DNA, Genetic Engineering, Cloning, and Bioethics
DNA and Genetic Engineering
1. DNA: A molecule that carries genetic information from generation to generation. It is part of the nucleic acids, which consist of repeating units called nucleotides.
- Gene: A unit of hereditary information that instructs the cell how to make proteins.
2. Genetic Engineering: A set of techniques for manipulating genes in a living being. It’s a double-edged sword because the same techniques can be used to improve health or to cause harm.
Applications of Genetic Engineering:
- Production of transgenic plants and animals
- Diagnosis of hereditary diseases
- Species identification
- Determination of genetic fingerprints
- DNA sequencing
- Fossil identification
- Nucleotide sequencing of the genomes of different species
The Human Genome and its Implications
3. Genome: The set of genes of a living being. The human genome refers to the complete set of genes in the human species, and the Human Genome Project aimed to determine the complete nucleotide sequence of the human genome.
Human Genome Project Findings:
- The number of human genes is much lower than initially expected.
- Human and fruit fly DNA share more than 80% similarity. The similarity with chimpanzees is 96%.
- A single gene can encode the synthesis of multiple proteins.
- Part of the DNA strand is made up of genes, while other parts are referred to as “junk DNA” and pseudogenes.
Assisted Reproduction
4. Assisted Reproduction (Artificial Insemination): Manipulation of gametes to achieve human reproduction through mechanisms other than sexual intercourse. Assisted reproductive techniques include:
- Artificial Insemination: Introduction of semen (either from the partner or a donor).
- In Vitro Fertilization with Embryo Transfer (IVF and ET): Removal of a female egg to fertilize it with previously obtained human sperm, facilitating their union in a test tube.
- Gamete Intrafallopian Transfer (GIFT): Sperm and eggs are placed directly into the woman’s fallopian tube via laparoscopy. This technique is intermediate between insemination and in vitro fertilization.
Cloning
5. Cloning Organisms: Obtaining one or more individuals from a non-sexual cell or a nucleus from another individual, so that the cloned individuals are genetically identical (or nearly identical) to the original.
- The method used to create Dolly the sheep involved obtaining a sheep egg and removing its nucleus. This enucleated egg then received a nucleus from an adult sheep cell. The resulting embryo was implanted into a third sheep, which served as a surrogate mother. Therefore, Dolly had three “mothers” and no father.
Stem Cells
6. What are Stem Cells? Characteristics and Types:
Stem Cells: Cells that have not yet fully differentiated, either forming part of an embryo in its early stages or existing as reserves of immature cells in the adult organism.
Characteristics:
- Self-Renewal: The ability to produce more stem cells.
- Differentiation: The capacity to give rise to daughter cells that differentiate into various specialized cell types.
Types of Stem Cells: Totipotent, pluripotent, multipotent, embryonic, and adult stem cells.
Euthanasia and Eugenics
7. Euthanasia: Any act, usually performed by medical personnel, that causes the death of a human being in order to avoid intolerable suffering.
Eugenics: The belief in improving human hereditary traits. Currently, positive intervention (improving biological characteristics) is not generally practiced. Negative interventions include preventing reproduction in individuals carrying genetic defects, eliminating embryos generated in vitro that have a defect or predisposition to a defect, and abortion of fetuses that may present defects.