What happens in an electron transport chain?
The electron transport chain is a series of molecules that accept or donate electrons easily. By moving step-by-step through these, electrons are moved in a specific direction across a membrane. The movement of hydrogen ions are coupled with this. This means that when electrons are moved, hydrogen ions move too.
What is the end result of the electron transport chain?
The three main steps in the electron transport chain are:
- Generation of a proton gradient across the mitochondrial membrane. Proton accumulation occurs in the intermembrane space of mitochondria.
- Reduction of molecular oxygen and formation of water.
- ATP synthesis by chemiosmosis.
What is the Order of the electron transport chain?
The electron transport chain releases the energy stored within the reduced hydrogen carriers in order to synthesise ATP This is called oxidative phosphorylation , as the energy to synthesise ATP is derived from the oxidation of hydrogen carriers
What are the components of electron transport chain?
Substances
- Electron Transport Chain Complex Proteins
- Multienzyme Complexes
- Electron Transport Complex IV
- Electron Transport Complex I
- Electron Transport Complex III
What is the electron transport chain?
In cellular biology, the electron transport chain is one of the steps in your cell's processes that make energy from the foods you eat. It is the third step of aerobic cellular respiration. Cellular respiration is the term for how your body's cells make energy from food consumed. The electron transport chain is where most ...
How many protein complexes are in the electron transport chain?
Protein Complexes in the Chain. There are four protein complexes that are part of the electron transport chain that functions to pass electrons down the chain. A fifth protein complex serves to transport hydrogen ions back into the matrix. These complexes are embedded within the inner mitochondrial membrane.
How many molecules of ATP are produced in the Krebs cycle?
In all, two molecules of ATP and two molecules of NADH (high energy, electron carrying molecule) are generated. The second step, called the citric acid cycle or Krebs cycle, is when pyruvate is transported across the outer and inner mitochondrial membranes into the mitochondrial matrix. Pyruvate is further oxidized in the Krebs cycle producing two ...
How does ATP synthase work?
ATP synthase moves H + ions that were pumped out of the matrix by the electron transport chain back into the matrix. The energy from the influx of protons into the matrix is used to generate ATP by the phosphorylation (addition of a phosphate) of ADP. The movement of ions across the selectively permeable mitochondrial membrane and down their electrochemical gradient is called chemiosmosis.
What is the third step of aerobic cellular respiration?
This movement of protons provides the energy for the production of ATP. The electron transport chain is the third step of aerobic cellular respiration.
How are electrons passed from a protein complex to a protein complex?
Electrons are passed along the chain from protein complex to protein complex until they are donated to oxygen. During the passage of electrons, protons are pumped out of the mitochondrial matrix across the inner membrane and into the intermembrane space. The accumulation of protons in the intermembrane space creates an electrochemical gradient ...
What happens when electrons are passed along the chain from protein complex to protein complex?
This happens when electrons are passed along the chain from protein complex to protein complex until they are donated to oxygen forming water. ATP chemically decomposes to adenosine diphosphate (ADP) by reacting with water. ADP is in turn used to synthesize ATP. In more detail, as electrons are passed along a chain from protein complex ...
What is the electron transport chain?
The electron transport chain involves a series of redox reactions that relies on protein complexes to transfer electrons from a donor molecule to an acceptor molecule. As a result of these reactions, the proton gradient is produced, enabling mechanical work to be converted into chemical energy, allowing ATP synthesis.
What is the process of generating more ATP?
The process of generating more ATP via the phosphorylation of ADP is referred to oxidative phosphorylation since the energy of hydrogen oxygenation is used throughout the electron transport chain. The ATP generated from this reaction go on to power most cellular reactions necessary for life.
What is the name of the complex that the electrons are transferred to?
The cytochromes then extend into Complex IV, or cytochrome c oxidase. Electrons are transferred one at a time into the complex from cytochrome c. The electrons, in addition to hydrogen and oxygen, then react to form water in an irreversible reaction.
How many electrons does NADH have?
The NADH now has two electrons passing them onto a more mobile molecule, ubiquinone (Q), in the first protein complex (Complex I). Complex I, also known as NADH dehydrogenase, pumps four hydrogen ions from the matrix into the intermembrane space, establishing the proton gradient.
How do electrons move in the electron transfer chain?
In the electron transfer chain, electrons move along a series of proteins to generate an expulsion type force to move hydrogen ions, or protons, across the mitochondrial membrane. The electrons begin their reactions in Complex I, continuing onto Complex II, traversed to Complex III and cytochrome c via coenzyme Q, and then finally to Complex IV. The complexes themselves are complex-structured proteins embedded in the phospholipid membrane. They are combined with a metal ion, such as iron, to help with proton expulsion into the intermembrane space as well as other functions. The complexes also undergo conformational changes to allow openings for the transmembrane movement of protons.
What is the mechanism that drives ATP synthesis?
Often, the use of a proton gradient is referred to as the chemiosmotic mechanism that drives ATP synthesis since it relies on a higher concentration of protons to generate “proton motive force”. The amount of ATP created is directly proportional to the number of protons that are pumped across the inner mitochondrial membrane. ...
Which protein transfers electrons to the last complex?
ISP and cytochrome b are proteins that are located in the matrix that then transfers the electron it received from ubiquinol to cytochrome c1. Cytochrome c1 then transfers it to cytochrome c, which moves the electrons to the last complex. (Note: Unlike ubiquinone (Q), cytochrome c can only carry one electron at a time).
Key Points
While glucose catabolism always produces energy, the amount of energy (in terms of ATP equivalents) produced can vary, especially across different species.
Key Terms
catabolism: Destructive metabolism, usually including the release of energy and breakdown of materials.
ATP Yield
In a eukaryotic cell, the process of cellular respiration can metabolize one molecule of glucose into 30 to 32 ATP. The process of glycolysis only produces two ATP, while all the rest are produced during the electron transport chain.
How Energy Is Made
The First Steps of Cellular Respiration
- The first step of cellular respiration is glycolysis. Glycolysis occurs in the cytoplasmand involves the splitting of one molecule of glucose into two molecules of the chemical compound pyruvate. In all, two molecules of ATP and two molecules of NADH (high energy, electron carrying molecule) are generated. The second step, called the citric acid cycle or Krebs cycle, is when pyruvate is tr…
Protein Complexes in The Chain
- There are four protein complexes that are part of the electron transport chain that functions to pass electrons down the chain. A fifth protein complex serves to transport hydrogen ionsback into the matrix. These complexes are embedded within the inner mitochondrial membrane.
Complex I
- NADH transfers two electrons to Complex I resulting in four H+ ions being pumped across the inner membrane. NADH is oxidized to NAD+, which is recycled back into the Krebs cycle. Electrons are transferred from Complex I to a carrier molecule ubiquinone (Q), which is reduced to ubiquinol (QH2). Ubiquinol carries the electrons to Complex III.
Complex II
- FADH2 transfers electrons to Complex II and the electrons are passed along to ubiquinone (Q). Q is reduced to ubiquinol (QH2), which carries the electrons to Complex III. No H+ions are transported to the intermembrane space in this process.
Complex III
- The passage of electrons to Complex III drives the transport of four more H+ions across the inner membrane. QH2 is oxidized and electrons are passed to another electron carrier protein cytochrome C.
Complex IV
- Cytochrome C passes electrons to the final protein complex in the chain, Complex IV. Two H+ ions are pumped across the inner membrane. The electrons are then passed from Complex IV to an oxygen (O2) molecule, causing the molecule to split. The resulting oxygen atoms quickly grab H+ions to form two molecules of water.
ATP Synthase
- ATP synthase moves H+ ions that were pumped out of the matrix by the electron transport chain back into the matrix. The energy from the influx of protonsinto the matrix is used to generate ATP by the phosphorylation (addition of a phosphate) of ADP. The movement of ions across the selectively permeable mitochondrial membrane and down their electrochemical gradient is calle…
Sources
- "Electron Transport in the Energy Cycle of the Cell." HyperPhysics, hyperphysics.phy-astr.gsu.edu/hbase/Biology/etrans.html.
- Lodish, Harvey, et al. "Electron Transport and Oxidative Phosphorylation." Molecular Cell Biology. 4th Edition., U.S. National Library of Medicine, 2000, www.ncbi.nlm.nih.gov/books/NBK21528/.