The gene is a branch of biology who aims to study how is the transmission of genetic material over the generations, the chemical nature of this material and its mode of action. Current genetics covers controversial topics, such as the Human Genome Project, gene therapy, cloning, transgenics, genetic counseling and prenatal diagnosis.
They are considered controversial because they involve political, ethical and religious issues, especially when related to the human species.
Mendel and the first steps of genetics
The monk Gregor Mendel (1822-1884) studied the genetic inheritance of some characteristics of the pea plant, such as the shape of the seed, color, texture and others. The peas were grown in the garden of the monastery of Brno, in the Czech Republic.
This type of plant was chosen because it has advantageous characteristics for genetic experiments, as it is easy to cultivate, allows controlled manipulation, has short generations and a large number of descendants, facilitating data analysis. Mendel concluded that each characteristic (character) is determined by a pair of factors that can be pure or hybrid (mixed by crossing).
The DNA molecule is formed by smaller units called nucleotides (Photo: depositphotos)
The chemical nature of the genetic material started to be known around 1969, when Miescher (1844-1895) isolated large molecules from the cell nucleus that he called nucleins and later, other scientists called nucleic acids. In the 20th century, two types of nucleic acid were identified: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
The importance of DNA
The DNA molecule is made up of smaller units called nucleotides. Each nucleotide corresponds to a deoxyribose sugar molecule, a phosphate molecule and a nitrogenous base (adenine and guanine or thymine and cytosine). The DNA has a three-dimensional configuration in the form of a double helix and the two strands are complemented by polynucleotides joined by hydrogen bonds.
See also : DNA – Chromosomes, genes, genome and RNA
The importance of DNA lies in the ability it has to store and transmit genetic information between future generations , due to its duplication being semiconservative, that is, before duplication, the two strands are untangled and each of them serves as a template for the formation of a new complementary tape. At the end of duplication, there are two newly formed DNA molecules that retain 50% of the information of the initial molecule (mother molecule).
During the duplication of DNA some errors and flaws can happen, generating genetic mutations (modifications). Mutations happen in the cells in general, however, when they happen in the germ cells (egg or sperm) such information can be transmitted through the generations, from parents to children.
Mutations can be spot, affecting only one nucleotide and leading to small changes in the sequence or number of nucleotides. There are also gene mutations, where nucleotide substitution, loss or addition can occur in the DNA molecule during its duplication. As an example, there is sickle cell anemia, a disease in which red blood cells have a sickle aspect due to the presence of defective hemoglobin molecules. In this case, a stretch of genes was replaced by another sequence of nucleotides, changing the function of the protein.
See also : First baby is born from an infertile couple with the DNA of three parents
Genetic diseases can cause cognitive, motor and psychological deficiencies . The progeria is a lethal disease that manifests in children aged 5 and 6 years, making the 8 or 9 they already have the appearance of an old man. The causes of proge