Genetics, as a branch of biology, deals with finding traits in patterns across different species with relation to their immediate and distant ancestors. It is a study that also involves research on the commonalities between species which have diversified with evolution in relation to their gene mapping. The field of genetics is broadly divided in cytogenetics and molecular genetics. Both these branches of genetics are very important in understanding a number of factors like the hereditary disease, evolution, prediction of certain diseases like cancer and predisposition to medical conditions like schizophrenia and diabetes in humans.
In cytogenetics, the number of chromosomes and their structures are the base of the study. It also involves studying the relation of chromosomes with the behaviour of cells during the process of cell division. Chromosomal deformities and abnormalities fall under the realm of Cytogenetics. 'Chromosomal abnormalities' means an increase or decrease in the number of chromosomes or translocation of one chromosome with another. The chromosomes are inside the nuclei of the cells which are responsible for carrying the genetic information from a parent to the offspring. In Cytogenetics, we can study the link between the changes in chromosomes and a genetic disorder. This field of genetics helps us learn disorders that are either genetically inherited or caused by abnormalities of the chromosomes; Down syndrome, e.g., is a disorder caused by the presence of an extra copy of chromosome 21 in the affected person. Similarly, a girl child born with only one X chromosome has turner syndrome, and an extra X chromosome in a male child causes Klinefelter syndrome due to a total of 47 chromosomes.
Molecular genetics is a molecular level study of chromosomes and segments of DNA is undertaken with the help of DNA technology. Studies like physical examination of a mutated gene fall under the realm of molecular genetics. In molecular genetics, the gene-expression profiling (GEP) helps us determine the level at which genes are expressed in an individual or group. When the field of genetics was in its infantile stage, scientists were baffled whether inheritance was due to the protein or DNA in chromosomes. There were several experiments and researches conducted in which it was proven that dead bacteria can transfer the genetic material to alive bacteria. In another study, it was proven that it was the DNA of viruses that was responsible for infecting the bacteria. This was when it was ruled out that the DNA is the carrier of inheritable information from parent to offspring. This was the preliminary step towards molecular genetics. Later studies went on to discover the types of chromosomes that were linked to the gender of an organism, the number of chromosomes and genes in them etc.
There are a lot of researches done in the field of genetics. Some types of genetic abnormalities and congenital defects that are extremely rare need better understanding with regards to their causes. For instance, atavism is a phenomenon, in which an organism is born with a trait which was lost in the course of evolution; e.g., some human babies are born with tails, a physical characteristic which was lost in the course of millions of years of evolution; detailed genetic scrutiny can help geneticists to determine as to what made the trait reappear and what interplay of which genes made it happen. Such analysis can be a part of both Cytogenetics and molecular genetics; with the help of cytogenetics, a geneticist can understand what all structural and numeric changes have taken place in the chromosome and genes, respectively, as a result of the reintroduction of a dormant gene.
1. Are molecular genetics and cytogenetics unrelated studies?
Answer: Both these fields of genetics are interrelated, although their administration is often carried out separately. A student genetic science as a field of biology will have to study both aspects of genetics; nevertheless, he or she may not get to work in an environment dealing with both these aspects. Deep understanding of both can, however, help a student or an aspiring geneticist with better scrutiny of a phenomenon which is subjected to the study of genetics.
2. What are the fields of biology the study of molecular genetics and cytogenetics are related to?
Answer: Molecular genetics and cytogenetics are the two major fields of study in genetics. They can help a student or a geneticist with a better input on or finding new discoveries in evolutionary biology, microbiology, methods of transmission of genetic information like sexual, asexual, hybridisation, bacterial conjugation, i.e. exchange of genetic material between bacteria, and many other fields in biology.