Passage
Catabolism is an oxidative process in which electrons are transferred from lipids, proteins, and carbohydrates to generate high-energy electron carriers from nicotinamide adenine dinucleotide (NADH/NAD⁺) and flavin adenine dinucleotide (FADH₂/FAD) . Both are used in the electron transport chain (ETC) as electron providers in a series of reactions. The transfer of electrons provides energy that drives oxidative phosphorylation and the production of ATP. Reduction of NAD⁺ proceeds according to the following half-reaction:
Reaction 1Reactions in the ETC occur in four protein complexes (I-IV) located in the inner mitochondrial membrane. Here high-energy electrons are shuttled from complexes I, II, and III to complex IV, where O₂ serves as the final electron acceptor. The net result of NADH oxidation is described by Reaction 2.
NADH+H++12O2→NAD++H2OReaction 2At complexes I, III, and IV, hydrogen ions move from the mitochondrial matrix to the intermembrane space and create the electrochemical gradient, or proton motive force (pmf) , that drives ATP synthesis. Each NADH molecule drives the net pumping of 10 protons across the membrane, as per Reaction 3.
NADH+11H++12O2→NAD++10H++H2OReaction 3
Adapted from Garrett R, Grisham CM, Sabat M. Biochemistry. Cengage Learning; 2011.
-For biological processes, which of the following is true of oxidation-reduction reactions?Reduction often involves the formation of bonds to hydrogen.Oxidation often involves the formation of bonds to oxygen.Reducing agents undergo a change to a lower oxidation state.

Question

Passage
Catabolism is an oxidative process in which electrons are transferred from lipids, proteins, and carbohydrates to generate high-energy electron carriers from nicotinamide adenine dinucleotide (NADH/NAD⁺) and flavin adenine dinucleotide (FADH₂/FAD) . Both are used in the electron transport chain (ETC) as electron providers in a series of reactions. The transfer of electrons provides energy that drives oxidative phosphorylation and the production of ATP. Reduction of NAD⁺ proceeds according to the following half-reaction:

Reaction 1Reactions in the ETC occur in four protein complexes (I-IV) located in the inner mitochondrial membrane. Here high-energy electrons are shuttled from complexes I, II, and III to complex IV, where O₂ serves as the final electron acceptor. The net result of NADH oxidation is described by Reaction 2.

NADH+H++12O2→NAD++H2OReaction 2At complexes I, III, and IV, hydrogen ions move from the mitochondrial matrix to the intermembrane space and create the electrochemical gradient, or proton motive force (pmf) , that drives ATP synthesis. Each NADH molecule drives the net pumping of 10 protons across the membrane, as per Reaction 3.

NADH+11H++12O2→NAD++10H++H2OReaction 3
Adapted from Garrett R, Grisham CM, Sabat M. Biochemistry. Cengage Learning; 2011.
-For biological processes, which of the following is true of oxidation-reduction reactions?Reduction often involves the formation of bonds to hydrogen.Oxidation often involves the formation of bonds to oxygen.Reducing agents undergo a change to a lower oxidation state.

Quizplus · Accepted Answer

11ecba2d_119d_ed76_a3bf_e51f628c472f_MD0008_00 Oxidation-reduction (redox) reactions are reactions in which electrons are transferred from one molecule to another. One way to remember the flow of electrons in an oxidation-reduction reaction is with the acronym "OIL RIG": oxidation is loss of electrons, reduction is gain of electrons. However, different compounds transfer electrons in different ways. Unlike metals, which transfer electrons directly and have an oxidation state equal to their net charge, organic molecules generally transfer electrons via hydrogen or oxygen. When hydrogen forms a bond to carbon, the more electronegative carbon atom takes the electron from hydrogen and is reduced (Number I). Loss of a bond to hydrogen or formation of a bond to electronegative oxygen results in carbon losing electrons, which is oxidation (Number II). A simple way to determine the oxidation state of an organic molecule is to count the number of C-O and C-H bonds. For example, an aldehyde is in a higher oxidation state than an alcohol because it has two C-O bonds in the form of a double bond compared to the single C-O bond in alcohols. Alkanes are more reduced than alkenes because they have more bonds to hydrogen. (Number III) Reducing agents cause the reduction of other molecules and become oxidized in the process. They change toward a higher oxidation state. Educational objective: For organic molecules, oxidation involves the loss of electrons by forming bonds to oxygen or losing bonds to hydrogen; reduction is the opposite process. The compound that becomes oxidized is the reducing agent, and the compound that becomes reduced is the oxidizing agent.

Passage Catabolism Is an Oxidative Process in Which Electrons Are Transferred