How Eukaryote Cells Came into Life Essay Example | Topics and Well Written Essays - 1500 words

How Eukaryote Cells Came into Life - Essay Example Prokaryotes had been first found around 3.5 billion years, which is just a billion years following the formation of the earth’s crust. Till today these life forms remain to be the most profuse ones, and since they have a very varied metabolism as compared to the eukaryotes, we can find a great many kinds of prokaryotic types. Since eukaryotic cells comprise of a huge majority of multi-cellular organisms and other complex cells, their origin has been considered a great highlight in the evolution of life. It is not really possible to determine when exactly these cells came into existence but according to Knoll (2006) it was around 1.6 – 2.1 billion years ago that eukaryotic cells took form. Certain acritarchs have been said to have originated 1650 million years ago and Grypania is an alga that was probably discovered to be approximately 2100 million years back. Besides this, it is the opinion of biomarkers that stem eukaryotes had come into being even before this and, as an example, steranes were found to be present in Australian shales almost 2.7 billion years ago. In 1966 the endosymbiosis theory was proposed by Lynn Margulis and he said that the prokaryotic cells and the initial eukaryotic cells lived together. At the beginning there was much hesitation in the acceptance of this theory. Eukaryote cells are more complicated and are set inside membranes while prokaryote cells do not have any membrane bound organelle. Another difference between these two cells is that eukaryotes have a cell nucleus while prokaryotes do not. This nucleus contains the DNA of the cell. Secondly, the size of eukaryotes is bigger as in the width and thus the volume is also more as compared to the prokaryotes. Chromosomes are present in eukaryotes which are actually where the DNA is. The movement of eukaryotes are controlled by motile cilia, also called flagella; and the flagella of eukaryotes are quite simple as compared to those in prokaryotes. Besides this, eukaryotes are like prokaryotes in respect to the plasma membrane and its function, but there is slight difference in the setup. Symbiosis as a mutually beneficial relationship happens when there are two species living together or closely for very long durations. This association is actually known as symbiotic, the word meaning to live together. Now there are different kinds of such a relationship and one is mutualism in which both the species get something out of the relationship. A very common example is that between plants and fungi. MAIN BODY Eukaryotes have been explained through various ways. An attempt has been made to explain the origin of these cells through the endosymbiotic theory as well, which was first proposed in 1905. This theory is basically concerned with the mitochondria, plastids and similar other organelles of the eukaryotes. This theory proposes that there were some specific kinds of organelles which actually came into being as free living bacteria. These were then taken within another cell as endosymbionts. Thus took place the development of cells and proteobacteria resulted in mitochondria while cyanobacteria lead to chloroplasts. In 1966 this theory was again proposed by Lynn Margulis and he said that the prokaryotic cells and the initial eukaryotic cells lived together. At the beginning there was much hesitation in the acceptance of this theory. Eukaryotes have double membranes around them. Within these membrane-bound compartments take place certain metabolic activities. As