Unit 8- Lesson 2 (ATP)

Energy and ATP

• Energy comes in many forms:

– light
– thermal (heat)
– electrical
– mechanical
– nuclear
– chemical

Energy and ATP

• Energy can be stored in the chemical bonds of

molecules and compounds

• In living things, chemical energy is stored in the

chemical bonds of
– Carbohydrates
– Proteins
– Lipids (Fats)

Cells need energy

• Energy in cells is carried

in the form of ATP

• ATP = adenosine

triphosphate

ATP consists of:

– adenine (nitrogen base)

– ribose (a 5-carbon sugar)

– 3 phosphate groups

ATP is a type of nucleotide

Adenine

Ribose

3 Phosphate

groups

Where does ATP come from?

• Fooddoes not contain ATP

• Digestion breaks down food into smaller

molecules that can be used to make ATP (by the
mitochondria)

• How much ATP is made is related to the number

of Calories in the food

• # of ATP produced also depends on the type of

molecule broken down- carbohydrate, lipid or protein

ATP/ADP Cycle

Releasing Energy

●To release the energy stored in ATP molecules,
bonds between their phosphate groups are broken
through hydrolysis.
●Hydrolysis is a chemical reaction in which a water
molecule splits another molecule.
● As a result of hydrolysis, energy is released and
ATP loses a phosphate to become ADP (Adenosine
diphosphate).

ATP/ADP Cycle

Storing Energy

● Small amounts of energy can be stored in a
cell by adding phosphate groups to ADP
molecules (called phosphorylation), producing
ATP.
● ADP is constantly recombined with phosphate
groups to form new molecules of ATP to support
the work of the cell.