Genetic Engineering

Question 1

How is recombinant DNA produced?

Answer 1

1. RESTRICTION ENDONUCLEASES cut out DNA containing the gene, isolating it and leaving sticky ends
2. Plasmid DNA is cut with the same restriction endonucleases, making complementary exposed sticky ends. The gene and the plasmid bases pair up in annealing and DNA LIGASE joins the sugar phosphate backbone.
3. The recombinant DNA is placed back into a host organisms using a vector - a gene gun, microinjection, harmless virus or a liposome.

Question 2

How are recombinant cells identified?

Answer 2

Replica plating - process of growing bacteria on an agar plate than transferring a replica of that growth on other plates containing inhibitors or promoters to see if they have the plasmid.

Marker genes - within the modified DNA that signal which cells have recombinant DNA. They can be antibiotic resistance genes, so only cells that successfully took up the vectors will grow when put on a plate with antibiotics.
However there’s the risk that if theses genes spread into the environment they would carry genes for antbiotic resistance making it harder to treat bacterial infections.
- Genes that make bacteria dependent on a specific nutrient or cause the organism to fluoresce in UV light are used as markers.

Question 3

What are ‘knockout mice’

Answer 3

Mice are used as animal models to investigate gene function for research.

• This is done by damaging a gene and observing its effects to find a genes function. In mice this is done by modifying embryonic stem cells and using them to grow modified adults
• Marker genes are in the modified DNA to make it obvious which modification mice inherited.
• Some genes can’t be investigated as its vital for mice to live.

Question 4

What can knockout mice be used for?

Answer 4

Cancer, Parkinson’s disease (low level dopamine) and cystic fibrosis

Question 5

List the methods to insert recombinant DNA into other cells.

Answer 5

• Gene guns
• Virus (harmless virus can be incorporated into host cell and integrate the desired gene)
• Liposome (fuse with cell membrane and pass into cells DNA)
• Microinjection

Question 6

How do you produce a transgenic plant

Answer 6

1. Ti plasmid is extracted from AGROBACTERIUM TUMEFACIANS
2. Genes causing crown gall are removed with new gene.
3. Plasmid inserted back in Agrobacterium and infects the plant, making the plasmid apart of plant chromosome

These genes can improve crop yield or pest resistance, specific levels of nutrients to stop overcome malnutrition, withstand extreme weathers

Question 7

Why were soya beans GMed?

Answer 7

Their fatty acids are altered to stop OXIDATION of soya products for longer shelf life.
GM soya produces linoleum and more oleic acid which is oxidised less easily.
GM soya is monounsaturated so healthier