Cambridge A-Level Biology – Principles of Genetic Technology
Principles of Genetic Technology
Definition of Recombinant DNA
Recombinant DNA (rDNA) is a molecule of DNA that has been artificially created by combining genetic material from two or more different sources so that it carries new genetic information not normally found together in a single organism.
Key Features
Involves the insertion of a gene of interest into a vector (e.g., plasmid, virus).
The resulting DNA molecule can be replicated and expressed in a host cell.
Allows the production of proteins, study of gene function, and creation of genetically modified organisms (GMOs).
Typical Steps in Creating Recombinant DNA
Isolation of DNA: Extract DNA containing the target gene and a suitable vector.
Restriction Digestion: Use restriction enzymes to cut both DNA fragments at specific sequences, producing compatible ends.
Ligation: Join the gene fragment to the vector with DNA ligase, forming the recombinant molecule.
Transformation/Transfection: Introduce the recombinant DNA into a host cell (bacterial, yeast, or mammalian).
Selection: Grow cells on selective media to identify those that have taken up the recombinant DNA.
Expression and Analysis: Induce expression of the inserted gene and verify its function.
Comparison of Natural vs. Recombinant DNA
Aspect
Natural DNA
Recombinant DNA
Origin of sequences
All sequences derived from a single organism.
Sequences derived from two or more different organisms.
Formation
Result of natural evolutionary processes.
Created deliberately using molecular techniques.
Purpose
Encodes the organism’s native traits.
Designed to confer new traits or produce useful proteins.
Suggested diagram: Schematic of the recombinant DNA process showing restriction digestion, ligation, and insertion into a host cell.