Organ Transplants, Human Reproduction, and Genetic Engineering

Posted on Dec 11, 2024 in Biology

Types of Transplants

  • Autograft: Donor and recipient are the same individual.
  • Isotransplant: Donor and recipient are identical twins.
  • Xenotransplantation: Donor and recipient are different species.
  • Allogeneic: Donor and recipient are of the same species but are not genetically identical.

Problems of Transplants

  • Immune Rejection: White blood cells detect something odd and try to destroy it. So, if the donor and recipient are not identical, rejection will occur. To avoid rejection, powerful drugs called immunosuppressants are used.
  • Shortage of Organs Available
  • Inability to Obtain Certain Tissues: This means that, currently, it is not possible to obtain nerve cells that could cure certain conditions.

Fertilization and Embryonic Development

Fertilization: Is the union of an egg and sperm and occurs inside the female genital system in a tube called the fallopian tube. The result is the egg cell or zygote.

Development: A set of changes produced in any living being throughout their lives. Embryonic development ends at birth, and postnatal development begins at the time of birth and continues for the rest of life.

Stages of Embryonic Development

  1. Fertilization (formation of the zygote)
  2. First Division
  3. Morula (32 cells)
  4. Early Blastocyst (a cavity forms inside the morula that adopts the form of a hollow ball)
  5. Late Blastocyst (referred to as a compact mass)
  6. Nidation (the embryo implants in the uterine wall covered with a layer called the endometrium)

Key Points in Embryonic Development

  • Implantation: The embryo is implanted in the endometrium.
  • Formation of the Nervous System: The embryo continues to grow, and a group of cells forms its nervous system.
  • Organs Begin to Operate: The fetal period begins.

Human Reproduction

  • Artificial Insemination: A method that introduces sperm artificially within the female genital tract.
  • In Vitro Fertilization: Consists of fertilizing an egg with sperm outside the woman’s body. It has 3 stages:
    • Obtaining Ova: Hormone treatment stimulates the production of eggs in the ovaries.
    • Fertilization: Ova are fertilized by sperm in a laboratory test tube.
    • Embryo Transfer: The embryos are introduced into the woman’s uterus.

Types of Stem Cells

  • Totipotent: Cells capable of producing a complete individual.
  • Pluripotent: Cannot produce a complete individual but retain the ability to generate each cell type that forms.
  • Multipotent: Cells capable of originating, not all, but some types of cells.
  • Oligopotent: Adult stem cells that can produce only one or a few cell types.

Cloning of an Animal

  1. Obtain a differentiated cell of the individual to be cloned.
  2. Extract an egg from a donor cow.
  3. Remove the egg nucleus.
  4. Transfer the nucleus of the cell to be differentiated into the nucleus-free egg.
  5. Cultivate cells in the laboratory until the embryo begins to develop.
  6. When it reaches the morula stage or a little further, transfer it to the uterus of a recipient mother.
  7. A new individual is born.

Stages of Therapeutic Cloning

  1. A biopsy is taken from a patient who needs a transplant, and the nucleus of some cells is removed.
  2. The nucleus is introduced into a donor egg from which its own nucleus has been removed.
  3. It is allowed to develop to the blastocyst stage. This gives rise to what are called somatic embryos.
  4. Embryonic stem cells are obtained from the cell mass of the blastocyst and cultured in vitro to increase their number.
  5. Having gained a sufficient number, the cells are arranged in the proper media for differentiation.

Obtaining a Transgenic Organism

First Stage or Processing: Introduce the desired gene into the genome of a body cell to be modified.

Second Stage of Reclamation: Obtaining an animal or plant from the cell whose genome has been modified.

Genetic Engineering

A group of techniques used by biologists to provide living cells with new properties, changing their genetic material.

Risks of GMOs

  • Food Industry: Procurement of food with special features.
  • Pharmaceutical Industry: Production of drugs or vaccines.
  • Agriculture and Livestock: Enhancing agronomic characters.
  • Environment: Toxic waste disposal using plants with the capacity to resist the presence of toxic substances and accumulate them in their bodies, or the production of biofuels from plants rich in energy compounds.
  • Medical Research: Obtaining transplant organs from transgenic animals that do not raise rejection, or use in basic research.

Objectives of the Human Genome Project

  • Identify existing genes and determine how chromosomes are organized and where each gene is located on that chromosome.
  • Accurately determine the nucleotide sequence of each gene to obtain the encoded protein and its alterations.

Genetic Diseases

Genetic disorders occur when a gene, or a normal chromosome, is altered, i.e., it mutates and does not perform its vital role. If the change affects all body cells, the genetic disease is hereditary. Inherited genetic diseases can be:

  • Chromosomal: Are the result of issues affecting a complete chromosome.
  • Monogenic: Are due to changes in a single gene and are inherited like any other character.