recombination

Examples of recombination 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.
  • Some of the recent advances made possible by recombinant DNA technology are:
  • Isolating proteins in large quantities: many recombinant products are now available, including follicle stimulating hormone (FSH), Follistim AQ vial, growth hormone, insulin and some other proteins.

• 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 conserved across all three domains of life as well as viruses.
  • Homologous recombination is a major DNA repair process in bacteria.
  • This type of resolution produces only one type of recombinant (non-reciprocal).

• 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.
  • Most modern vectors contain a variety of convenient cleavage sites that are unique within the vector molecule (so that the vector can only be cleaved at a single site) and is located within a gene (frequently beta-galactosidase) whose inactivation can be used to distinguish recombinant from non-recombinant organisms at a later step in the process.
  • 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.
  • Therefore, recombinant clones are easily identified .

• 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.
  • The recombinant DNA is then introduced into a host organism (typically an easy-to-grow, benign, laboratory strain of E. coli bacteria).
  • 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".

• Genetically Engineered Vaccines

  • Despite the early success demonstrated with the hepatitis B vaccine, no other recombinant engineered vaccine has been approved for use in humans.
  • Although recombinant subunit vaccines hold great promise, they do present some potential limitations.
  • In addition to being less reactogenic, recombinant subunit vaccines have a tendency to be less immunogenic than their conventional counterparts.
  • Recombinant subunit vaccines may also suffer from being too well-defined, because they are composed of a single antigen.
  • This problem can be minimized, where necessary, by creating recombinant vaccines that are composed of multiple antigens from the same pathogen.

• Antibody Genes and Diversity

  • The first stage is called somatic, or V(D)J, which stands for variable, diverse, and joining regions recombination.
  • V(D)J recombination takes place in the primary lymphoid tissue (bone marrow for B cells, and thymus for T cells) and nearly randomly combines variable, diverse, and joining gene segments.
  • The second stage of recombination occurs after the B cell is activated by an antigen.
  • Affinity maturation occurs after V(D)J recombination, and is dependent on help from helper T cells.
  • Outline the two stages which result in antibody diversity: somatic (V(D)J) and recombination stages

• Large-Scale Fermentations

  • Fermentation is also utilized in the mass production of various recombinant products.
  • These recombinant products include numerous pharmaceuticals such as insulin and hepatitis B vaccine.
  • The mass production of insulin is performed by utilizing both recombinant DNA technology and fermentation processes.
  • An additional recombinant product that utilizes the fermentation process to be produced is the hepatitis B vaccine.
  • The creation of this vaccine utilizes both recombinant DNA technology and fermentation.

• Hosts for Cloning Vectors

  • E. coli and plasmid vectors are in common use because they are technically sophisticated, versatile, widely available, and offer rapid growth of recombinant organisms with minimal equipment.
  • For example, if the experimentalists wish to harvest a particular protein from the recombinant organism, then an expression vector is chosen that contains appropriate signals for transcription and translation in the desired host organism.
  • Whatever combination of host and vector are used, the vector almost always contains four DNA segments that are critically important to its function and experimental utility--(1) an origin of DNA replication is necessary for the vector (and recombinant sequences linked to it) to replicate inside the host organism, (2) one or more unique restriction endonuclease recognition sites that serves as sites where foreign DNA may be introduced, (3) a selectable genetic marker gene that can be used to enable the survival of cells that have taken up vector sequences, and (4) an additional gene that can be used for screening which cells contain foreign DNA.

• 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.

• Isotype Class Switching

  • Immunoglobulin class switching (or isotype switching, or isotypic commutation, or class switch recombination (CSR)) is a biological mechanism that changes a B cell's production of antibody from one class to another; for example, from an isotype called IgM to an isotype called IgG.
  • Class switching occurs by a mechanism called class switch recombination (CSR) binding .
  • Class switch recombination is a biological mechanism that allows the class of antibody produced by an activated B cell to change during a process known as isotype or class switching.
  • Mechanism of class switch recombination that allows isotype switching in activated B cells.
  • Describe the process of class switch recombination that results in changes in the antibody-heavy chain