Evolution, What is Chognogeny (part – 2)

Chognogeny (Nature of primitive life and its Evolution)continued selection of more successful eobionts accompanied with the formation of first cell. Earliest cells were called anaerobic prokaryotic, & chemo heterotrophic.

They derive nutrition (organic compound) from Seas. So these cells grew to enormous size. To restrict their size chemoheterotrophs started cell mitosis and so increased their number. Some of chemoheterotrophs shows modification to form chemoautotroph. These started to synthesizing their own organic food from inorganic Compounds in presence of chemical energy and enzymes e.g. sulphate Reducing bacteria etc. Main force for this kind of evolution was proposed to be of mutation.

First photoautotrophs were anoxygenc as these did not use water as a raw Material in photosynthesis. Later these developed true chlorophyll & started using the water as a reagent so O2 was evolved in process Of photosynthesis.

First oxygenic and aerobic photoautotrophic were the cyanobacteria that believed to evolve about 3500 million years ago. Only forms of life on the earth were bacteria, moulds and cyanobacteria. Gradually blue green algae evolved into other forms of algae. It is Estimated that eukaryotes developed around 1600 million years back, they evolved from either mutation in prokaryotes or symbiotic association of different prokaryotes. Later many algae protozoans and other living Organisms were developed.

Evolution What is Chemogenic Evolution (Part – 2)

  1. Chemogenic Evolution Condition on primitive earth about4-billion year ago was such which Favored chemical evolution. Where temperature is too much high and atmosphere had nitrogen in the form of ammonia, carbon in form of methane and oxygen in the form of water vapors (H2o) but there was no free oxygen so the primitive atmosphere was reducing. These Compounds were called protoplasmic compounds. As earth cooled down, it developed a solid crust which later formed Depressions and elevations. Atmospheric vapors condensed and finally came to surface as rain Thus ocean form.

Haldane proposed that these Simple organic compounds gradually accumulated in water bodies and finally thin hot soup or broth was formed. This set the stage for the chemical reaction. Oparin and Sydney Fox proposed that complex organic compounds Synthesized abiogenetically on primitive earth later accumulate and Formed large colloidal cell like aggregates called probionts.

This form of life probably originated 3-billion years back. These would have giant molecules containing RNA-protein polysaccharides etc. these maintain an internal environment. But their main drawback was that they were unable to reproduce. These microscopic structures were called Coacervates