Modern theory of origin of life

Formation of simple inorganic chemical compound
At the beginning, the earth was very hot containing gases substance. At that time the substances are present in ionic form- cation & anion with the passes of time, earth was getting cooler slowly and gases ionic substances combine with each other to form element, light elements form gases atmosphere and remain in the upper part while heavier element settle in the form of hard crust of earth.
The atmosphere contains different gases like Hydrogen, Oxygen, Nitrogen, Sulphur etc. This element reacts or combine with each other forming simple inorganic compounds like water, carbon dioxide, carbon mono oxide, NO2, H2S etc. with the decreasing of earth temperature moisture or vapor condains and came as heavy rain which made depletion and elevation in the hot crust.
Rain water was collected in the depreation giving birth to sea and ocean. Water contain different inorganic chemical in dissolve state.
Formation of simple organic compound
With the decrease of earth temperature gradually, the simple inorganic compounds dissolve in sea water reactate with each other to form simple organic compound.
The heat required for the reaction provided by sun light with ultra violet rays, lighting & heat of the earth. The formation of simple organic compounds from inorganic compound was experimentally demonstrated by 2 scientist Urey and Miller. Their experiment is later called Urey-Miller experiment. This experiment was done in laboratory taking sterilized glass apparatus. They kept different chemicals like H, O, N, NH3, CO2, CO, H2S. In this apparatus, the apparatus was provided with rays from electrode and the apparatus also have heating and cooling system. This experiment was kept for 7 days. At the end they analysis the product and found simple organic compound like C6H12O6, ammonia acid, fatty acid, etc.
Formation of complex organic compound
When the earth was gradually cooling, the simple organic compounds present in the water of ocean react with each other ot form complex organic compound. The energy for the reaction is provided by heat of the earth and sunlight. Another scientist S.W. fox experimentally proved the formation of complex organic compound like carbohydrate, protein, fat, etc. from simple chemical compound C6H12O6, ammonia acid, fatty, etc.
Formation of molecular aggregate or coecercate
The complex organic compound present in the water were attracted each other with the help of molecular attraction force and formed a large unit. The unit thus form moves together and shows the increase in size and divisible into small unit. The unit containing large number of complex organic compound, molecular aggregate or coecercate. The water is thicken and also called organic shup. This coecercate started to achieve like living organism so, they were also called pre-cell or protobiont.
Formation of origin of first life

Coervate or prebiont, later developed into first life by evolution. First life was unicellular, microscopic and anaerobic. It took organic substances present in water as food. Therefore, they were also called ‘chemo-heterotrophs’. These organisms increased in number. They reproduce asexually by mitosis like cell division and exploited organic food present in water. Still anaerobic bacteria are found in the bottom of deep water bodies.
Development of chemosynthesis
When the population of chemo-heterotrophs was increase in large number, organic food present in water might have decrease and ocarsity of food occurred for them. Chemo-heterotrophs were later evolved into new type of unicellular organisms. These organisms could take simple organic and inorganic substances present in water and organized or synthesized their food inside the body. They were called ‘chemo-autotrophs’. Nitrogen fixing bacteria, iron bacteria, sulphur bacteria, nitritying bacteria are still found in earth.
Development of photosynthesis
When the population of ‘chemo-autotrophs’ was increased in large number, inorganic & simple organic substances present in the water might have decreases and ocarcity of food occurred for them. Chemo-autotrophs were later, evolved into new type of unicellular organisms. These organisms could make their food from the energy of sunlight and simple inorganic substance (that is CO2 & H2O). these could occur as they developed green chlorophyll in the body. These organisms was called ‘photo-autotrophs’. They proliferated in large numer as a raw material of food was never decreased. From it, advanced type of plant and animals developed later.