Lecture_Presentation_20 - Biotechnology

Chapter 20: DNA Tools and Biotechnology

  • Lecture Presentations by: Nicole Tunbridge and Kathleen Fitzpatrick

  • © 2021 Pearson Education, Inc.

Key Techniques in Biotechnology

Main Techniques

  • DNA Sequencing: Determines the exact sequence of nucleotides in DNA.

  • Gene Cloning: Involves replicating a specific gene to produce multiple copies.

  • Expressing Genes: Producing gene products (proteins) in living systems.

  • Analyzing Gene Expression: Understanding how genes are expressed in cells.

Applications

  • Medicine: Development of treatments using cloned genes.

  • Agriculture: Production of genetically modified crops for better yield.

  • Environmental Cleanup: Using biotechnological methods for pollution management.

  • Forensics: Applications in crime scene investigations and ancestry tracing.

DNA Technology

  • DNA Technology: Techniques for sequencing and manipulating DNA.

  • Nucleic Acid Hybridization: Base pairing between complementary DNA strands.

  • Genetic Engineering: Direct manipulation of an organism's genes for practical benefits.

DNA Sequencing Techniques

First Generation - Sanger Sequencing

  • Developed by Frederick Sanger, this method involves dideoxy or chain termination sequencing to determine a gene's nucleotide sequence.

Next-Generation Sequencing

  • Includes rapid techniques that allow sequencing of many fragments simultaneously.

  • Sequencing by Synthesis: Immobilizes DNA fragments and synthesizes complementary strands one nucleotide at a time.

Third-Generation Sequencing

  • Even faster techniques that sequence long DNA molecules using a nanopore.

  • Identification of bases based on interruptions in an electric current.

DNA Cloning

  • DNA Cloning: Producing multiple identical copies of DNA segments using plasmids.

  • Plasmids: Small circular DNA molecules that replicate independently in bacterial cells.

Process of Cloning

  1. Insertion of DNA: DNA from one source is inserted into a plasmid to create a recombinant DNA molecule.

  2. Transformation: Plasmid is introduced into a bacterial cell.

  3. Cell Growth: Bacteria are cultured to produce clones containing the gene of interest.

Gene Cloning Applications

  • Human growth hormone and blood clotting proteins produced for medical use.

Techniques for Creating Recombinant DNA

Using Restriction Enzymes

  • Restriction Enzymes: Cut DNA at specific sequences (restriction sites).

  • Most useful enzymes create sticky ends to facilitate the joining of DNA fragments.

DNA Ligase

  • An enzyme that joins the fragments of DNA by sealing the bonds between restriction fragments, forming recombinant DNA.

Gel Electrophoresis

  • Used to separate DNA fragments for visualization and verification of recombinant plasmids.

Polymerase Chain Reaction (PCR)

Overview

  • PCR amplifies specific DNA segments through a series of temperature cycles which include:

    • Denaturation: Heating to separate strands.

    • Annealing: Cooling to allow primers to bind to target sequences.

    • Extension: DNA polymerase synthesizes new DNA strands.

Taq Polymerase

  • A heat-stable DNA polymerase critical for PCR's effectiveness.

Applications of PCR

  • Amplification from ancient DNA sources, forensic samples, and other low-quantity biological samples.

Conclusion

  • Cloned genes can be expressed in bacteria or eukaryotic cells for research or practical applications.

  • The techniques discussed play a vital role in advancing biotechnology, genetics, and molecular biology.