Chapter 9 outline

Chapter 9 outline - Chapter 9 Cellular Respiration Energy...

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Chapter 9 – Cellular Respiration Energy flows through ecosystems while the chemicals within an ecosystem are recycled Energy flow: Light => organic molecules => ATP + heat ---Oxygen is an energy rich molecule--- Respiration: An Overview Cellular respiration and fermentation are catabolic pathways – both are energy- producing mechanisms o Fermentation pathway in which both electron donors acceptors are organic – is only used in cases where oxygen is not present and in organisms that cannot do cellular respiration NO ATP production organic electron donors and acceptors o Cellular respiration – generates electrons by moving food molecules catabolism of organic molecules ATP production inorganic electron acceptor – many times it is oxygen the removal of energy from organic molecules and storing it as ATP C 6 H 12 O 6 + 6 O 2 => 6 CO 2 + 6 H 2 O + Energy (ATP + heat) How much energy is there?? ΔG = -686 kcal/mol of sugar. The ATP generated is used for work and then regenerated.
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Redox: A Brief Review Redox reactions release energy when electrons move closer to electronegative atoms. o Redox reactions (a.k.a. Oxidation-reduction reactions) These are chemical reactions which involve a partial or complete transfer of electrons from one reactant to another. This is a combustion reaction that gives off heat as energy. All combustion reactions are redox reactions Oxidation – Something that loses electrons Reduction – Something that is gaining electrons **Bonds here are non-polar covalent bonds because of the equally shared electrons** Generalized redox reaction Xe - + Y => X + Ye - Xe - is oxidized to X and Y is reduced to Ye - X is the reducing agent, and Y is the oxidizing agent The transfer of electrons doesn’t have to be a complete transfer (shown above) it may only be a partial transfer (e.g., combustion of methane) >Cellular respiration as a redox reaction< C 6 H 12 O 6 + 6 O 2 => 6 CO 2 + 6 H 2 O Carbon and hydrogen of C 6 H 12 O 6 is oxidized to 6 CO 2 and 6 H 2 O , oxygen of 6 O 2 is reduced to 6 H 2 O. The reaction moves the bonds from an equal sharing to an unequal sharing that lets off energy. The valence electrons of carbon and hydrogen lose potential energy as they shift toward the more electronegative oxygen atoms; the released energy is used to make ATP Cellular fuels (e.g., carbohydrates and fats) are rich in C-H bonds
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Coenzymes: The Role of NAD + - 4.1.6 The redox “fall” of electrons in cellular respiration is stepwise and uses (NAD + ) Nicotinamide adenine dinucleotide energy is pulled out little bits at a time. o Electrons removed from glucose during cellular respiration are not transferred directly to oxygen, but are first passed to a special electron receptor NAD + NAD + Coenzyme R R | dehydrogenase | H-C-OH + NAD + =======> C=O + NADH + H + | | R’ R’ NAD + is reduced to NADH , and CHRR’OH is oxidized to CRR’O NAD + has only slightly greater affinity for electrons than other organic molecules. Cellular respiration is a cumulative function of
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This note was uploaded on 08/29/2010 for the course BIOL 1201 taught by Professor Wishtichusen during the Fall '07 term at LSU.

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Chapter 9 outline - Chapter 9 Cellular Respiration Energy...

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