The Krebs cycle, also known as the Citric Acid cycle, is a very important process in cellular respiration. Without this portion, respiration would not be possible. This is because the Krebs cycle uses the pyruvate molecules from glycolysis to produce high energy molecules essential for the electron transport chain (ETC) which follows soon after.
Described by Hans Adolf Krebs in 1937
A feature of cell chemistry shared by all types of life.
A complex series of reactions beginning and ending with the compound oxaloacetate.
Where does Krebs cycle takes place?
Both prokaryotic and eukaryotic cells use the citric acid cycle to help meet their energetic and molecular needs. In respiring prokaryotes, the citric acid cycle takes place in the cytosol. In eukaryotic cells, such as the cells of the human body, the cycle takes place within the mitochondrial matrix.
What is the function of Krebs cycle?
To produce high energy molecules such as NADH and FADH2, which act as electron carriers in the electron transport chain. The ETC is where most of the cell's ATP (energy currency) is produced. Additionally, many different precursor molecules are made that can be utilized by a cell.
The Krebs cycle is what is known as Amphibolic, in that it is both catabolic (breaks down molecules) and anabolic (builds molecules).
Reactions in Krebs cycle
Step 1. Pyruvate molecules (3-carbon) from glycolysis are converted into another type of molecule called Acetyl-CoA in a process known as pyruvic oxidation. This conversion occurs when the pyruvate is broken down by an enzyme, releasing a carbon atom which goes on to form carbon dioxide (CO2). The 2 remaining carbon molecules bond with coenzyme A forming Acetyl-CoA. During this process, electrons and a hydrogen ion are passed to NAD+, thus oxidizing the pyruvate, hence the name of the process.
Step 2. The Acetyl-CoA then enters the Krebs cycle. It initially combines with a 4-carbon molecule called oxoaloacetic acid, forming a