Genetics Chapter: Chromosomes and Inheritance

Chromosomes and Inheritance

• All living organisms inherit characteristics from their parents through chromosomes.
• Chromosomes are long strands of genetic information found within the nucleus of cells.
• Most cells contain matching pairs of chromosomes called homologous chromosomes.
• One chromosome in each pair is inherited from the mother, and the other from the father.
• Humans have 46 chromosomes (23 pairs).
• Different species have differing numbers of chromosomes.
  • Fruit fly: 8 chromosomes.
  • Maize: 20 chromosomes.
  • Cat: 38 chromosomes.
  • Chicken: 78 chromosomes.

Genetic Engineering

• Genetic engineering is the direct manipulation of an organism's genes using biotechnology.
• It involves changing the genetic makeup of cells, including transferring genes between species.
• Genetic engineering can be used to produce improved or novel organisms.

Transgenics

• Transgenics refers to organisms that contain DNA from a different species.
• Foreign DNA, including human DNA, can be inserted into animals.
• This can be used to produce specific proteins in the transgenic animal.
• For example, human antibodies can be produced in the milk of transgenic goats.

Applications of Genetic Engineering

• Genetic engineering has various applications, including:
  • Production of vaccines (e.g., Hepatitis B vaccine)
    • Transgenics
      • Producing proteins (e.g., antibodies), like in the example of transgenic goats.
      • This method can produce higher antibody levels more easily and cheaply than using genetically modified bacteria or mammalian cells.
      • Can produce desired proteins at a specific time in a desired tissue.
    • GM Crops
      • Increased yields of staple crops.
      • Crops resistant to pests, requiring fewer chemical sprays.
      • Crops with enhanced nutritional value (e.g., increased vitamin content).
      • Improved crops that can survive in harsher conditions.

Ethical Considerations

• Ethical concerns related to genetic engineering include:
  • Savior Siblings: Should parents be allowed to have children with specific genetic traits to help a sibling with a disease?
  • Gene therapy: This involves replacing faulty genes with healthy ones, but ethical considerations regarding potential risks and unforeseen consequences exist.
  • Pre-implantation Genetic Diagnosis (PGD): PGD allows the selection of embryos before implantation, but the ethical implications of choosing embryos based on genetic traits require careful consideration.
  • Designer babies: The possibility of designing offspring with specific traits raises moral and ethical dilemmas.

Risks Associated with Genetic Engineering

• Potential risks associated with genetic engineering include:
  • The transfer of engineered genes to other non-engineered organisms.
  • The creation of new allergens in GM crops.
  • The potential for unintended consequences in the environment.

Advantages and Disadvantages of GM Crops

• Advantages:
  • Increased yields.
  • Pest resistance.
  • Enhanced nutritional value.
  • Reduced reliance on pesticides.
  • Crops that can survive in harsher conditions.
  • Cheaper food production.
• Disadvantages:
  • Increased cost of seeds.
  • Potential for accidental transfer of genes to other plants.
  • Potential for new allergens.
  • Potential for reduced biodiversity.
  • Unforeseen impacts on the environment.

Summary of Genetic Engineering Process

• DNA from a desired source (e.g., human) is isolated and inserted into a vector (e.g., plasmid).
• The vector carries the DNA into a host organism (e.g., bacterium).
• The host organism replicates the DNA, producing many copies of the desired gene.
• The desired protein can then be purified and used.