Genetic Engineering and Stem Cells: Advances in Biotechnology
The Genetic Engineering Process
Genetic engineering involves a precise process:
- The DNA containing the desired gene is cut with specific restriction enzymes.
- Vector DNA is cut with the same restriction enzymes to ensure complementary ends.
- The DNA fragment with the desired gene is ligated (bound) to the vector.
- The resulting molecule is recombinant DNA (DNA from different sources). This recombinant DNA is then introduced into a host cell.
- The host cell, typically a bacterium, divides many times, creating a population of identical cells, all containing the desired gene.
- The desired gene can then be recovered from host cells, purified, and analyzed.
For example, through this process, the gene carrying information for producing insulin has been successfully introduced into bacteria (host cells). By dividing many times, these bacteria have produced large quantities of pure insulin. Insulin for diabetics is now manufactured through genetic engineering.
Applications of Genetic Engineering
Genetic engineering has numerous applications, primarily in two areas:
- In Biotechnology: Advancing various industrial and agricultural processes.
- In Medicine:
- In the Diagnosis of Diseases: Genetic engineering discovers potential genetic alterations in DNA itself. This is crucial in prenatal diagnosis.
- In the Treatment of Diseases: Using gene therapy to cure diseases by replacing an altered gene with a normal one. Research is ongoing into its use for conditions like AIDS and cancer.
- In Forensic Medicine: Each person has a characteristic DNA pattern, known as a genetic fingerprint, obtained using restriction enzymes. This fingerprint allows for highly reliable identification of a person.
Stem Cells and Cloning
Every cell in our body contains the complete genetic material (DNA) necessary to become any other cell type. However, once specialized, cells lose this capacity. Following the fertilization of an ovum by sperm, the egg cell or zygote begins to divide rapidly, giving rise to new cells.
As the body develops from the fertilized egg at the moment of conception, cells differentiate: “I will be a neuron,” “I will be a bone cell (osteocyte),” or “I will be a skin cell.” This specialization occurs because certain cellular genes are inactivated while others are activated. As this process progresses, the path back is irreversible.
Stem Cell Definition and Types
Stem cells are undifferentiated or poorly differentiated cells that possess the ability to regenerate one or more cell types within a living organism. They are classified according to their origin into two groups:
- Embryonic Stem Cells: These are part of an embryo and are capable of generating all cell types of an organism. They are also known as pluripotent stem cells.
- Adult Stem Cells: Present in adults, these cells can generate specialized cells of different tissues, but not all. Their function is to continuously regenerate tissues such as skin or blood. They are also known as multipotent cells.
Key Differences: Embryonic vs. Adult Stem Cells
- Potency: Embryonic cells are pluripotent (can form all cell types); Adult cells are multipotent (can form specialized cells of specific tissues).
- Versatility: Embryonic cells are more versatile; Adult cells are less versatile.
- Abundance & Location: Embryonic cells are very numerous in early embryos; Adult cells are few and scattered throughout the body.
- Obtainability: Embryonic cells are relatively easy to obtain from embryos; Adult cells are harder to obtain.
- Growth & Tumor Risk: Embryonic cells may favor uncontrolled cell growth and the development of cancer; Adult cells exhibit normal cell growth and do not create tumor masses.
- Source & Ethical Issues: Embryonic cells are obtained by destroying embryos, which involves ethical issues; Adult cells are obtained from adult tissues or umbilical cord without destroying embryos, thus involving no ethical problems.