It's back. Yup. Here we go again, cellular respiration is back. For those of you that mix up when it's the Krebs cycle and when it's the Calvin cycle I have a little way that you might be able to remember it a little better. Though, it would involve you learning the meaning of one German word- you guessed it "Krebs". In German this word means crab. A crab is an animal. Animals cannot photosynthesize, but they can undergo cellular respiration, so the Krebs (crab) cycle occurs during cellular respiration.
On to the steps. Sigh.- The Krebs cycle follows the Link reaction and takes place in the matrix of the mitochondria
- One of the two, two-carbon Acetyl CoA molecules enter the Krebs cycle
- Already in the Krebs cycle is a four carbon molecule called oxaloacetate
- One of the Acetyl CoA molecules will bind with oxaloacetate forming a six carbon compound, this compound is called citrate. The CoA (Co enzyme A) will recycled, and return to the link reaction.
- Citrate will be oxidized and decarboxylated (lose a carbon), this will result in a five carbon compound, a NADH molecule (which was reduced from NAD+), and one CO2 molecule.
- The five carbon compound will again be oxidized and decarboxylated, resulting in a four carbon compound, another NADH molecule, and another CO2 molecule
- This four carbon compound will be oxidized again, and undergo further modification. Resulting in another NADH molecule, one FADH2 molecule (reduced FAD), and one ATP molecule.
- By the time all of this has occurred the four carbon compound is oxaloacetate again, and the cycle can begin again.
- Keep in mind this cycle with occur twice for every molecule of glucose as two Acetyl CoA molecules are produced during the link reaction.
6 NADH (electron carrier)
2 FADH (electron carrier)
4 CO2
2 ATP
Thank you again to my biology teacher for teaching me everything I know about this!
Thank you again to my biology teacher for teaching me everything I know about this!
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