Introduction to Cellular Respiration - Online Tutor, Practice Problems & Exam Prep

Aerobic cellular respiration is an oxygen-requiring process that breaks down glucose (C₆H₁₂O₆) to produce ATP, carbon dioxide, and water. This process occurs in four stages: glycolysis, pyruvate oxidation, the Krebs cycle, and the electron transport chain. It is a redox reaction where glucose is oxidized, losing electrons, while oxygen is reduced, gaining electrons. The primary goal is to generate ATP through substrate-level and oxidative phosphorylation, making it essential for cellular energy production.

Introduction to Cellular Respiration

In this video, we're going to begin our introduction to aerobic cellular respiration. Aerobic cellular respiration, as its name implies with the term "aerobic," is an aerobic process itself, and we'll define what aerobic means down below here shortly. But more specifically, aerobic cellular respiration is the aerobic process of breaking down glucose to make lots and lots of ATP or energy for the cell. This is the main purpose of aerobic cellular respiration: to make lots and lots of ATP or energy for the cell. The term aerobic refers to the requirement of the presence of oxygen gas or O₂, which is the chemical formula for oxygen gas. Aerobic cellular respiration is an aerobic process which means that it needs or requires oxygen gas in order to break down glucose and make lots of ATP. As we move forward in our course, we're going to talk more about aerobic cellular respiration. What we'll learn is that aerobic cellular respiration occurs in multiple stages, and we'll discuss these stages as we continue. Most stages of aerobic cellular respiration occur inside the mitochondria of the cell, allowing us to make an association between mitochondria and aerobic cellular respiration.

If we take a look at our example image down below, we'll find the overall chemical equation for aerobic cellular respiration. Because most of the stages occur inside the mitochondria, notice over here we have an image of the mitochondria of the cell, so we're already starting to associate the mitochondria with cellular respiration. Cellular respiration takes food such as sugar or a monosaccharide called glucose. It converts glucose, along with oxygen gas, into carbon dioxide gas, water, and arguably the most important product, ATP or energy for the cell. Ultimately, what we see with cellular respiration is that it takes foods such as glucose, sugars, and oxygen gas from the atmosphere and uses those to create lots of ATP or energy for the cell. It also creates carbon dioxide and water as byproducts. Once again, cellular respiration is shown here as just one reaction arrow. However, it consists of multiple stages, and we will discuss these stages moving forward in our course.

This here concludes our brief introduction to aerobic cellular respiration. We'll learn more as we move forward in our course. I'll see you all in our next video.

Aerobic Cellular Respiration is a Redox Reaction

In this video, we're going to talk about how aerobic cellular respiration is a redox reaction. And so once again, the overall chemical equation for aerobic cellular respiration is a redox reaction. This recalls from our previous lesson videos just means that it involves the transfer of electrons between molecules. Recall the way that we can remember redox reactions is by remembering LEO, the lion goes grrr. Substances that lose electrons are oxidized, whereas substances that gain electrons are reduced. By the very end of the process of aerobic cellular respiration, glucose is going to lose electrons which means that glucose is going to be oxidized. On the other hand, oxygen gas is going to gain electrons and so oxygen gas is going to be reduced. What we'll learn much later in our course is that oxygen is going to be the final electron acceptor, meaning that it's going to be the last thing that accepts or gains the electrons. This goes hand in hand with oxygen being reduced.

Let's take a look at our example down below at the chemical equation for aerobic cellular respiration. Notice over here on the left-hand side, we're showing you the chemical structure for glucose, and you all should know that glucose's chemical formula is C₆H₁₂O₆. Aerobic cellular respiration is going to take glucose as well as oxygen gas, more specifically six molecules of oxygen gas, and it's going to convert the glucose and the six molecules of oxygen gas into six molecules of carbon dioxide gas, six molecules of water, and a whole bunch of ATP, somewhere between 30 to 38 ATP. Making lots of ATP is really the main point of aerobic cellular respiration to make lots of ATP. It breaks down foods such as sugars like the monosaccharide glucose using oxygen, and when it breaks down that glucose, those foods, it is able to form lots of ATP. It also makes carbon dioxide and water as a byproduct. The glucose molecule is going to lose electrons during this process. The glucose molecule is going to be oxidized and all of those electrons are going to be used to generate ATP. The oxygen gas molecule here is going to be gaining the electrons. We'll learn later in our course that oxygen is the final electron acceptor that gains the electrons. And because it's gaining the electrons, oxygen gas is going to be reduced and ultimately converted into water.

This here is a chemical reaction that you should all be very familiar with and be able to recognize for your exam since professors tend to want their students to be very familiar with this overall chemical equation for aerobic cellular respiration. This concludes our introduction to how aerobic cellular respiration is a redox reaction, and we'll be able to get some practice applying these concepts as we move forward in our course. We'll also continue to learn more and more about aerobic cellular respiration as we move forward as well. I'll see you all in our next video.

Which one of the following molecules is a by-product of cellular respiration?

a) Water.

b) Glucose.

c) Pyruvate.

d) Oxygen.

e) ADP.

• A. Water.
• B. Glucose.
• C. Pyruvate.
• D. Oxygen.
• E. ADP.

Which of the summary statements below describes the results of the following reaction?

C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O + Energy

a) C₆H₁₂O₆ is oxidized and O₂ is reduced.

b) O₂ is oxidized and H₂O is reduced.

c) CO₂ is reduced and O₂ is oxidized.

d) O₂ is reduced and CO₂ is oxidized.

• A. C₆H₁₂O₆ is oxidized and O₂ is reduced.
• B. O₂ is oxidized and H₂O is reduced.
• C. CO₂ is reduced and O₂ is oxidized.
• D. O₂ is reduced and CO₂ is oxidized.

Stages of Aerobic Cellular Respiration

So recall from our previous lesson videos that aerobic cellular respiration actually occurs in multiple stages, most of which occur inside of the mitochondria. And so here in this video, we're going to briefly introduce the stages of aerobic cellular respiration. But moving forward in our course, we're going to talk about each of these individual stages in more detail in their own separate videos. And so here we're saying that aerobic cellular respiration actually includes 4 metabolic pathways or reactions, or 4 stages, if you will. And so down below what we have is an image that's showing you once again the 4 stages of aerobic cellular respiration. And so the very first stage is going to be glycolysis. The third stage is the Krebs cycle, which is also commonly referred to as the citric acid cycle. And the fourth stage is going to be the electron transport chain and chemiosmosis. And so once again, as we move forward in our course, we'll talk about each of these 4 stages here in their own separate videos in more detail. But you should know that these are the 4 stages of aerobic cellular respiration, and you should be able to put them into the correct order. Also notice that most of the stages of aerobic cellular respiration occur inside of the mitochondria. And so this image that we have in the background here represents the mitochondria of the cell. And so notice that stages 2, 3, and 4 all occur inside of the mitochondria of the cell. Whereas glycolysis is the only stage of aerobic cellular respiration that does not occur inside of the mitochondria. It actually occurs just outside of the mitochondria in the area known as the cytoplasm. And so that's another takeaway that we'll continue to revisit, as we move forward in our course. But for now these here are the 4 stages of aerobic cellular respiration. And once again, we'll get to talk more and more about these stages as we move forward. So I'll see you all in our next video.

Remembering Stages of Aerobic Cellular Respiration

In this video, I'm going to share with you a silly way to help you remember the stages of aerobic cellular respiration. You might recall from our previous lesson videos that these stages are glycolysis, pyruvate oxidation, the Krebs Cycle, and the electron transport chain. All you need to do to remember the aerobic cellular respiration stages in the correct order is to recall that giant pandas killed Einstein. Notice below, we are showing you a giant panda that is attacking and killing Einstein right here. If you can remember "Giant Pandas killed Einstein", then hopefully, that can help you remember the four stages of aerobic cellular respiration in the correct order, which are once again glycolysis, pyruvate oxidation, the Krebs cycle, and the electron transport chain. The first letter of these words all match up. Again, it's just a silly way to help you remember these stages. That being said, this here concludes this video, and I'll see you all in our next one.

Introduction to Cellular Respiration Example 1

So here we have an example problem that's asking which of the following options list the stages of aerobic cellular respiration in the correct order. And we've got these 4 potential answer options down below. And so, of course, we know from our last lesson video that when it comes to remembering the stages of aerobic cellular respiration in the correct order, really all we need to remember is that giant pandas killed Elvis. And, by remembering that giant pandas killed Elvis, we'll be able to remember the stages in the correct order. And so recall that the giant pandas killing Elvis stands for the GPKE here, and the giant stands for glycolysis, the p stands for pyruvate oxidation, the k here stands for Krebs Cycle, and the e here stands for electron transport chain chemiosmosis. And so it needs to be these stages in this particular order. And the only answer option that matches this particular order from our mnemonic is option b, glycolysis, followed by pyruvate oxidation, followed by Krebs cycle, and then finally, the electron transport chain in chemiosmosis. And so, option b here is going to be the correct answer for this example problem. And that concludes this example, so I'll see you all in our next video.

Map of the Lesson on Cellular Respiration

In this video, we're going to introduce our map of the lesson on cellular respiration, which is this image down below right here. And so once again, you can use this image as a map for our lesson. And so the way that we're going to explore this map is by starting at the top and then following the leftmost branches first. And we'll cover the branches from left to right as we go. And then after we explore the leftmost branches, we'll start to explore the right branches and follow these pathways here. And so what you'll see from this map of the lesson is that cellular respiration can take place with oxygen, otherwise known as aerobic respiration, where oxygen is going to act as the final electron acceptor. And we already know from our previous lesson videos that the 4 stages of aerobic cellular respiration are glycolysis, pyruvate oxidation, the Krebs cycle, and the electron transport chain and chemiosmosis. And so we'll learn that the whole purpose of aerobic cellular respiration is to make lots and lots of ATP (ATP) for the cell, or make lots and lots of energy for the cell. And that energy, what we'll learn is that it can be made in 2 different ways. It can be made via substrate-level phosphorylation in glycolysis and in the Krebs cycle. And it can be made via oxidative phosphorylation in the electron transport chain and chemiosmosis. And so once again, after we explore aerobic cellular respiration in the presence of oxygen, then we'll zoom out and start to explore the right branches, cellular respiration in the absence of oxygen without oxygen being present. And we'll learn that glycolysis is actually, a process that can occur without oxygen. And then we'll talk about anaerobic respiration or fermentation, and how anaerobic respiration is going to have some alternative final electron acceptor other than oxygen. It's not going to be oxygen. And then we'll talk about 2 different types of fermentation, lactic acid fermentation and alcohol fermentation. And so once again, this image here represents the map of our lesson moving forward. And so you can refer back to this map here to make predictions about what topics we're going to be covering next, and where we are within our lesson before we transition to other parts of our lesson. And so this here concludes our introduction to our map of the lesson on cellular respiration, and we'll be able to get started by talking more and more about aerobic cellular respiration, specifically, the processes that involve substrate-level phosphorylation and oxidative phosphorylation. So we'll talk about that next and I'll see you all in our next video.

Introduction to Cellular Respiration Example 2

Alright. So here we have an example problem that says using the map above, which of the following occurs in the absence of oxygen or where no oxygen is present? And we've got these 4 potential answer options down below. And so when we take a look at our map of the lesson on cellular respiration from up above, notice that this entire left hand branch over here is occurring in the presence of oxygen with oxygen being present. That's this entire left branch. And notice that the entire right branch is occurring without oxygen being present in the absence of oxygen, and so that is this entire right branch. And so notice once again the problem is asking us which of the following occurs in the absence of oxygen where no oxygen is present. So it specifically wants us to choose an option on the right hand side of our map. And so when we look at some of these options such as aerobic respiration, oxidative phosphorylation, and oxygen serving as the final electron acceptor, notice that they all show up on the left hand side. Aerobic respiration is here, oxidative phosphorylation is here, and oxygen serving as the final electron acceptor is here. And so those three things are all occurring with oxygen being present. And the only one that occurs without oxygen being present is fermentation. And so fermentation, we can see over here on the right hand side, and there are 2 types that we're going to talk about moving forward, lactic acid fermentation and alcohol fermentation. But for now, for this example problem, what we can see is that fermentation is going to be the correct answer here, the one that occurs in the absence of oxygen. And so we can go ahead and indicate that here is the correct answer to this example problem, and that concludes this example. So I'll see you all in our next video.

Based on the map of cellular respiration, why do we need to breathe in oxygen?

a) Oxygen is the final electron acceptor for lactic acid fermentation.

b) Oxygen is the final electron acceptor for alcohol fermentation.

c) Oxygen is the final electron acceptor for aerobic cellular respiration.

d) Oxygen is not important for the purposes of cellular respiration.

• A. Oxygen is the final electron acceptor for lactic acid fermentation.
• B. Oxygen is the final electron acceptor for alcohol fermentation.
• C. Oxygen is the final electron acceptor for aerobic cellular respiration.
• D. Oxygen is not important for the purposes of cellular respiration.

Here’s what students ask on this topic:

What is the main purpose of aerobic cellular respiration?

The main purpose of aerobic cellular respiration is to produce ATP, which is the primary energy currency of the cell. This process involves breaking down glucose (C₆H₁₂O₆) in the presence of oxygen (O₂) to generate ATP, along with byproducts of carbon dioxide (CO₂) and water (H₂O). The energy released during this process is captured in the form of ATP, which is then used to power various cellular activities and functions.

What are the four stages of aerobic cellular respiration?

The four stages of aerobic cellular respiration are:

1. Glycolysis: Occurs in the cytoplasm and breaks down glucose into pyruvate, producing a small amount of ATP and NADH.
2. Pyruvate Oxidation: Converts pyruvate into acetyl-CoA in the mitochondria, producing NADH and releasing CO₂.
3. Krebs Cycle (Citric Acid Cycle): Takes place in the mitochondrial matrix, generating ATP, NADH, FADH₂, and releasing CO₂.
4. Electron Transport Chain and Chemiosmosis: Occurs in the inner mitochondrial membrane, where electrons are transferred through protein complexes, creating a proton gradient that drives ATP synthesis via oxidative phosphorylation.

How is aerobic cellular respiration a redox reaction?

Aerobic cellular respiration is a redox reaction because it involves the transfer of electrons between molecules. In this process, glucose (C₆H₁₂O₆) is oxidized, meaning it loses electrons, while oxygen (O₂) is reduced, meaning it gains electrons. The overall chemical equation for aerobic cellular respiration is:

$C_6{H}_{12}{O}_6+6O_2\to 6{\mathrm{CO}}_2+6H_2{O}_2+30-38\mathrm{ATP}$

Here, glucose is oxidized to CO₂, and O₂ is reduced to H₂O.

Where do the stages of aerobic cellular respiration occur in the cell?

The stages of aerobic cellular respiration occur in different parts of the cell:

• Glycolysis: Occurs in the cytoplasm.
• Pyruvate Oxidation: Takes place in the mitochondrial matrix.
• Krebs Cycle (Citric Acid Cycle): Also occurs in the mitochondrial matrix.
• Electron Transport Chain and Chemiosmosis: Occur in the inner mitochondrial membrane.

Most stages occur within the mitochondria, making it the powerhouse of the cell due to its role in ATP production.

What is the overall chemical equation for aerobic cellular respiration?

The overall chemical equation for aerobic cellular respiration is:

$C_6{H}_{12}{O}_6+6O_2\to 6{\mathrm{CO}}_2+6H_2{O}_2+30-38\mathrm{ATP}$

This equation shows that glucose and oxygen are converted into carbon dioxide, water, and ATP, highlighting the process's role in energy production.