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Feb 8, 2026
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Understanding Glycolysis: The Cellular Energy Process
K
Khally
@austinaensah_jniyzva
1 / 4
Glycolysis: Splitting Glucose for Energy
Glycolysis is your cell's first step in energy production, occurring in the cytoplasm without requiring oxygen. The process begins with a single glucose molecule (6 carbons) that gets phosphorylated on both ends, costing 2 ATP molecules upfront.
The phosphorylated glucose is then split in half, creating two 3-carbon molecules that eventually become pyruvate. During this transformation, each "half" generates 1 NADH (2 total) and 2 ATP (4 total). Since you invested 2 ATP at the start, the net gain is 2 ATP per glucose molecule.
Glycolysis maintains a balanced energy budget: it inputs one glucose molecule, 2 NAD+, 2 ATP, and 4 ADP+4P, while outputting 2 pyruvate molecules, 2 NADH, 2 ADP, and 4 ATP (net gain of 2 ATP).
Energy Insight: Glycolysis is your cellular "quick cash" system - it's fast but inefficient, providing just enough ATP to keep things running until the more profitable oxygen-dependent processes kick in.
Electron Carriers and the Preparatory Phase
Cellular respiration relies on special molecules that shuttle electrons between reactions. NAD+ (nicotinamide adenine dinucleotide) works as an oxidation-reduction coenzyme, accepting electrons to become NADH or donating them to reduce other molecules. Similarly, FAD (flavin adenine dinucleotide) functions as an electron carrier, accepting two electrons and two hydrogen ions to become FADH₂.
After glycolysis, pyruvate molecules enter the mitochondrial matrix during the preparatory phase. Here, each pyruvate undergoes a transformation where one carbon is released as CO₂, and the remaining two-carbon fragment attaches to Coenzyme A, forming acetyl-CoA. This reaction also generates one NADH per pyruvate.
This preparatory step is crucial because it converts pyruvate into a form that can enter the Krebs cycle (citric acid cycle). Since each glucose molecule produces two pyruvates during glycolysis, this preparation phase creates two acetyl-CoA molecules and two CO₂ molecules.
Remember this: Think of NAD+ and FAD as cellular "electron taxis" - they pick up electrons from one location and drop them off at another, making energy production possible!
The Citric Acid Cycle and Oxidative Phosphorylation
The Citric Acid Cycle (Krebs cycle) begins when a 2-carbon acetyl-CoA combines with a 4-carbon oxaloacetate to form a 6-carbon molecule. As this cycle progresses, two carbons get completely oxidized and released as CO₂. Each turn of the cycle generates 3 NADH, 1 FADH₂, 1 ATP, and 2 CO₂ molecules, while regenerating oxaloacetate for the next round. Since each glucose yields two acetyl-CoA molecules, the cycle turns twice per glucose.
Oxidative phosphorylation is where the real ATP production happens. The NADH and FADH₂ carriers (produced during earlier stages) deliver high-energy electrons to the electron transport chain (ETC) embedded in the inner mitochondrial membrane. As electrons move through this chain, their energy helps pump protons (H⁺) from the matrix into the intermembrane space.
This proton pumping creates a concentration gradient across the inner membrane. The energy stored in this gradient is like water behind a dam—it represents potential energy waiting to be used.
Cellular Power Plant: The electron transport chain works like a series of waterfalls, with each drop in electron energy being captured to pump protons, creating the cellular equivalent of a hydroelectric dam!
Completing the Energy Harvest
The final step in cellular respiration is the controlled flow of protons back into the mitochondrial matrix through a remarkable protein complex called ATP synthase. This enzyme works like a molecular turbine—as protons flow through it down their concentration gradient, they cause parts of the protein to rotate, which drives ATP synthesis.
This process, called chemiosmosis, is remarkably efficient at generating ATP. The spinning of ATP synthase converts ADP and phosphate into ATP, capturing the energy that was originally in glucose.
At the end of the electron transport chain, the electrons (now depleted of their energy) combine with oxygen and hydrogen ions to form water (H₂O). This is why oxygen is the final electron acceptor and explains why we need to breathe—without oxygen, the entire electron transport chain would back up and cellular respiration would grind to a halt.
Think About It: Your cells create energy using the same principle as hydroelectric power plants—both use the flow of particles down a gradient to turn a turbine that generates energy!
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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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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❗️❗️⚠️
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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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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.
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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
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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 Knowunity AI. 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 Knowunity AI. 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
Understanding Glycolysis: The Cellular Energy Process
K
Khally
@austinaensah_jniyzva
Cellular respiration is the powerhouse process that transforms glucose into ATP, the energy currency of your cells. This multi-stage process extracts energy through several key pathways, starting with glycolysis and culminating in oxidative phosphorylation. Understanding how your cells create energy... Show more
Glycolysis: Splitting Glucose for Energy
Glycolysis is your cell's first step in energy production, occurring in the cytoplasm without requiring oxygen. The process begins with a single glucose molecule (6 carbons) that gets phosphorylated on both ends, costing 2 ATP molecules upfront.
The phosphorylated glucose is then split in half, creating two 3-carbon molecules that eventually become pyruvate. During this transformation, each "half" generates 1 NADH (2 total) and 2 ATP (4 total). Since you invested 2 ATP at the start, the net gain is 2 ATP per glucose molecule.
Glycolysis maintains a balanced energy budget: it inputs one glucose molecule, 2 NAD+, 2 ATP, and 4 ADP+4P, while outputting 2 pyruvate molecules, 2 NADH, 2 ADP, and 4 ATP (net gain of 2 ATP).
Energy Insight: Glycolysis is your cellular "quick cash" system - it's fast but inefficient, providing just enough ATP to keep things running until the more profitable oxygen-dependent processes kick in.
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Electron Carriers and the Preparatory Phase
Cellular respiration relies on special molecules that shuttle electrons between reactions. NAD+ (nicotinamide adenine dinucleotide) works as an oxidation-reduction coenzyme, accepting electrons to become NADH or donating them to reduce other molecules. Similarly, FAD (flavin adenine dinucleotide) functions as an electron carrier, accepting two electrons and two hydrogen ions to become FADH₂.
After glycolysis, pyruvate molecules enter the mitochondrial matrix during the preparatory phase. Here, each pyruvate undergoes a transformation where one carbon is released as CO₂, and the remaining two-carbon fragment attaches to Coenzyme A, forming acetyl-CoA. This reaction also generates one NADH per pyruvate.
This preparatory step is crucial because it converts pyruvate into a form that can enter the Krebs cycle (citric acid cycle). Since each glucose molecule produces two pyruvates during glycolysis, this preparation phase creates two acetyl-CoA molecules and two CO₂ molecules.
Remember this: Think of NAD+ and FAD as cellular "electron taxis" - they pick up electrons from one location and drop them off at another, making energy production possible!
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The Citric Acid Cycle and Oxidative Phosphorylation
The Citric Acid Cycle (Krebs cycle) begins when a 2-carbon acetyl-CoA combines with a 4-carbon oxaloacetate to form a 6-carbon molecule. As this cycle progresses, two carbons get completely oxidized and released as CO₂. Each turn of the cycle generates 3 NADH, 1 FADH₂, 1 ATP, and 2 CO₂ molecules, while regenerating oxaloacetate for the next round. Since each glucose yields two acetyl-CoA molecules, the cycle turns twice per glucose.
Oxidative phosphorylation is where the real ATP production happens. The NADH and FADH₂ carriers (produced during earlier stages) deliver high-energy electrons to the electron transport chain (ETC) embedded in the inner mitochondrial membrane. As electrons move through this chain, their energy helps pump protons (H⁺) from the matrix into the intermembrane space.
This proton pumping creates a concentration gradient across the inner membrane. The energy stored in this gradient is like water behind a dam—it represents potential energy waiting to be used.
Cellular Power Plant: The electron transport chain works like a series of waterfalls, with each drop in electron energy being captured to pump protons, creating the cellular equivalent of a hydroelectric dam!
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Completing the Energy Harvest
The final step in cellular respiration is the controlled flow of protons back into the mitochondrial matrix through a remarkable protein complex called ATP synthase. This enzyme works like a molecular turbine—as protons flow through it down their concentration gradient, they cause parts of the protein to rotate, which drives ATP synthesis.
This process, called chemiosmosis, is remarkably efficient at generating ATP. The spinning of ATP synthase converts ADP and phosphate into ATP, capturing the energy that was originally in glucose.
At the end of the electron transport chain, the electrons (now depleted of their energy) combine with oxygen and hydrogen ions to form water (H₂O). This is why oxygen is the final electron acceptor and explains why we need to breathe—without oxygen, the entire electron transport chain would back up and cellular respiration would grind to a halt.
Think About It: Your cells create energy using the same principle as hydroelectric power plants—both use the flow of particles down a gradient to turn a turbine that generates energy!
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 Knowunity AI. 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 Knowunity AI. 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