Biotechnology: Principles and Processes

About this unit

Biotechnology uses living organisms, cells or their enzymes to make products and processes useful to humans. This unit explains the two core techniques of modern biotechnology, genetic engineering and bioprocess engineering, and the tools that make recombinant DNA technology possible: restriction enzymes, DNA ligase, cloning vectors such as plasmids, and competent host cells. It then follows the steps of making recombinant DNA, from isolating DNA and amplifying it by PCR to growing transformed cells in bioreactors and purifying the product.

Key ideas

• Recombinant DNA (rDNA) is formed by joining DNA from two different sources.
• Restriction endonucleases cut DNA at specific palindromic recognition sequences.
• DNA ligase joins DNA fragments; vectors carry foreign DNA into hosts.
• A vector needs an origin of replication (ori), selectable markers and cloning sites.
• PCR amplifies a gene using primers, a thermostable DNA polymerase and repeated cycles.
• Bioreactors grow cells on a large scale; downstream processing purifies the product.

How to prepare

Learn the naming rule for restriction enzymes (for example EcoRI), the features of pBR322, and the three steps of a PCR cycle with their purpose. Practise reasoning questions on insertional inactivation and blue–white selection. Remember who made the first recombinant DNA and which enzymes break open bacterial, plant and fungal cells.