Oparin proposed that the 1st form of life could have come from pre- existing non- loving organic molecules ( RNA, protein) and that formation of life was preceded by chemical evolution. The conditions on earth were high temperature, volcanic storms, reducing atmospheric condition CH4, NH3 etc....

Miller, an american scientist created similar conditions in a laboratory scale. He created electric discharge in closed flask containing CH4, H2, NH3 & water vapour at 800°C. He observed the formation of amino acid.
The diagrammatic representation is give in the ATTACHMENT
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