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 redox reaction involves glucose being oxidized while oxygen is reduced, acting as the final electron acceptor. The process occurs in four stages: glycolysis, pyruvate oxidation, the Krebs cycle, and the electron transport chain, primarily within the mitochondria. The main goal is to generate energy efficiently through substrate-level and oxidative phosphorylation, essential for cellular functions.

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. And really, this is the main purpose of aerobic cellular respiration: to make lots and lots of ATP or energy for the cell. Now, this 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 and lots of ATP. As we move forward in our course, we're going to talk more and more about aerobic cellular respiration, and what we'll learn is that aerobic cellular respiration actually occurs in multiple stages. And we'll talk about all of these stages as we move forward in our course. But what we'll learn is that most of the stages of aerobic cellular respiration occur inside of the mitochondria of the cell. And so, you want to be able to make an association between mitochondria and aerobic cellular respiration.

And so, down below, if we take a look at our example image, we'll find the overall chemical equation for aerobic cellular respiration. And once again, because most of the stages occur inside of 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. Notice that cellular respiration takes food such as sugar or a monosaccharide called glucose, so basically, it takes glucose and it's able to convert glucose, along with oxygen gas into carbon dioxide gas, water, and arguably the most important product, ATP or energy for the cell. And so ultimately, what we'll 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 and lots of ATP or energy for the cell.

And then it also creates carbon dioxide and water as byproducts. And so, once again, cellular respiration we're showing here as just one reaction arrow, but it turns out that cellular respiration consists of multiple stages. And so, we're going to talk about these stages as we move forward in our course. And so this here concludes our brief introduction to aerobic cellular respiration. And once again, we'll get to learn more and more as we move forward in our course.

So 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, which recall from our previous lesson videos just means that it involves the transfer of electrons between molecules. And recall the way that we can remember redox reactions is by remembering LEO the lion goes grrr. And so recall from our previous lesson videos that substances that lose electrons are oxidized whereas substances that gain electrons are reduced. And so what we'll learn here is that by the very end of the process aerobic cellular respiration, glucose is going to lose electrons which means that glucose is going to be oxidized.

And on the other hand, oxygen gas is going to gain electrons and so oxygen gas is going to be reduced. And 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. So that goes hand in hand with oxygen being reduced. So let's take a look at our example down below at the chemical equation for aerobic cellular respiration. And so 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.

And so you should be able to recognize C₆H₁₂O₆ as the chemical formula for glucose. And so aerobic cellular respiration is going to take glucose as well as oxygen gas, more specifically 6 molecules of oxygen gas, and it's going to convert the glucose and the 6 molecules of oxygen gas into 6 molecules of carbon dioxide gas, 6 molecules of water, and a whole bunch of ATP, somewhere between 30 to 38 ATP. And, really, once again, making lots and lots of ATP is really the main point of aerobic cellular respiration — to make lots and lots of ATP. So basically, what it does is 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 and lots and lots of ATP. And it also makes again carbon dioxide and water as a byproduct.

Now, what you'll notice here is that the glucose molecule is going to be losing electrons during this process. So the glucose molecule is going to be oxidized and all of those electrons are going to be used to generate ATP. And also, the oxygen gas molecule here is going to be gaining the electrons. We'll learn later in our course that oxygen is the final acceptor that gains the electrons. And because it's gaining the electrons, oxygen gas is going to be reduced and ultimately converted into water.

And so, this here is a chemical reaction that you all should 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. And so, this here 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. And we'll also continue to learn more and more about aerobic cellular respiration as we move forward as well. So 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.

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.

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 will 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, and so you can put a one here in this yellow circle. The second stage is going to be pyruvate oxidation. 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. And 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. What you might recall from our previous lesson videos is glycolysis, pyruvate oxidation, the Krebs cycle, and the electron transport chain. And so all you need to do to remember the aerobic cellular respiration stages in the correct order is that giant pandas killed Einstein. And so notice down below we're showing you here, a giant panda, that is attacking and killing Einstein right here. And so 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.

And so the first letters here of these words are all matching up. And so again, it's just a silly way to help you remember these stages. And so 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. 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 in 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. 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. 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. 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. We'll learn that the whole purpose of aerobic cellular respiration is to make lots and lots of ATP for the cell or make lots and lots of energy for the cell. That energy, what we'll learn, can be made in two 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, we'll zoom out and start to explore the right branches, cellular respiration in the absence of oxygen without oxygen being present. We'll learn that glycolysis is actually a process that can occur without oxygen. 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 two 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, 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. 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 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 aerobic cellular respiration and why is it important?

Aerobic cellular respiration is a metabolic process that requires oxygen to break down glucose (C₆H₁₂O₆) into carbon dioxide (CO₂), water (H₂O), and ATP (adenosine triphosphate). The overall chemical equation for this process is:

$C_6{H}_{12}{O}_6+6O_2\to 6{\mathrm{CO}}_2+6H_{2}O+30-38\mathrm{ATP}$

This process is crucial because it generates ATP, the primary energy currency of the cell, which is essential for various cellular functions and activities.

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: Occurs in the mitochondria, where pyruvate is converted into acetyl-CoA, producing NADH and releasing CO₂.
3. Krebs Cycle (Citric Acid Cycle): Also in the mitochondria, this cycle processes acetyl-CoA to produce ATP, NADH, FADH₂, and CO₂.
4. Electron Transport Chain and Chemiosmosis: Located in the inner mitochondrial membrane, this stage uses NADH and FADH₂ to generate a large amount of ATP through oxidative phosphorylation.

How is aerobic cellular respiration a redox reaction?

Aerobic cellular respiration is a redox (reduction-oxidation) 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 reaction can be summarized as:

$C_6{H}_{12}{O}_6+6O_2\to 6{\mathrm{CO}}_2+6H_{2}O+30-38\mathrm{ATP}$

Here, glucose is oxidized to CO₂, and O₂ is reduced to H₂O, facilitating the production of ATP.

What is the role of the mitochondria in aerobic cellular respiration?

The mitochondria play a crucial role in aerobic cellular respiration as the site where most of the process occurs. Specifically, the mitochondria host three of the four stages: pyruvate oxidation, the Krebs cycle, and the electron transport chain. These stages collectively generate the majority of ATP produced during cellular respiration. The inner mitochondrial membrane is where the electron transport chain and chemiosmosis occur, facilitating oxidative phosphorylation, which produces a significant amount of ATP. Thus, mitochondria are often referred to as the 'powerhouses' of the cell due to their essential role in energy production.

What are the byproducts of aerobic cellular respiration?

The byproducts of aerobic cellular respiration are carbon dioxide (CO₂) and water (H₂O). During the breakdown of glucose (C₆H₁₂O₆), CO₂ is released as a waste product during the Krebs cycle and pyruvate oxidation. Water is produced at the end of the electron transport chain when oxygen (O₂) acts as the final electron acceptor and combines with electrons and protons (H⁺). These byproducts are expelled from the cell and organism, with CO₂ being exhaled and water being used or excreted.