43. Recombinant DNA technology – restriction endonucleases, DNA vectors, recombinant proteins.
Covers recombinant DNA technology, starting with the insert and vector concept and cloning, then restriction endonucleases, their cut types and naming, and DNA vectors such as plasmids and phages. It explains genomic and cDNA cloning, the pBluescript vector, and the production of recombinant proteins in E. coli, yeast and other hosts. Four mnemonics summarise the components, enzyme naming, vector types and protein hosts. A short section on cell micromanipulation closes the note.
Topic 44 of 105 in the MU Sofia syllabus for Biology (Medicine, Year 1). The free AceMed note covers it in 11 sections, about 1,386 words (10 min of reading), with 12 flashcards.
In this note
Recombinant DNA technology - restriction endonucleases, DNA vectors, recombinant proteins.
Restriction Endonucleases
DNA Vectors
Types of Cloning Using Vectors
Recombinant Proteins
Why Recombinant Proteins Are Important
MNEMONICS
Cell micromanipulations
Introduction to Cell Micromanipulation
Essential Equipment for Cell Micromanipulation
Applications in Reproductive Medicine
Recombinant DNA technology - restriction endonucleases, DNA vectors, recombinant proteins.
Recombinant DNA technology involves creating synthetic DNA molecules by joining together fragments of DNA from different sources.
This technique allows scientists to isolate specific genetic sequences that are difficult to study within their natural genomic context.
A major goal of recombinant DNA technology is to extract a DNA segment from its original genome and introduce it into a different DNA molecule that can be easily manipulated and purified in a laboratory setting.
This process is known as cloning, where:
The DNA segment to be studied is referred to as the insert.
The DNA molecule that receives and replicates the insert is called the vector.
The technology enables researchers to study genes in detail and produce proteins in large quantities.
Restriction Endonucleases
Restriction endonucleases are enzymes originally found in bacteria that serve as a defense mechanism against invading viruses, such as bacteriophages.
These enzymes cut DNA at specific recognition sites, usually sequences of four to six base pairs that are palindromic in nature.
There are two main types of cuts made by restriction enzymes:
Blunt ends, where the DNA strands are cut straight across at the same position.
Sticky ends, where the cuts are staggered, creating short single-stranded overhangs that can easily bind to complementary sequences.
These enzymes are named systematically:
One letter is taken from the genus of the bacterium.
Two letters from the species name.
Additional letters or numbers may refer to the strain.
A Roman numeral is added to indicate the order in which the enzyme was discovered.
Example: EcoRI comes from Escherichia coli, strain RY13, and was the first enzyme isolated from that strain.
In recombinant DNA experiments, scientists use the same restriction enzyme to cut both the DNA containing the gene of interest and the vector, ensuring that the sticky or blunt ends are compatible for insertion.
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