Biology notes chapter 9

Biology notes chapter 9 - ATP + Heat Energy Respiration...

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Unformatted text preview: ATP + Heat Energy Respiration (Mit ochondr ia) C 6 H 12 O 6 + O 2 Light Energy Photosynthesis (Chloroplasts) CO 2 + H 2 O NET: 2 CO 2 produced 3 NADH produced 1 FADH 2 produced 1 ATP produced [For each acetyl group that ent ers the cycle] Biology notes chapter 9 Cellular Respiration Energy flows through an ecosystem as light and leaves as heat. Catabolic Pathways are metabolic pathways that release stored energy by the breakdown of complex molecules. Examples of catabolic processes are fermentation , (the breakdown of sugars without the use of oxygen) and cellular respiration (the breakdown of an organic fuel with the use of oxygen). Catabolism is linked to work via the assembly of ATP from ADP and P. Respiration: In Eukaryotic cells, the equipment for respiration are housed in mitochondria. Sugars are preferably used to fats, carbohydrates and proteins. C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + Energy (ATP + Heat) The breakdown of glucose is exergonic meaning that G is negative and the reaction is spontaneous. Redox Reactions: The transfer of electrons in chemical processes yield energy stored in molecules. This energy is then used in the formation of ATP. Oxidation- The loss of electrons Reduction- The gain of electrons Reducing Agent- Loses electrons Oxidising Agent- Gains electrons Not all redox reactions involve the complete transfer of electrons; it can also involve the change in the amount of sharing of electrons in a covalent bond. So dipoles formed can qualify as gaining or losing electrons. An electron loses potential energy when it shifts from a less electronegative atom to a more electronegative one. In cellular respiration, glucose is oxidised and oxygen is reduced and energy is liberated for ATP synthesis. Gradual Energy Liberation and the Electron T ransport Chain: Energy must be released in small amounts to be useful. 1. Electrons are stripped from a glucose 2. Each electron travels with a proton (thus a H atom) 3. The H atoms are passed to a coenzyme NAD + (Nicotinamide adenine dinucleotide) 4. NAD + functions as an oxidising agent by accepting electrons. 5. An enzyme called Dehydrogenase removes a pair of H atoms (2 electrons, 2 protons) from the sugar, oxidising it. The enzyme then delivers the two electrons and one proton to NAD + forming the energetically neutral NADH and releasing the other proton into the solution as H + . Sugar + NAD + hydrocarbon with carboxyl group + NADH + H + 6. The Electron transport chain is used to make the fall of electrons to Oxygen into several energy releasing steps. Proteins built into the inner membrane of a mitochondrion shuttle the electrons from the top (higher energy) to the bottom (lower energy). Free-energy change = -222KJ per mol 7. Oxygen captures the electrons with Hydrogen nuclei forming water....
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This note was uploaded on 04/20/2008 for the course BIOL 1010 taught by Professor Anafi/quinlan during the Fall '08 term at York University.

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Biology notes chapter 9 - ATP + Heat Energy Respiration...

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