BRAINCAKEVectors
A vector is used to carry a gene into a host cell. The two main types are plasmids and viruses.
Plasmids
Plasmids are small circles of DNA found in bacteria. Plasmids used as vectors contain:
• an origin of replication, so the plasmid is copied inside the bacterium
• one or more restriction sites where the gene can be inserted
• a marker gene, such as antibiotic resistance, to identify transformed cells
• a promoter so the inserted gene is transcribed.
Bacteria do not normally take up plasmids easily. They are made more permeable by treatment with ice-cold calcium chloride solution followed by a brief heat shock, or by electroporation, where a short electric pulse makes temporary pores in the membrane.
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Key terms in this lesson
- bacteriophage
- A virus that infects bacteria, sometimes used as a vector to carry genes into bacterial cells.
- retrovirus
- An RNA virus that inserts a DNA copy of its genes into a host cell's chromosomes, sometimes used as a gene therapy vector.
More in Gene Technology
- Producing Recombinant DNA
- Identifying Transformed Organisms
- Gene Guns
- Liposome Wrapping
- Microinjection
- Gene Silencing
- Transgenic Plants
- Cloning Plants
All 17 lessons in Gene Technology · All Edexcel A-level Biology topics