Cloning and DNA Technology

Examples of Genetically Modified Bacteria

• Example 1: E. coli

  • Purpose: Used to produce insulin. The insulin gene is inserted into E. coli, which then produces insulin that is harvested for diabetic patients.

• Example 2: Bacillus thuringiensis (Bt)

  • Purpose: Genetically modified to produce a toxin that is effective against certain insect pests, reducing the need for chemical pesticides.

• Example 3: Agrobacterium tumefaciens

  • Purpose: Used in plant genetic engineering as it transfers DNA to plant cells, facilitating the introduction of new traits, such as herbicide resistance.

Cloning Process - Nuclear Transfer

• Nuclear Transfer Process:

  1. A somatic cell is taken from an adult organism, which contains the nucleus with DNA.
  2. An egg cell is collected from a donor organism, and its nucleus is removed (enucleated).
  3. The nucleus from the somatic cell is then inserted into the enucleated egg cell.
  4. The egg cell is stimulated to divide and develop into an embryo.
  5. The embryo is implanted into a surrogate mother, resulting in a clone of the original organism.

• Difference from Sexual Reproduction:

  • Sexual reproduction involves the combination of genetic material from two parents, leading to genetic variation, whereas nuclear transfer produces an organism that is genetically identical to the donor of the somatic nucleus.

DNA and Chromosomes of a Clone vs. Original Organism

• Clones contain the same DNA and chromosomes as the original organism from which they were cloned, meaning all genetic material is identical and there are no additional mutations or variations introduced.

Genetically Modified Foods: Positives and Negatives

• Positives for Farmers:

  • Increased crop yields and resistance to pests, reducing costs of pest control.
  • Extended shelf life and improved nutritional content of crops.

• Negatives for Farmers:

  • Potential for reliance on specific seeds and loss of biodiversity.
  • Possible emergence of resistant pests and weeds.

• Positives for Consumers:

  • Availability of diverse and high-quality food products.

• Negatives for Consumers:

  • Concerns over health effects and environmental impact of genetically modified organisms (GMOs).
  • Ethical concerns regarding the modification of food sources.

Restriction Enzymes

• Definition: Enzymes that cut DNA at specific sequences, allowing for the manipulation of genetic material.
• Sticky Ends: Produced when the cuts are made in a staggered fashion, leaving single-stranded overhangs, which can easily join with complementary DNA sequences.
• Uses in Genetic Engineering:
  • Creation of recombinant DNA.
  • Gene cloning and insertion into vectors.
  • Genetic testing and mapping.

Key Definitions

• Human Genome Project:

  • An international research effort aimed at mapping and understanding all the genes of the human species, completed in 2003.

• Gel Electrophoresis/DNA Fingerprinting:

  • A technique used to separate DNA fragments based on size; employed for paternity testing, forensic analysis, and genetic identification.

• Gene Therapy:

  • A technique that modifies genes to treat or prevent disease by inserting a healthy copy of a gene into the body’s cells.

• Polymerase Chain Reaction (PCR):

  • A method used to amplify specific DNA sequences, making millions of copies of a particular genetic segment for analysis.

• Cloning Vector:

  • A DNA molecule used to carry foreign genetic material into another cell for cloning.

Embryonic vs. Adult Stem Cells

• Embryonic Stem Cells:

  • Derived from early embryos, they are pluripotent, meaning they can develop into almost any cell type in the body.

• Adult Stem Cells:

  • Found in various tissues, they are multipotent with a more limited capability to differentiate into other cell types compared to embryonic stem cells.

Knowledge from the Human Genome Project

• Identification of all human genes and their functions.
• Required mapping of genetic variations associated with diseases.
• Understanding of genetic predisposition to various conditions and diseases.
• Advances in personalized medicine through genetic information.

Reproductive vs. Therapeutic Cloning

• Reproductive Cloning:

  • Aims to produce a cloned organism (e.g., Dolly the sheep); used for creating animals with desirable traits or endangered species preservation.

• Therapeutic Cloning:

  • Intended for creating stem cells that can regenerate diseased tissues; holds potential for treating conditions such as Parkinson's disease, spinal cord injuries, and diabetes.