LEARNING OBJECTIVES
By the end of this chapter, you should be able to:
- explain bacterial usefulness
- describe yeast and enzyme uses
- explain fermenter control
- outline genetic modification
- evaluate GM crops
THE BIG IDEA
How microorganisms, enzymes and recombinant DNA produce useful materials.
This chapter builds each process from its structures, inputs and outputs. Follow the connections rather than memorising isolated facts, then use precise biological terms when explaining cause and effect.
SECTION 01
Microorganisms and enzymes
Bacteria reproduce rapidly, make complex molecules and contain plasmids; their manipulation raises fewer ethical concerns than many animals.
DETAILED EXPLANATION
- Yeast anaerobic respiration produces ethanol for biofuel and carbon dioxide for bread.
- Pectinase breaks down pectin, increasing juice yield and clarity.
- Washing-powder proteases, lipases and amylases digest protein, fat and starch stains.
- To compare biological washing powders, use equal stained samples, equal detergent volumes and the same washing time. Change temperature only, repeat the test and compare stain removal.
- Lactase breaks lactose into simpler sugars to produce lactose-free milk.
SECTION 02
Fermenters
Industrial fermenters grow microorganisms to make insulin, penicillin, mycoprotein and other products.
DETAILED EXPLANATION
- Control temperature and pH near enzyme optima.
- Supply nutrients and suitable oxygen; mixing distributes materials and heat.
- Cooling removes respiratory heat; sterile equipment prevents contamination; waste is removed.
SECTION 03
Genetic modification
Genetic modification removes, changes or inserts individual genes. A plasmid can carry a human gene and direct bacteria to make its protein.
DETAILED EXPLANATION
- The same restriction enzyme cuts gene and plasmid, making complementary sticky ends.
- DNA ligase joins them into a recombinant plasmid.
- The plasmid enters bacteria, which multiply and express the gene.
- Uses include human proteins and crops with herbicide resistance, insect resistance or improved nutrition.
SECTION 04
GM crop evaluation
Benefits may include yield, nutrition and pest control with less insecticide. Concerns include gene flow, resistant pests, non-target effects, reduced diversity, seed cost and dependence on suppliers.
DETAILED EXPLANATION
- Evaluate each crop and inserted gene using evidence rather than treating all genetic modification as identical.
QUICK CHAPTER SUMMARY
The ideas to carry forward
- Microorganisms support biotechnology.
- Fermenters control growth.
- Restriction enzymes and ligase make recombinant plasmids.
- Modified genes produce proteins or crop traits.
- GM decisions balance evidence and context.