how do living organism came on to earth?

Asked by Abhilash | 9th Jan, 2013, 07:01: PM

Expert Answer:

There is no conclusive proof to establish the way life first originated on Earth. Different scientists have proposed various theories.
The most widespread theory is that expressed in 1953 by the Nobel prize winning chemist Harold Urey and his student Stanley Miller. They proposed that some four billion years ago the first living cell arose out of the primordial soup of amino-acids and other simple molecules. 
According to them, life arose spontaneously in an early atmosphere of methane, ammonia, and other chemicals, activated by lightning. Further chemical reactions would permit the simple compounds of life to develop into increasingly complex molecules, eventually producing the DNA double helix, or the single stranded RNA, both of which possess the power of reproduction.
Eventually some of the large chemicals joined together and became the forerunners of the first cells.
The first cells were probabaly heterotrophs that used the chemicals in their surroundings for energy.

Answered by  | 13th Jan, 2013, 08:57: PM

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