1. ATP
The Need for Energy

2. Cell Energy
All living organisms must be able to produce, store, and use energy.
Several cell processes require energy, such as active transport and cell division.
Adenosine triphosphate (ATP) is an energy-storing molecule that can be quickly and easily used by cells.

3. ATP
ATP is made of an adenosine molecule with three phosphate groups attached.
The phosphate groups are charged molecules that do not like being close to each other.

4. Forming and Breaking Down ATP
Because phosphate groups are charged, bonding them together to form ATP takes a lot of energy.
Breaking the bond between two phosphate groups releases energy and forms adenosine diphosphate (ADP).

5. Forming and Breaking Down ATP cont.
The energy of ATP becomes available when the molecule is broken down.
ADP can reform into ATP by bonding another phosphate group, forming a cycle.

6. How do cells use energy in ATP?
Cellular proteins have a specific site where ATP can bind.
When the phosphate bond is broken, the cell can use the released energy for different processes.

7. Uses of Cell Energy
Cells use energy for making new molecules - such as enzymes, cell membrane components, organelles, etc.
Cells use energy to maintain homeostasis, transmit nerve impulses, move cilia, remove wastes, etc.