Cellular Respiration - Basic Biology - Lecture Slides, Slides of Biology

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Chapter 9

Cellular Respiration: Harvesting Chemical Energy

• Overview: Life Is Work
• Living cells
  • Require transfusions of energy from outside sources to perform their many tasks

• Energy
  • Flows into an ecosystem as sunlight and leaves as heat

• Concept 9.1: Catabolic pathways yield energy by

oxidizing organic fuels

• Cellular respiration
  • Is the most prevalent and efficient catabolic pathway
  • Consumes oxygen and organic molecules such as glucose
  • Yields ATP

Redox Reactions: Oxidation and

• Catabolic pathways yield energyReduction
  • Due to the transfer of electrons from high potential energy (i.e. in animal cell from Glucose) to
  • Low potential energy (electron acceptor usually an electron carrier, but ultimately delivered to oxygen in the mitochondria)

• In oxidation
  • A substance loses electrons, or is oxidized
• In reduction
  • A substance gains electrons, or is reduced

• Examples of redox reactions

Na + Cl Na +^ + Cl–

becomes oxidized (loses electron)

becomes reduced (gains electron)

Stepwise Energy Harvest via NAD+

and the Electron Transport Chain

• Cellular respiration
  • Oxidizes glucose in a series of steps

• Electrons from organic compounds
  • Are usually first transferred to NAD+^ , a coenzyme- electron carrier

• If electron transfer is not stepwise
  • A large release of energy occurs
  • As in the reaction of hydrogen and oxygen to form water

The Stages of Cellular Respiration: A

• Respiration is a cumulative function of three Preview

metabolic stages

• Glycolysis
• The citric acid cycle
• Oxidative phosphorylation

• Oxidative phosphorylation
  • Is driven by the electron transport chain that occurs in the Mitochondria
  • Generates ATP

• Mitochondria are enclosed by two membranes
  • A smooth outer membrane
  • An inner membrane folded into cristae