Aerobic Respiration is the second part
of cellular respiration. Aerobic respiration is the release of energy from glucose
or another organic substrate in the presence of Oxygen. Aerobic means in air, but it is the Oxygen in the air which is
necessary for aerobic respiration. This is the part of cellular respiration that most of the ATP is produced. After
glycolysis, if oxygen is present in the cells environment, pyruvic acid is broken down and NADH is used to make a large amount
of ATP through this process. Oxygen is important to aerobic respiration because oxygen allows additional electrons to
pass along the chain and if they didn't ATP synthesis would stop. In aerobic respiration pyruvic acid is converted into Carbon
Dioxide and water, producing a large amount of ATP. Aerobic respiration has two major stages known as the Krebs Cycle
(named after a German biochemist, Hans Krebs), and the elctron transport chain. In the Krebs Cycle the oxidation of glucose
is complete. The Krebs cycle takes 2 full turns during cellular respiration. In a prokaryote Aerobic respiration takes
place in the cytosol, but in a eukaryote aerobic respiration takes place in the mitochondria.(The Krebs cycle in the mitochondrial
matrix and the electron transport chain in the inner membrane.) Most of the ATP molecules are produced during the
Krebs Cycle. It may make up to 34 molecules of ATP.
1.Acetyl combines with Oxaloactic acid to produce citric acid.
2.The citric acid releases a carbon dioxide and a hydrogen atom.
3.The carbon compound formed in step 2 also releases a carbon dioxide and hydrogen
4.The new 4-carbon compound forms another 4-carbon compound by releasing a hydrogen
5. Now, the new 4-carbon compound produced in step 4 releases a hydrogen atom to
regenerate oxaloacetic acid, which keeps the Kreb cycle going.
The Electron Transport Chain
1.NADH and FADH2 give up electrons to the electron transport chain.
2.The molecules are passed down the chain. As they move through each molecule they
lose more and more energy.
3.The energy lost from the electrons is used to pump protons from the matrix.
4.The concentration and electrical gradients of protons drive the synthesis of
ATP by chemiosmosis (the same process that generates ATP in photosynthesis).As protons move through ATP synthase and
down their concentrational and electrical gradients, ATP is made from ADP and phosphate.
5.Oxygen is the final acceptor of electrons that have been passed down the chain.
The protons, electrons, and oxygen all combine to make water.