The Basics of the Electron Transport Chain Essays - Biology

The Basics of the Electron Transport Chain Article Summary:The electron transport chain is the most complex and productive pathway of cellular respiration. Here's a straightforward, simplified explanation of how the ETC works. All living things run on energy. If the organism is a plant or autotrophic microbe, the energy comes from sunlight. For all other forms of life, energy is extracted from nutrients through the reactions of metabolism--cellular respiration. Cellular Respiration the Electron Transport Chain Regardless of whether the original form of energy is sunlight or food, it must ultimately be converted to the cellular energy currency of adenosine triphosphate (ATP). or most organisms, this conversion is accomplished though cellular respiration, a series of biochemical pathways in which glucose (asugar) is broken down and the energy extracted is converted to ATP. The pathways of cellular respiration include: 1. glycolysis, 2. conversion of acetyl-CoA, 3. Kreb's cycle 4. electron transport. Electron transport is the most complex and productive pathway of cellular respiration. Duringaerobic respiration, the ETC produces 34 of the 38 ATP molecules obtained from every molecule of glucose. or most organisms, this conversion is accomplished though cellular respiration, a series of biochemical pathways in which glucose (asugar) is broken down and the energy extracted is converted to ATP. Where the Electron Transport Chain Is Located Electron transport requires a membrane in order to work. Inprokaryotic cells, those of bacteria and bacteria-like Archaeans, electron transport takes place in the cell's plasma membrane, in folded areas called mesosomes. For most organisms, this conversion is accomplished though cellular respiration, a series of biochemical pathways in which glucose (asugar) is broken down and the energy extracted is converted to ATP. The pathways of cellular respiration include: 1. glycolysis 2. conversion of acetyl-CoA 3. Kreb's cycle 4. electron transport. Electron transport is the most complex and productive pathway of cellular respiration. Duringaerobic respiration, the ETC produces 34 of the 38 ATP molecules obtained from every molecule of glucose. Whichever type of membrane houses the cell's electron transport chains (plasma membrane, inner membrane of mitochondria or the tylakoid membrane of chloroplasts)cells have many ETCs running continuously, to produce the ATP energy required for cells to survive and thrive. How the ETC Works Most of theATPmade incellular respiration comes from the stepwise release of energy, of a series of oxidation-reduction reactions between molecules embedded in the plasma membrane(prokaryotes)or mitochondria(eukaryotes). It is easiest to understand how electron transport works by dividing this process into three main events: 1.Oxidation Reduction Reactions During glycolysis, synthesis of acetyl-CoA and Kreb's cycle, the electron carriers NAD+ and FADH are reduced to form NADH and FADH2 respectively. These molecules are like little rechargeable batteries, and when NAD+ and FADH are reduced, this means that they accept and carry electrons and hydrogen ions (H+), potential energy that can be used later in cellular respiration. In the electron transport chain, these electron carriers are oxidized, transferring their electrons to the carrier molecules embedded in the ETC membrane. In aerobic respiration, these electrons are passed from one carrier molecule to another in a series of oxidation-reduction reactions, and ultimately to the final electron acceptor, oxygen (O2), that combines with hydrogen, resulting a water (H2O), a metabolic waste product. 2.Creation of Hydrogen Ion Gradient The energy from each electron being passed down the chain is used to pump a proton (H+) through each carrier molecule, from one side of the membrane to the other. This creates a proton gradient, a type ofconcentration gradient(difference in concentration of a substance between two sides of a membrane), and gradients are potential energy available for cellular work. 3.Phosphorylation of ADP(The payoff!) The hydrogen ions (H+), on the side of the membrane where most concentrated, will eventually flow back across the membrane, down the proton gradient, through anenzymecalledATP synthase. As each H+ moves back across the membrane, the enzyme ATP synthase phosphorylates (adds a phosphate to) adenosine diphosphate (ADP) to make the high energymolecule ATP, which can be used for many different energy-requiring reactions throughout the cell. Taken from : http ://www.scienceprofonline.com/metabolism/electron-transport-chain-cellular-respiration-3.html 10 QUESTIONS How does the ETC works? If the organism is a plant or autotrophic microbe, the energy comes from sunlight. For all other forms of life, energy is extracted from nutrients through the reactions of metabolism--cellular respiration. Which are the pathways of cellular respiration? glycolysis conversion of acetyl-CoA Kreb's cycle electron transport. During aerobic respiration ,how many