Why DNA can be transferred
Recombinant DNA technology introduces a selected DNA fragment from one biological source into a different recipient organism or cell.
The technique works because the genetic code is universal: a particular codon specifies the same amino acid in almost all organisms. Transcription and translation also operate using the same basic mechanisms, so a transferred coding sequence can be expressed by a suitable recipient cell.
| Term | Meaning |
|---|---|
| Recombinant DNA (rDNA) | DNA containing nucleotide sequences that have been combined from different sources. |
| Transgenic organism | An organism containing nucleotide sequences introduced from another species. |
| Genetically modified organism (GMO) | An organism whose genetic material has been altered by introducing genetic material. |
General sequence
- Identify the required gene or DNA sequence.
- Obtain the required DNA fragment.
- Amplify the DNA when more copies are required; PCR provides an in vitro method.
- Insert the DNA fragment into a suitable vector.
- Introduce the vector into host cells.
- Detect genetically modified cells using a marker gene.
- Culture selected transformed cells when in vivo amplification is required.
Important components of these procedures include restriction endonucleases, reverse transcriptase, DNA ligase, vectors and marker genes.
Exam Tip: In a recombinant-DNA sequence, name the enzyme responsible for each step and state separately what the vector and marker gene do.