Genes are the ones to blame!

The bell rang for morning assembly and all the kids in Chinu's class aligned in line and marched to the school ground. Chinu, being the tallest one in the class, always had to stand at the very end of the line in the class. He despised that because his best friend Shaii was shorter than him and had to stand ahead in the line.

And so, after school, Shaii and Chinu sit and try to find ways to stand together in the morning assembly. But they couldn't think of any. Finally, throwing his hands up, Shaii cries, "Why do we have different heights though? Why can't all the students in our class have the same height?". 

Chinu starts to ponder and says, "We all are of the same age, but we have different heights, complexions, body weights, and everything except that we all share the common human anatomy." 

Shaii says, "Yes, don't you know, we look like our parents? My parents are short and so am I. It seems like it was predetermined for us to look a certain way." 

Chinu's eyes shine as he says, "As if something is controlling it. Is it our brain that controls how we look like? I heard the brain is where all the processing of information happens."

School children showing the phenotypic variations. Source: Pinterest

Shaii and Chinu, now in deep contemplation, even ignored Shweta when she offered them ice cream. They both sat with their arms and legs crossed and looked determined that whatever is controlling the emergence of varying forms of life will be discovered today. 

Shweta passes by again and asks them, "What are you both thinking today?"

Chinu narrates everything and asks her, "It is the brain, right?"

Shweta was surprised that the boys' quest to understand inheritance started by simply wanting to be together in the morning assembly. 

She continues, "One scientist who studied the garden pea back in the 19th century, Gregor Mendel, enlightened us all as to the factors responsible for how parents pass on their traits to their children. Later on, these factors were called genes. And after the discovery of various biomolecules, we were trying to identify the factor that Mendel talked about, that out of all the biomolecules, which is the one that is responsible for inheritance."

Shaii wonders what all these biomolecules might be and so he asks Shweta, "Didi, what all biomolecules may be related to inheritance?" No, wait. What is a biomolecule?"

Chinu jumps midway, "I guess molecules associated with living organisms or biological processes will be the biomolecules. Right, Shweta didi?" 

"Yes, Chinu." Replies Shweta. She continues, "These biomolecules are divided into four classes: lipids, proteins, nucleic acids, and carbohydrates. The nucleic acids are Deoxyribonucleic Acid or DNA and Ribonucleic acid or RNA." 

cartoon showing very basic structure of four major classes of biomolecules. Source: Pinterest

Chinu was wondering what the genes are and which biomolecule out of these four makes up the gene. He says, "So, out of all these, which are the genes made up of?"

Shweta says, "This is what scientists kept on pondering till 1952, as they remained confused about proteins being the genetic material. But then two marvelous scientists, Alfred Hershey and Martha Chase, while experimenting on viruses that infect bacteria, called bacteriophages, proved that DNA is the genetic material and not protein, contrary to the prevalent belief."

Shaii and Chinu looked at each other and smiled, enjoying their 'eureka' moment. They both shout, "So, it's the DNA!"

But then Shaii says, "Wait, but Mendel said it is the gene, responsible for the inheritance, but Hershey and Chase proved that it is DNA. So, is it DNA or the genes?"

Shweta smiles, as it brought back memories of being confused about the same concept of genetics in her school days. And she says, "See, DNA is a long polymer, of three units consisting of its monomer which is present in the nucleus of a cell, coiled in the form of chromatin. The DNA codes for another type of nucleic acid called RNA, and this RNA is a messenger molecule that converts the information contained in DNA to proteins. These proteins now govern the way our body will function. This is called the Central Dogma of life. Francis Crick and James Watson proposed it in the mid-20th century. So, the parts of DNA that encode the formation of the product are the genes. We all have a majority of the same DNA, that's why we all grow four limbs, one nose, one stomach, one pair of eyes, and so on. But the DNA still varies in some amount, and these variations in genotype which is the genetic constitution of an organism cause us to have variations in our phenotype which is the observable properties of an organism that are produced by the interaction of the genotype and the environment." 

The DNA present in the nucleus of a cell in the form of chromatin, which organises itself as chromosome during cell division. The picture also shows the coding parts of DNA, called genes, making the final product, the proteins. Source: Pinterest  

Chinu says, "So, DNA has parts that code for a product and these parts of DNA are genes. Genes determine how we look. Right?"

Shaii asks, "But if the genes are inherited from our parents then we should look exactly like them, but we don't. Why?"

Shweta was impressed by the boy's question, as they were heading in the right direction to find an answer to the fundamental questions of life. She continues, "Firstly, yes, Chinu, you're correct. And Secondly, Shaii, this is a wonderful question. You know we don't get the same copies of our parents' DNA. During the copying and fusion of DNA from both parents, few errors occur, leading to a combination of genetic material unique to each individual. And this is a topic to be discussed some other day, in-depth, that what happens at molecular level giving us a unique DNA, after fusion of our parent's DNA." 

Shaii, satisfied with the answer, tells Chinu, "So, it's all the work of genes, mate, we gotta cherish how unique we all are but still we are made up of the same biomolecules." 

And that's how the boys learned to accept the way they looked, without any more comparisons. 

In essence, we are all made up of the same atoms, even inanimate objects. This is the beauty of life. Every matter in this universe shares in common, at the most fundamental level the basic building blocks. Our distinguishing features are the patterns of arrangement, and wonderful combinations, giving rise to fascinating existing forms. And that's how we are all united. We are all ONE.