9.1 LESSON Energy of Life

Learning Objectives

▪ Describe why ATP is useful to cells.
▪ Describe what happens during the process of

photosynthesis.

Adenosine Triphosphate (ATP)

Adenosine triphosphate (ATP) is one of the most important
compounds that cells use to store and release energy.

3 phosphate groups

ribose

adenine

Adenosine Diphosphate (ADP)

Adenosine diphosphate (ADP) has two phosphate groups
instead of three.

adenine

ribose

2 phosphate groups

Storing Energy

When a cell has energy available, it can store small
amounts of it by adding phosphate groups to ADP
molecules, producing ATP.

Releasing Energy

When a cell needs energy, it can release it by breaking
the bond between the second and third phosphate
groups in ATP.

ATP and Batteries

ATP Production

Cells must produce ATP. In photosynthesis, plants convert
the energy of sunlight into chemical energy stored in the
bonds of sugar. Sugar is a better way to store larger amounts of energy in a cell for a longer amount of time. The energy from sugar is used to add phosphates to ADP to "recharge the battery".

Heterotrophs and Autotrophs

Organisms that make their own food are autotrophs.
Plants and phytoplankton are autotrophs.
Organisms that obtain food by consuming other living things
are heterotrophs.
Animals, Fungi and zooplankton are heterotrophs.