B6.2.5 Flashcards
How are organisms genetically engineered
- Identify gene that codes for the desired characteristic
- Remove gene from donor organism
- Insert the gene into a host organism, often bacterium
Why do scientists genetically engineer bacteria
To produce useful substances including hormones, vaccines and antibodies.
What are used to move genes between organisms
Enzymes
What do restriction enzymes do
Restriction enzymes cut the donor DNA at specific base sequences. They make a staggered cut, leaving few exposed unpaired bases on the ends of the DNA strands. These are called “sticky ends”. The same restriction enzymes are used to cut open the bacterial plasmid.
What are ligase enzymes used for
They region the DNA strands at the sticky ends. As both host and donor DNA have the same sticky ends, the new gene is joined into the plasmid DNA.
What is the plasmid called
They are called vectors.
Because genetic engineering was not always successful what do scientists do
Need to check that the gene has been successfully transferred into the hosts’s genome
What is a method to check that the gene has been transferred
To add a gene for antibiotic resistance into the plasmid at the same time as inserting the gene coding for the desired characteristic.
Transfer the bacteria to an agar late containing the selected antibiotic. Incubate and allow time for the bacteria to grow.
Any bacterial colonies present will survive because they now contain the antibiotic resistance marker gear. These bacteria will also contain the desired gene.
