Chapter+7_cellular-respiration Notes - BIOLOGY 325:...

BIOLOGY 325: Inquiries in Biological Science
Chapter 7 Notes

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Cellular
Respiration
Energy in Living Systems
Glycolysis
Oxidation of Pyruvate and the Citric Acid Cycle
Oxidative Phosphorylation
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Metabolism without Oxygen

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Cellular
Respiration
(continued)
Connections of Carbohydrate, Protein, and Lipid Metabolic
Pathways
Regulation of Cellular Respiration
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• Introduction
•
Electrons and Energy
•
ATP in Living Systems
Energy in Living Systems
Cellular Respiration > Energy in Living Systems
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• Organisms ingest organic molecules like the carbohydrate glucose to obtain the
energy needed for cellular functions.
• The energy in glucose can be extracted in a series of chemical reactions known
as cellular respiration.
• Cellular respiration produces energy in the form of ATP, which is the universal
energy currency for cells.
Introduction
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Energy Plant
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Cellular Respiration > Energy in Living Systems

• When electrons are added to a compound, the compound is reduced; a
compound that reduces another is called a reducing agent.
• When electrons are removed from a compound, the compound is considered
oxidized; a compound that oxidizes another is called an oxidizing agent.
• The transfer of energy in the form of electrons allows the cell to transfer and use
energy in an incremental fashion.
•
The principle electron carriers are NAD+ and NADH because they can be easily
oxidized and reduced, respectively.
•
NAD+ is the oxidized form of the niacin and NADH is the reduced form after it
has accepted two electrons and a proton.
Electrons and Energy
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579
The structure of NADH and NAD+
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Cellular Respiration > Energy in Living Systems

• Cells require a constant supply of energy to survive, but cannot store this energy
as free energy as this would result in elevated temperatures and would destroy
the cell.
•
Cells store energy in the form of adenosine triphosphate, or ATP.
• Energy is released when the terminal phosphate group is removed from ATP.
•
To utilize the energy stored as ATP, cells either couple ATP hydrolysis to an
energetically unfavorable reaction to allow it to proceed or transfer one of the
phosphate groups from ATP to a protein substrate, causing it to change
conformations and hence energetic preference.