Energy of Life

Why do Cells Need Energy?

• To maintain homeostasis• For growth and

development• For the movement of

materials• For the building/breaking

down of molecules• To respond to their

environment

Cells use Chemical Energy

• Energy is stored in the bonds between atoms.

• Energy is released when those chemical bonds break.

ATP and ADP• Cells cannot use sugars for energy, so they must convert

them to a usable form - - - ATP.

• 1 glucose can break down and create 38 ATP molecules.

• This happens in the mitochondria.

ATP and ADP• Energy is stored in the bonds of ATP– Adenine– Ribose (sugar)– 3 phosphate groups

• Energy is released when ATP loses a phosphate group to form ADP.

• Human cells use about 125 pounds of ATP every day so the moleculesmust be recycled again and again.

ATP and ADP• Recap……..– ATP is adenosine triphosphate• It has stored energy like a charged battery

– ADP is adenosine diphosphate• It has less energy like a partially charged battery

Limits of ATP

– ATP is not good for storing energy for a long time.

– Glycogen, starch, glucose, fat, are better for long term storage.

How Do Organisms Get Energy ?

Autotrophscreate their own food

Photosyntheticconvert light to chemical energy

Chemosyntheticuse inorganic chemicals for energy

Ex: Plants, algae, archaebacteria

How Do Organisms Get Energy ?

Heterotrophs

must consume their food

Ex: Humans, other animals