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Aliki 🩵
14/12/2025
Biology
Biology: Inheritace (DNA + evolution + antibiotic resistance)
95
•
14 Dec 2025
•
Understanding Inheritance: Genetics, Evolution, and Antibiotic Resistance
Aliki 🩵
@study_wabbit
1 / 4
Inheritance Basics and DNA Structure
Ever wondered why you look like your family members? It's all down to genes - sections of DNA that code for specific proteins. We inherit chromosomes in homologous pairs - one from mum, one from dad - making us diploid organisms.
When it comes to our traits, we have different alleles (versions of genes) that can be dominant (shown with capital letters like "R") or recessive (shown with lowercase letters like "r"). If both alleles are the same, we're homozygous; if they're different, we're heterozygous. What we look like (our phenotype) is determined by our genes plus environmental effects.
DNA (deoxyribonucleic acid) forms the famous double helix structure, made of two strands of nucleotides. Each nucleotide contains a sugar-phosphate backbone and one of four bases: Adenine, Thymine, Guanine, or Cytosine. These bases pair specifically through hydrogen bonds - A-T has 2 bonds, while C-G has 3, making them stronger.
Try this! Create a Punnett square for a cross between two heterozygous parents (Rr × Rr). You'll find the offspring have a 75% chance of showing the dominant trait and 25% chance of showing the recessive trait.
DNA Replication and Protein Synthesis
Your body makes an exact copy of DNA through replication. First, hydrogen bonds break and the DNA "unzips." Then, new nucleotides attach to each parent strand following the base-pairing rules. This creates two identical daughter strands - perfect copies of the original!
DNA can't leave the nucleus, so how does it make proteins? Through RNA (ribonucleic acid)! RNA is similar to DNA but has the sugar ribose instead of deoxyribose and uses uracil (U) instead of thymine (T). The genetic code works like this: three bases (a triplet) code for one amino acid, and a sequence of amino acids forms a protein.
Protein synthesis happens in two main stages. First, transcription occurs when RNA polymerase creates messenger RNA (mRNA) from DNA. Then, during translation, this mRNA travels to ribosomes where transfer RNA (tRNA) brings amino acids that link together to form proteins.
Remember: Blood types (A, B, AB, O) are determined by three alleles: Iᴬ and Iᴮ (both dominant) and i (recessive). This is different from most traits that only have two possible alleles!
Mutations and Variation
Mistakes sometimes happen in DNA, causing mutations - changes in the DNA sequence. These can occur randomly or be triggered by mutagens like radiation or chemicals. Mutations come in several types: insertions (adding bases), deletions (removing bases), substitutions (swapping bases), or inversions (flipping sections).
Not all mutations are bad news! Silent mutations don't change the protein at all. Missense mutations change one amino acid, which might cause problems. The most serious are nonsense mutations, which create a premature "stop" signal that cuts the protein short.
These mutations contribute to variation - the differences between individuals in a species. Variation comes from genetic factors (inherited from parents, like eye colour), environmental factors (like scars or language), or a combination of both (like height or weight). This variation is crucial because it provides the raw material for evolution.
Think about it: Every time your cells divide, your entire genome (3 billion base pairs) must be copied. Even with an error rate of just 1 in a billion, mistakes can happen - these are the mutations that drive variation and evolution!
Evolution and Antibiotic Resistance
Evolution occurs when populations change over time through natural selection. When organisms with advantageous traits survive and reproduce more successfully, they pass these beneficial traits to their offspring. Over many generations, this can lead to significant changes in a population.
Sometimes a population can split and evolve so differently that they can no longer breed together to produce fertile offspring - they've become separate species. This process is called speciation and is how the amazing diversity of life on Earth developed.
A concerning example of evolution in action is antibiotic resistance. Bacteria reproduce every 20 minutes, giving them many opportunities for random mutations. When antibiotics kill susceptible bacteria but leave resistant ones alive, these survivors multiply and create a new resistant population. This natural selection process happens incredibly quickly!
Warning: Antibiotic resistance is worsening due to over-prescription, patients not finishing courses, and agricultural overuse. This means some infections may become untreatable, making even routine surgeries dangerous. You can help by always completing your prescribed antibiotic course!
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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 Inheritance: Genetics, Evolution, and Antibiotic Resistance
Aliki 🩵
@study_wabbit
Inheritance and DNA are the keys to understanding how our traits get passed from one generation to the next. These concepts explain why you might have your mum's eye colour or your dad's height, and they're essential for understanding how... Show more
Inheritance Basics and DNA Structure
Ever wondered why you look like your family members? It's all down to genes - sections of DNA that code for specific proteins. We inherit chromosomes in homologous pairs - one from mum, one from dad - making us diploid organisms.
When it comes to our traits, we have different alleles (versions of genes) that can be dominant (shown with capital letters like "R") or recessive (shown with lowercase letters like "r"). If both alleles are the same, we're homozygous; if they're different, we're heterozygous. What we look like (our phenotype) is determined by our genes plus environmental effects.
DNA (deoxyribonucleic acid) forms the famous double helix structure, made of two strands of nucleotides. Each nucleotide contains a sugar-phosphate backbone and one of four bases: Adenine, Thymine, Guanine, or Cytosine. These bases pair specifically through hydrogen bonds - A-T has 2 bonds, while C-G has 3, making them stronger.
Try this! Create a Punnett square for a cross between two heterozygous parents (Rr × Rr). You'll find the offspring have a 75% chance of showing the dominant trait and 25% chance of showing the recessive trait.
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DNA Replication and Protein Synthesis
Your body makes an exact copy of DNA through replication. First, hydrogen bonds break and the DNA "unzips." Then, new nucleotides attach to each parent strand following the base-pairing rules. This creates two identical daughter strands - perfect copies of the original!
DNA can't leave the nucleus, so how does it make proteins? Through RNA (ribonucleic acid)! RNA is similar to DNA but has the sugar ribose instead of deoxyribose and uses uracil (U) instead of thymine (T). The genetic code works like this: three bases (a triplet) code for one amino acid, and a sequence of amino acids forms a protein.
Protein synthesis happens in two main stages. First, transcription occurs when RNA polymerase creates messenger RNA (mRNA) from DNA. Then, during translation, this mRNA travels to ribosomes where transfer RNA (tRNA) brings amino acids that link together to form proteins.
Remember: Blood types (A, B, AB, O) are determined by three alleles: Iᴬ and Iᴮ (both dominant) and i (recessive). This is different from most traits that only have two possible alleles!
Sign up to see the contentIt's free!
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Improve your grades
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By signing up you accept Terms of Service and Privacy Policy
Mutations and Variation
Mistakes sometimes happen in DNA, causing mutations - changes in the DNA sequence. These can occur randomly or be triggered by mutagens like radiation or chemicals. Mutations come in several types: insertions (adding bases), deletions (removing bases), substitutions (swapping bases), or inversions (flipping sections).
Not all mutations are bad news! Silent mutations don't change the protein at all. Missense mutations change one amino acid, which might cause problems. The most serious are nonsense mutations, which create a premature "stop" signal that cuts the protein short.
These mutations contribute to variation - the differences between individuals in a species. Variation comes from genetic factors (inherited from parents, like eye colour), environmental factors (like scars or language), or a combination of both (like height or weight). This variation is crucial because it provides the raw material for evolution.
Think about it: Every time your cells divide, your entire genome (3 billion base pairs) must be copied. Even with an error rate of just 1 in a billion, mistakes can happen - these are the mutations that drive variation and evolution!
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
Evolution and Antibiotic Resistance
Evolution occurs when populations change over time through natural selection. When organisms with advantageous traits survive and reproduce more successfully, they pass these beneficial traits to their offspring. Over many generations, this can lead to significant changes in a population.
Sometimes a population can split and evolve so differently that they can no longer breed together to produce fertile offspring - they've become separate species. This process is called speciation and is how the amazing diversity of life on Earth developed.
A concerning example of evolution in action is antibiotic resistance. Bacteria reproduce every 20 minutes, giving them many opportunities for random mutations. When antibiotics kill susceptible bacteria but leave resistant ones alive, these survivors multiply and create a new resistant population. This natural selection process happens incredibly quickly!
Warning: Antibiotic resistance is worsening due to over-prescription, patients not finishing courses, and agricultural overuse. This means some infections may become untreatable, making even routine surgeries dangerous. You can help by always completing your prescribed antibiotic course!
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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Most popular content: Punnett Square
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Quotes from every main character
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Can't find what you're looking for? Explore other subjects.
Students love us — 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 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