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21 Dec 2025
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AQA A Level Biology: Eukaryotic Cell Structure Notes for Year 12
Lucy
@lucy_sldh
1 / 3
Mitochondria and Golgi Apparatus
Think of mitochondria as your cell's power stations - they're where all the energy gets made! These oval-shaped organelles have a clever double membrane design with the inner layer folded into cristae (like accordion folds) to create more surface area. Inside the matrix, special enzymes work flat out during aerobic respiration to produce ATP, which is basically your cell's currency for energy.
You'll find loads of mitochondria in really active cells like muscle cells because they need tons of energy to function properly. The more active the cell, the more mitochondria it needs - it's that simple!
The Golgi apparatus is like your cell's post office and packaging centre rolled into one. It's made up of stacked, flattened sacs called cisternae that look a bit like pancakes piled on top of each other.
Quick Tip: Remember that proteins enter at the cis face (receiving side) and leave at the trans face (shipping side) - think of it like a conveyor belt system that processes and packages lipids and proteins before sending them off to where they're needed.
Endoplasmic Reticulum and Ribosomes
The endoplasmic reticulum (ER) is basically your cell's highway system - a massive network of membranes that transport stuff around. There are two types, and they're dead easy to tell apart.
Rough ER looks bumpy because it's covered in ribosomes stuck to its surface. Its main job is folding and processing all the proteins that those ribosomes have just made - think of it as a protein finishing school where everything gets properly shaped and prepared.
Smooth ER has no ribosomes attached, so it looks, well, smooth! Instead of dealing with proteins, it focuses on making and processing lipids - the fats and oils your cell needs.
Ribosomes are the tiny protein-making machines of your cell. They're made of proteins and RNA and can either float freely in the cytoplasm or attach to the rough ER. What's interesting is they don't have a membrane around them like most other organelles.
Memory Trick: Rough ER = Ribosomes = pRotein processing. Smooth ER = Synthesises lipids. The alliteration makes it stick!
Ribosomes and Chloroplasts
Ribosomes might be small, but they're absolutely crucial - they're the site where proteins are made. Each ribosome has two parts: a large subunit and a small subunit that work together like a perfectly coordinated team to build proteins from amino acids.
Chloroplasts are the green powerhouses found only in plant cells, and they're where photosynthesis takes place. Like mitochondria, they've got a double membrane, but inside there's something really special - stacks of membranes called granum (plural: grana) connected by lamellae.
The thylakoids are where the light reactions of photosynthesis happen, whilst the stroma is where the darker reactions take place. It's like having two different workshops in the same factory!
Chloroplasts even have their own DNA and ribosomes, which suggests they might have once been independent organisms that got incorporated into plant cells millions of years ago.
Fun Fact: Chloroplasts are basically solar panels for plants - they capture sunlight and convert it into chemical energy that the whole plant can use!
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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
AQA A Level Biology: Eukaryotic Cell Structure Notes for Year 12
Lucy
@lucy_sldh
Ever wondered what makes your cells tick? Inside every eukaryotic cell, there's a bustling city of tiny structures called organelles, each with its own special job to keep you alive and healthy.
Mitochondria and Golgi Apparatus
Think of mitochondria as your cell's power stations - they're where all the energy gets made! These oval-shaped organelles have a clever double membrane design with the inner layer folded into cristae (like accordion folds) to create more surface area. Inside the matrix, special enzymes work flat out during aerobic respiration to produce ATP, which is basically your cell's currency for energy.
You'll find loads of mitochondria in really active cells like muscle cells because they need tons of energy to function properly. The more active the cell, the more mitochondria it needs - it's that simple!
The Golgi apparatus is like your cell's post office and packaging centre rolled into one. It's made up of stacked, flattened sacs called cisternae that look a bit like pancakes piled on top of each other.
Quick Tip: Remember that proteins enter at the cis face (receiving side) and leave at the trans face (shipping side) - think of it like a conveyor belt system that processes and packages lipids and proteins before sending them off to where they're needed.
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Endoplasmic Reticulum and Ribosomes
The endoplasmic reticulum (ER) is basically your cell's highway system - a massive network of membranes that transport stuff around. There are two types, and they're dead easy to tell apart.
Rough ER looks bumpy because it's covered in ribosomes stuck to its surface. Its main job is folding and processing all the proteins that those ribosomes have just made - think of it as a protein finishing school where everything gets properly shaped and prepared.
Smooth ER has no ribosomes attached, so it looks, well, smooth! Instead of dealing with proteins, it focuses on making and processing lipids - the fats and oils your cell needs.
Ribosomes are the tiny protein-making machines of your cell. They're made of proteins and RNA and can either float freely in the cytoplasm or attach to the rough ER. What's interesting is they don't have a membrane around them like most other organelles.
Memory Trick: Rough ER = Ribosomes = pRotein processing. Smooth ER = Synthesises lipids. The alliteration makes it stick!
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Ribosomes and Chloroplasts
Ribosomes might be small, but they're absolutely crucial - they're the site where proteins are made. Each ribosome has two parts: a large subunit and a small subunit that work together like a perfectly coordinated team to build proteins from amino acids.
Chloroplasts are the green powerhouses found only in plant cells, and they're where photosynthesis takes place. Like mitochondria, they've got a double membrane, but inside there's something really special - stacks of membranes called granum (plural: grana) connected by lamellae.
The thylakoids are where the light reactions of photosynthesis happen, whilst the stroma is where the darker reactions take place. It's like having two different workshops in the same factory!
Chloroplasts even have their own DNA and ribosomes, which suggests they might have once been independent organisms that got incorporated into plant cells millions of years ago.
Fun Fact: Chloroplasts are basically solar panels for plants - they capture sunlight and convert it into chemical energy that the whole plant can use!
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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
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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