controls the cell and contains DNA organised into chromosomes. Mitochondria are the powerhouses, producing energy through respiration with their folded inner membranes called cristae.
Ribosomes make proteins either freely in the cytoplasm or attached to the rough endoplasmic reticulum (RER). The smooth endoplasmic reticulum (SER) lacks ribosomes and handles lipid synthesis instead.
The Golgi apparatus modifies and packages proteins from the ER, whilst lysosomes digest waste materials. Plant cells additionally have chloroplasts for photosynthesis and cell walls made of cellulose for support.
Memory Trick: Think of the cell as a factory - each organelle has a specific job in the production line!
Sign up to see the contentIt's free!
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Sign up to see the contentIt's free!
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Sign up to see the contentIt's free!
Access to all documents
Improve your grades
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Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
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Sign up to see the contentIt's free!
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Improve your grades
Join milions of students
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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?
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: Organelle
Most popular content in Biology
Most popular content
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
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 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