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Chapter 07
How Cells Harvest
Energy
BIOLOGY
Thirteenth Edition
Raven, Johnson, Mason, Losos,
Duncan
© 2023 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom.
No reproduction or further distribution permitted without the prior written consent of McGraw Hill, LLC.
, Respiration
Organisms can be classified based on how they obtain
energy:
Autotrophs
• Able to produce their own organic molecules through
photosynthesis.
Heterotrophs
• Live on organic compounds produced by other organisms.
All organisms use cellular respiration to extract energy from
organic molecules
© McGraw Hill, LLC 2
, Cellular Respiration
Cellular respiration is a series of reactions
Oxidized − loss of electrons
Reduced − gain of electron
Dehydrogenation − lost electrons are accompanied by
protons
• A hydrogen atom is lost (1 electron, 1 proton).
© McGraw Hill, LLC 3
, Redox Reactions
During redox reactions, electrons carry energy from one
molecule to another
Nicotinamide adenosine dinucleotide (NAD+ )
• An electron carrier and enzymatic cofactor.
• NAD+ accepts 2 electrons and 1 proton to become NADH.
• Reaction is reversible.
© McGraw Hill, LLC 4
Chapter 07
How Cells Harvest
Energy
BIOLOGY
Thirteenth Edition
Raven, Johnson, Mason, Losos,
Duncan
© 2023 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom.
No reproduction or further distribution permitted without the prior written consent of McGraw Hill, LLC.
, Respiration
Organisms can be classified based on how they obtain
energy:
Autotrophs
• Able to produce their own organic molecules through
photosynthesis.
Heterotrophs
• Live on organic compounds produced by other organisms.
All organisms use cellular respiration to extract energy from
organic molecules
© McGraw Hill, LLC 2
, Cellular Respiration
Cellular respiration is a series of reactions
Oxidized − loss of electrons
Reduced − gain of electron
Dehydrogenation − lost electrons are accompanied by
protons
• A hydrogen atom is lost (1 electron, 1 proton).
© McGraw Hill, LLC 3
, Redox Reactions
During redox reactions, electrons carry energy from one
molecule to another
Nicotinamide adenosine dinucleotide (NAD+ )
• An electron carrier and enzymatic cofactor.
• NAD+ accepts 2 electrons and 1 proton to become NADH.
• Reaction is reversible.
© McGraw Hill, LLC 4
