recombinant DNA technology

Examples of recombinant DNA technology in the following topics:

• Biochemical Products of Recombinant DNA Technology

  • Many practical applications of recombinant DNA are found in human and veterinary medicine, in agriculture, and in bioengineering.
  • Recombinant DNA technology is the latest biochemical analysis that came about to satisfy the need for specific DNA segments.
  • Recombinant DNA technology engineers microbial cells for producing foreign proteins, and its success solely depends on the precise reading of equivalent genes made with the help of bacterial cell machinery.
  • Recombinant DNA technology, apart from being an important tool of scientific research, has also played a vital role in the diagnosis and treatment of various diseases, especially those belonging to genetic disorders.
  • Some of the recent advances made possible by recombinant DNA technology are:

• Genetic Engineering

  • In genetic engineering, an organism's genotype is altered using recombinant DNA, created by molecular cloning, to modify an organism's DNA.
  • Genetic engineering is the alteration of an organism's genotype using recombinant DNA technology to modify an organism's DNA to achieve desirable traits.
  • Recombinant DNA technology, or DNA cloning, is the process of transferring a DNA fragment of interest from one organism to a self-replicating genetic element, such as a bacteria plasmid, which is called a vector.
  • The addition of foreign DNA in the form of recombinant DNA vectors generated by molecular cloning is the most common method of genetic engineering.
  • The organism that receives the recombinant DNA is called a genetically-modified organism (GMO).

• Recombinant DNA Technology

  • Recombinant DNA technology also referred to as molecular cloning is similar to polymerase chain reaction (PCR) in that it permits the replication of a specific DNA sequence.
  • To improve the ratio of recombinant to non-recombinant organisms, the cleaved vector may be treated with an enzyme (alkaline phosphatase) that dephosphorylates the vector ends.
  • The creation of recombinant DNA is in many ways the simplest step of the molecular cloning process.
  • Insertion of the foreign DNA into the beta-galactosidase coding sequence disables the function of the enzyme, so that colonies containing recombinant plasmids remain colorless (white).
  • Therefore, recombinant clones are easily identified .

• Mammalian Proteins and Products

  • Recombinant DNA technology not only allows therapeutic proteins to be produced on a large scale but using the same methodology protein molecules may be purposefully engineered.
  • Bacterial expression systems, due to their simplicity, are often not able to produce a recombinant human protein identical to the naturally occurring wild type.
  • Recombinant clotting factors have eliminated this problem.

• Generalized Recombination and RecA

  • In homologous recombination, a type of genetic recombination, nucleotide sequences are exchanged between two similar molecules of DNA.
  • Homologous recombination is a type of genetic recombination in which nucleotide sequences are exchanged between two similar or identical molecules of DNA.
  • Homologous recombination is a major DNA repair process in bacteria.
  • Double-strand DNA breaks in bacteria are repaired by the RecBCD pathway of homologous recombination .
  • The RecBCD pathway is the main recombination pathway used in bacteria to repair double-strand breaks in DNA.

• Genetically Modified Organisms (GMOs)

  • Transgenic modification, adding recombinant DNA to a species, has led to the expression of desirable genes in plants and animals.
  • Animals that have been modified to express recombinant DNA are called transgenic animals.
  • Mice have been used extensively for expressing and studying the effects of recombinant genes and mutations.
  • Plants that have received recombinant DNA from other species are called transgenic plants.
  • Antisense RNA technology was used to slow down the process of softening and rotting caused by fungal infections, which led to increased shelf life of the GM tomatoes.

• Selection

  • DNA recombination has been used to create gene replacements, deletions, insertions, inversions.
  • Subsequently, these fragments are then combined with vector DNA to generate recombinant DNA molecules.
  • This will generate a population of organisms in which recombinant DNA molecules are replicated along with the host DNA.
  • Thus, both the resulting bacterial population, and the recombinant DNA molecule, are commonly referred to as "clones".
  • Strictly speaking, recombinant DNA refers to DNA molecules, while molecular cloning refers to the experimental methods used to assemble them.

• Gene rearrangement within genomes

  • In meiosis and mitosis, recombination occurs between similar molecules (homologs) of DNA.
  • In both meiotic and mitotic cells, recombination between homologous chromosomes is a common mechanism used in DNA repair.
  • Genetic recombination and recombinational DNA repair also occurs in bacteria and archaea.
  • Recombination can be artificially induced in laboratory (in vitro) settings, producing recombinant DNA for purposes including vaccine development.
  • Recombination can occur between DNA sequences that contain no sequence homology.

• Obtaining DNA

  • Molecular cloning is a set of experimental methods in molecular biology that are used to assemble recombinant DNA molecules and to direct their replication within host organisms.
  • Molecular cloning generally uses DNA sequences from two different organisms: the species that is the source of the DNA to be cloned, and the species that will serve as the living host for replication of the recombinant DNA.
  • The creation of recombinant DNA is in many ways the simplest step of the molecular cloning process.
  • Whichever method is used, the introduction of recombinant DNA into the chosen host organism is usually a low efficiency process; that is, only a small fraction of the cells will actually take up DNA.
  • Explain the methods of obtaining DNA for molecular cloning experiments and the process of creating a recombinant DNA molecule

• Prokaryotic Reproduction

  • Binary fission does not provide an opportunity for genetic recombination or genetic diversity, but prokaryotes can share genes by three other mechanisms .
  • Transduction results in a recombinant organism.
  • The DNA transferred can be in the form of a plasmid or as a hybrid, containing both plasmid and chromosomal DNA.
  • The DNA may remain separate as plasmid DNA or be incorporated into the host genome.
  • In (b) transduction, a bacteriophage injects DNA into the cell that contains a small fragment of DNA from a different prokaryote.