Recombinant DNA 4 Flashcards
(14 cards)
What is a transgenic animal ?
An animal that has exogenous DNA inserted into its genome
How to make a transgenic animal ?
- Gene of interest isolated from organism
- Gene inserted into a vector
- Gene is injected directly into the male pronucleus (2pL)- it ligates and inserts itself into the chromosome
- Implant modified egg into surrogate mother
- 25% off offspring are transgenic, 75% are non-transgenic
What are AquAdvantage Salmon ?
The first GM animal approved for human consumption.
It was engineered to grow faster than normal salmon.
The modification involves inserting a growth hormone-regulating gene from the Pacific Chinook salmon and an antifreeze promoter sequence from the ocean pout so it can grow all year round.
What are advantages of the AquAdvantage salmon ?
- Increased growth rate
- Improved utilisation of diet
What are disadvantages of the AquAdvantage salmon ?
- Human health- altered levels of hormones
- Environment- escaped transgenic fish may breed with wild population
What are transgenic goats that produce pharmaceutical proteins ?
A human antithrombin gene is injected into goat embryos. The goats then produce human antithrombin in their milk which can be purified into ATryn which is used as an anticoagulant.
Why are transgenic plants produced ?
- Manufacturing commercially important proteins
- “Improving” agricultural species eg. By resistance to insects, herbicides etc.
How are transgenic plants made using the Ti plasmid ?
- Tumour inducing genes in the Ti plasmid are removed
- Exogenous DNA is inserted into the T-region of the Ti plasmid
- Plasmid is transformed into Agrobacterium
- Exogenous DNA inserted into the plants genome
What are some examples of transgenic plants ?
- Bt corn and cotton- Bacillus thuringienesis synthesises an insecticidal protein
- Herbicide resistant Soya
What is CRISPR ?
Clustered regularly interspaced short palindromic repeats
They are DNA sequences found in the genomes of prokaryotes- derived from DNA bacteriophages that had previously infected the prokaryote
What is Cas9 ?
An endonuclease enzyme that uses CRISPR sequences as a guide to recognise and cleave specific strands of DNA
How are double stranded breaks in eukaryotic cells repaired ?
- Homology directed repair- accurate
DNA template is provided - Non-homologous end joining- error prone
How does the adaptive immune response from bacteria and archaea work ?
- Bacteriophage DNA inserted into the bacterial genome at the CRISPR locus
- Transcription of these fragments produces CRISPR RNA. This forms a complex with a trans-acting RNA and a DNAse enzyme (Cas9)
- If infected again by the same type of bacteriophage, the Cas9/crRNA complex recognises the bacteriophage DNA and cleaves it
What makes the double stranded breaks ?
Cas9
