Biotechnology: Principles and Processes — Part 2: Getting genes into hosts and making products: visual lesson, ISC Class 12 Biology

Lesson

From recombinant DNA to product

Part 2 — putting recombinant DNA into cells, finding the right cells, copying genes and scaling up production.

In this lesson you will

Describe how recombinant DNA is transferred into competent hosts
Explain selection of recombinants by antibiotic resistance, insertional inactivation and blue-white screening
Describe gene amplification by PCR and in vivo, and the use of bioreactors and downstream processing

Concept

Making host cells competent

DNA is hydrophilic and cannot pass easily through cell membranes. Bacteria are made competent by treating them with a divalent cation such as calcium.

Table of the steps of making bacteria competent
Step	Purpose
Treat cells with calcium chloride	Increases the efficiency with which DNA enters
Incubate cells with recombinant DNA on ice	DNA binds the cells
Heat shock at 42 °C briefly	DNA is taken up
Return to ice	Cells recover

Concept

Other methods of gene transfer

Different hosts need different methods.

Table of methods of gene transfer
Method	How	Hosts
Microinjection	DNA injected directly into the nucleus with a fine needle	Animal cells
Biolistics (gene gun)	Gold or tungsten particles coated with DNA are fired at high velocity	Plant cells
Disarmed pathogen vectors	Agrobacterium or retroviruses deliver the gene	Plants and animals

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