Most are proteins and a few are RNA

Amino acids (proteins), ribonucleotides (RNA)

Ribosomes (proteins), nucleus (eukaryotes)

Inside the cell, outside the cell, outside the organism

Living cells

Has biocatalytic effect

Pasteur: Fermentation requires the participation of living yeast bacteria

Büchner: Obtained extracts from cells containing enzymes that caused fermentation

Scientists speculate that enzymes are proteins

Sumner: Obtained urease and proved that urease is a protein

Other scientists: Obtained crystals of pepsin, trypsin and many other enzymes and proved that these enzymes are proteins

Cech and Altman discover that a small number of RNAs also have biocatalytic functions

Ensure rapid cell metabolism

The efficiency of enzymes is relative to that of inorganic catalysts. Therefore, it must be compared with the catalytic effect of inorganic catalysts to prove that enzymes are highly efficient.

Each enzyme can only catalyze one or a type of chemical reaction to ensure that cell metabolism proceeds in an orderly manner.

①Enzymes only have catalytic function and have no regulatory function ②The chemical properties and quantity of the enzyme remain unchanged before and after the reaction ③Enzymes can function both inside and outside cells ④ Under the catalysis of enzymes, cell metabolism proceeds rapidly under mild conditions ⑤Enzymes generally work by combining with specific substrates

① Water bath heating, FeCl3 solution and catalase can all speed up the decomposition rate of hydrogen peroxide ② Compared with the inorganic catalyst FeCl3, the catalytic efficiency of catalase is much higher

① Heating provides energy for the reaction and cannot reduce the activation energy. ②The essence of enzyme catalysis is to reduce the chemical energy in chemical reactions

experiment

in conclusion

experiment

in conclusion