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Prokaryotic Cells & Viruses Notes for AQA A-Level Biology
Prokaryotic Cells and Viral Structure
Prokaryotic cells are fundamentally different from the cells in your body - they're like stripped-down versions without many of the fancy compartments you'd find in human cells. The cytoplasm contains no membrane-bound organelles, just smaller ribosomes floating about doing their protein-making job.
The plasma membrane acts as the cell's bouncer, controlling what gets in and out through its mix of lipids and proteins. Surrounding this is the cell wall made of glycoprotein murein, which keeps the cell's shape intact and provides crucial support.
Instead of a proper nucleus, prokaryotic DNA just floats freely in the cytoplasm as one long, coiled circular strand - no histone proteins attached. Plasmids are brilliant little extras: small DNA loops that carry handy genes like antibiotic resistance and can be shared between cells like trading cards.
Some prokaryotes have a flagellum - essentially a biological propeller that spins to help them swim around. Others sport a capsule made of slime that acts like armour against immune system attacks.
Quick Tip: Remember that prokaryotes lack a nucleus - the name literally means "before nucleus"!
Binary Fission and Viruses
Binary fission is how prokaryotes reproduce - it's much simpler than the complex cell division you'll learn about in eukaryotes. The circular DNA and plasmids copy themselves first, then the cell grows larger and splits the genetic material to opposite ends before dividing completely into two daughter cells.
Viruses are in a league of their own - they're not even technically alive! They're basically genetic material (DNA or RNA) wrapped in a protein coat called a capsid, with attachment proteins sticking out like keys looking for the right lock.
Viruses are masters of deception. They use their attachment proteins to bind to specific receptor proteins on host cells - this is why some viruses only infect certain cell types. Once attached, they inject their genetic material and essentially turn the host cell into a virus-making factory.
Exam Focus: Understanding how viruses target specific cells through protein recognition is crucial for explaining why different viruses cause different diseases.
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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
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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 itโs 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 didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm 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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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
Prokaryotic Cells & Viruses Notes for AQA A-Level Biology
Ever wondered what makes bacteria so different from your own cells, or how viruses manage to hijack our bodies? Understanding prokaryotic cells and viruses is crucial for grasping how life works at its most basic level - and it's essential... Show more
Prokaryotic Cells and Viral Structure
Prokaryotic cells are fundamentally different from the cells in your body - they're like stripped-down versions without many of the fancy compartments you'd find in human cells. The cytoplasm contains no membrane-bound organelles, just smaller ribosomes floating about doing their protein-making job.
The plasma membrane acts as the cell's bouncer, controlling what gets in and out through its mix of lipids and proteins. Surrounding this is the cell wall made of glycoprotein murein, which keeps the cell's shape intact and provides crucial support.
Instead of a proper nucleus, prokaryotic DNA just floats freely in the cytoplasm as one long, coiled circular strand - no histone proteins attached. Plasmids are brilliant little extras: small DNA loops that carry handy genes like antibiotic resistance and can be shared between cells like trading cards.
Some prokaryotes have a flagellum - essentially a biological propeller that spins to help them swim around. Others sport a capsule made of slime that acts like armour against immune system attacks.
Quick Tip: Remember that prokaryotes lack a nucleus - the name literally means "before nucleus"!
Binary Fission and Viruses
Binary fission is how prokaryotes reproduce - it's much simpler than the complex cell division you'll learn about in eukaryotes. The circular DNA and plasmids copy themselves first, then the cell grows larger and splits the genetic material to opposite ends before dividing completely into two daughter cells.
Viruses are in a league of their own - they're not even technically alive! They're basically genetic material (DNA or RNA) wrapped in a protein coat called a capsid, with attachment proteins sticking out like keys looking for the right lock.
Viruses are masters of deception. They use their attachment proteins to bind to specific receptor proteins on host cells - this is why some viruses only infect certain cell types. Once attached, they inject their genetic material and essentially turn the host cell into a virus-making factory.
Exam Focus: Understanding how viruses target specific cells through protein recognition is crucial for explaining why different viruses cause different diseases.
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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 itโs 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
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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 didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm 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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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 itโs 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 didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm 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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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