Chapter 7: Cellular Respiration

Transfer of Energy Through the Ecosystem

• energy flows in as sunlight

• leaves as heat

fermentation

partial degradation of sugars that occurs without O2

aerobic respiration

consumes organic molecules and O2 and yields ATP

anaerobic respiration

similar to aerobic respiration but consumes compounds other than O2

Stage 1 of Cellular Respiration

glycolysis - cytoplasm

Stage 2 of Cellular Respiration

pyruvate oxidation - mitchondria

Stage 3 of Cellular Respiration

citric acid cycle - mitochondria

Stage 4 of Cellular Respiration

oxidative phosphorylation - mitcochondria

Cellular Respiration - Chemical Formula

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

• exergonic process

• oxidative breakdown of Glucose

oxidation (OIL)

loss of electron

reduction (RIG)

addition of electrons

Redox Reactions

• some do not transfer electrons but change the electron sharing in covalent bonds

Decomposition of Glucose

• driven by redox reactions

• fuel (glucose) = oxidized

• O2 = reduced

• abundance of hydrogen = source of high energy electrons

Oxidation of Glucose

• NAD+ & FAD electron carriers

  energy stored in glucose → harnessed in electron carriers → glucose oxidized into carbon dioxide

Reduction of Oxygen → Water

• final electron acceptor in cellular respiration

oxidative phosphorylation

• powered by redox reactions

• the process that generate almost 90% of ATP

substrate-level phosphorylation

a smaller amount of ATP is formed in glycolysis and the citric acid cycle by…

Gylcolysis

2 sages:

1. glucose is split into 2 3-C molecules (need energy)

2. Atom rearrangements generate pyruvate (generates stored chemical E)

Phase 1: Energy-Consuming Reactions

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Phase 2: Splitting Glucose

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Phase 3: Energy-Producing Reactions

xxxxx

multienzyme complex catalyzed 3 reactions

• oxidation of pyruvate and release of Co2

• reduction of NAD+ to NADH

• Combination of the remaining two-carbon and fragments and coenzyme A to from acetyl CoA