BIOL 111 Chapter 17 PowerPoint Lecture 13th Edition

Chapter 17: Biotechnology

17.1 Recombinant DNA

  • Recombinant DNA: A single DNA molecule created from two different sources.

  • First constructed in the 1970s using viral and bacterial DNA.

  • The ability to isolate and manipulate DNA has revolutionized biotechnology.

17.2 Amplifying DNA Using the Polymerase Chain Reaction (PCR)

  • PCR mimics DNA replication to produce millions of copies of a DNA sequence.

  • Components of PCR:

    • DNA template

    • Primers that flank the region of interest.

  • Steps in PCR Cycle:

    1. Denaturation: High temperature separates DNA strands.

    2. Annealing of Primers: Lower temperature allows primers to attach.

    3. DNA Synthesis: Intermediate temperature for DNA polymerase to extend primers.

  • Taq polymerase: A thermostable enzyme used in PCR.

17.3 Creating, Correcting, and Analyzing Genetic Variation

Restriction Endonucleases

  • Enzymes that cleave DNA at specific sites utilized by bacteria against viruses.

  • Important for their ability to:

    • Cut DNA into specific fragments.

    • Aid in genome mapping.

Types of Restriction Enzymes

  • Type I and III: Cleave DNA imprecisely, not ideal for manipulation.

  • Type II:

    • Recognizes specific DNA sequences (4-12 base pairs).

    • Cleavage creates sticky ends or blunt ends for joining.

Gel Electrophoresis

  • A technique to separate DNA fragments by size using an electric field.

  • Visualization: Uses fluorescent dyes for viewing DNA after separation.

  • The separation of fragments allows for analysis and purification for recombinant DNA construction.

17.4 Constructing and Using Transgenic Organisms

Creating Transgenic Plants

  • Gene alteration can be facilitated by Ti plasmid from Agrobacterium tumefaciens.

  • The gene of interest is inserted into the Ti plasmid which is introduced into plants, integrating into their DNA.

Transgenic Animal Models

  • Knockout Mice: Engineered to disrupt specific genes to study gene functions and phenotypes.

    • Marker gene conferring neomycin resistance used for selection.

  • Knockin Mice: Introduces specific mutations while preserving normal alleles.

Genome Editing Tools

  • CRISPR/Cas9: A simple method for altering DNA sequences in living cells, allowing targeted deletions or modifications.

  • RNA interference (RNAi): Reduces gene product levels, allowing studies of gene function without creating permanent mutants.

17.5 Environmental Applications

  • Bioremediation: Use of microorganisms to degrade environmental pollutants.

  • Biofuels: Derived from biomass; microalgae can be cultured for efficient lipid production.

17.6 Medical Applications

  • Recombinant Proteins: Produced in bacteria (e.g., human insulin) for therapeutic uses.

  • FISH: A hybridization technique for detecting specific DNA sequences invaluable in cancer diagnosis.

17.7 Agricultural Applications

  • Genetically Modified Organisms (GMOs): Engineered for herbicide resistance (e.g., glyphosate), pest resistance (e.g., Bt crops), and enhanced nutrients (e.g., Golden rice with β-carotene).

  • Social Issues: Concerns regarding crop safety, biodiversity impacts, and gene flow to wild relatives.

Additional Notes

DNA Libraries

  • cDNA Library: Represents expressed genes in a specific cell type or time, contrasting with genomic libraries which represent total genetic information.

PCR Applications in Genomics

  • Next-generation sequencing: Uses PCR for rapid sequencing, reducing time and cost significantly.

Novel Vaccine Technologies

  • Discuss the advancement in vaccine development including mRNA vaccines due to the COVID-19 pandemic.

Conclusion

  • Biotechnology presents extensive applications in medicine, agriculture, and environmental science, shaping new tools for scientific advancement.