5.7 ATP: The Energy Currency
of the Cell
 
 
Adenosine triphosphate
(ATP) is the main energy
currency of the cell
Due to electrostatic
repulsion between
phosphate groups
Each ATP molecule is
composed of three parts:
Fig. 5.11
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5.7 ATP: The Energy Currency
of the Cell
 
Most energy exchanges in the cell involve cleavage
of only the outermost bond in ATP
Provided through
photosynthesis or
aerobic respiration
Used to power
many of the
cell’s activities
Fig. 5.12
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Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display
Oxidation-Reduction
 
Many reactions involve the passage of
electrons from one atom/molecule to another
 
 
 
Oxidation is the loss of electrons
Reduction is the gain of electrons
Oxidation reduction reactions always take
place together
  Note that the transfer of electrons through
these redox reactions also transfers energy
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Fig. 5.13 Redox reactions
Loss of electron (oxidation)
o
A
o
+
B
A
_
+
e –
B
A*
B*
Gain of electron (reduction)
Low energy
High energy
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