Oxidation & Reduction involves electron transfer & How enzymes find their substrate
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The document explains the concepts of oxidation and reduction, emphasizing electron transfer during metabolic processes in cells, contrasting it with combustion. It highlights the role of enzymes in facilitating substrate interactions, detailing how enzyme-substrate binding and molecular motion influence reaction rates. Additionally, it discusses diffusion and random molecular motion, illustrating how enzymes encounter substrates effectively within cellular environments.
Oxidation & Reduction involves electron transfer & How enzymes find their substrate
- 2. OXIDATION & REDUCTION INVOLVES ELECTRON TRANSFER
- 3. Organic material Burn Single Step Heat Direct addition of oxygen Metabolism Multiple Steps Enzymes No direct addition of oxygen Cellular process Vs Burning
- 4. Oxidation - reduction • Oxidation is loss of electrons • Reduction is gain of electrons – Oxidation is always accompanied by reduction • The total number of electrons is kept constant • Oxidizing agents oxidize and are themselves reduced • Reducing agents reduce and are themselves oxidized
- 6. Combustion of sugar (or respiration). • The number of electrons is conserved • Oxidation and reduction always occurs simultaneously • Glucose reacts with molecular oxygen to produce carbon dioxide and water. • The carbon atoms in glucose are oxidized. That is, they lose electron and go to a higher oxidation state. • The oxygen atoms in molecular oxygen are reduced. That is, they add electrons and go to a lower oxidation state
- 7. Reaction
- 8. Formation of Polar Covalent Bond
- 9. Hydrogenation & Dehydrogenation Increase C-H Bonds (Hydrogenation/Reduction) Decrease C-H Bonds (Dehydrogenation/Oxidation)
- 10. HOW ENZYMES FIND THEIR SUBSTRATE: THE ENORMOUS RAPIDITY OF MOLECULAR MOTIONS
- 11. How do E & S find each other? • Enzyme Substrate reaction rate = (1000 substrate molecules/ Seconds ) • Thus Enzyme bind to substrate for a milliseconds • High Molecular level motions due to heat energy – Translational motion – Vibration – Rotations Meaured by spectroscopic techniques
- 12. Diffusion & Random walk • Molecules are also in constant translational motion, which causes them to explore the space inside the cell very efficiently by wandering through it-a process called diffusion. • Every molecule in a cell collides with a huge number of other molecules each second. As the molecules in a liquid collide and bounce off one another, an individual molecule moves first one way and then another, its path constituting a random walk
- 13. • Average net distance that each molecule travels (as the crow flies) from its starting point is proportional to the square root of the time – 1second to travel 1 µm – 4 seconds to travel 2 µm – 100 seconds to travel 10 µm • A small organic molecule, for example, takes only about one-fifth of a second on average to diffuse a distance of 10 pm Random Walk
- 14. Rate of Encounter • The rate of encounter of each enzyme molecule with its substrate will depend on the concentration of the substrate molecule. For example, – some abundant substrates are present at a concentration of 0.5 mM. Since pure water is 55.5 M, there is only about one such substrate molecule in the cell for every 10s water molecules. • Active site on an enzyme molecule that binds this substrate will be bombarded by about 500,000 random collisions with the substrate molecule per second.
- 15. Stronger the binding of the enzyme & substrate, the slower their rate of dissociation. • Once an enzyme and substrate have collided and smuggled together properly at the active site, they form multiple weak bonds with each other that persist until random thermal motion causes the molecules to dissociate again • when two colliding molecules have poorly matching surfaces, they form few non-covalent bonds and their total energy is negligible compared with that of thermal motion. Two molecules dissociate as rapidly as they come together, preventing incorrect Link between an enzyme and the wrong substrate