Cellular Respiration Harvesting Chemical Energy

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Slide 1

Life Is Work

Living cells require energy from outside sources

Some animals, such as the giant panda, obtain energy by eating plants, and some animals feed on other organisms that eat plants

Slide 2

Fig. 9-1

Slide 3

Energy flows into an ecosystem as sunlight and leaves as heat

Photosynthesis generates O2 and organic molecules, which are used in cellular respiration

Cells use chemical energy stored in organic molecules to regenerate ATP, which powers work

Slide 4

Fig. 9-2

Light

energy

ECOSYSTEM

Photosynthesis

in chloroplasts

CO2 + H2O

Cellular respiration

in mitochondria

Organic

molecules

+ O2

ATP powers most cellular work

Heat

energy

ATP

Slide 5

Concept 9.1: Catabolic pathways yield energy by oxidizing organic fuels

Several processes are central to cellular respiration and related pathways

Slide 6

Catabolic Pathways and Production of ATP

The breakdown of organic molecules is exergonic

Fermentation is a partial degradation of sugars that occurs without O2

Aerobic respiration consumes organic molecules and O2 and yields ATP

Anaerobic respiration is similar to aerobic respiration but consumes compounds other than O2

Slide 7

Cellular respiration includes both aerobic and anaerobic respiration but is often used to refer to aerobic respiration

Although carbohydrates, fats, and proteins are all consumed as fuel, it is helpful to trace cellular respiration with the sugar glucose:

C6H12O6 + 6 O2  6 CO2 + 6 H2O + Energy (ATP + heat)

Slide 8

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

Slide 9

The Principle of Redox

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)