Explain Oparin-Haldane theory of chemical evolution of life.
Class XII
Evolution
Answers
This theory is the most accepted theory and was given by a Russian biochemist A.L. Oparin(1923) & an English biologist J.B.S. Haldane(1928). According to this theory, spontaneous generation of life under present day conditions is not possible. When the earth was formed 4.6 billion years ago, that time its atmosphere was very much different from that of today. That time it was reducing atmosphere & consisted of H2, water vapours(H2O), NH3 and methane. It is called Primary Atmosphere. Temp of the earth was very high & a lot of energy was available from solar radiations, UV rays(ozone shield absent), electric discharges, volcanic eruptions and cosmic rays were frequent. Such an Atmosphere where 1 right type of chemicals were present 2 Oxygen was absent 3 Lots of energy sources were available was required for the formation of earth. It is believed that before the origin of life first there was a long chain of evolution of chemicals. then these chemicals gave rise to organisms. This formation of living organisms from the non- living organisms is known as abiogenesis. The evolution of chemicals & the abiogenesis has taken place in the following ways:
a) Formation of early Molecules: As the earth cooled, free atoms of different elements came together at random & formed inorganic molecules. The earliest molecules formed by reactions between these elements were gases likeH2, NH3, H2O(water vapours), CH4, CO, CO2.
b) Formation of simple organic molecules: The early molecules reacted with one another to form simple organic molecules e.g sugars, fatty acids, glycerols, amino acids, purines, and pyrimidines. All the organic molecules got collected in the sea water and continued to stay there.
Answer:
Question
Answers
Related Questions
What is Oparin Haldane theory? Can life be originated abiotically inside the laboratory today?
Answer
VerifiedVerified
119.1k+ views
14.3k+ likes
Hint: The modern theory is also known as a chemical theory or naturalistic theory or primary abiogenesis or Oparin Haldane theory. The idea of abiogenesis is life always comes from preexisting life.
Complete Answer:
Oparin and Haldane held that spontaneous generation of life under the environmental conditions is not possible. Earth’s surface and atmosphere during the first billion years of its existence were radically different from today’s condition.
Earth’s initial atmosphere was a reducing one. The first life arose from a collection of chemicals through a progressive series of chemical reactions in which atoms combine into inorganic molecules, inorganic molecules into simple organic compounds, simple organic compounds into complex organic compounds, polymers into aggregates, which finally got organized into living matter.
Several organic molecules like polypeptides, polysaccharides, polynucleotides, and fats gathered to form a coacervate. These coacervates were capable of dividing by budding. A layer of water and fats surrounded them. They were present in hot seawater, which provided conditions for their metabolism. This led to the appearance of the first cell. This abiogenesis occurred about 4 billion years ago. Solar radiation, heat radiated by earth, and lightning provided energy for the evolution of molecules.
Since a lot is known about the metabolic processes today, life can be created in the lab. Urey and Miller successfully demonstrated the precipitation of a coacervate-like structure in their famous lightning experiment. Hence, life can be created in the lab today.