Electron Transport Chain: An Introduction
The electron transport chain is a protein cluster that transfers electrons through a membrane within mitochondria to form a proton gradient that drives the production of adenosine triphosphate (ATP). The cell uses ATP as an energy source for metabolic processes and cellular functions.
In mammalian cells, the electron transport chain (ETC) is the primary O2 consumer. The ETC is responsible for transporting electrons from NADH and FADH2 to protein complexes and mobile electron carriers. In the ETC, Coenzyme Q (CoQ) and Cyt c are mobile electron carriers, and O2 is the final electron recipient.
What is the Electron Transport Chain?
The electron transport system occurs in the mitochondrial cristae, which contains a number of cytochromes and coenzymes.
These cytochromes and coenzymes act as transporter atoms, moving particles around.
They accept high-energy electrons and transfer them to the next atom in the system.
The energy of electrons transports protons across the layer into the mitochondrion's outer membrane at key proton-pumping sites.
Each NADH particle is extremely energetic, representing the exchange of six protons into the mitochondrion's outer compartment.
Each FADH2 atom represents a four-proton exchange.
The electron progression is similar to that of photosynthesis. Electrons move from NAD to FAD, then to various cytochromes and coenzymes, eventually losing their electrons.
The final electron acceptor in cellular respiration is an oxygen molecule. The electrons combine with an oxygen molecule in their energy-depleted state. The electron-oxygen reaction then produces two hydrogen particles (protons) to form a water particle (H2O).
Functions of the Electron Transport Chain
It serves two important purposes:
Regeneration of Electron Carriers: NADH and FADH2 transfer electrons to the electron transport chain, reverting to NAD+ and FAD. This is significant because the oxidised forms of these electron carriers are required for glycolysis and the citric acid cycle to function properly.
Generates a Proton Gradient: The transport chain creates a proton gradient across the inner mitochondrial membrane, with more H+ in the intermembrane space and less in the matrix. This gradient represents a form of stored energy and is used to make ATP.
Location of Electron Transport Chain
As the citric acid cycle occurs in the mitochondria, high-energy electrons are also present within the mitochondria. As a result, in eukaryotes, the electron transport chain also occurs in the mitochondria.
Mitochondria are organelles inside eukaryotic cells that produce adenosine triphosphate (ATP), the fundamental energy atom utilised by the cell.
The outer membrane of mitochondria is permeable to different particles since it contains a mitochondrial porin, which is a pore-shaping protein.
The inner membrane of mitochondria is impermeable to most ions and polar atoms and only permeable to ATP, pyruvate and citrate due to metabolite carriers.
Electron Transport Chain Complexes
Image: Electron Transport Chain Diagram
The electron transport chain has four complexes:
Complex 1-NADH-Q Oxidoreductase:
It includes enzymes comprising iron-sulphur and FMN.
Here, two electrons are carried to the first complex aboard NADH.
FMN is derived from vitamin B2.
Complex 2-Succinate-Q Reductase:
FADH2 that isn't gone through complex 1 is received straightforwardly from complex 2.
Compound ubiquinone (Q) combines first and second complexes.
The Q atom is dissolvable in water and moves uninhibitedly in the hydrophobic core of the membrane.
In this stage, an electron is conveyed straightforwardly to the electron protein chain.
The quantity of ATP obtained at this stage is straightforwardly relative to the number of protons that are pumped across the inner layer of the mitochondria.
Complex 3-Cytochrome C Reductase:
This complex includes Fe-S protein, Cytochrome b, and Cytochrome c proteins.
Cytochrome proteins comprise the heme group.
This complex is liable for pumping protons across the membrane.
It likewise passes electrons to the cytochrome c where it is moved to the fourth complex of enzymes and proteins.
Here, Q is the electron giver and Cytochrome C is the electron acceptor.
Complex 4-Cytochrome c Oxidase:
This complex involves cytochrome c, a and a3.
There are two heme groups and every one of them is available in cytochrome c and a3.
The cytochromes are answerable for holding oxygen atoms among copper and iron until the oxygen content is totally diminished.
In this stage, the decreased oxygen picks two hydrogen particles from the surroundings to make water.
Inhibitors of Electron Transport Chain
Conclusion
The final and most important step in cellular respiration is the electron transport chain. Glycolysis and the citric acid cycle are used to produce the necessary precursors, whereas the electron transport chain produces the vast majority of ATP. It is essential for both photosynthesis and cellular respiration. This article gives insight into the location, function and major components of the electron transport chain. The final acceptor electron in the transport chain is oxygen.
FAQs on Electron Transport Chain
1. Explain the 3 Main Steps in the Electron Transport Chain?
The three main Electron transport chain steps are as follows:
Pumps with protons generate an electrochemical gradient (proton motive force)
ATP synthase synthesizes ATP by using the resulting release of protons (chemiosmosis).
Oxygen allows water to form electrons and protons.
2. What is the Importance of Electron Transport Chain in Cellular Respiration?
The electron transport chain is a series of four protein complexes that couple redox reactions, creating an electrochemical gradient that leads to the creation of ATP in a complete system named oxidative phosphorylation. It occurs in mitochondria in both cellular respiration and photosynthesis
3. Explain the Main Biochemical Function of the Electron Transport Chain?
The electron transport chain is a series of four protein complexes that couple redox reactions, creating an electrochemical gradient that leads to the creation of ATP in a complete system named oxidative phosphorylation. It occurs in mitochondria in both cellular respiration and photo synthesis.
4. Explain How is Water Produced in the Electron Transport Chain?
This begins with the movement of protons through the cell through NADH and FADH2, producing ATP through a series of reactions. The hydrogen from the coenzymes enters the oxygen consumed by the cell towards the end of the electron transport chain, and interacts with it to form water.
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6. How many ATPs are produced from the electron transport chain?
If we consider that one molecule of NADH produces three molecules of ATP and one molecule of FADH2 produces two molecules of ATP. The electron transport chain produces 30-32 ATP molecules.
NADH molecules in the matrix donate electrons to the chain's beginning and produce three ATP per hydrogen carrier. Later in the chain, cytosolic NADH (from glycolysis) donates electrons and produces only 2 ATP per hydrogen carrier. FADH2 also donates electrons later in the chain, resulting in only two ATP per hydrogen carrier.
(8* Matrix NADH) + (2*Cytosolic NADH) + (2*FADH2 ) = (8*3) + (2*2) +(2*2) = 32 ATP
7. Why is the electron transport chain an aerobic process?
The electron transport chain is the final component of aerobic respiration and the only component of glucose metabolism that utilises atmospheric oxygen. Since oxygen is required in the process, the electron transport chain is an aerobic process. The terminal electron acceptor is oxygen. Most of the aerobic respiration occurs in the mitochondria, whereas the anaerobic respiration takes place in the cytoplasm of the cell. Most of the electrons move downhill in this process of aerobic respiration.
Glucose—> NADH—> ETC—> Oxygen.
8. What are the most important questions asked from the electron transport system?
Examination frequently asks questions about the step electron transport chain step by step explanation, sequence of the different complexes in this system, which complex is responsible for donating electrons at the terminal, which acts as the final acceptor and which molecule is formed in the end. These are one of the most important and repeated questions asked in the examination. Students shouldn’t avoid the electron transport system as questions are asked almost every year from this. The electron transport chain reaction and electron transport chain diagram should be seen by the students properly.
