Why does krebs need oxygen

It is the process by which baking yeasts cause bread to rise and brewing yeasts add alcohol to beer and wine. Your muscle cells also add a fermentation step to glycolysis when they don't have enough oxygen. They convert pyruvate to lactate. This lactate can cause inflammation of muscle tissues, which is why muscles can be sore after vigorous exercise. Why do some cells add fermentation steps in the absence of oxygen? Fermentation steps act to increase the rate of glycolysis.

If oxygen is present, pyruvate from glycolysis is sent to the mitochondria. The pyruvate is transported across the two mitochondrial membranes to the space inside, which is called the mitochondrial matrix. There it is converted to many different carbohydrates by a series of enzymes. This process is called the Krebs cycle. Many of your body's cells can also use fatty acids in the Krebs cycle.

Fatty acids are the major components of fats. When fats are being used to make ATP, fatty acids are released into the blood by fat cells, taken up by other cells, sent to the mitochondria, and consumed by the Krebs cycle. Respiratory electron transport is a current of electrons that passes through proteins in the inner mitochondrial membrane. Two carbon atoms come into the citric acid cycle from each acetyl group. Two carbon dioxide molecules are released on each turn of the cycle; however, these do not contain the same carbon atoms contributed by the acetyl group on that turn of the pathway.

The two acetyl-carbon atoms will eventually be released on later turns of the cycle; in this way, all six carbon atoms from the original glucose molecule will be eventually released as carbon dioxide. It takes two turns of the cycle to process the equivalent of one glucose molecule. These high-energy carriers will connect with the last portion of aerobic respiration to produce ATP molecules.

One ATP or an equivalent is also made in each cycle. Several of the intermediate compounds in the citric acid cycle can be used in synthesizing non-essential amino acids; therefore, the cycle is both anabolic and catabolic.

Unless otherwise noted, images on this page are licensed under CC-BY 4. Text adapted from: OpenStax , Concepts of Biology. OpenStax CNX. The resulting molecule is attached to a co-enzyme, which starts the Krebs Cycle. As the electrons are transferred to each carrier within the electron transport chain, free energy is released and is used to form ATP.

Oxygen is the final acceptor of electrons in the electron transport chain. Without oxygen, the electron transport chain becomes jammed with electrons. Consequently, NAD cannot be produced, thereby causing glycolysis to produce lactic acid instead of pyruvate, which is a necessary component of the Krebs Cycle.

Thus, the Krebs cycle is heavily dependent on oxygen, deeming it an aerobic process. Janice has been a writer for almost 10 years. What Is Nadph in Photosynthesis? How Does Glycolysis Occur?