Enzyme functioning
Sub units: Active sites | Test your knowledge | Enzyme specificity | Maintenance of enzyme specificity | Activation energy | Action of enzymes | Intracellular and extracellular enzymes | Activation energy graph

Enzymes can function both inside cells (intracellular) or outside cells (extracellular).

Extracellular enzyme activity

For example, the enzymes that function in our digestive systems are manufactured in cells - but work extracellularly. Spiders and flies are two examples of animals that have taken extracellular digestion a step further. They secrete an enzyme soup into or on their food. In spiders, this is injected into the prey's body. The enzyme soup digests the prey's body contents (specific enzymes breaking down proteins to amino acids, lipids into fatty acids and glycerol and polysaccharides into monosaccharides) and the spider simply sucks up the resulting already digested food. Saprophytic fungi also secrete enzymes through their hyphal tips in order to digest their food.

Intracellular enzyme activity

Enzymes that act inside cells are responsible for catalysing the millions of reactions that occur in metabolic pathways such as glycolysis in the mitochondria and in the photosynthetic pathway in the chloroplast. The lysosome contains many enzymes that are mainly responsible for destroying old cells.


Sub units: Active sites | Test your knowledge | Enzyme specificity | Maintenance of enzyme specificity | Activation energy | Action of enzymes | Intracellular and extracellular enzymes | Activation energy graph


 

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