what are the stages of aerobic respiration also where is the site of each stage?

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Glycolysis

The first stage of aerobic respiration is called glycolysis. Glycolysis is a series of chemical reactions that occurs in the cytoplasm of cells in all living organisms, the process being completely anaerobic (without oxygen). The process begins by converting a molecule of glucose into two molecules of pyruvate. The reaction yields energy as four molecules of ATP are produced as well, though two are consumed to start the reaction in the preparatory phase. To break down the glucose, the addition of a phosphate occurs to facilitate the split into two triose sugars, which will eventually lead to the creation of the pyruvate. In the second half of glycolysis, four phosphate groups transfer to ADP to create four ATP, resulting in two NADH. At the end of glycolysis we have two pyruvate, two NADH, two ATP, two positive hydrogens and two molecules of water.

Link Reaction

A cluster of enzymes known as the pyruvate dehydrogenase complex that can be found in the mitochondria of eukaryotic cells or the cytosol of prokaryotes, oxidizes the pyruvate into acetyl-CoA and carbon dioxide. As this occurs, one molecule of NADH is formed for every pyruvate oxidized and 3 moles of ATP result for each mole of pyruvate. This step is called either the oxidative decarboxylation of pyruvate, or the link reaction because it links glycolysis and the Krebs cycle. The link reaction is not always referred to as a stage on its own since it is more like a bridge between two stages. Cells will either undergo aerobic or anaerobic respiration depending on the presence of oxygen, and a lack of oxygen will cause a skipping of the link reaction and the fermentation of anaerobic respiration will begin.

The Krebs Cycle

The Krebs cycle can also be called the tricarboxylic acid cycle. The Krebs cycle will not occur if there has been no oxidization of the pyruvate in the link reaction and anaerobic respiration will begin. When the link reaction has occurred, the acetyl-CoA will enter the mitochondrial matrix and be oxidized to carbon dioxide, and reduce NAD to NADH to be used in the electron transport chain. As two acetyl-CoA are oxidized, water and carbon dioxide are created. To get through the process there are eight steps, with eight different enzymes, the end result being a net energy gain of 3 NADH, 1 FADH and 1 ATP (double that for one whole glucose molecule).

Electron Transport Chain

The electron transport chain, also called oxidative phosphorylation, occurs in the cristae of the mitochondria. The electron transport chain refers to the proton gradient that goes across the inner membrane of the mitochondria. This occurs when NADH that was produced in the Krebs cycle is oxidized. The chemiosmotic gradient that results drives the phosphorylation of ADP and creates the greatest amount of ATP synthesis in all of aerobic respiration. In ideal circumstances, at the end of aerobic respiration, the one glucose molecule yields 36 net molecules of ATP, though more often than not, there are a few molecules lost throughout due to the cost of moving the molecules through the process. The extra electrons get transported to oxygen, and two protons are added to create water. The electron transport stage is sometimes grouped in with the Krebs cycle as part of that step.

I thought there were three stages: Glycolysis, Kreb's cycle and Electron Transport

Glycolysis takes place in the cytoplasm. Krebs cycle in the mitochondria, and electron transport takes place within the membrane of the mitochondria (simply in the mitochondria as well).

The 3 Main Steps of Aerobic Respiration:

1) Glycolysis- Makes 2 net ATP

2) Krebs Cycle- 2 ATP

3) Electron Transport- 32 ATP

After glycolysis occurs, pyruvates enter the mitochondria and diffuse to the matrix.

At the matrix, the Krebs Cycle occurs. Here, the remaining hydrogen atoms and their energy rich electrons are removed.

In one turn of the Krebs Cycle, 2 ATP, 1 FADH2, and 3 NADH are made.

In one turn of the Krebs Cycle, 2 CO2 are released.

The 2 ATP are available for use by the cell.

The FADH2 and 3 NADH proceed to the Cristae where they provide energy for Electron Transport (also known as oxidative phosphorylation).

The energy provided by all the NADH and FADH2 is used

a. to pump H ions into the outer compartment.

b. this creates a charge imbalance across the cristae (high potential energy).

c. as H ions diffuse back to the matrix, they pass through a protein channel with an enzyme, ATP synthase, which takes the energy released by the H ions and uses it to create ATP (from ADP + P).

d. Oxygen bonds with 2 hydrogen ions (removing them so aerobic respiration can continue) to form water.