Genetics is basically a summary of all that has been done by scientists to understand why parents and children share similar features. In this article, I will be taking you through the basics of genetic while trying not to bore you
It doesn't take much to notice similarities between parents and children. This is not to say that the contributions of the classical era were useless. I will probably write about this again some other time, the thing is everything from the classic era is basic now because we all have accepted it but back then there were resistances to accepting such knowledge.
The people who moved crowds with their theories in the classical era were Hippocrates and Aristotle. They probably developed their ideas from Anaxagoras (a presocratic Greek philosopher).
Socrates had this idea that semen, which he saw as purified blood when it interacted with menstrual blood, gave rise to a zygote. I think at that time they had already figured out that semen was involved in the making of babies, judging from Onan's story in the bible.
So while you can say confidently that a person inherited that nose from his father now, before then it took time for everyone to accept the knowledge that seems so basic now.
Hemophilia, a genetic disease was first observed to affect certain families by an Arabian Physician in 1000 CE by the name of Al-Tasrif.
Modern genetics centered around molecules known as DNA was developed in 1910 when American Thomas Hunt Morgan showed that chromosomes had specific segments known as genes. Today we know that all genetic material is held by the DNA molecule.
The DNA molecule is like a special recipe that contains the requirements for different dishes. The dishes are the proteins that form the buffet that is the cell. Each protein has its specific function in the cell and gives each and every cell its unique features.
Reproduction is a process that allows parents to pass characteristics to another generation. Genetics is the reason behind the similarities parents and offspring have physically and even psychologically. The environment also has an influence on the genes that are shown physically in an individual. In the 9th century, Al-Tasrif made consideration of the role of the environment in having animals survive.
By 1944 scientists were closing in on the structure of DNA. Many experiments had already found that the constituents of the cell center had deoxyribonucleic acid in it. Chemistry in the 1940s was not developed as it is now but at that time we (as a species) had already started playing around with deeper subatomic particles when compared with chromosomes and genes.
Avery–MacLeod–McCarty experiment was performed by Oswald Avery, Colin MacLeod, and Maclyn McCarty in 1944. In this experiment, they were able to isolate DNA as the genetic material but named it the transforming principle.
James Watson (alive) Francis Crick (1916-2004) and Rosalinda Franklin (1920-1958) were the ones who developed the structure of DNA as a double helix. When genetics is discussed it is never fully described without including its basic structure.
The DNA is described as a helix structure and is usually bound to another DNA comprising of nucleic acid.
The DNA replicates in cell division and the cell so formed after the division has the same DNA as the formal cell that gave rise to them.
Gregor Mendel lived from 1856 to 1865 before the development of all the theories and experiments known about genetics he made experiments using the pea plant Pisum sativum studying its pattern of inheritance.
He found that genotypes (the genetic make of an individual) and phenotype (the physical make of the individual) were predictable and that some traits took preference over the other in physical presentation. These traits that take preference are called dominant traits. He applied statistics to inheritance and demonstrated that this was possible. He disputed the hypothesis that comprised the blending theory that floated in the 19th century.
Taking a look at the chromosome, it is a coiled mess, but it has segments that are the recipes for the proteins. Organisms have up to 100,000 gene segments that code for different proteins with their specific functions in the cell.
By the 19 century when Mendel made those theories, it was already established that genes are the unit of heredity. The genes in every daughter cell are derived from its mother cell. If they have the same genes it means they will have the same proteins and will function the same way.
That is why bacteria with a flagellum (long whip-like structure for movement) will give rise to bacterium exactly like it and its flagella will perform the same basic function.
For physical traits that have variabilities like eye color or the features Gregory Mendel studied, the same physical traits can have different presentations. Using eye color as an example, people have brown or blue eyes. One-color can come from the mother and the other from the father. One individual can have both of these alleles or one of them. They are also determined by a mixture of different genes. The environment as found by Al-Tasrif also affects these traits.
With a light microscope, it is possible to see chromosomes found by scientists in the 19th century. Chromosomes were was first recognized by Walther Flemming. During cell division, the chromosome is formed and its number is constant for every species. Humans have 46, the African Rhinosrus has up to 84 and the male Australian ant has only 2 chromosomes.
The latest development in the world of genetics has been the CRISPR-Cas protein. In the years of its existence, it has revolutionized the way we see genetics and even other fields like evolution. These tools can change the information on a gene and can alter genetic traits.
In an article I read recently by @hadji, he described how this would one day be used to make extinct animals. The medical community is also excited about the prospect of this biotechnology.
Humans have come a long way from the invention of the microscope and simple observations made in genetics and we might be making extinct animals soon. With Jurassic park not too far away from us, the question on my mind is what will be the next advancement after this?