Biotechnology: Principles and Processes Class 12 Notes Biology Chapter 11

CHAPTER AT A GLANCE

  • Biotechnology is the application of techniques ofusing live organism to get desired product of human welfare. It includes recombinant DNA, gene cloning, gene therapy.
  • Biotechnology deals with large scale production and marketing of products and processes using living organisms, cells or enzymes.
  • Examples of biotechnology are GMO (Genetically modified organisms), IVF (in vitro fertilisation), Test tube babies, DNA vaccines and gene therapy.
  • Two main techniques in biotechnology are-
    • Genetic engineering.
    • Application of genetic engineering in production of bulk of products like antibiotics, vaccines and enzymes.
  • Genetic engineering is manipulation of genes by man.
  • Genetic engineering includes several techniques that facilitate the alteration of genetic material i.e. RNA or DNA, in order to introduce them in host organisms.
  • Paul berg is the father of genetic engineering.
  • Enzymes used in genetic engineering are restriction endonucleases, DNA ligase, exonuclease, endonuclease, DNA polymerase, and reverse transcriptase.
  • Three techniques of genetic engineering are:
  • rDNA (recombinant DNA technology)
  • Gene cloning/gene amplification
  • Gene therapy
  • rDNA technology is hybridisation of genes to achieve desired genotype and phenotype.
  • Tools of rDNA technology are –
    • Vector – plasmid, bacteriophage, cosmid, BAC, YAC.
    • Host -with Ori C [origin ofreplication].
    • Restriction enzymes – Endonuclease with well defined recognition site.
  • Steps of rDNA technology are :
    • Isolation of desired gene by cutting with molecular scissors called “restriction endonuclease”.
    • Introduction of gene into vector (cloning vehicle).
    • Absorption of vector by host organism in culture media.
    • Production of transformed cells.
    • Screening of transformed cells for desired result.
  • Vectors are cloning vehicles required to transfer DNA of interest from one organism to another. Vectors are grouped into bacterial plasmid, bacteriophage, cosrnids & phasrnids.
    • Plasmid is an autonomously replicating extra chrornosornal genetic content present in the bacteria. It is different from the chrornosornal DNA. It is used as a vehicle for transfer of gene of interest into the host cell.
    • Bacteriophage is virus which infect bacteria. They have special sticky “cos” site to accept foreign DNA. As bacteriophage multiply faster, so transformation efficiency is higher in bacteriophage.
    • Cosmid can be defined as the hybrid vectors derived from plasmids which contain cos site of phage 1.
    • A phage genome containing att site and one rnore plasmid molecule is called phasmid.
  • BAC (Bacterial Artificial Chrornosorne) is episorne + foreign DNA.
  • Palindromic sequences are the ones which read sarne in one orientation on both the strands.
  • Restriction endonuclease cut DNA at specific sites end exonuclease digest the base pairs on 5′ or 3′ end of a single stranded DNA or at single stranded nicks or gaps in double stranded DNA.
  • Nomenclature of restriction endonuclease are-
  • 1st letter – Generic narne
  • 2nd letter – Species narne
  • 3rd letter – Strain narne
  • 4th letter – Order in which enzyme is isolated from that strain of bacteria [Roman Numeral] e.g., EcoRY13 stands for Escherichia coli strain RY numbered 13.
  • Desirable properties of cloning vector are –
  • High copy number
  • Presence of origin of replication (Ori)
  • Presence of selectable marker
  • Presence of unique recognition site in cloning site
  • Ability to sustain in bacterial cell/low incompatibility quotient.
  • Ori C is sequence where replication starts and any piece of DNA linked here will be replicated. Ori C also controls copy number of vector.
  • Selectable marker allow to select those host cells that contain the vector from amongst those which do not.
  • For cloning : First an artificial plasmid is synthesised by combining marker gene to it, e.g., pUC 11 (plasmid developed at University of California) and pBR322.
  • Agrobacterium tumefaciens is cloning vector for plants which is T-DNA (transforming DNA), to transform normal plant cell into tumour and direct them to form mass of cells called galls which start secreting chemicals required by bacteria.
  • In vitro synthesis of DNA of interest can be done by PCR (polymerase chain reaction). In this reaction, multiple copies of the gene (or DNA) of interest is synthesised in vitro using two sets of primers (small chemically synthesised oligonucleotides that are complementary to the regions of DNA) and the enzyme DNA polymerase. The enzyme extends the primers using the nucleotides provided in the reaction and the genomic DNA as template.
  • The product from rDNA can be obtained at large scale in bioreactors – where from an inlet, large volume of culture medium is fed and from an outlet, used media is thrown out.
  • Bioreactor provide optimum conditions for achieving desired product by providing optimum growth conditions [temperature, pH, salt, sugar, vitamin].
  • Downstream processing is separation and purification of products achived from bioreactors. The product is converted into formulation for usage, tested for human use, undergoes quality control and then marketed.

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