If asked, what is life or who are you, we generally reply philosophically, without even caring or respecting the fact that whatever we are is a result of a very long process, which is initiated by a smallest macro molecule you can imagine! We are what our DNA is, what every single information on that DNA.
We all know what a DNA is, at some point in our life we’ve heard of DNA and basically have idea of what it does. But ever wondered how it does, whatever it does? DNA has, something called Base pairs, also known as building blocks of DNA. There are four types of base pairs, Adenine (A), Guanine (G), Cytosine (C), and Thymine (T). What DNA actually does it, in simple words, transfers these base pairs so that they can form amino acids. And how does that take place?
It’s called the Central Dogma, which describes the molecular flow of genetic information. DNA has all the genetic information, the blue prints. So let’s call our DNA, an Engineer who knows what and how to make it! But, the engineer doesn’t go to the field and make the structure himself. He just directs the worker to do it, he never leaves his office. Why? You may ask, well in this case, if the DNA leaves its home, which we called Nucleus, it might as well get damaged because of various chemicals that are present the cytoplasm which is the outside of Nucleus! So he sends the message to an RNA, his worker so that the RNA will carry it to the outside, but again RNA doesn’t do the work, he is just the messenger, so again he translates our engineer’s message to amino acids, which are our builders and finally when they receive the message they build whatever they are asked to build, since they’ve received the blue prints from the engineer.
What does the blue print have?
Well, as I’ve mention before, what DNA has is base pairs, A T G C and since I just mentioned them and didn’t explain what they do. So here’s the part where they come. When we say, DNA is the blue print, what we mean is DNA has codes, Genetic Code, the codes are in the form of base pairs, ATGC and what our Engineer does is, transcribes those codes to RNA, while doing so replacing T or Thymine with Uracil, because instead of T from DNA, RNA has U, or Uracil. So, if DNA sends the code as ATG, it becomes AUG in RNA, and when RNA translates it to code for methionine which is an amino acid. Amino acids are building blocks of proteins!! So in this way various amino acids are coded and in the end proteins are formed in Ribosomes in accordance with the Central Dogma!!
This is what it looks like!
What if the Codes are lost in the between?
Well, when Engineer sends for the his worker to take the blue print to the builders, sometimes, on the road, he might lose some files, data’s or sometimes something written with pencil could be erased. Then, what happens is the code is changed and if the Blue print said, The door should be facing north, it might now face south.
For eg. AUG codes for Methionine, but if the G is replaced by another A then it will code for the Amino acid Isoleucine.
Lets say the code was AUGA in a sequence of AUGAAUCGGCA etc.. but the base that was coded was AUG, and the 3rd one the G is deleted on its way and A comes after U. So, the code which was meant to code for Methionine ends up coding for Isoleucine.
Methionine is a sulfur-containing essential amino acid that plays a crucial role in metabolism and growth, where as function of isoleucine is proteinogenesis in the body, which means it is a building block for the proteins your body cells make. So metabolic part is hampered and such events are termed as Mutation.
So, if you’re reading this and you don’t have much problem then you’re perfect because if you weren’t then you’d not be here right now! Because there are 3 billion base pairs in humans and even if one of them went missing or deleted or replaced then you might have some trouble, at times major, so consider yourself lucky!
And, that is how DNA works, now moving on to rest of the part.
How is DNA transferred from one person to another? Well I shouldn’t go into much detail of that should I ? haha!
But anyways, another important thing is, Chromosome, we always heard that as well right? And, that we have 23 pairs or 46 chromosomes. In every part of our body, the cell division results in formation of same number of chromosome. But in case of sex cells, the number is reduced to 23! Why?
Because the next set of 23 comes from your partner!
So, here’s a recap!
The 46 chromosome that you have came from you parents! 23 from your father, 23 from your mother! You were made up of 46 Chromosomes. And your sperms are made up of only 23, and when they fuse with your partner’s ova, which again has 23, your offspring or for the time being, Zygote again has 46!!
Lets get into detail, you have 46 chromosome, now they have to be 23, but how are they selected? I mean which 23 out of 46 goes into your sperm?
Lets say, there are 23 volumes of Book in a Library, a book called Chromosomes, with 23 volumes of it! There are two books for each volume, one black another brown. Lets say that book volume no. 12 has the blue print for making an eye! Volume 12 A makes Black eye and Volume 12 B has blue print for Green eyes! So, there’s a fight between those books, to decide which gets to be on top, in this case, with our normal frequency the black one wins, because green is a recessive character. In this way the 23 chromosomes are selected out of 46 which can be divided into two 23-23 chromosomes coding for the same thing! And if, one of the volume is lost, you’re in trouble and if one volume is added more, or there are 24 volumes in display, you have Down’s syndrome! Haha! See how important your life is?
Now, to the final part! The sperm with blue print, with 23 pairs of chromosomes which has the base pair sequence or blue prints travels or swims to reach the ova! Fuses to for the Egg! And then when the Sperm fertilizes the eggs, it becomes the zygote and it starts to divide into various cells and organs!
Btw another interesting thing is that, the formation of various organs work as per induction, i.e. presence of one tissue influences the development of others. Eg,
If the ureteric bud fails to arise from the mesonephric duct the metanephros will not be induced to form a kidney, and such complication results in death and if not death, abnormal conditions which will cause big problem once born! And this is just one example! There are thousands of such complications! And if you don’t have any, you are perfect, you’ve gone through such a complicated process and everything was perfect, with out perfection you’d not be here!
This is just a brief explanation and if I were to get down to all of it, it would make a book! Just the brief one has almost got me to my 7th page haha!
Anyways life is complex important process and fucking important! Don’t waste it!