Biotechnology and DNA Technology

Chapter 9: Biotechnology and DNA Technology

Introduction to Biotechnology

  • Biotechnology:
    • Definition: The use of microorganisms, cells, or cell components to make a product.
    • Examples of products include foods, antibiotics, vitamins, and enzymes.
  • Recombinant DNA (rDNA) Technology:
    • Definition: Insertion or modification of genes to produce desired proteins.
  • Key Definitions:
    • Vector: A self-replicating DNA used to carry the desired gene to a new cell.
    • Clone: A population of cells arising from one cell; each carries the new gene.

Historical Context and Application of Microorganisms

  • For thousands of years, people consumed foods produced by microorganisms (e.g., bread, chocolate, soy sauce).
  • Scientific discovery (over 100 years ago) confirmed microorganisms as responsible for these products.
  • Post-World War I: Use of microbes for producing chemicals like ethanol, acetone, and citric acid.
  • Post-World War II: Production of antibiotics using microorganisms.
  • Modern uses include enzymatic processes in manufacturing paper, textiles, and fructose.
  • Advantages of Using Microbes:
    • Use inexpensive, abundant raw materials.
    • Function at normal temperatures and pressures.
    • Minimize toxic waste production.
  • Recent inclusion of DNA technology enhances product development.

Learning Objectives and Tools

  • Tools and techniques for product research and development.
  • Application of DNA technology in tracking infectious diseases and forensic microbiology, with a focus on HIV tracking.

Comparison of Key Concepts

  • Biotechnology vs. Recombinant DNA Technology:
    • Biotechnology encompasses a broader range of applications using biological systems, whereas rDNA specifically refers to the manipulation of DNA.
  • Role of Clones and Vectors in Making Recombinant DNA:
    • Clones: Populations of cells that carry the desired gene.
    • Vectors: DNA molecules that transport foreign genetic material into another cell.

Processes in Biotechnology

Genetic Modification Procedure
  • Steps to modify genetic material include:
    • Isolate a vector (e.g., plasmid).
    • Cleave DNA containing the gene of interest using restriction enzymes.
    • Insert the desired gene into the plasmid.
    • Transformation: Introduction of the plasmid into a host cell (e.g., bacterium).
    • Result: Cloning of cells with the gene and production of protein products (e.g., human growth hormone, enzymes for fabric treatment).
    • Applications include inserting genes for pest resistance in plants and toxic waste degradation in bacteria.

Selection and Mutation in Microbial Cultures

  • Selection: The process of cultivating naturally occurring microbes that produce the desired product.
  • Mutation: Induced changes that may result in desirable traits using mutagens.
  • Site-Directed Mutagenesis: Specific alterations to DNA code to change protein function.

Restriction Enzymes

  • Definition: Enzymes that cut specific sequences of DNA.
  • Function: Destroy bacteriophage DNA in bacterial cells, cannot digest host DNA with methylated cytosines.
  • Role in rDNA: They produce sticky ends that allow for joining fragments of DNA.

Vectors in Genetic Engineering

  • Purpose: Carry new DNA to desired cells.
  • Types: Plasmids and viruses; shuttle vectors can exist in multiple species.
  • Criteria for Good Vectors:
    1. Self-replicating capability.
    2. Sufficient size for manipulation.
    3. Resistance to destruction (e.g., circular plasmid).
    4. Marker gene for easy selection.

Polymerase Chain Reaction (PCR)

  • Overview of PCR steps:
    1. Incubate target DNA at 94°C for 1 minute to separate strands.
    2. Add primers, deoxynucleotides (dNTP), and DNA polymerase.
    3. Primers bind to single-stranded DNA at 60°C for 1 minute.
    4. DNA polymerase copies DNA at 72°C for 1 minute.
    5. Cycle of heating and cooling is repeated to amplify DNA.
  • Applications include cloning DNA for recombination, diagnosing genetic disease, and detecting pathogens.

Techniques for DNA Insertion

  1. Electroporation: Electric fields increase cell permeability for DNA uptake.
  2. Transformation: Uptake of naked DNA by a competent cell.
  3. Protoplast Fusion: Fusion of cells after enzymatic removal of cell walls.
  4. Gene Gun: Shoots DNA-coated particles into cells.
  5. Microinjection: Direct injection of DNA into a cell.

Genomic Libraries

  • Made by cutting an entire genome into pieces and storing them in vectors like plasmids or phages.
  • Process: Isolate DNA, fragment it, clone it in vectors, and store as a library.

Complementary DNA (cDNA)

  • Created from mRNA using reverse transcriptase.
  • Involves the transcription of genes containing exons and introns, followed by processing to result in mRNA which is then converted to cDNA.

Identifying Recombinant Clones

  • Blue-White Screening: Test for recombinant bacteria via the lacZ gene and ampicillin resistance.
    • Results: Blue colonies indicate non-recombinant; white colonies indicate successful foreign DNA insertion.
  • Colony Hybridization: Use of DNA probes to hybridize with colonies containing the desired genes and facilitate identification.

Applications of rDNA Technology

  1. Healing and Therapeutics: Production of human enzymes, subunit vaccines, and gene therapy for genetic disorders.
  2. The Human Genome Project: Involves sequencing nucleotides to understand diseases at the genetic level.
  3. Applications in Forensic Microbiology: Use of PCR and real-time PCR in evidence collection and tracking outbreaks (e.g., anthrax, norovirus).
  4. Nanotechnology in Biotechnology: Use of bacteria for creating nanoscale materials (e.g., chains of selenium).
  5. Genetic Engineering with Agrobacterium: Employ Ti plasmid technology for genetic modification in plants.

Safety Issues and Ethical Considerations

  • Concerns include accidental releases of genetically modified organisms (GMOs), food safety, and genetic information privacy.
  • Discussion around benefits and potential hazards of genetic modifications in agriculture and medicine.
  • Important to maintain established ethical standards in biotechnology applications.