Biology

• Low-tech methods in biotechnology include:

  • Selective breeding: changing populations by allowing only individuals with desired traits to breed
  • Hybridization: crossing two different organisms to obtain desired traits from both, e.g., mule
  • Inbreeding: keeping a variety of plant/animal "pure" by breeding it with closely related individuals, e.g., dogs
• Advantages of inbreeding:

  • Keeps desired traits

  Disadvantages:

  • Can bring together recessive alleles for genetic disorders
• Increasing Variation in selective breeding is essential because it requires variation to generate new varieties using mutagens like radiation and chemicals, e.g., oil-digesting bacteria, polyploid plants with huge fruit
• Modern tools of molecular biology include:

  • Restriction Enzymes: used to cut DNA into smaller fragments, each cutting DNA at a specific sequence of bases
  • Gel Electrophoresis: sorts DNA fragments by size using an electric current through a gel
  • DNA Fingerprinting: isolates DNA, cuts it at specific places, and uses gel electrophoresis to compare bands to identify individuals
  • PCR (Polymerase Chain Reaction): makes millions of copies of a selected gene for study/work
  • DNA Sequencing: can be done by machine
  • Plasmid transformation: uses plasmids to insert new DNA into a cell, e.g., making insulin
• Transgenic Organisms (GMOs) express genes from other organisms, like bacteria expressing human proteins, animals with extra genes like growth hormones, and plants with genes for resistance or other traits
• Cloning is the production of an organism genetically identical to another, including:

  • Cloning plants by planting clippings
  • Animal clones like identical twins or clones produced from a single animal cell in mice, sheep, dogs, etc.
• Gene Therapy uses viruses to insert helpful genes into host cell DNA, with CRISPR-CAS9 being a breakthrough tool to edit genes and potentially cure genetic diseases
• Epigenetics refers to the study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself
• 97% of DNA doesn’t code for protein, but some of it has other functions known as the epigenome
• Certain environmental factors can cause DNA methylation, where carbons are attached to DNA in specific places
• Highly methylated DNA is less likely to be used compared to unmethylated DNA
• Contrary to previous beliefs, epigenetics shows that some methylation-type changes can be passed on to offspring, influenced by factors like smoking, overeating, or starvation