Did Life On Earth Come From Outer Space?

image 1 : The never ending universe (Image taken from phobia.wikia.org)

The theory as to how the first cell came into existence is still debated by many scientists. But there are few ideas far more prominent and accepted than the others. It’s really interesting to think about, how out of possibly no living or biological matter, an extremely complicated structure like the cell came to be, and later on how it evolved to form this even more complex structure known as the human body and all its systems.

Recent discoveries and studies show that meteorites and extraterrestrial objects contain particles that are essential for the formation of nucleic acids. So, it’s entirely and most probably possible that life originated from somewhere in outer space, and that we are not alone in the entire vast universe.

Coming back to the formation of the first cell, theory has it that nucleic acids were created by some sort of chemical reaction involving the basic elements such as amino acids to make proteins, phosphates and sugars. Thus, the first mRNA was formed, and by repeated division, the first prokaryotic cell was created.

Image 2 : A prokaryotic cell

A prokaryotic cell is basically a less evolved, primitive type of cell. It differs from eukaryotic aka modern cells in a few crucial ways. For instance, it doesn’t have a nucleus, instead it’s genetic material floats around in the cytoplasm. Another difference is the absence of mitochondria.

Over years of evolution, by a process known as endosymbiosis, prokaryotes evolved into the modern day cell. Endosymbiosis is a relatively simple process.

Image 3 : Endosymbiosis process (Image taken from ib.bio.ninja.com.au)

An extremely vital part of an eukaryotic cell is the nucleus. A prokaryotic cell has the genetic material that is enclosed within the cell, but it doesn’t have the nuclear membrane to bind it. So, in endosymbiosis (refer to image 3), as the first step, the plasma membrane which surrounds the cell, gets folded inwards. Basically, these narrow ridges form which lead all the way towards the genetic material. From there, the folded membrane gets cut off, to form the nuclear membrane. Thus, giving the cell a distinct nucleus. Now, since a prokaryotic cell doesn’t have a mitochondria, it cannot produce its own energy. Instead, it engulfs little aerobic bacteria. But sometimes, instead of getting digested, the bacteria remains intact inside the cell. These bacteria, over a period of time, get modified into a sort of primal form of organelles such as mitochondria and chloroplasts.

And thus, the modern aka eukaryotic cell was formed. Simple right?

From here, you probably know – multiple cells join to form tissues, tissues form organs, organs form organ systems, and organ systems form the organism.

Image 4 : Organization of organisms.

This is how life on Earth came to be… at least according to theory. Whether it is true or not is a question that may actually remain unanswered for all of eternity.

Pranav Karthik, Grade 11 student