Pyruvate Oxidation & Krebs Cycle

Megan Heemskerk

Big picture

Our bodies break up fats and sugars, like glucose, to create energy for cell tasks. Everything, from building muscle and replicating DNA to making proteins and fighting viruses, uses energy, which can be found in the form of ATP. Pyruvate oxidation and the Krebs cycle break down the sugars from our food that we eat to release hydrogen. When hydrogen is released, so is a lot of energy, which is collected and transferred by other processes, such as the electron transport chain. In cellular respiration, there are three main goals. Ravi Zaccharius The first is to break carbon-carbon bonds, the second to break carbon-hydrogen bonds, and the last is to produce ATP.

Pyruvate Oxidation

After the original glucose molecule is broken down by glycolysis, we are left with two pyruvate molecules. These have three carbons each. During pyruvate oxidation, one carbon is taken off in the form of CO₂ and the free electrons are captured by NADH, which takes them to the electron transport chain. The co-enzyme A is added to the leftover two carbons, which creates acetyl-coA. Acetyl-coA makes the molecule bigger so it can fit into the next enzyme. From here the molecule enters the Krebs cycle.

Big Goals accomplished:

Break carbon-carbon bonds

Krebs Cycle

The Krebs cycle takes the acetyl-coA molecule and adds four more carbons, called oxaloacetate, to it to make it easier to break apart. Co-enzyme A is taken off and reused in pyruvate oxidation, while the rest of the molecule, called citrate, continues through the Krebs cycle. CO₂ is taken off this molecule twice to gather the last two carbons from the original glucose molecule. Once again, NADH takes the free electrons over to the electron transport chain so they can be converted into energy, or ATP. GTP, which is pretty much the same thing as ATP, is taken off as well as FADH₂ and NADH. Oxaloacetate is left over again and it is re-inserted into the cycle.

Big Goals Accomplished:

Break carbon-carbon bonds

Break carbon - hydrogen bonds

2 ATP produced

References

Khan Academy. (n.d.). The citric acid cycle. Retrieved October 12, 2017, from https://www.khanacademy.org/science/biology/cellular-respiration-and-fermentation/pyruvate-oxidation-and-the-citric-acid-cycle/a/the-citric-acid-cycle

Khan Academy. Krebs cycle / citric acid cycle. (2009, December 11). Retrieved October 17, 2017, from https://www.khanacademy.org/science/biology/cellular-respiration-and-fermentation/pyruvate-oxidation-and-the-citric-acid-cycle/v/krebs-citric-acid-cycle

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