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eleanor ๐
10/12/2025
Biology
alevel biology Nucleic Acids
101
โข
10 Dec 2025
โข
A-Level Biology: Nucleotides and Nucleic Acids Mind Map
eleanor ๐
@eleanor.calder
1 / 3
Nucleic Acids and DNA Structure
Think of DNA (deoxyribonucleic acid) as a twisted ladder where the rungs are made of four chemical letters: A, T, C, and G. These bases always pair up the same way - A with T, and C with G - like a perfect molecular match.
DNA has a double helix structure with two strands running in opposite directions, held together by hydrogen bonds. The backbone is made of sugar and phosphate groups connected by phosphodiester bonds. RNA is similar but uses U instead of T and has just one strand.
ATP (adenosine triphosphate) is your cell's energy currency. When ATP breaks down into ADP, it releases energy that powers everything from muscle contractions to thinking. The triplet code means every three DNA bases (called codons) code for one amino acid - and this code is universal across all life forms.
Key Point: The fact that all organisms use the same genetic code suggests we all evolved from a common ancestor millions of years ago.
DNA Replication
Your cells need to copy DNA every time they divide, and they do this through semi-conservative replication - meaning half of each new DNA molecule comes from the original strand.
The process starts when DNA helicase unzips the double helix by breaking hydrogen bonds between base pairs. Each separated strand then acts as a template for building a new complementary strand using free-floating nucleotides.
DNA polymerase joins these new nucleotides together, following the base-pairing rules (A with T, C with G). The result? Two identical DNA molecules, each containing one original and one newly-made strand.
The famous Meselson and Stahl experiment proved this happens by tracking heavy and light nitrogen isotopes through bacterial generations. They showed that DNA replication is indeed semi-conservative, not conservative or dispersive.
Remember: Semi-conservative replication ensures genetic information is accurately passed from parent to daughter cells during cell division.
Protein Synthesis
Protein synthesis happens in two main stages: transcription (making mRNA) and translation (making proteins). Think of it as copying a recipe from a cookbook, then following that recipe to cook a meal.
During transcription, RNA polymerase attaches to DNA and creates a complementary mRNA copy of a gene. The DNA uncoils, one strand serves as a template, and the mRNA molecule is built using base-pairing rules (except A pairs with U in RNA). The finished mRNA then leaves the nucleus through nuclear pores.
Translation occurs at ribosomes in the cytoplasm. tRNA molecules, shaped like three-leaf clovers, carry specific amino acids and have anticodons that match mRNA codons. As the ribosome reads the mRNA sequence, tRNA molecules bring the correct amino acids in order.
Ribosomal RNA (rRNA) catalyses the formation of peptide bonds between amino acids, creating a growing polypeptide chain. The process continues until a stop codon is reached, producing a complete protein.
Top Tip: Remember the flow: DNA โ mRNA โ protein. Each step ensures the genetic code is accurately translated into functional proteins.
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Best app on earth! no words because itโs too good
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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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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
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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
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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 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 THE SCHOOLGPT. 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 THE SCHOOLGPT. 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
A-Level Biology: Nucleotides and Nucleic Acids Mind Map
eleanor ๐
@eleanor.calder
DNA is basically your body's instruction manual, storing all the genetic information needed to make youโฆ well, you! This module covers how DNA works, copies itself, and creates proteins - the essential processes that keep every living thing functioning.
Nucleic Acids and DNA Structure
Think of DNA (deoxyribonucleic acid) as a twisted ladder where the rungs are made of four chemical letters: A, T, C, and G. These bases always pair up the same way - A with T, and C with G - like a perfect molecular match.
DNA has a double helix structure with two strands running in opposite directions, held together by hydrogen bonds. The backbone is made of sugar and phosphate groups connected by phosphodiester bonds. RNA is similar but uses U instead of T and has just one strand.
ATP (adenosine triphosphate) is your cell's energy currency. When ATP breaks down into ADP, it releases energy that powers everything from muscle contractions to thinking. The triplet code means every three DNA bases (called codons) code for one amino acid - and this code is universal across all life forms.
Key Point: The fact that all organisms use the same genetic code suggests we all evolved from a common ancestor millions of years ago.
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DNA Replication
Your cells need to copy DNA every time they divide, and they do this through semi-conservative replication - meaning half of each new DNA molecule comes from the original strand.
The process starts when DNA helicase unzips the double helix by breaking hydrogen bonds between base pairs. Each separated strand then acts as a template for building a new complementary strand using free-floating nucleotides.
DNA polymerase joins these new nucleotides together, following the base-pairing rules (A with T, C with G). The result? Two identical DNA molecules, each containing one original and one newly-made strand.
The famous Meselson and Stahl experiment proved this happens by tracking heavy and light nitrogen isotopes through bacterial generations. They showed that DNA replication is indeed semi-conservative, not conservative or dispersive.
Remember: Semi-conservative replication ensures genetic information is accurately passed from parent to daughter cells during cell division.
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Protein Synthesis
Protein synthesis happens in two main stages: transcription (making mRNA) and translation (making proteins). Think of it as copying a recipe from a cookbook, then following that recipe to cook a meal.
During transcription, RNA polymerase attaches to DNA and creates a complementary mRNA copy of a gene. The DNA uncoils, one strand serves as a template, and the mRNA molecule is built using base-pairing rules (except A pairs with U in RNA). The finished mRNA then leaves the nucleus through nuclear pores.
Translation occurs at ribosomes in the cytoplasm. tRNA molecules, shaped like three-leaf clovers, carry specific amino acids and have anticodons that match mRNA codons. As the ribosome reads the mRNA sequence, tRNA molecules bring the correct amino acids in order.
Ribosomal RNA (rRNA) catalyses the formation of peptide bonds between amino acids, creating a growing polypeptide chain. The process continues until a stop codon is reached, producing a complete protein.
Top Tip: Remember the flow: DNA โ mRNA โ protein. Each step ensures the genetic code is accurately translated into functional proteins.
We thought youโd 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 โ all at your fingertips.
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Students love us โ 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 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 THE SCHOOLGPT. 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 THE SCHOOLGPT. 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