Monday, February 8, 2016

Biology example question #3 Explain the processes involved in the Krebs Cycle

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.