Before getting deep into something, we must know the basics. Here we go with some basic questions and their answers.
Question number 1: What are the three major domains of Biological system?
Prokaryotes ; Archaea ; Eukaryotes
Prokaryotes: Example: Bacteria
They lack true nucleus. They have cell wall. They lack membrane bound organelles.
The bacteria which is used mostly are Escherchia coli (E.coli)
Eukaryotes: Example: "WE" - Homo sapiens (Humans)
The eukaryotes are well developed, multicellular. They do not have cell wall (but plants do have, there are certain exceptions). They have well developed nucleus, membrane bound organelles.
Archaea: (False bacteria)
They survive extreme conditions (extremophiles). They were isolated even from volcanic hot springs, imagine, how good they are in surviving extreme conditions. They look similar to bacteria but their metabolic pathways and genes are closely related to eukaryotes.
Question Number 2: Why eukaryotes don't have cell wall? While prokaryotes do?
Prokaryotes are just single cells, there is no need for them to contact or transfer molecules between other cells (but, they do during reproduction, generally not needed). They need not interact with neighboring cells to form tissues.
But, Eukaryotes, they have to interact to form tissues and further organs. That's why, for interaction, Eukaryotes don't have rigid cell wall!
Question number 3: Who discovered Structure of DNA?
I was thinking, it was James Dewey Watson and Francis Crick, but, two others also contributed, they were Maurice Wilkins and Rosalind Franklin. But, Watson, Crick and Wilkins were only awarded with nobel prize because, Franklin died before that due to cancer.
This discovery of DNA structure was the starting for genetic engineering.
Bye Bye! :)