Human Genome and Genetic Engineering: Advances and Implications
The Human Genome
The human genome is the complete set of genes within a human being. It contains all the information necessary for basic human development. In the human species, the genome is packaged into 46 chromosomes: 23 from the father and 23 from the mother. These 46 chromosomes are grouped in pairs. 22 pairs are autosomes, which do not carry information about sex characteristics, and one pair are sex chromosomes. Females have two identical X chromosomes (XX), while males have one X and one Y chromosome (XY). The karyotype is the complete set of chromosomes in a species.
The Human Genome Project was an international effort to locate and sequence all the genes that constitute the human genome. It began in 1990 and was completed in 2003. The information obtained from the human genome is expected to lead to advances in medicine, particularly in:
- New ways to prevent, predict, diagnose, and treat genetically transmitted diseases.
- The ability to prevent or delay the onset of diseases.
- The design of drugs for populations that share certain sequences in their genome.
There are ethical, legal, and social implications arising from the human genome project. We must assess the advisability of making decisions based on information that, in many cases, is only a probability, such as the tendency to have a given disease. Privacy rights, non-discrimination, and dignity may be compromised with the information obtained from the human genome project.
Genetic Research
Genetic research is broad, but can be grouped into four basic approaches:
- Research into the genetics of transmission: Studies the mechanism of inheritance of characters. Human family trees are used to study the inheritance of a character.
- Cytogenetic Research: Analyzes chromosomes.
- Molecular or biochemical level genetic research: Studies the structure of genes and their functions.
- Research in the field of population genetics: Analyzes the genetic traits that are selected or lost in the evolutionary process.
Genetic Engineering
Genetic engineering is defined as the set of technologies used to manipulate the genetic material of a living being, i.e., to change genes. This manipulation includes:
- Introducing new genes into a genome.
- Deleting genes existing in a genome.
- Modifying the information in a particular gene.
The new genetic combinations are introduced into organisms capable of transmitting them to subsequent generations. This is also called recombinant DNA technology because most techniques rely on recombining DNA fragments.
Genetic Engineering Tools
To obtain new combinations of heritable material, the following tools are used:
- Restriction enzymes: These are proteins that recognize a specific DNA fragment and cut it. Different restriction enzymes can produce different DNA fragments. Each restriction enzyme recognizes a specific sequence of nucleotides and cuts each of the DNA strands at that point. The remaining free ends are called sticky ends because they can bind to other DNA fragments cut with the same restriction enzyme.
- Vectors: These are carrier agents capable of introducing DNA into host cells. Cloning vectors are small DNA molecules that can replicate themselves inside host cells. Two types of cloning vectors are often used:
- Plasmids: These are circular DNA molecules that bacteria have in addition to their bacterial chromosome. A new DNA fragment (gene) is inserted into the plasmid, and then the plasmid is introduced into the organism where the gene is to be introduced.
- Viruses: The process is similar; the desired gene is inserted into the viral DNA, and then the virus is introduced into the organism where the gene is to be introduced.