Gene therapy:
- Gene therapy is an attempt to cure hereditary or genetic diseases.
- Genes are inserted into a person’s cells and tissue to treat the disease.
- The first clinical gene therapy was given in 1990 to a 4-yr old girl with adenosine deaminase (ADA) deficiency.
- This enzyme is required for breakdown of deoxyadenosine into uric acids.
- In the absence of ADA toxic deoxyadenosine is accumulated and destroy the infection fighting immune cells called T-cells and B-cells.
- This disorder is caused due to the deletion of the gene for adenosine deaminase in chromosome 20.
Treatment:
- Treated by bone marrow transplantation.
- Enzyme replacement therapy, involving repeated injections of the ADA enzyme
- Lymphocytes from the blood of the patient are grown in a culture. A functional ADA cDNA is then introduced into these lymphocytes and returned into the body.
- The patient required periodic infusion of genetically engineered lymphocytes because these cells are not immortal.
- Functional ADA cDNA introduced into cells at early embryonic stages, could be the permanent cure.
Molecular diagnosis:
- Early detection of disease is not possible by conventional methods (serum and urine analysis)
Molecular diagnosis techniques:
- Recombinant DNA technology.
- Polymerase chain reaction (PCR)
- Enzyme linked Immuno-sorbent Assay (ELISA)
- Very low concentration of a bacteria or virus can be amplified and detected by PCR.
- It used to detect genetic disorders.
- PCR is use full to mutation in genes in suspected cancerous patient:
- A single stranded DNA or RNA tagged with radioactive molecule (probe) is allowed to hybridize to its complementary DNA in a clone of cells followed by detection using autoradiography.
- The clone having mutated gene unable make complementary bonding of probe, hence not appears in photographic film.
TRANSGENIC ANIMALS:
- Animals that have an alien DNA which able to express in it is called transgenic animals.
Reasons for creation of transgenic animals:
- Normal physiology and development:
- Transgenic animals are specifically designed to allow study of:
- How the genes are regulated.
- How the gene affects normal functioning of body
- How it affects growth and development. E.g. insulin like growth factor.
- The animals made transgenic to know the biological effect and result.
- Study of disease:
- Transgenic animals are designed to understand how genes contribute to the development of disease like cancers, cystic fibrosis, rheumatoid arthritis and Alzheimer’s.
- Biological products:
- Transgenic animals are used to produce biological product of human interest:
- α-1-antitrypsin used to treat emphysema.
- Proteins for treatment for PKU and cystic fibrosis.
- Transgenic cow Rosie, produce human protein enriched milk (2.4 gm/lit. human α-lactalbumin)
- Vaccine safety:
- Transgenic mice are being developed and use in testing the safety of vaccines before they are used for humans.
- Polio vaccine is tested in mice.
- Chemical safety testing:
- This is also known as toxicity/safety testing.
- Transgenic animals are made to known the effect of toxic chemicals.
ETHICAL ISSUES:
- GEAC (Genetic Engineering Approval Committee) set up by Indian Govt, which will make decisions regarding validity of GM research and safety of introducing GM-organisms for public services.
- A patent is the right granted by a government to an inventor to prevent others from commercial use of his invention.
- Patents granted for biological entities and for products derived from them; these patents are called biopatents.
- 27 documented varieties of Basmati are grown in India.
- Biopiracy is the term used to refer to the use/exploit or patent, of biological resources by multinational companies and other organizations without proper authorization from the countries and people concerned without compensatory payment.
CBSE Biology (Chapter Wise) Class XII ( By Mr. Hare Krushna Giri )
Email Id : [email protected]
