BRAINCAKEExtra-Cellular and Intracellular Enzymes
Enzymes can be grouped by where they act.
Intracellular enzymes are made and act inside cells. They may be free in the cytoplasm or inside organelles. Examples:
• catalase, found in most cells, breaks down hydrogen peroxide, a toxic by-product of metabolism, into water and oxygen: 2H2O2 → 2H2O + O2
• DNA polymerase and RNA polymerase in the nucleus
• the enzymes of respiration in the cytoplasm and mitochondria
Extracellular enzymes are made inside cells but secreted to act outside them. The protein is made on ribosomes of the rough endoplasmic reticulum, modified and packaged in the Golgi apparatus, and released in vesicles by exocytosis. Examples:
Sign in free to see the rest of this lesson, the R.E.C.I.P.E. recall steps and the quiz
BrainCake is free. Make an account in seconds and pick up where this page stops.
Key terms in this lesson
- amylase
- An enzyme that hydrolyses the glycosidic bonds in starch, producing maltose.
- trypsin
- A protease enzyme made in the pancreas that hydrolyses proteins to peptides in the small intestine.
- exocytosis
- The bulk transport of material out of a cell in a vesicle that fuses with the cell surface membrane, releasing its contents.
More in Enzymes
- Enzymes
- Biological Catalysts
- Lock and Key Hypothesis
- Induced Fit Hypothesis
- Measuring Rate of Reaction
- Effect of Substrate Concentration
- Effect of Temperature
- Effect of pH
All 14 lessons in Enzymes · All Edexcel AS-level Biology topics