What are buffers and why are they so important to living systems?

Question

What are buffers and why are they so important to living systems?

Answer 1

Many chemical reactions are affected by the acidity of the solution in which they occur. In order for a particular reaction to occur or to occur at an appropriate rate, the pH of the reaction medium must be controlled. Such control is provided by buffer solutions, which are solutions that maintain a particular pH. Biochemical reactions are especially sensitive to pH. Most biological molecules contain groups of atoms that may be charged or neutral depending on pH, and whether these groups are charged or neutral has a significant effect on the biological activity of the molecule.

     In all multicellular organisms, the fluid within the cell and the fluids surrounding the cells have a characteristic and nearly constant pH. This pH is maintained in a number of ways, and one of the most important is through buffer systems. Two important biological buffer systems are the dihydrogen phosphate system and the carbonic acid system.

Answer 2

Buffers are weak acids or bases. They are not fully ionized most of the time. They can absorb or release H+ ions, and therefore can maintain pH. The buffering capacity is highest at their pKa's. Each enzyme has its own pH optimum. Therefore it is important to maintain the pH in living systems.