BIOL 1406

PreLab 3.5

What is a buffer?

A buffer is a mixture of molecules that release or bind H+ in order to maintain a relatively stable pH. Note that the function of a buffer is NOT to keep a solution neutral (at pH 7); its function is to minimize the change in pH when base or acid is added to the solution. Also note that there are many different buffers, and each one will stabilize the pH of a solution only within a specific pH range. One buffer may be effective within a range of pH 2 to pH 6, while another may be effective within a range of pH 10 to pH 12. Beyond its buffering range, a buffer no longer acts to stabilize the pH of the solution.

Buffers are extremely important to living organisms because most biochemical processes proceed normally only when the pH remains within a fairly narrow range. An excess of H+ or OH- can interfere with the structure and activity of many biomolecules, especially proteins. Therefore, buffers are commonly used in living organisms to help maintain a relatively stable pH. In humans, for example, buffers act to maintain blood pH between 7.35 and 7.45 even though acids and bases are continually being added to and removed from the blood as it travels through the body. The 3 main buffer systems in our bodies are the bicarbonate buffer system, the phosphate buffer system, and the protein buffer system.

In the laboratory, molecular and cellular biologists make extensive use of buffers to stabilize the pH of aqueous solutions. When studying biomolecules in a test tube, the biomolecules may be altered or may behave in ways that are uncharacteristic of their natural behavior if they are in a solution with a pH that is significantly different from the pH of their natural environment.
 
 

Buffers help maintain a stable pH

 

Use the interactive exercise below to learn more about acids, bases, and buffers.


 

YOUR TURN
Indicate whether each of the following statements is true or false:
A buffer is a mixture of molecules that acts to keep the pH of a solution close to neutral.
 		 Check your answer.
Buffers are extremely important to living organisms because all biochemical processes proceed normally only when the pH remains close to 7.
 		 Check your answer.
When studying biomolecules in a test tube, the biomolecules may behave in ways that are uncharacteristic of their natural behavior if they are in a solution with a pH that is significantly different from the pH of their natural environment.
 		 Check your answer.

 

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