Concept 6.3 - ATP powers cellular work by coupling exergonic reactions to endergonic reactions

Chemical work

The pushing of endergonic reactions that would not occur spontaneously, such as the synthesis of polymers from monomers

Transport work

The pumping of substances across membranes against the direction of spontaneous movement

Mechanical work

Such as the beating of cilia, the contraction of muscle cells, and the movement of chromosomes during cellular reproduction

Energy coupling

The use of an exergonic process to drive an endergonic one

What kind of reaction causes ATP to become ADP?

Hydrolysis; exergonic reaction

What is the structure of ATP?

Consists of the sugar ribose, the nitrogenous base adenine, and a chain of three phosphate groups

Why is ATP crucial for energy coupling?

Crucial for energy coupling and is one of the nucleoside triphosphates used to make RNA

High-energy phosphate bonds

Misleading; energy release comes from the chemical change to a state of lower free energy, not from the bonds themselves

How is ATP unstable?

Three phosphate groups in ATP are negatively charged and repel each other; contributes to the molecule’s instability and the high energy release upon hydrolysis