Stem Cells, Genetic Engineering, and GMOs: Key Concepts

Posted on Feb 3, 2025 in Biology

Stem Cells: Types and Applications

1 – Embryo Cryopreservation: Embryos are frozen in liquid nitrogen at -160ºC. This process stops the vital functions of the embryo without causing death.

2 – Legal and Ethical Considerations in Spain: Spanish legislation prohibits choosing the sex or any other characteristics of children. However, embryo selection is permitted in specific cases, such as:

  • To prevent genetic abnormalities in children: If a hereditary disease is sex-linked, the sex of implanted embryos can be selected.
  • If another child in the family has a serious illness that can be treated with a transplant from a compatible donor: Embryo selection can be performed to ensure the new child is a compatible match for their sick sibling who needs a transplant.

3 – Stem Cell Characteristics and Types: Stem cells are unspecialized cells with the ability to multiply for extended periods and differentiate into specialized cell types.

Types of Stem Cells:

  • Totipotent: These cells can generate a complete individual. Besides the zygote, the first eight cells resulting from its division are totipotent. This means that if this cell group is divided into two, each group can develop into a complete individual.
  • Pluripotent: These cells cannot create a complete individual but retain the capacity to give rise to every cell type that makes up an organism.
  • Multipotent: Also known as adult stem cells, somatic stem cells, or tissue stem cells, these cells retain some ability to give rise to specific cell types.

4 – Induced Pluripotent Stem Cells (iPSCs): These are specialized adult cells that, after undergoing various treatments, dedifferentiate and revert to pluripotent embryonic stem cells. Although their use in regenerative medicine treatments is still far off, they offer the possibility of obtaining embryonic stem cells without using embryos.

Therapeutic and Reproductive Cloning

5 – Therapeutic Cloning: This process involves obtaining embryonic stem cells for transplants that can be used without the risk of rejection. The steps are as follows:

  1. A biopsy is taken from the patient needing the transplant, and the nucleus is removed from some of the obtained cells.
  2. The nucleus is introduced into an egg from a donor, from which its own nucleus has been extracted.
  3. The egg is allowed to develop under laboratory conditions until it reaches the blastocyst stage.
  4. Embryonic stem cells are obtained from the cell mass of the blastocyst and cultured in vitro to increase their numbers.
  5. Once a sufficient number of stem cells is obtained, they are placed in appropriate media for differentiation.

6 – Reproductive Cloning: This process involves the following steps:

  1. A differentiated cell is obtained from the individual to be cloned.
  2. An egg is extracted from a female donor.
  3. The egg’s nucleus is removed.
  4. The nucleus of the differentiated cell is transferred to the enucleated egg.
  5. The cell is grown in the laboratory in a special medium until the embryo begins to develop.
  6. When it reaches the morula stage, it is transferred to the uterus of a recipient mother.
  7. After the gestation period, a new individual is born, which is a clone of the individual that provided the nucleus.

DNA, Genetics, and Genetic Engineering

1 – DNA Structure and Function:

  • DNA has a double helix structure consisting of two intertwined chains.
  • Each chain is formed by the binding of nucleotides.
  • The two chains are joined through nitrogenous bases.
  • Genetic information is stored in the sequence of these bases.

Key Genetic Terms:

  • Gene: A portion of a DNA base sequence that determines the appearance of a specific trait.
  • Chromosome: The organized structure of DNA within the nucleus of cells.
  • Genome: The complete set of genes of an organism.

2 – Genetic Engineering Definition and Tools: Genetic engineering is the modification of DNA. The primary tools used are enzymes, which catalyze chemical reactions.

3 – Genetic Engineering Process:

Stage 1: Introducing the Desired Gene

  1. All DNA is extracted.
  2. The desired gene is located and removed.
  3. The gene is cloned.
  4. The exogenous gene is modified.
  5. The modified gene is introduced into the nucleus of the cell to be altered.
  6. It is verified that the cell incorporates the modified gene.

Stage 2: Obtaining a Modified Organism

This stage involves obtaining a plant or animal from the cell whose genome has been modified. It requires the use of organism culturing techniques.

Genetically Modified Organisms (GMOs) and Food

4 – GMO Labeling in Food:

  1. What is a genetically modified (GM) food?
  2. What is a product that contains GMOs?
  3. What is a food produced from GMOs?

Exceptions to Labeling:

  1. Foods containing only 0.9% or less of GMOs.
  2. Second or third-generation products.
  3. Foods in which transgenic organisms are used for fermentation.