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Understanding Prokaryotic and Eukaryotic Cells - OCR A Level Biology 2.6

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Imy

11/12/2025

Biology

A level biology - OCR - 2.6 Prokaryotic and Eukaryotic cells

220

11 Dec 2025

2 pages

Understanding Prokaryotic and Eukaryotic Cells - OCR A Level Biology 2.6

Every living thing is made up of cells, but not... Show more

# 2.6 Prokaryotic and eukaryotic cells

Prokaryotic cells
Among earliest forms of life, always unicellular with relatively simple structure,

Prokaryotic Cells: Life's Simple Beginnings

Prokaryotic cells are amongst the earliest forms of life on Earth and represent nature's minimalist approach to cellular design. These single-celled organisms pack everything they need into a surprisingly simple structure without the fancy compartments you'll find in more complex cells.

The most striking feature is that their DNA floats freely in the cell rather than being tucked away in a nucleus. This genetic material is typically organised as one supercoiled chromosome, with genes cleverly grouped into operons so multiple genes can be switched on or off together - think of it as a biological light switch controlling several bulbs at once.

Ribosomes in prokaryotes are smaller than their eukaryotic cousins (70S rather than 80S), but they're still perfectly capable of making proteins. The cell wall is made from peptidoglycan, a tough polymer that gives these cells their shape and protection.

Key insight: Prokaryotic flagella work differently from eukaryotic ones - they're powered by chemiosmosis rather than ATP, spinning like tiny molecular motors to propel the cell forward!

# 2.6 Prokaryotic and eukaryotic cells

Prokaryotic cells
Among earliest forms of life, always unicellular with relatively simple structure,

Eukaryotic vs Prokaryotic: The Ultimate Cellular Showdown

Eukaryotic cells are the overachievers of the cellular world, featuring complex internal organisation that makes prokaryotes look positively basic. The biggest game-changer is the nucleus, which houses DNA that's wrapped around proteins called histones to form chromatin.

This comparison isn't just academic - it explains why eukaryotes can grow into massive multicellular organisms whilst prokaryotes remain single-celled. Membrane-bound organelles in eukaryotes create specialised compartments, allowing for more sophisticated cellular processes.

The structural differences are telling: eukaryotic ribosomes are larger (80S), their DNA is linear rather than circular, and they can reproduce both sexually and asexually. Meanwhile, prokaryotes stick to binary fission and have plasmids - bonus circles of DNA that can carry useful genes.

Remember: The presence or absence of a nucleus is the defining feature - 'pro' means 'before' and 'eu' means 'true', referring to whether cells have a 'true' nucleus or not.



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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.

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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.

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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

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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

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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

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

 

Biology

220

11 Dec 2025

2 pages

Understanding Prokaryotic and Eukaryotic Cells - OCR A Level Biology 2.6

Every living thing is made up of cells, but not all cells are created equal. Understanding the fundamental differences between prokaryotic and eukaryotic cells is crucial for grasping how life works at its most basic level - from bacteria to... Show more

# 2.6 Prokaryotic and eukaryotic cells

Prokaryotic cells
Among earliest forms of life, always unicellular with relatively simple structure,

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Prokaryotic Cells: Life's Simple Beginnings

Prokaryotic cells are amongst the earliest forms of life on Earth and represent nature's minimalist approach to cellular design. These single-celled organisms pack everything they need into a surprisingly simple structure without the fancy compartments you'll find in more complex cells.

The most striking feature is that their DNA floats freely in the cell rather than being tucked away in a nucleus. This genetic material is typically organised as one supercoiled chromosome, with genes cleverly grouped into operons so multiple genes can be switched on or off together - think of it as a biological light switch controlling several bulbs at once.

Ribosomes in prokaryotes are smaller than their eukaryotic cousins (70S rather than 80S), but they're still perfectly capable of making proteins. The cell wall is made from peptidoglycan, a tough polymer that gives these cells their shape and protection.

Key insight: Prokaryotic flagella work differently from eukaryotic ones - they're powered by chemiosmosis rather than ATP, spinning like tiny molecular motors to propel the cell forward!

# 2.6 Prokaryotic and eukaryotic cells

Prokaryotic cells
Among earliest forms of life, always unicellular with relatively simple structure,

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

Eukaryotic vs Prokaryotic: The Ultimate Cellular Showdown

Eukaryotic cells are the overachievers of the cellular world, featuring complex internal organisation that makes prokaryotes look positively basic. The biggest game-changer is the nucleus, which houses DNA that's wrapped around proteins called histones to form chromatin.

This comparison isn't just academic - it explains why eukaryotes can grow into massive multicellular organisms whilst prokaryotes remain single-celled. Membrane-bound organelles in eukaryotes create specialised compartments, allowing for more sophisticated cellular processes.

The structural differences are telling: eukaryotic ribosomes are larger (80S), their DNA is linear rather than circular, and they can reproduce both sexually and asexually. Meanwhile, prokaryotes stick to binary fission and have plasmids - bonus circles of DNA that can carry useful genes.

Remember: The presence or absence of a nucleus is the defining feature - 'pro' means 'before' and 'eu' means 'true', referring to whether cells have a 'true' nucleus or not.

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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

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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