Consider an analogy between reaction-coupling and money. In a simple economy, barter provides a means of direct exchange of material goods

For example, the owner of a cow may have excess milk and need eggs, whereas a chicken owner has excess eggs and needs milk. Provided that these two people are in close proximity and can communicate, they may exchange or barter eggs for milk. But in a more complex economy, money serves as a mediator for the exchanges of goods or services. For instance, the cow owner with excess milk may not need other goods until three months from now, or may want goods from someone who does not need milk. In this case, the "energy" from providing milk to the economy can be temporarily "stored" as money, which is a form of "energy" used for many transactions in the economy. Using barter and money as analogies, describe two mechanisms that can serve to drive an unfavorable chemical reaction in the cell.


Barter is analogous to the direct coupling of a favorable to an unfavorable reaction by a single enzyme. Money is analogous to the storage of energy from a favorable reaction in the form of high-energy bonds in an activated carrier molecule. Such activated carrier molecules can later be used to drive a huge variety of other unfavorable reactions in the cell, either by being hydrolyzed to provide the needed energy for a reaction or by transferring an activated chemical group to another molecule.

Biology & Microbiology

You might also like to view...

A pigment absorbs a photon if the energy of the photon is ____

a. exactly enough to boost an electron of the pigment to a higher energy level b. slightly more than the energy of the electron absorbing the photon c. significantly more than the energy of the electron absorbing the photon d. exactly twice the energy of the electron absorbing the photon e. significantly less than the energy of the electron absorbing the photon

Biology & Microbiology

A former patient calls, hoping to locate x-rays taken more than five years ago. What should you say?

What will be an ideal response?

Biology & Microbiology

What type of reproduction includes the binary fission used by single-celled bacteria to produce genetically identical daughter cells?

A) sexual reproduction B) asexual reproduction C) fertilization D) condensation

Biology & Microbiology

The human papilloma virus (HPV) causes

A) gonorrhea. B) vaginal yeast infections. C) genital herpes. D) syphilis. E) genital warts.

Biology & Microbiology