Edexcel A Level (IAL) Biology -8.19 Transfer of Recombinant DNA into Other Cells- Study Notes- New Syllabus

Insertion of Recombinant DNA into Host Cells

🌱 Introduction

After creating recombinant DNA (rDNA), it must be introduced into a host cell so the host can replicate and/or express the gene. This process is key to producing proteins like insulin, vaccines, or growth hormones.

🌟 Methods of Introducing rDNA into Cells

1. Transformation (Bacteria)

• Bacteria take up plasmid DNA from their environment.
• Often made competent using chemicals (e.g., calcium chloride) or electric pulses (electroporation).
• Once inside, plasmid replicates and expresses the foreign gene.

2. Transfection (Eukaryotic Cells)

• DNA is introduced into animal or plant cells.
• Methods:
  • Chemical transfection: DNA enters cells via liposomes.
  • Electroporation: short electrical pulse opens pores in cell membrane.
  • Viral vectors: harmless viruses carry DNA into host cells.

3. Microinjection

• rDNA is directly injected into the nucleus of a single cell using a fine glass needle.
• Used for creating transgenic animals or modifying embryos.

4. Biolistics (Gene Gun)

• DNA coated on tiny gold or tungsten particles.
• Particles shot into plant cells or tissues at high speed.
• DNA integrates into the genome → transgenic plants produced.

Key Points

• rDNA must enter nucleus in eukaryotes to be expressed.
• Selectable markers are often included in plasmids to identify cells that have taken up rDNA.
• The method depends on the type of host cell (bacterial, plant, or animal).

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