Why do yeasts, humans, potatoes have catalase?

Question

breakup hydrogen peroxide in the cell.

Answer 1

http://en.wikipedia.org/wiki/Catalase

<<Catalase is a common enzyme found in nearly all living organisms. Its functions include catalyzing the decomposition of hydrogen peroxide to water and oxygen.[1] Catalase has one of the highest turnover rates of all enzymes; one molecule of catalase can convert millions of molecules of hydrogen peroxide to water and oxygen per second.>>

<<Hydrogen peroxide is a harmful by-product of many normal metabolic processes: To prevent damage, it must be quickly converted into other, less dangerous substances. To this end, catalase is frequently used by cells to rapidly catalyze the decomposition of hydrogen peroxide into less reactive gaseous oxygen and water molecules.[13]

The true biological significance of catalase is not always straightforward to assess: Mice genetically engineered to lack catalase are phenotypically normal, indicating that this enzyme is dispensable in animals under some conditions.[14]

Some human beings have very low levels of catalase (acatalesimia), yet show few ill effects. It is likely that the predominant scavengers of H2O2 in normal mammalian cells are peroxiredoxins rather than catalase.>>

Answer 2

All known animals use catalase in every organ, with particularly high concentrations occurring in the liver.