Chapter 8Section 3 - ATP

Three main types of work

• Mechanical work – cilia beating, muscle cells contracting, chromosomes moving

• Transport work – pumping substances across membranes against the gradient

• Chemical work – Synthesis of polymers from monomers

• Energy coupling – the use of an energy releasing reaction to drive an energy requiring one.

ATP Structure

Hydrolysis of ATP

• ATP + water = ADP + P

• Releases energy

• Why is ATP able to release so much energy?• The three phosphate groups are all negatively

charged and repel each other so they act like a loaded spring.

Hydrolysis of ATP

ATP produces……

• When ATP is hydrolyzed in a test tube the release of energy heats the surrounding water

• In an organism the process of shivering uses ATP hydrolysis during muscle contraction to generate heat and warm the body

• Our bodies need to do much more than keep us warm when we are cold so how is this energy transferred to other processes that require energy?

Phosphorylation

• Enzymes couple the energy of ATP hydrolysis to reactions requiring energy by transferring a phosphate group to another molecule.

• The recipient of the phosphate group is said to be PHOSPHORYLATED.

• The phosphorylated molecule undergoes a change that performs work

Regeneration of ATP

• ATP is a renewable resource in the cell

• ATP cycle is extremely fast

• ATP is made through the processes of cellular respiration in the mitochondria and photosynthesis in the chloroplasts of plants.

The ATP cycle