Electron Transport Chain and Oxidative Phosphorylation

Know the processes of ETC and oxidative phosphorylation

See earlier post: Cell Biology- Introduction and Energy Production

Another thing worth mentioning is that the transport of electrons goes down an energy gradient: electrons move from a higher energy state to a lower energy state.

Regular aerobic exercise training can increase our mitochondrial volume and electron transport chain components, making the oxidative phosphorylation process more efficient.

Also, it's always fun to learn about what can go wrong :P Leigh's Disease, also known as Subacute Necrotising Encephalomyopathy, is caused by dysfunctions in the complexes in the electron transport chain and/or mutations in the ATP synthase. Cyanide poisoning occurs when cyanide binds to Fe³⁺ in the haem of cytochrome oxidase (complex IV), preventing electrons from being passed further along. This creates a "backup" of electrons, which ultimately ceases the transport of protons. This stops ATP from forming, eventually causing death.

Describe the alternate pathway of anaerobic metabolism

When oxygen isn't available, it can't accept electrons at the end of the electron transport chain. This causes a backup of NADH. As mentioned here, NADH can inhibit the phosphorylation and activation of pyruvate dehydrogenase. Inhibition of pyruvate dehydrogenase causes pyruvate to accumulate and eventually get turned into lactate in animals or plants, or ethanol in yeast.

In animals and plants, lactate/lactic acid is formed. Lactate dehydrogenase breaks down pyruvate into lactate, converting NADH to NAD⁺ as it does so. Eventually, lactic acid does need to be metabolised, but this metabolism requires oxygen, leading to an "oxygen debt."

In yeast, as well as in some plants, ethanol can be formed. Firstly, pyruvate is converted into acetaldehyde, releasing carbon dioxide. Alcohol dehydrogenase can then break down acetaldehyde into ethanol, converting NADH to NAD⁺ as it does so.

Also, as you should probably know, not too much ATP can be produced if pyruvate can't enter the citric acid cycle and undergo oxidative phosphorylation (only 2ATP per molecule of glucose can be produced in anaerobic metabolism, whereas 38ATP can be produced in aerobic metabolism).

Explain the purpose of generating lactate

When lactate is generated, NADH is recycled to NAD⁺. This allows it to be reused in further glycolysis.

Describe the Cori cycle & explain its role

The Cori cycle recycles lactate back to glucose. Lactate is co-transported out of cells of the body, along with H⁺. It can then enter the liver, where lactate dehydrogenase restores it to pyruvate. (Yup, lactate dehydrogenase again. I just sent an email asking my lecturer how lactate dehydrogenase can modulate the conversion of pyruvate into lactate AND the conversion of lactate into pyruvate.) Pyruvate can then be converted to glucose in the process of gluconeogenesis (i.e. producing glucose from sources that aren't glycogen).

Explain why different parts of the metabolic pathways occur in different cell types

Different parts of the metabolic pathways occur in different cell types due to different expression of proteins, enzymes and so on. I'm guessing that blood supply may also play a role.