Electron transport chain and oxidative phosphorylation


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Electron transport chain and oxidative phosphorylation


Biochemistry and metabolism


Citric acid cycle

Electron transport chain and oxidative phosphorylation


Glycogen metabolism

Pentose phosphate pathway

Physiological changes during exercise

Amino acid metabolism

Nitrogen and urea cycle

Fatty acid synthesis

Fatty acid oxidation

Ketone body metabolism

Cholesterol metabolism

Metabolic disorders

Essential fructosuria

Hereditary fructose intolerance


Pyruvate dehydrogenase deficiency

Glucose-6-phosphate dehydrogenase (G6PD) deficiency

Lactose intolerance

Glycogen storage disease type I

Glycogen storage disease type II (NORD)

Glycogen storage disease type III

Glycogen storage disease type IV

Glycogen storage disease type V


Metachromatic leukodystrophy (NORD)

Krabbe disease

Gaucher disease (NORD)

Niemann-Pick disease types A and B (NORD)

Niemann-Pick disease type C

Fabry disease (NORD)

Tay-Sachs disease (NORD)

Mucopolysaccharide storage disease type 1 (Hurler syndrome) (NORD)

Mucopolysaccharide storage disease type 2 (Hunter syndrome) (NORD)


Hartnup disease


Ornithine transcarbamylase deficiency

Phenylketonuria (NORD)

Cystinuria (NORD)


Maple syrup urine disease


Familial hypercholesterolemia



Disorders of carbohydrate metabolism: Pathology review

Disorders of fatty acid metabolism: Pathology review

Dyslipidemias: Pathology review

Glycogen storage disorders: Pathology review

Lysosomal storage disorders: Pathology review

Disorders of amino acid metabolism: Pathology review


Electron transport chain and oxidative phosphorylation


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USMLE® Step 1 questions

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High Yield Notes

12 pages


Electron transport chain and oxidative phosphorylation

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USMLE® Step 1 style questions USMLE

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An investigator is studying the effects of carbon monoxide (CO) on the electron transport chain (ETC). Which of the following best describes the effect of CO on ETC?  

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Content Reviewers

Rishi Desai, MD, MPH


Marisa Pedron

Tanner Marshall, MS

Your heart is constantly working. Whether you’re swimming or taking a nap, your heart is always on the go.

The main form of energy that keeps our heart cells, and really all of our body cells, going is adenosine triphosphate, or ATP.

In most cells, the main ATP producing factory is the mitochondria, which has an inner and an outer membrane, and it’s along the inner membrane where a process called oxidative phosphorylation occurs.

“Oxidative” refers to oxidation - which is when a molecule donates its electron, and “phosphorylation” which refers to the addition of a phosphate group to adenosine diphosphate, or ADP, to form ATP.

So oxidative phosphorylation is the process of making ATP by donating electrons to complexes embedded within the inner mitochondrial membrane.

These complexes are proteins or lipids coupled with metals like iron and copper that facilitate the movement of electrons.

Together, they form the electron transport chain.

During the electron transport chain, electrons are passed on from complex to complex, and finally to oxygen, creating a proton gradient that will be used to make ATP.

The electron transport chain begins with two key molecules that want to donate their electrons: nicotinamide adenine dinucleotide, or NADH, and flavin adenine dinucleotide, or FADH2, both of which get oxidized in the electron transport chain.

NADH and FADH2 are primarily generated in the citric acid cycle which occurs in the mitochondria, but it can also come directly from glycolysis - which is the breakdown of glucose in the cytoplasm, or fatty acid oxidation, which is the breakdown of fats in the mitochondria.

Enzymes called dehydrogenases help generate the electron-rich NADH and FADH2.

And when those molecules are coming from the cytoplasm they can only enter the mitochondria using a specific shuttle.

When using the malate-aspartate shuttle, electrons enter the electron transport chain as NADH.

When using the glycerol-3-phosphate shuttle, electrons enter electron transport chain as FADH2.


The electron transport chain and oxidative phosphorylation are two biochemical processes that occur in the mitochondria of cells. The electron transport chain is a series of proteins that transfer electrons from donors to acceptors, and oxidative phosphorylation is the process by which the energy released by these electrons is used to generate ATP, which is the cellular currency of energy. The electron transport chain and oxidative phosphorylation are important for generating energy in all cells, but they are especially important in muscle cells, because muscles use a lot of energy.


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