In this way, pH determines which enzymes are active and thus which biochemical reactions can occur.īuffer Systems in Living Organisms Learning Goal 41ĭescribe the buffer action that controls the pH of the cytoplasm and bloodīecause all biological processes are dependent on pH, cells and organisms must maintain a specific and constant pH in order to keep their enzymes in the optimum state of protonation.Ĭontrolled by the phosphate buffer system: If the enzyme needs to be protonated in order to be active, then the enzyme will only work in the pH range in which the majority of the enzyme molecules have their carboxyl group protonated. The structure of that group will depend on the pH: Most enzymes only work within a certain pH range.įor example, consider an enzyme with a carboxyl group. This is especially important for enzymes, which are proteins that act as catalysts for important biological reactions. Therefore, changes in the pH around the macromolecule will determine which groups are protonated and which are not, which in turn determines properties of the molecule. These acidic and basic groups act as weak acids and bases, with Ka values which determine the extent of dissociation of the group depending on the pH of the system. Thus, we talk about macromolecules as having acidic and basic groups rather than as being acids and bases. However, due to the size of these molecules, they often contain several different groups that accept or donate protons instead of just one such group. Just as in other acid-base systems, biological macromolecules act as acids and bases by donating and accepting protons. Experiments such as biological enzymatic assays require a certain pH.The cell environment is always buffered at approximately pH 7.Proton dissociable groups are found in macromolecules (such as proteins) as well as the small molecules we have discussed already.It gives a qualitative measure for many problems in cell biology and related fields.Reasons why we should be concerned about pH in biological systems: Therefore, all the acid-base and pH concepts we have discussed so far are extremely important to biochemistry, which is the study of the chemistry of biological systems. Describe the importance of pH in biological systemsĪll living things are water-based systems, which means that they depend heavily on aqueous equilibria, especially acid-base equilibria.
0 kommentar(er)
