Electron Transport Chain

The electron transport system is the final stage of aerobic respiration.

The electrons are transferred from NADH and FADH2 via several electron acceptors to the final electon acceptor, which is molecular oxygen. 

During this process, the energy is produced in the form of ATP. This process is called oxidative phosphorylation. 

The inhibitors such as cyanide and carbon monoxide will inhibit the function of the electron transport chain.

The electron transport system is a chain of electron acceptors embedded in the inner membrane of the mitochondrion.

The electron transport system accepts electrons from the energy carriers such as NADH and FADH2 produced from glycolysis and Krebs cycle.

The electron transport chain consists of mostly cytochromes which are proteins with a prosthetic group.

One water molecule is formed from oxygen at the end of the elctron transport system.

One NADP produces three ATP and one FADH2 produces teo ATP through the electron transport system.

The net energy gain is 34 ATP molecules in Electron Transport Chain.

Krebs Cycle

Krebs cycle is a series of interrelated biochemical reactions occurring in all living cells, which takes place in the inner membrane of mitochondria. 

This involves a metabolic patyway during which pyruvate is broken down into carbon dioxide and water to generate energy. 

Krebs cycle also called citric acid cycle or tricarboxylic acid (TCA) cycle.

Link Reaction

Pyruvates enter mitochondria and initiates the link reaction between glycolysis and Krebs cycle by forming acetyl CoA.

Krebs Cycle

Acetyl CoA initiates the Krebs cycle by combining with oxaloacetate(4C) to form citrate. Citrate is decarboxylated and dehydrogenated through a series of reactions.

Energy is stored in the form of NADH, FADH2 AND GTP.

Two molecule of carbon dioxide are released as waste product during Krebs cycle.

NAD and FAD are hydrogen acceptors.

One molecule of ATP is gained at the end of the cycle.

Krebs cycle provides hydrogen for use in ETC to provide energy for the formation of ATP.

Glycolysis

Glycolysis takes place in the cytoplasm.

Glycolysis involves two phases, energy investment phase and energy pay off phase.

In the energy investment phase, glucose is broken down into two molecules of 
glyceraldehydes 3-phosphate.

Two molecules of ATP are utilized in this phase.

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In the energy pay off phase, two molecules of G3P are converted into two molecules of pyruvate.

During this phase 4ATP is formed by substrate level phosphorylation.

The net gain of energy during glycolysis is 2ATP and 2NADH.