Autotroph and Heterotroph
• Autotrophs are
organisms that are
able to use sunlight
to produce food
• Heterotrophs are
organisms that
obtain energy from
the food they
consume
Adenosine Triphosphate
• Organisms use the molecule adenosine
triphosphate (ATP) as a source of “energy”
Adenosine Triphosphate
• The three phosphate groups are the key
• When ATP releases a phosphate group,
energy is released for use
– As a result, ATP turns into adenosine
diphosphate (ADP)
Adenosine Triphosphate
• One can think of the phosphate groups as
“stored charge”, like a rechargeable battery
– The more phosphate groups, the greater the charge
ATP
High Charge
ADP
AMP
Low Charge
Example of a Use of ATP
• A common example of ATP use involves active
transport
– ATP can also be used to synthesize proteins, nucleic
acids, or even produce light