The Krebs Cycle and Electron Transport Chain are two critical... Show more
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Krebs Cycle
The Krebs Cycle takes place in the matrix of mitochondria in eukaryotes or in the cytoplasm of aerobic prokaryotes. During this process, the Acetyl CoA molecules (remnants from glucose) are oxidized, transferring their energy to electron carriers NAD+ and FAD, which become NADH and FADH2.
Two ATP molecules per glucose are produced through substrate level phosphorylation, where phosphate groups transfer directly from succinyl-CoA to ADP. By the end of the Krebs Cycle, all carbon atoms from the original glucose are released as carbon dioxide gas.
You don't need to memorize every step of this complicated cycle, but remember three key points: Acetyl CoA is oxidized with energy transferred to electron carriers, carbon atoms are released as CO2, and ATP is created via substrate level phosphorylation.
💡 Think of the Krebs Cycle as an energy transfer station - it takes the energy from food molecules and packages it into electron carriers (like NADH) that can power the next phase of respiration.
Electron Transport Chain Basics
The Electron Transport Chain (ETC) occurs on the cristae (folds) of the inner mitochondrial membrane in eukaryotes or on the cell membrane folds in aerobic prokaryotes. These folds increase surface area, allowing for greater ATP production.
The ETC transfers energy from electron carriers (NADH and FADH2) through a series of reactions that establish a hydrogen ion gradient across membranes. This process oxidizes the electron carriers formed during glycolysis and the Krebs Cycle to generate large amounts of ATP.
The chain itself consists of proteins called cytochromes that are highly conserved across all organisms. The process begins when NADH is oxidized by the first cytochrome (FMN), and electrons move through the chain from less electronegative to more electronegative locations.
As electrons move through three proton pumps, their energy powers the pumping of hydrogen ions from the matrix into the intermembrane space, creating a concentration gradient that stores potential energy. The larger this gradient, the more potential energy is available.
ATP Production and Oxygen's Role
ATP synthase is an enzyme embedded in the inner membrane that allows protons to flow back into the matrix. As protons move through this channel, their kinetic energy is harnessed to add a phosphate group to ADP, creating ATP. This process, called chemiosmosis, produces most of the ATP created during cellular respiration.
Each NADH molecule powers the pumping of three protons, ultimately providing energy for three ATP molecules. FADH2, which enters the chain later, only provides energy for two ATP molecules. In total, the electron transport chain can produce up to 34 ATP molecules per glucose molecule.
Oxygen plays a crucial role as the final electron acceptor in the chain. Because of its high electronegativity, oxygen pulls electrons from the final cytochrome, preventing a buildup of negative charge that would shut down respiration. The negatively charged oxygen then combines with hydrogen ions to form water.
🔑 Without oxygen as the final electron acceptor, the entire electron transport chain would back up and stop working - this is why we need to breathe oxygen to sustain life!
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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.
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Brad T
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Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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!
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Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
Step-by-Step Guide to the Krebs Cycle
The Krebs Cycle and Electron Transport Chain are two critical processes in cellular respiration that transform the energy from glucose into ATP. These processes occur after glycolysis and are responsible for producing most of the ATP molecules that power cellular... Show more
Krebs Cycle
The Krebs Cycle takes place in the matrix of mitochondria in eukaryotes or in the cytoplasm of aerobic prokaryotes. During this process, the Acetyl CoA molecules (remnants from glucose) are oxidized, transferring their energy to electron carriers NAD+ and FAD, which become NADH and FADH2.
Two ATP molecules per glucose are produced through substrate level phosphorylation, where phosphate groups transfer directly from succinyl-CoA to ADP. By the end of the Krebs Cycle, all carbon atoms from the original glucose are released as carbon dioxide gas.
You don't need to memorize every step of this complicated cycle, but remember three key points: Acetyl CoA is oxidized with energy transferred to electron carriers, carbon atoms are released as CO2, and ATP is created via substrate level phosphorylation.
💡 Think of the Krebs Cycle as an energy transfer station - it takes the energy from food molecules and packages it into electron carriers (like NADH) that can power the next phase of respiration.
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Electron Transport Chain Basics
The Electron Transport Chain (ETC) occurs on the cristae (folds) of the inner mitochondrial membrane in eukaryotes or on the cell membrane folds in aerobic prokaryotes. These folds increase surface area, allowing for greater ATP production.
The ETC transfers energy from electron carriers (NADH and FADH2) through a series of reactions that establish a hydrogen ion gradient across membranes. This process oxidizes the electron carriers formed during glycolysis and the Krebs Cycle to generate large amounts of ATP.
The chain itself consists of proteins called cytochromes that are highly conserved across all organisms. The process begins when NADH is oxidized by the first cytochrome (FMN), and electrons move through the chain from less electronegative to more electronegative locations.
As electrons move through three proton pumps, their energy powers the pumping of hydrogen ions from the matrix into the intermembrane space, creating a concentration gradient that stores potential energy. The larger this gradient, the more potential energy is available.
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ATP Production and Oxygen's Role
ATP synthase is an enzyme embedded in the inner membrane that allows protons to flow back into the matrix. As protons move through this channel, their kinetic energy is harnessed to add a phosphate group to ADP, creating ATP. This process, called chemiosmosis, produces most of the ATP created during cellular respiration.
Each NADH molecule powers the pumping of three protons, ultimately providing energy for three ATP molecules. FADH2, which enters the chain later, only provides energy for two ATP molecules. In total, the electron transport chain can produce up to 34 ATP molecules per glucose molecule.
Oxygen plays a crucial role as the final electron acceptor in the chain. Because of its high electronegativity, oxygen pulls electrons from the final cytochrome, preventing a buildup of negative charge that would shut down respiration. The negatively charged oxygen then combines with hydrogen ions to form water.
🔑 Without oxygen as the final electron acceptor, the entire electron transport chain would back up and stop working - this is why we need to breathe oxygen to sustain life!
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the 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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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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user