Genetics and Recombinant DNA. BIT 120. Cotton Pests. Cotton Bollworm. Cotton Pests. Cotton Leaf Perforator. How Do Farmers Deal With Pest Insects?. Chemical Control Biological Control. Recombinant DNA.
converts a GAG codon (for Glu) to a GTG codon for Val
abolishes a sequence (CTGAGG, which spans codons 5, 6, and 7) recognized and cut by one of the restriction enzymes.
DEAE dextran - an inert carbohydrate polymer (dextran) coupled to a positively charged chemical group (diethylaminoethyl -DEAE). DNA probably sticks to DEAE-dextran via its negatively charged phosphate groups.
Calcium phosphate - forms an insoluble precipitate with DNA. It was discovered that cells efficiently take up this precipitate. More efficient than DEAE dextran or many cell types and can be used for both transient and stable transfection. Not suitable for cells which grow in suspension culture.
Electroporation - Cells are concentrated, mixed with the DNA and placed in a small chamber with electrodes connected to a specialised power supply. A brief electric pulse is applied, which is thought to ‘punch holes’ in the cell membrane, enabling the cell to take up DNA.
Lipofection - (liposome-mediated gene transfer) several lipid- based methods have been developed in which DNA is encapsulated by synthetic lipid bilayers which resemble cell membranes. Liposomes are essentially spheres of synthetic membrane filled with DNA. These fuse spontaneously with cell membranes, releasing their contents into the cytoplasm.