Introduction
 Energy – the ability to do work
 Without the ability to obtain energy life would not
exist.
Autotrophs and Heterotrophs
 Energy come from food.
 Most energy in food comes from the sun.
 Plants and some other organisms use light energy from
the sun to produce food.
 These are called autotrophs or producers.
 Other organism must get their energy indirectly by
consuming other organisms.
 These are called heterotrophs or consumers.
 Some get their energy by feeding on decomposing
organisms and are called decomposers.
 Organisms must release the energy in sugars and
other compounds.
Chemical Energy and ATP
 There are many forms of energy, such as light, heat,
and electrical.
 It can also be stored in chemical compounds which are
released when high energy bonds are broken and
replaced by low energy bonds.
 Adenosine triphosphate (ATP) is one of the major
chemical compounds that cells use to store and release
energy.
ATP
 Consists of adenine, a 5-
carbon sugar called
ribose, and 3 phosphate
groups.
 The high energy bonds
between the phosphate
groups are the key to
ATP’s ability to store and
release energy.
Storing Energy
 Adenosine diphosphate (ADP) only has 2 phosphate
groups.
 This is the key to the way organisms store energy.
 When energy is available, cells add a phosphate group
to ADP making it ATP.
Releasing Energy
 Energy is released when the chemical bond between
the second and third phosphate is broken.
 ATP has enough energy to power a variety of cellular
activities.
 The characteristics of ATP make it exceptionally useful
as the basic energy source of all cell.
Using Biochemical Energy
 One way cells use the energy provided by ATP is to
carry out active transport.
 Sodium-Potassium Pump
 Move proteins throughout the cell.
 Powers other important cellular events
 Synthesis of proteins, nucleic acids, and responses to
chemical signals
 Produce light
 ATP is a great molecule for transferring energy but not
for storing it.
 Glucose stores more than 90 times the chemical energy
of a molecule of ATP.
 This makes it more efficient for a cell to keep only a
small amount of ATP.
 Cells can make more ATP from ADP by using the
energy in glucose.
ATP Cycle