Last Updated on March 19, 2022 by QCity Editorial Stuff
The Krebs cycle and the Calvin cycle are two major energy cycles that occur in living cells. The Krebs cycle is a metabolic pathway that takes place inside mitochondria, whereas the Calvin Cycle takes place within chloroplasts. They both have their own set of enzymes, intermediates, and cofactors that are required for them to work properly. These pathways create adenosine triphosphate (ATP), which is an important molecule for many cellular processes including powering muscle contraction or creating proteins from amino acids. The differences between these two pathways include how they obtain carbon dioxide, what type of reaction they undergo to produce ATP, how much ATP one reaction can produce compared to another reaction’s capacity for producing ATP, as well as other minor differences. One similarity between the two pathways is that they both use carbon dioxide as a carbon source.
The Krebs cycle and the Calvin cycle are two metabolic cycles that help produce energy in most organisms. The Krebs cycle is a process of aerobic respiration, while the Calvin cycle is an aspect of photosynthesis. Both processes use different enzymes to break down glucose, which provides the energy for cells to function properly. The difference between these two processes lies in how they react with oxygen. Oxygen is used by mitochondria in the Krebs cycle to create ATP molecules, while oxygen has no role at all during photosynthesis because it occurs underwater. This blog post will summarize what each process entails and then contrast them so you can see their differences more clearly.
Comparison between Krebs cycle and the Calvin cycle
| Parameters of Comparison | Krebs cycle | Calvin cycle |
| System | The Krebs cycle is a series of chemical reactions that take place in the mitochondria | Calvin cycle takes place in chloroplasts |
| Carbon dioxide | In the Krebs cycle, carbon dioxide and water are converted into sugars and other substances (such as ketones). | In the Calvin cycle, carbon dioxide and water are converted into glucose or other carbohydrates. |
| Start with | The Krebs cycle starts with a molecule of acetyl-CoA and ends with CO2 and H2O | The Calvin cycle starts with a molecule of RuBP, which is the product of photosynthesis, and ends with glucose |
| GTPorGDP | Can be converted to ADP | Can be converted to ADP |
What is the Krebs cycle?
The Krebs cycle, also known as the citric acid cycle, is a series of biochemical reactions that occur in the cells of all living organisms. The cycle is responsible for the production of adenosine triphosphate (ATP), the primary energy source for cellular reactions. In this post, we’ll take a closer look at the Krebs cycle and explore some of its key components.
The Krebs cycle is the final stage of cellular respiration. It takes place in the mitochondrial matrix and occurs when pyruvic acid or oxaloacetic acid are acted upon by enzymes, converting them to carbon dioxide through a series of steps. The Krebs cycle starts with acetyl-CoA which is converted into two molecules of citrate. This process also generates one molecule each of ATP, NADH, FADH2, and CO2. As a result, it is sometimes called the citric acid cycle after its end product citric acid.
The Krebs cycle is a metabolic pathway that produces the energy-carrying molecule ATP. It begins with glycolysis, which breaks down glucose into pyruvate. The end product of glycolysis is an intermediate substance called “pyruvic acid.” This substance enters the Krebs cycle and undergoes oxidation to produce carbon dioxide, water, and high-energy electrons. These electrons are then used to create more ATP for cellular use in oxidative phosphorylation.
What is the Calvin cycle?
The Calvin cycle is the process of producing sugar in plants. It takes place in the stroma of chloroplasts, which are found in plant cells. The process starts with carbon dioxide (CO2) and water (H2O), which combine to form a simple sugar called glycerate 3-phosphate or G3P for short. This reaction is catalyzed by ribulose bisphosphate carboxylase/oxygenase, also known as Rubisco.
The Calvin cycle is a fundamental process in photosynthesis that converts energy from the sun into useful organic molecules for plants. It is named after its discoverer, Melvin Calvin. The steps of the Calvin cycle are carbon fixation, reduction, and regeneration. In carbon fixation, CO2 is converted into a 3-carbon molecule called phosphoglycerate. Reduction involves the addition of electrons to this molecule, yielding two molecules of glyceraldehyde 3-phosphate (G3P). Finally, regeneration uses G3P to convert ADP and Pi back into ATP, the cellular energy currency. The Calvin cycle is an important step in producing food for plant growth and humans alike.
10 Differences between the Krebs cycle and the Calvin cycle
1. The Krebs cycle is a series of chemical reactions that take place in the mitochondria, while the Calvin cycle takes place in chloroplasts.
2. In the Krebs cycle, carbon dioxide and water are converted into sugars and other substances (such as ketones).
3. In the Calvin cycle, carbon dioxide and water are converted into glucose or other carbohydrates.
4. The process of photosynthesis occurs during daylight hours because plants need sunlight for energy to complete their cycles.
5. Photosynthesis converts light energy from photons into potential chemical energy stored in ATP molecules.
6. During respiration, cells convert ATP back to ADP so they can use it again later on – this releases oxygen as a byproduct which we breathe out when we exhale.
7. The Krebs cycle starts with a molecule of acetyl-CoA and ends with CO2 and H2O.
8. The Calvin cycle starts with a molecule of RuBP, which is the product of photosynthesis, and ends with glucose.
9. In both cycles, GTP or GDP can be converted to ADP or Pi.
10. Both cycles use enzymes as catalysts for reactions; however, different types of enzymes are used depending on whether it’s a Kreb’s or Calvin Cycle reaction (i.e., pyruvate kinase).
Interesting Statistics or Facts of Krebs cycle
1. The Krebs cycle is a series of chemical reactions that occur in the mitochondria, which are organelles found in most eukaryotic cells.
2. It is named after Hans Adolf Krebs, who was a German-born British biochemist and physician.
3. A major function of this cycle is to generate energy for cellular processes through oxidative phosphorylation.
4. This process occurs when pyruvic acid enters the citric acid cycle as acetyl coenzyme A (acetyl CoA).
5. Pyruvic acid can be formed from glucose or fatty acids by breaking down molecules such as glycogen or lipids; it can also be converted to lactic acid during periods without oxygen.
6. The first reaction of the cycle converts pyruvic acid into oxaloacetic acid with an added hydrogen ion (H+) and coenzyme A (CoA) molecule; this reaction releases energy that is stored as ATP molecules inside the cell’s mitochondria.
Interesting Statistics or Facts of Calvin cycle
1. The Calvin cycle is a series of chemical reactions that convert carbon dioxide and water into sugars.
2. The cycle was discovered by Melvin Calvin in the 1950s.
3. It takes place in the stroma of chloroplasts, which are organelles found inside plant cells.
4. For this reaction to take place, there must be an input of energy from sunlight or other sources.
5. This process only occurs during photosynthesis when the chloroplast absorbs light.
6. A molecule called NADPH provides electrons for this reaction to occur.
Conclusion
The Krebs cycle and the Calvin cycle are both cycles of chemical reactions in our cells that take place under aerobic conditions. They differ in how they change carbon dioxide into sugar, but also produce other compounds like water or oxygen as a result. While different, these two processes work together to create energy for living organisms by converting sugars from food sources through cellular respiration. Understanding their differences can help you better understand what is happening at a molecular level inside your cells when you eat.
References:
Resource 01: https://www.sciencedirect.com/topics/engineering/krebs-cycle
Resource 02: https://www.nationalgeographic.org/media/calvincycle/
