A chemical reaction having a common intermediate in which energy is transfered from one side of the reaction to the other.

Examples:

1. The formation of ATP is endergonic and is coupled to the dissipation of a proton gradient.

2. ATP + glucose -> ADP + glucose-1-phosphate     and     glucose-1-phosphate + fructose -> sucrose + phosphate
    - a molecule of sucrose is synthesized from glucose and fructose at the expense of the energy stored in ATP and transfered by glucose-1-phosphate