Biotechnology and Genetic Engineering: Applications and Techniques
Biotechnology vs. Traditional Genetic Engineering
Traditional genetic engineering is slow, requiring many generations to achieve desired traits. It involves recombining genetic material of the same species without directly manipulating the DNA sequence of genes.
Biotechnology, on the other hand, allows for rapid genetic changes in a single generation. It enables the recombination of DNA from different species and the production of new genes.
Key Concepts
- Recombinant DNA Technology: A procedure involving the isolation, cutting, joining, and amplification of DNA from different species to obtain useful quantities. It is a fundamental tool of genetic engineering.
- Genetic Engineering: The deliberate alteration of the information content of DNA molecules, resulting in genetic changes.
Activities of Recombinant DNA Technology
- Procedures based on enzymes to cut DNA molecules.
- Insertion of DNA fragments into cloning vectors, such as plasmids.
- Identification of fragments containing genes of interest.
Objectives of Genetic Engineering
- Enhance understanding of inheritance and gene expression.
- Improve understanding and treatment of diseases and genetic disorders.
- Generate economic and social benefits through efficient production of biological molecules and improvement of plants and animals.
Natural Recombination
a. Sexual Reproduction: During Meiosis I, DNA exchange occurs between maternal and paternal chromosomes, creating new combinations of alleles in homologous chromosomes.
b. Bacterial DNA Transfer: Bacteria can acquire DNA from the environment. Genes within plasmids can enable bacteria to spread and infect new hosts. For example, antibiotic-resistant plasmids can spread within a patient.
c. Viral Infection: Within an infected cell:
- Viral genes are replicated, and viral proteins are synthesized. These components assemble and are released to infect new cells.
- Host DNA segments can be incorporated into the viral genome and transferred to other hosts.
Recombinant DNA in the Laboratory
DNA is cut into specific, reproducible pieces and inserted into a cloning vector for replication.
Steps in Recombinant DNA Technology
- Isolation of the gene or genes of interest.
- Fragmentation of DNA using restriction enzymes (molecular scissors).
- Isolation and cutting of a cloning vector with the same enzyme used for genomic DNA.
- Joining of vector DNA with the gene of interest using ligases (molecular glue).
- Introduction of recombinant DNA into a host organism for replication.
- Selection and detection of the desired clone from the genomic library.
A genetic library contains the complete genome of an organism, fragmented into smaller pieces.
Transgenic Plants
Genetic engineering in plants is challenging due to the lack of suitable vectors for plant cells.
The thick cell wall hinders DNA insertion. One approach uses a bacterium that causes tumor growth as a gene delivery system.
Other techniques include gene guns and electroporation (using electricity to create pores in the plasma membrane).
Transgenic Animals
Techniques like microinjection and vortex mixing are used to insert genes into animal eggs.
Offspring resulting from the fertilization of these eggs are transgenic. For example, animals can be engineered to receive the gene for growth hormone.
Human Proteins Produced Through Genetic Engineering
- Insulin for diabetes treatment: Human gene inserted into bacteria.
Gene Therapy
Involves inserting genetic material into human cells.
Advantage: Potential to detect diseases or defective genes and initiate early treatment.
Disadvantage: If the gene is not incorporated effectively into a sufficient number of cells, it may not be expressed efficiently.