Recombinant DNA processes BIO3B

Gene cloning In gene cloning the host cell's biochemical processes are used to make many copies of the inserted gene and the protein it codes for.

Gene therapy Gene therapy involves insertion of DNA to replace faulty genes It is used when a single defective gene can be identified and a healthy one is available eg cystic fibrosis, Huntington’s disease, muscular dystrophy, cystic fibrosis, diabetes Germ line therapy refers to replacement of DNA in sperm or ova and therefore aims for treatment that will be passed on to offspring. It has not been attempted due to the difficulty and the ethical considerations of changing the human genome Somatic cell gene therapy refers to replacement of DNA in non-reproductive body cells and therefore aims for treatment that will be effective in the sufferer, but can not be passed on to offspring.

Gene therapy In ex vivo gene transfer, genes are transferred into cells grown in culture. The cells are then transferred back into the patient. This is done when tissues can be removed and grown outside the body without harm to the patient or the tissues (eg muscle, skin) In in vivo gene transfer, genes are transferred directly into the tissues of the body in the patient. This is done when tissues can not be removed and grown outside the body without harm to the patient or the tissues (eg brain)

Inserting genes Introduction of new genes can be done by viral or non-viral means. With viral means, DNA is inserted into a virus which is then injected into the tissue culture or patient. When the virus infects the cells it alters their DNA – thus adding the replacement gene

Tissue culture Tissue culture is the growth of tissues and/or cells separate from the organism in a growth medium – this can be liquid or solid (eg on agar). In plants this has been used for centuries for propagation. In animals it is being used to grow tissues for research and medical treatments (eg skin grafts) Another recent area of research is tissue culture to produce meat products, instead of raising animals to be killed for food – animal tissue will be grown in vats and harvested.

Transgenic organisms These are organisms with inserted genes. They are also known as genetically modified organisms or GMO’s. Uses include inserting genes for: pest or disease resistance eg cotton turning off the gene for ripening to give a longer shelf life eg tomatoes ability to cope with salt or drought eg wheat add nutrients to food eg omega 3 fatty acids into vegetable create cyanobacteria capable of making ‘diesel’ fuel

DNA profiling DNA sequencing involves identifying the precise order of nucleotide in DNA. In DNA profiling sequences are compared between individuals (DNA fingerprint or profile) Special enzymes called restriction enzymes are use to split the DNA into segments so the sequence of nucleotides can be identified. It is used to identify the genetic relationships between individuals (eg to confirm paternity, identify species) forensic science (eg identifying criminals) look for genetic disease

Genetic probes Probes are nucleic acid bases arranged in a sequence which is complementary to a sequence in the genome They usually have radioactive or chemical markers that are used to make them easily visible They can be used to detect if a genomic sequence is present, deleted or altered. They are often used to identify the presence of a gene for a disease

Uses of DNA fingerprinting Identify whether either of these alleged fathers could be the father of the child How can electrophoresis results such as for the deer be used in taxonomy or evolutionary studies.

Uses of DNA fingerprinting Identify whether either of these alleged fathers could be the father of the child A couldn’t be, B could be How can electrophoresis results such as for the deer be used in taxonomy or evolutionary studies. This could be used to produce a phylogenic tree or clade to show degree of relationship eg as shown Species 1 Species 2Species 3Species 4