Covers restriction endonucleases and RFLP analysis, then vectors and their major types including plasmids, phages, cosmids, BACs and YACs, followed by the basic steps of gene cloning with blue–white screening. Closes with applications in medicine, agriculture, industry, research and forensics. Includes a classification of restriction enzyme types and a list of vector types.
Topic 18 of 63 in the MU Pleven syllabus for Biology (Medicine, Year 1). The free AceMed note covers it in 9 sections, about 694 words (5 min of reading), with 12 flashcards.
In this note
Recombinant DNA technology
(Gene engineering)
RECOMBINANT DNA TECHNOLOGY (GENE ENGINEERING)
A) RESTRICTION ENDONUCLEASES & RFLP
Types:
B) VECTORS
Major types:
C) GENE CLONING
D) APPLICATIONS OF RECOMBINANT DNA TECHNOLOGY
A) RESTRICTION ENDONUCLEASES & RFLP
Restriction enzymes recognize specific palindromic DNA sequences, usually 4–8 bp long, ensuring precise and reproducible cleavage sites.
They function as part of the bacterial restriction–modification system, protecting bacteria from foreign DNA such as bacteriophage genomes.
Sticky ends allow directional cloning, increasing ligation efficiency, while blunt ends provide universal compatibility though with lower ligation efficiency.
In RFLP, variation arises due to insertions, deletions, point mutations, or loss/gain of restriction sites, making patterns unique between individuals.
RFLP analysis involves digestion, gel electrophoresis, transfer to membrane, and hybridization with a labeled probe to detect specific fragments.
Restriction endonucleases are enzymes that cut DNA at specific palindromic sequences.
Naturally found in bacteria as a defense mechanism against viral DNA.
Types:
Type I & III: cut at variable distances from recognition site.
Type II: cut within the recognition site → used in genetic engineering.
Produce sticky ends or blunt ends depending on the enzyme.
Essential for creating recombinant DNA fragments.
RFLP (Restriction Fragment Length Polymorphism):
Technique to detect variations in DNA sequence.
Mutation or polymorphism can change restriction sites, altering fragment lengths.
Used in genetic mapping, forensics, and disease diagnosis.
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