Cambridge O Level Biology · Syllabus 5090 · Biotechnology and Genetic Modification
Pectinase
What is Pectinase?
An enzyme used in fruit-juice production that breaks down pectin. Pectin is a substance found in plant cell walls and in the middle regions between neighbouring cells, where it acts as a cement holding the tissue together and holding the cell sap inside. When crushed fruit is treated with pectinase, the pectin is broken down, the cells separate and their contents are released, so a greater volume of juice is obtained from the same mass of fruit. Because fewer suspended fragments of tissue remain in the liquid, the juice is also clearer and easier to filter. Pectinase acts specifically on pectin; it does not digest cellulose.
This definition is part of the Biotechnology and Genetic Modification chapter in Cambridge O Level Biology.
Pectinase in context
Biotechnology is the use of living organisms, cells or enzymes to make useful products. Yeast respires anaerobically, converting glucose to ethanol and carbon dioxide: the carbon dioxide raises bread dough, and the ethanol is the product collected in ethanol manufacture. Bacteria are chosen for industrial production because they reproduce rapidly, can make complex molecules, contain plasmids that can receive selected genes, and raise fewer ethical concerns than using animals. They are grown in fermenters, in which temperature, pH, oxygen, nutrient supply and waste products are all controlled. Isolated enzymes do industrial jobs of their own — proteases and lipases in biological washing powders, pectinase in fruit juice, lactase in lactose-free milk. Genetic modification is changing an organism's genetic material by removing, changing or inserting individual genes; inserting the human insulin gene into bacterial DNA lets bacteria make human insulin, and inserting genes into crops can give herbicide resistance, insect-pest resistance or increased vitamin content — each with benefits and risks that have to be weighed rather than declared.
Common mistakes with Pectinase
- “Pectinase digests the whole plant cell wall.” Why wrong It acts on pectin. The cellulose of the cell wall is a different substance and needs a different enzyme. Say instead Pectinase breaks down the pectin in the cell walls and between the cells, so the cells separate and their contents are released.
Questions students ask about Pectinase
What is biotechnology?
Biotechnology is the use of living organisms, cells or enzymes to make useful products or to carry out useful processes. It includes using yeast to make bread and ethanol, growing bacteria in industrial fermenters, and using isolated enzymes such as proteases, pectinase and lactase. Genetic modification is one technique used within biotechnology, not another name for it.
What does pectinase do in fruit-juice production?
Pectinase breaks down pectin, which is found in plant cell walls and in the middle regions between cells and holds the tissue together. The cells therefore separate and their contents are released, so more juice is obtained from the same mass of fruit and the juice is clearer because fewer fragments remain suspended in it.