chapter 9

chapter 9 - 1. what chemical characteristic of oxygen...

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1. what chemical characteristic of oxygen accounts for its major role in cellular respiration? Oxygen is the most electronegative and thus the most potent of all oxidizing agents. The electronegativity of oxygen allows it to play a major role in cellular respiration. This electronegativity measures the attraction of an atom for the electrons in the bond. When oxygen is present the energy stored in NADH can be converted to ATP energy by the electron transport chain and oxidative- phosphorylation. In addition, the remaining chemical energy in pyruvate can be extracted by the Krebs Cycle. 2. Write the chemical equation for cellular respiration. Explain which compounds are oxidized and reduced in this reaction. why is cellular respiration called an oxidative process The glucose molecule is oxidized into six carbon dioxide molecules. The six oxygens are reduced into six water molecules. Cellular respiration takes energy out of storage and makes it available for ATP synthesis by oxidizing glucose. Cellular respiration is called an oxidative process because it is the oxidative phosphorylation in the final step that mass produces ATP. 3. In the primordial soup, the first catalyzed metabolic reactions were probably relatively simple, one-step reactions that released a lot of energy. Over time, metabolism has evolved into many series of “smaller” reactions. Why is this advantageous? The presence of oxygen in the catalyzed metabolic reactions a prime factor in the evolution of these reactions. Without the presence and affect of the smaller reactions, there would only be a single, explosive step that would transfer and emit all of the energy at once. This explosion of energy would hardly have a long- lasting, productive outcome. The smaller steps have evolved over time in order to avoid this waste of energy by creating a system that is efficient and productive. 4. what is an electron transport chain? The ETC is is a sequence of electron carrier molecule that shuttle electrons during the redox reactions that realease energy used to make ATP. An electron transport chain is used in respiration to break up the fall of electrons to oxygen into several energy-releasing steps instead of one impulsive reaction. The ETC is composed of molecules, mainly proteins, built into the inner membrane of mitochondria. Electrons flow down the chain from one carrier to the next until they finally reach oxygen, which is the final electrons acceptor. This constant movement down the chain is possible due to the increasing electronegativity of each consecutive electron. 5.
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This note was uploaded on 09/27/2011 for the course BIOL 101 taught by Professor Fevzidaldal during the Fall '08 term at UPenn.

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chapter 9 - 1. what chemical characteristic of oxygen...

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