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26 Nov 2025
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Understanding DNA and RNA: Structure and Functions
O
Olivia
@oliviag
1 / 3
Nucleic Acids - The Building Blocks of Life
Ever wondered how your body knows to make your heart beat or your hair grow? It's all down to nucleic acids - specifically DNA and RNA. These are polymers made up of smaller units called nucleotides, which act like molecular Lego blocks.
Think of nucleotides as having three essential parts: a phosphate group (like the backbone), a pentose sugar (the connecting piece), and a nitrogen-containing base (the information carrier). It's this simple three-part structure that creates the most complex molecules in your body.
The key difference between DNA and RNA starts with their sugars. DNA contains deoxyribose whilst RNA contains ribose - this small change makes a huge difference in how they function. Both molecules have two superpowers: they can carry instructions for your entire body and make perfect copies of themselves.
💡 Remember: Every cell in your body contains the same DNA, but different genes are switched on in different cells - that's why your liver cells are different from your brain cells!
The Four-Letter Alphabet of Life
Your genetic code uses just four letters, but these nitrogen-containing bases create infinite possibilities. There are two main families: purines (the bigger ones with double rings) and pyrimidines (the smaller ones with single rings).
The purine family includes adenine (A) and guanine (G) - think of them as the large letters in your genetic alphabet. The pyrimidines are cytosine (C), thymine (T) found only in DNA, and uracil (U) found only in RNA.
Here's where it gets clever: these bases follow strict pairing rules. In DNA, adenine always pairs with thymine and cytosine always pairs with guanine . RNA follows similar rules, except adenine pairs with uracil instead of thymine.
You can remember DNA base pairs with "Apples on a Tree" and "Car in the Garage" . This pairing system is what makes DNA replication and protein synthesis possible - it's like having a perfect molecular zip!
💡 Quick Tip: The only difference between DNA and RNA bases is that RNA swaps thymine for uracil - everything else follows the same rules!
DNA's Double Helix Structure
Picture DNA as a twisted ladder - this famous double helix structure is made from two polynucleotide strands running in opposite directions. This "antiparallel" arrangement is crucial because it allows the bases to pair up perfectly, like puzzle pieces fitting together.
The strands are held together by hydrogen bonds between complementary base pairs. Adenine-thymine pairs have 2 hydrogen bonds, whilst guanine-cytosine pairs have 3 hydrogen bonds. This difference makes G-C pairs stronger than A-T pairs.
These hydrogen bonds are strong enough to keep DNA stable, but weak enough to be broken when needed for DNA replication or protein synthesis. It's like having a zipper that's secure but can still be opened when necessary.
The antiparallel structure means one strand runs from 3' to 5' direction whilst the other runs 5' to 3'. This might seem like technical detail, but it's essential for how DNA copying works in your cells.
💡 Function Focus: DNA's main job is information storage - its long, stable structure and base-pairing rules make it perfect for storing your genetic blueprint and passing it on to the next generation!
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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 DNA and RNA: Structure and Functions
O
Olivia
@oliviag
DNA and RNA are the molecular superstars that control everything in your cells - from your eye colour to how your body fights infections. These incredible molecules are like instruction manuals written in a four-letter code that determines who you... Show more
Nucleic Acids - The Building Blocks of Life
Ever wondered how your body knows to make your heart beat or your hair grow? It's all down to nucleic acids - specifically DNA and RNA. These are polymers made up of smaller units called nucleotides, which act like molecular Lego blocks.
Think of nucleotides as having three essential parts: a phosphate group (like the backbone), a pentose sugar (the connecting piece), and a nitrogen-containing base (the information carrier). It's this simple three-part structure that creates the most complex molecules in your body.
The key difference between DNA and RNA starts with their sugars. DNA contains deoxyribose whilst RNA contains ribose - this small change makes a huge difference in how they function. Both molecules have two superpowers: they can carry instructions for your entire body and make perfect copies of themselves.
💡 Remember: Every cell in your body contains the same DNA, but different genes are switched on in different cells - that's why your liver cells are different from your brain cells!
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The Four-Letter Alphabet of Life
Your genetic code uses just four letters, but these nitrogen-containing bases create infinite possibilities. There are two main families: purines (the bigger ones with double rings) and pyrimidines (the smaller ones with single rings).
The purine family includes adenine (A) and guanine (G) - think of them as the large letters in your genetic alphabet. The pyrimidines are cytosine (C), thymine (T) found only in DNA, and uracil (U) found only in RNA.
Here's where it gets clever: these bases follow strict pairing rules. In DNA, adenine always pairs with thymine and cytosine always pairs with guanine . RNA follows similar rules, except adenine pairs with uracil instead of thymine.
You can remember DNA base pairs with "Apples on a Tree" and "Car in the Garage" . This pairing system is what makes DNA replication and protein synthesis possible - it's like having a perfect molecular zip!
💡 Quick Tip: The only difference between DNA and RNA bases is that RNA swaps thymine for uracil - everything else follows the same rules!
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
DNA's Double Helix Structure
Picture DNA as a twisted ladder - this famous double helix structure is made from two polynucleotide strands running in opposite directions. This "antiparallel" arrangement is crucial because it allows the bases to pair up perfectly, like puzzle pieces fitting together.
The strands are held together by hydrogen bonds between complementary base pairs. Adenine-thymine pairs have 2 hydrogen bonds, whilst guanine-cytosine pairs have 3 hydrogen bonds. This difference makes G-C pairs stronger than A-T pairs.
These hydrogen bonds are strong enough to keep DNA stable, but weak enough to be broken when needed for DNA replication or protein synthesis. It's like having a zipper that's secure but can still be opened when necessary.
The antiparallel structure means one strand runs from 3' to 5' direction whilst the other runs 5' to 3'. This might seem like technical detail, but it's essential for how DNA copying works in your cells.
💡 Function Focus: DNA's main job is information storage - its long, stable structure and base-pairing rules make it perfect for storing your genetic blueprint and passing it on to the next generation!
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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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