Photosynthesis vs. Cellular Respiration Comparison

Hello everyone! Welcome to BOGO Biology! This week we will explore energy transformation by comparing the processes of

photosynthesis

and

cellular

respiration

. Here's what the AP curriculum had to say on the topic. They want you to know that, quote, "biological systems use free energy and molecular components to grow, reproduce, and maintain dynamic homeostasis." Now, this is all true, but if you can't back up this claim with evidence, it's very useless. (And also no one talks this way...) So don't go anywhere, because we'll break down the processes of

photosynthesis

and

cellular

respiration

to help you understand them better.

To begin with, let us remember that all organisms require a constant supply of energy. However, they differ in how they obtain it. Most organisms perform photosynthesis, cellular respiration, or both, although there are some that get carried away and do something called chemosynthesis, which does not require sunlight. In photosynthesis, the goal is to store energy and in cellular respiration, the goal is to release energy for use. Today we will begin to delve into which organisms carry out each process, reactants and products, where each set of reactions occurs, and the main steps involved in each type of energy conversion.

Most people know that plants perform photosynthesis and that animals perform cellular respiration, but this is actually an incomplete picture. Several different types of organisms can perform each process, and some of them can even perform both. For example, plants use respiratory cells when they are germinating from their seeds and do not yet have leaves. Now let's talk about reactants and products. One of the most important molecules in biology is a rechargeable energy source that can be used again as ATP. The energy stored in ATP bonds drives the vast majority of cellular processes, but in the process of driving them, it is reduced to its lowest energy form called ADP.

However, through a complicated series of chemical reactions and some glucose, we can recharge the ADP molecule back into ATP. We call this replenishment process "cellular respiration." Another way to think about this is that photosynthesis decreases our supply of ATP, while cellular respiration replenishes the molecules. Seeing reactants and products often helps make relationships seem clearer. In photosynthesis, we put sunlight, ATP, carbon dioxide, and water into separate compartments in chloroplasts. Photosynthesis uses these reactants to convert the carbon in CO2 into a sugar called glucose in a process known as carbon fixation. We also produce oxygen as a waste product.

Now let's compare the reactants and products of photosynthesis with those of cellular respiration. In cellular respiration, the reactants are glucose and oxygen, and the process takes place in the cytoplasm and mitochondria, rather than in chloroplasts. The process produces ATP, carbon dioxide, water and some heat. Observe how the products of one series of reactions become reactants in another. This is exactly what happens in an ecosystem. Here's a quick look at ours so far. Next, we will deal with the location of two processes. As we mentioned earlier, photosynthesis occurs in chloroplasts and respiration occurs in both the cytoplasm and mitochondria.

However, there is more to it than that. Both chloroplasts and mitochondria have internal and external compartments that are crucial for reactions to work properly. In chloroplasts, the inner compartment is called the thylakoid and the outer compartment is called the stroma. In mitochondria, the inner compartment is called the matrix and the outer compartment is called the intermembrane space. This is what a chloroplast looks like. Thylakoids are discs filled with pigments stacked on top of each other. Under the microscope, they look a bit like pancakes. The stroma is a fluid-filled space around the thylakoids. The membrane that separates these two structures is an important part of photosynthesis.

This membrane is lined with several key proteins, including light-absorbing photosystem complexes and a protein called ATP synthase. Let's look at the membranes of the mitochondria and see if we can detect any similarities. This membrane is also dominated by key proteins, including our good friend ATP synthase. If we look a little closer, we will see that this ATP synthase protein works closely with something called a proton pump. The pump transports protons from one side of a membrane to the other to create a gradient. To travel back to the other side of the membrane and restore balance, protons must flow through ATP synthase.

When they do, they recover the inorganic phosphate for ADP in order to create a new ATP-laden molecule. The use of protons and ATP synthase occurs in both photosynthesis and cellular respiration. We call this process chemiosmosis. Here's another look at our table. To conclude, we will review the major steps of each process. We'll start by dividing photosynthesis into the "photo" part and the "synthesis" part. The "photo" part will involve light-dependent reactions, and the "synthesis" part will be light-independent reactions, also known as the Calvin Cycle. Reagents for light The dependent reactions are photons of light and water. These reactions produce ATP, NADPH, and some oxygen.

It passes oxygen into the atmosphere, but we use ATP and NADPH in light-independent reactions. Independent light reactions carry out a process called carbon fixation, in which they take carbon from carbon dioxide in the atmosphere and transform it into sugar. The sugar produced is a three-carbon molecule called PGAL and is essentially half a molecule of glucose. Now let's get into the subject by talking about breathing. When oxygen is present, aerobic respiration is capable of generating large amounts of ATP. The three main steps are glycolysis, the Krebs cycle, and the electron transport chain. Glycolysis also turns to glucose as an electron carrier called NAD+, and we also need to start the reaction with some ATP.

Glycolysis produces a molecule called pyruvate, a little more ATP, and some recharged electron carriers called NADH that we'll use later. The Crab cycle produces a little more NADH and it is also produced by another electron transporter called FADH2. The Krebs courses are maintained by returning the input of carbon atoms from glycolysis and also initiates some more ATP molecules and some carbon dioxide. Finally, electron carriers deliver their cargo to the electron transport chain. Electrons drive the same process we saw before. Electrons carried by NADH and FADH2 cause the pumping of protons from internal to external compartments within the mitochondria.

These protons then return to the internal compartment through ATP synthesis, generating ATP. Oxygen serves as the final electron acceptor in this process and the electron transport chain also initiates a water molecule. In short, both are very complicated processes, but they actually have a lot in common. We hope this video has given you a better idea of ​​how to compare and contrast these two processes and how different organisms obtain energy from their environment. That pretty much concludes this week's video, but I hope you check out some of the other work on Instagram, Twitter, and of course YouTube.

If you want to learn more about photosynthesis, click here. And, if you want to know more about mobile breathing, click here. Thanks again for watching and remember to subscribe!