CHAPTER 5: ORIGIN AND EVOLUTION OF LIFE

Q. 23: Describe microsphere theory of Sydney fox?

Ans.: 1) Sydney Fox (1959) after studying coacervates prebiotic atmosphere in laboratory.

2) He heated amino acids which polymerized into portends which are similar to proteins.

3) These aggregated into spherical colloidal droplets called microspheres.

4) Thus, it can be concluded that microspheres are fore runners of life form on earth.

Q. 24: Describe Miller’s experiment with conclusion and significance.

Ans.: 1) Stanley Miller and Harold very conducted an experiment in the laboratory which provides first experimental evidence in support of Oparin’s theory of chemical evolution.

2) As a part of their experiment they designed an apparatus and simulated pre biotic atmosphere.

3) The experiment can be explained as under:

a) In the experimental set up they used spark discharge glass apparatus of closed type with tungsten electrodes inserted into it.

b) The apparatus was consisting of large spark discharge glass chamber, with electrodes, flask for boiling water, side tube connected to a pump (vacuumed) cooling jacket and a U-trap.

c) Apparatus was evacuated to make it sterile.

d) Flask is filled with water partially and the, NH3 & H2 in the ratio 2:1:2 were added respectively at O.C. It created prebiotic atmosphere.

e) Then water was allowed to boil at low temp to provide vapour for the reaction.

f) This entire broth was then circulated continuously through the high electric spark of 75000 volts, for several days. (Simulating lightening), causing gases to interact.

g) These gases were then passed though condenses to form liquid. Which was collected at bottom.

4) Observation: The trapped content at the bottom was mixture of simple organic compounds specially sugars and amino acids.

5) Significance: Using a spark discharge apparatus, they demonstrated the formation of amino acids, sugars and other simple organic compounds by recreating the conditions that might have prevailed on the primitive earth in the laboratory.

6) Conclusion: The experiment provided the vital proof that the essential building blocks for the first living organism could have been formed on primordial earth. The synthesis of first protein was probably no enzymatic.