Genetic Engineering, Domestication

• Genetics is the study of heredity and variation in organisms

Genetic Engineering

• Genetic engineering involves modifying or introducing genes into organisms or cells
• The processes in genetic engineering should be outlined
• Classical breeding and modern genetic engineering techniques should be compared
• Procedures for DNA insertion should be described
• Methods for determining genetically modified organisms should be explained

Domestication of Plants and Animals

• Humans domesticate plants and animals for desirable traits
• Domestication of animals and plants began centuries ago
• Favorable traits provide food, medicine and other purposes
• Classical breeding involves mating organisms with the desired traits

Enhancement or Introduction of Highly Valued Traits

• Examples include
  • Kobe/Wagyu Beef which is modified by classical breeding.
    • Kobe beef is Wagyu beef from the Tajima strain of Japanese Black cattle.
    • The meat is a delicacy, valued for its flavor, tenderness, and fatty, well-marbled texture.
  • Macapuno, which is modified by classical breeding
    • Macapuno is a naturally occurring coconut cultivar with an abnormal development of the endosperm.
    • Results in soft, translucent jelly-like flesh filling the central cavity of coconut seeds, with little to no coconut water.
  • Guapple (large guava) which is modified by classical breeding
    • Guapple is an improved guava variety with crunchy flesh, considered an all-season fruit.
    • A fruit weighs an average of 0.5 kilograms but can reach up to one kilo.
  • Human insulin-producing bacteria uses Recombinant DNA technology
    • Bacterial cells are genetically modified
    • Modified to have the gene for producing human insulin.
    • As these modified bacteria grow, they produce human insulin.
    • This protein can be purified and supplied to diabetics.
  • GMO Flavr Savr Tomato (delayed ripening) uses Recombinant DNA technology
    • A genetically modified tomato, the first commercially grown genetically engineered food licensed for human consumption.
    • It has a longer flavor shelf life than conventional tomatoes due to delayed ripening.

DNA Recombination and Technology

• Recombinant chromatids result from exchanged DNA segments after crossing over
• DNA recombination can be manipulated by:
  • Cutting DNA segments where genes of interest are located
  • Transferring to a host

Recombinant DNA Technology

• Biotechnology integrates biology and technology in products and research
• Genetic engineering manipulates genetic structure to change or modify desired traits via recombinant DNA technology
  • Introducing new traits.
  • Increasing gene expression to enhance traits.
  • Disrupting inhibition to enhance traits.

Procedures in Recombinant DNA Technology

Purification, Isolation, and Splicing of Foreign DNA Segments

• The gene-of-interest source, called foreign DNA, is purified
• Restriction enzymes cut DNA at certain points, leaving sticky ends for later
• Restriction enzymes naturally occur in cells and are cultured in labs
• The segments may or may not contain the gene-of-interest.

Ligation of Foreign DNA Fragments and Vector DNA

• Vectors combine with foreign DNA and replicate easily in the host cell, such as E. coli plasmid or Lambda phage
• Ligation "glues together" the sticky ends with DNA ligase
• Vectors with biomarkers are usually used with a known sequence for antibiotic resistance

Transformation of Recombinant DNA into Host Cell

• Transformation, plasmid insertion into the host cell, increases copies of recombinant DNA, includes methods like:
  • Biolistics, using a "gene gun" to insert DNA-coated pallets into host tissues to express DNA
  • Heat shock treatment: rapid temperature changes widen membrane pores
  • Electroporation: electric shock expands membrane pores for plasmids to enter

Selection of Transformed Cells

• Select transformant host cells containing plasmids using biomarkers
  • Adding antibiotics to select resistant cells that are transformants
• Select only transformants with recombinant DNA as opposed to empty plasmids
  • Uses blue-white screen test where white indicates recombinant DNA

DNA Sequencing

• From a transformant cell, foreign DNA fragments are purified, isolated, and transferred to a plate for DNA sequencing
• Sanger's sequencing method employs:
  • Basic principles of DNA replication
  • Electrophoresis to sort fragments by size and derive the sequence

Amplifying Small Amounts of DNA

• DNA cloning or amplification makes more copies when starting with a small DNA sample.
• The polymerase chain reaction (PCR) method produces higher DNA amounts faster compared to traditional cloning using vectors and host cells

Conclusions

• Genetic engineering uses biotechnology to enhance qualities or introduce new traits
• Recombinant DNA technology aligns with DNA replication principles
• PCR technology enables studying DNA with small sampling amounts