Please turn in the lab from Tuesday if you haven’t done so already. Homework: Chapter 7 – Due Wed, Nov 5 th at 10:00 pm

Chapter 7 Oxidation and Reduction Energy transfers

Overview: Life Is Work Living cells require energy from outside sources. © 2014 Pearson Education, Inc.

Figure 7.2 Light energy ECOSYSTEM Photosynthesis in chloroplasts CO 2  H 2 O Cellular respiration in mitochondria Organic molecules  O2 O2 ATP ATP powers most cellular work Heat energy

Concept 7.1: Catabolic pathways yield energy by oxidizing organic fuels The breakdown of organic molecules is exergonic. Fermentation is a partial degradation of sugars that occurs without O 2. Aerobic respiration consumes organic molecules and O 2 and yields ATP. Anaerobic respiration is similar to aerobic respiration but consumes compounds other than O 2. © 2014 Pearson Education, Inc.

Although carbohydrates, fats, and proteins are all consumed as fuel, it is helpful to trace cellular respiration with the sugar glucose. C 6 H 12 O 6  6 O 2  6 CO 2  6 H 2 O  Energy (ATP  heat) © 2014 Pearson Education, Inc.

Redox Reactions: Oxidation and Reduction The transfer of electrons during chemical reactions releases energy stored in organic molecules. This released energy is ultimately used to synthesize ATP. © 2014 Pearson Education, Inc.

The Principle of Redox transfer electrons Chemical reactions that transfer electrons between reactants are called oxidation-reduction reactions, or redox reactions. In oxidation, a substance loses electrons, or is oxidized. In reduction, a substance gains electrons, or is reduced (the amount of positive charge is reduced). © 2014 Pearson Education, Inc.

The Principle of Redox transfer electrons Chemical reactions that transfer electrons between reactants are called oxidation-reduction reactions, or redox reactions. © 2014 Pearson Education, Inc.

Figure 7.UN01 becomes oxidized (loses electron) becomes reduced (gains electron)

Figure 7.UN02 becomes oxidized becomes reduced

Figure 7.3 Reactants Products Methane (reducing agent) Oxygen (oxidizing agent) Carbon dioxide Water becomes reduced becomes oxidized