Gene Technology Flashcards
What is recombinant DNA?
DNA that is formed artificially by combining DNA from different organisms
What is genetic engineering?
Modification of the characteristics of an organism by changing its genetic material
What are the stages of genetic engineering?
- Isolating required gene
- Inserting gene into a vector
- Transformation of gene to required cell
- Identification of host cells that have taken up the gene
- Grow cells with new gene on a large scale
What are the three types of isolation?
-Gene machine
-Reverse transcriptase
-Restriction endonuclease
How is reverse transcriptase used to produce recombinant DNA?
-Taking mRNA molecule transcribed from a gene and using it to produce the correct DNA sequence
-Uses reverse transcriptase to form complimentary DNA
-The cDNA can now act as an artificial gene
How is restriction endonuclease used to produce recombinant DNA?
-Use restriction endonuclease to cut DNA strands into small pieces
-Cuts DNA at palindromic sequences and sometimes leaves sticky ends
-Must cut DNA from the host organism with the same restriction enzyme so the fragment ends are complimentary
-Complimentary bases pair up and DNA ligase joins them to the DNA backbone
What are sticky ends and what do they do?
-A restriction endonuclease cuts the DNA which leaves some base pairs longer on one strand than the other
-Easier to attach new pieces of DNA to them
How does the gene machine produce recombinant DNA?
-DNA fragment is created in the lab using a computer
-The amino acid sequence is identified
-The mRNA and DNA sequence can then be worked out
-This is put into the computer to create oligonucleotides which are stuck together to produce the DNA fragment
What does a vector do?
Used to transport DNA into host cell e.g. a plasmid
How is a gene inserted into a vector?
-The gene and a plasmid is cut with the same restriction enzyme
-The plasmid is cut with sticky ends so the gene can easily combine
-DNA ligase joins the gene to the DNA backbone
What are the methods of transforming a gene to the host cell?
-Liposome wrapping = gene is wrapped in a liposome so it can fuse with cell membrane to pass through and deliver DNA to the cytoplasm
-Microinjection = injecting DNA into a cell through the micropipette
-Gene guns = DNA is shot into cell at high speed on gold pellets
-Viruses = engineer a virus to carry a desired gene and use it to infect cells
What bacteria is used to grow GM crops?
Agrobacterium tumefaciens bacterium
How are GM plants made?
-Remove a plasmid from the bacterium and cut the T-DNA with a restriction enzyme
-The foreign DNA is cut with the same restriction enzyme
-The foreign DNA is inserted into the T-DNA
-The plasmid is reinserted into the bacterium
-The bacterium is used to insert the T-DNA carrying the foreign DNA into the chromosome of a plant cell
-The plant cells are grown in a culture
What are the main advantages of GM crops?
-Produce disease resistance crops (no need for pesticides so reduces environmental damage)
-Higher yields produced (more profit, reduces famine and malnutrition)
-Increase nutritional content (e.g. rice being modified to contain more vitamin A in countries with a deficiency)
What are the main disadvantages of GM crops?
-Possible unknown impacts on human health in the long term (ethical issues)
-Transmission of genetic material from GM crops to non GM crops
-Pests may become resistance against GM crops (so would need to use pesticides anyways)
What is a knockout mouse?
A laboratory mouse which has been genetically modified to have one or more genes turned off
What is the purpose of a knockout mouse?
To create an animal model of a disease to make it easier for scientists to develop treatments or cures
What does transgenic mean?
Genetically modified
