7.4 Gene technology Flashcards
What is gene engineering?
Insertion of genes from one organism into the genetic material of another
/ Changing the genetic material of another organism
How is recombinant DNA produced?
Manipulation by DNA with enzymes including restriction endonucleases and DNA ligase
How is the gene isolated?
Restriction endonucleases can cut out a section of DNA, including the gene
Reverse transcriptase can make DNA from mRNA
Sequence can be worked out from amino acid sequence and DNA built to match
How are genes inserted into a vector?
Plasmids are often used
- Plasmid DNA cut with the restriction endonuclease
- Leaving complementary sticky ends
- Gene and open plasmid are mixed so bases pair up
- DNA ligase joins sugar phosphate backbone
What do restriction endonucleases do?
- Cut DNA at specific base sequence
- Staggered cut creates sticky ends
What does DNA ligase do?
- Forms a bond between deoxyribose and phosphate to reform the DNA strand
List ways of getting recombinant DNA into a cell
Gene guns
Liposome wrapping
Microinjection
Viruses
Sticky ends
How do gene guns work?
DNA is shot into a cell at high speed, carried on gold/tungsten bullets
Some cells survive and accept the DNA as part of the genetic material
How does liposome wrapping work?
The gene to be inserted is wrapped in liposomes
These fuse with the cell membrane and can pass through it to deliver DNA to the cytoplasm
How do microinjections work
DNA is injected into a cell through a very fine micropipette
How do viruses work as a vector?
A harmless virus can be engineered to carry a desirable gene and then infect animal cells
How do sticky ends work as vectors?
Cut the DNA in a way that leaves a few base pairs longer on one strand than the other, forming a sticky end
Sticky ends make it easier to attach new pieces of DNA to them
How are fluorescent antibiotic resistance marker genes and replica plating used to identify recombinant cells?
Bacteria are transferred from a ‘master plate’ onto plates with antibiotics sterile block
If they don’t grow, the gene was inserted successfully and the colonies are still on the ‘master plate’
How are knockout mice used to investigate gene function?
One or more genes are silenced via the insertion of a similar gene that makes the original impossible to read
Makes the function of a disease more clear
How were soy beans genetically modified?
- Ti plasmid extracted f
- Bacterial genes with the disease removed are inserted into plasmid via genetic modification
- Plasmid is returned to the bacterium
- Plant is infected with the bacterium
- Plant grows a crown gall, containing the inserted genes
