The 8 branches of Genetics (and their characteristics)
These are the branches of genetics and their technological and scientific applications.
Without genetics, explaining life is impossible. All living beings have at least one cell, and for a cell to be a cell, it must contain genetic material in the form of DNA and be able to self-replicate on its own. on its own.
Thanks to enzymatic activity (DNA polymerase, among others), substrates (nucleotides) and a template strand, life is able to generate a copy or more of a DNA double helix, and thus new life.
This simple premise explains the permanence of living beings on Earth and much more complex things, such as the mechanisms of inheritance. Thanks to cell division by meiosis, gametes can be generated with half the genetic information of a normal parental cell, a condition known as haploidy (n). When two haploid gametes unite, a diploid (2n) zygote is generated, containing half of the information from the mother and half from the father. This is how, for example, inheritance works in our species.
However, the deterministic and Mendelian view of genetics is being challenged. Over the years, humans have come to realize that the genome is not restricted only to parental inheritance, but that there are mutations and environmental variations that can modify gene expression throughout life, giving rise to the unusual phenotypic diversity of species. In the following lines, we will see which are the branches of genetics and their characteristics.
What are the branches of genetics?
Genetics can be defined as a branch of the science (specifically biology) that deals with the study of genes, genetic variation and the mechanisms of inheritance in organisms.. The main objective of this discipline is to understand, with the help of biochemical and physiological bases, how the inheritance of genotype and phenotype occurs from generation to generation in different species, with even more attention to the human species.
Before going directly into the subject, it is necessary that you have certain clear ideas. As we have said, half of the information in each of our cells comes from the mother, and the other half from the father. In other words, we have a total of 23 pairs of chromosomes (46= 23 maternal + 23 paternal). In addition, each chromosome contains protein or RNA coding sequences, called "genes".
Since we have two chromosomes of each type (1 to 23), we will have two copies of the same gene, one present on the paternal chromosome and the other on the maternal chromosome, at a fixed position.. Each of the variations that a gene can adopt is known as "allele", so we can also affirm that all our genes present two alleles in the genome of the individual, one maternal and one paternal.
With these data, we only need to know that a typical allele can be dominant (A) or recessive (a). Thus, for the same gene, an individual can be homozygous dominant (AA), homozygous recessive (aa) or heterozygous (Aa). With these bases in place, let us see which are the branches of genetics.
1. Mendelian genetics or classical genetics
This branch of genetics is the one that approaches the study of genes without the use of molecular tools, as did Gregor M. Mendel.as Gregor Mendel did in his day with his experiments on peas over different generations. Briefly, we review Mendel's three laws in this list:
- Principle of uniformity: if two homozygotes (AA and aa) for a gene are crossed, all the offspring will be heterozygous (Aa). The trait shown will be the dominant one, i.e. the one encoded by the allele (A).
- Segregation principle: if the generation of heterozygotes (Aa) is crossed with each other, things change. ¼ of the offspring will be homozygous dominant (AA), ¼ will be homozygous recessive (aa) and 2/4 will be heterozygous (Aa). The dominant trait is expressed in 3 out of 4.
- Principle of independent transmission: if two genes are sufficiently separated from each other or on two different chromosomes, they can be inherited with independent frequencies.
Although Mendelian genetics has been very useful in establishing the basis of modern genetics, it is not very useful today. Without the use of molecular tools, it is very difficult to establish the range of action of a geneMany traits are polygenic and are explained by more than two alleles (such as eye color, encoded by more than 3 genes).
Molecular genetics
As its name suggests, molecular genetics is the branch of this discipline that studies the structure and functionality of genes at the molecular level, using techniques such as PCR (Polymerase Chain Reaction) or DNA cloning in the bacterial environment. In other words, is responsible for the research, description and management of the physical and functional unit of heredity: the gene..
Developmental genetics
In this case, genetics is used to describe the process by which a cell eventually develops into a complete and functional multicellular being.. It is in charge of investigating what conditions (at the nuclear and gene level) that a cell specializes in one function or another during development, among other things.
Population genetics
In the natural world, genetic viability is often much more important than the population numbers of a species in a given ecosystem.. If there are 500 animals in a given nucleus but only 4 reproduce each year, there is a tendency towards reduced variability and thus homozygosity.
As a general rule, homozygosity and inbreeding are associated with a more fatalistic prognosis in a population, since the low variability in genes implies that responses to the environment will be very similar among animals, for better and for worse, in addition to a higher rate of accumulation of deleterious mutations. Effective population numbers, percent heterozygosity, allele frequencies and much more are quantified in population genetics studies to determine the "welfare" of a species.to determine the "welfare" of a species, beyond the number of individuals.beyond the number of specimens.
5. Quantitative genetics
Referring back to previous points, quantitative genetics studies those phenotypes (traits encoded by the genotype) that cannot be classified by typical Mendelian criteria, i.e. by an allele.that is, by a dominant allele (A) and a recessive allele (a).
A very clear example of this is skin color, which is encoded by the genes TYR, TYRP1, OCA2, SLC45A2, SLC24A5 and MC1R, in addition to environmental parameters and lifestyle. When a trait is polygenic or oligogenic, the approach must be very different.
6. Phylogeny
This is the branch of genetics that studies the kinship between the different taxa of living beings, creating in the process the famous "trees of life", which are used to group species into orders, families, genera and species (also subfamilies, subspecies, tribes, etc.).These are used to group species into orders of families, genera and species (also subfamilies, subspecies, tribes, etc.). DNA (nuclear or mitochondrial) and RNA sequences from tissue samples can help evolutionary biologists to infer kinship between living things that, at first, have nothing to do with each other externally.
7. Genetic engineering
Genetic engineering is based on the direct manipulation of an organism's genes, either through injections in culture media, the transfer of mutated viruses or many other mechanisms for transmitting information.
The aim of this branch of science is usually to improve the productive capacities of species. (especially in the agricultural environment), in order to achieve faster growth, better product quality, greater crop resistance, or not being affected by pests, among other things.
8. Epigenetics
Epigenetics is a very novel branch of classical genetics, whose role is to explore the mechanisms that inhibit or promote the expression of genes throughout an individual's life without changes in his or her genome.
There are several ways in which a gene can be transiently "inactivated", and these are mediated by sequences of genes.These are mediated by sequences in the genome that were originally thought to be useless. Epigenetics, although still in its infancy, promises answers to many headaches that today seem to have no solution.
Summary
As you can see, genetics is applicable to practically all fields of life. From maintaining ecosystems to solving diseases, studying evolution, improving crops or understanding human fetuses, everything around us is determined by our genes.
(Updated at Apr 12 / 2024)