chemical evolution and biological origin of life

describe about evolutionary process of life through chemical and biological

1. Chemical & Biological Origin of Life BY- UTTARAN MODHUKALYA 1

2. CONTENT Introduction Chemical evolution Biological evolution SUMMARY OF THE ORIGIN OF LIFE REFERANCE CONCLUSION 2

3. INTRODUCTION No one knows exactly when and how life first appear on the earth. Different hypothesis and theories have been put forwarded concerning the origin of life by the modern as well as the earlier scientist. In the past it was believed that the presence forms of plants and animals have been their from the beginning of earth and would continued to exist. 3

4. Chemical evolution The Atomic Phase :Early earth had innumerable atoms of all those elements. e.g, hydrogen, carbon, nitrogen sulpher, phosphorus etc. Which are essential for formation of protoplasm. Formation of inorganic molecule : Free atom combine and form H 2 , N 2 ,H 2 O,CH 4 ,NH 3 ,CO 2 . Hydrogen is most numerous and reactive in primitive atmosphere and it combine with oxygen, nitrogen etc. 4

5. Chemical evolution Formation of simple organic molecule(monomer) : The inorganic molecule interacted and produced simple organic molecule such as Simple sugar (ribose, deoxyribose, glucose etc), Nitrogenous base (purine, pyrimidines), amino acid, glycerol , fatty acid etc. Stanley Miller in 1953 demonstrated it clearly that ultraviolet radiation or electrical discharge or heat or a combination of these can produce complex organic compounds from a mixture of methane, ammonia, hydrogen and water vapour . The ration of methane, ammonia, hydrogen is 2:2:1 respectively. 5

6. Water vapor Condensed liquid with complex, organic molecules Condenser Mixture of gases ("primitive atmosphere") Heated water ("ocean") Electrodes discharge sparks (lightning simulation) Water Origin of Organic Molecules * Abiotic synthesis 1920 Oparin & Haldane propose reducing atmosphere hypothesis 1953 Miller & Urey test hypothesis formed organic compounds amino acids adenine CH 4 NH 3 H 2 6

7. Stanley Miller University of Chicago Produced - 1. amino acids 2.hydrocarbons 3.nitrogen bases 4.other organics 7

8. Chemical evolution Formation of complex organic molecule(macromolecule) :A variety of amino acid, fatty acid, hydrocarbon, purine and pyrimidines bases, simple sugar and other organic compounds accumulated in the ancient seas. In the primeval atmosphere electrical discharge, lightning, solar energy, ATP and polyphosphates might have provided the source of energy for polymerization reactions of organic synthesis. S.W. Fox demonstrated that if a nearly dry mixture of amino acid is heated then polypeptide molecules are forms. Similarly simple sugars could form polysaccharide, nucleotide can form DNA, RNA, fatty acid can form fats etc. 8

9. Chemical evolution 9

10. BIOLOGICAL EVOLUTION As a result of chemical evolution various macromolecules and nucleoproteins were found which remained dissolved in ocean . The various molecules form some colloidal masses as insoluble droplets. These droplets aggregate to form a large colloidal system called coacervates and Fox’s microspheres which posses some of the basic prerequisites of protocells. A] Coacervates : It can selectively absorb chemicals from the surrounding water and incorporate them into their structure. These nonliving structure that led to the formation of the first living cells from which the more complex cells have today evolved. Oparin speculated that a protocell consisted a carbohydrates, proteins, lipids and nucleic acids that accumulated to form a coacervate. B] Microspheres : It is a nonliving collection of organic macromolecules with double layered outer boundary. It is formed by proteinoides(protein like structure consist of branched chains of amino acids). Microspheres swells or shrink depending on the osmotic potential in the surrounding solution. Using ATP, microsphere can from polypeptide and nucleic acid and can absorb material from the surrounding medium. 10

11. BIOLOGICAL EVOLUTION Origin of prokaryotes : It was originated from protocell about 3.5 billion years ago in the sea. The atmosphere was anaerobic due to absence of oxygen. It is absence of nuclear membrane, cytoskeleton. Mode of nutrition : A] heterotrophs : The earliest prokaryotes presumbly obtained energy by the fermentation of organic molecules from the sea. B] Autotrophs : They can produce their own food by chemosynthesis C] Chemoautotrophs : It prepared organic food by using energy released during certain inorganic chemical reaction. D] Photoautotrophs : Evolution of chlorophyll molecule enabled certain protocells to utilize light energy and synthesize carbohydrate and they were anaerobic photoautotrophs . 11

12. BIOLOGICAL EVOLUTION Oxygen revolution and ozone layer formation : As the no. of Photoautotrophs increase oxygen release in the sea and atmosphere the reaction occur given below- CH4+ 2 O2 CO2+ 2 H2O 4 NH3+ 3 O2 2 N2+ 6 H2O As oxygen accumulated in the atmosphere, the ultraviolet light changed some of oxygen into ozone. The ozone formed a layer in the atmosphere, blocking the ultraviolet light and leaving the visible light as the main source of energy. 2 O2+O2 2 O3 12

13. BIOLOGICAL EVOLUTION Origin of eukaryotes : Eukaryotes developed from primitive prokaryotic cells about 1.5 billion years ago. Two types of view regarding in the origin of eukaryotes- A] Symbiotic origin : Some anaerobic predator host cells engulfed primitive aerobic bacteria but did not digest them. These aerobic bacteria established themselves inside the host cells as symbionts. Such predator host cells became the first eukaryotic cells. Animal cells are only engulfed the aerobic bacteria by predator host cell. But in case of plant eukaryotic cell the predator engulf both the aerobic bacteria and blue green algae. B] Origin by invagination : The cell organelles of eukaryotic cells might have originated by invagination of surface membrane of primitive prokaryotic cells. 13

14. BIOLOGICAL EVOLUTION infolding of the plasma membrane DNA cell wall plasma membrane Prokaryotic cell Prokaryotic ancestor of eukaryotic cells Eukaryotic cell Endoplasmic reticulum nuclear envelope Nucleus plasma membrane 14

15. Origin of plant and animal cell 15 Eukaryotic cell with mitochondrion photosynthetic bacterium Endosymbiosis Eukaryotic cell with chloroplast & mitochondrion chloroplast mitochondrion internal membrane system aerobic bacterium mitochondrion Fig: Symbiosis origin of eukaryotic cells

16. Origin of multicellular organism Once the unicellular organisms were developed the cells could gather to form colonies. Later cell differentiation occurred to form the multicellular organisms. The latter gave rise to all the different forms of life by gradual modification over the ages. The advantage of multicellularity is based on division of labour between the component cells. First multicellular organism was algae formed in 1.5 b.y.a. .After “snowball earth”(long ice age), the Cambrian explotion occurred creating all the phyla that currently exist and 1 st predator-prey interaction. 16

17. SUMMARY OF THE ORIGIN OF LIFE 17

18. REFERENCE TRUEMAN ELEMENTARY BIOLOGY EXPLORING BIOLOGY INTERNET OUR RESPECTED TEACHER’S NOTE A BOOK OF LIFE SCIENCE WIKIPEDIA A BOOK OF EVOLUTION 18

19. CONCLUSION From the above discussion we can concluded that in case of origin of life, first inorganic atoms are combines and form inorganic molecule. After that forms the organic molecule and later forms the proto cell. The proto cell then develops into the prokaryotic cell and by engulfing of bacteria forms the eukaryotic cells are form. i.e , firstly chemical evolution and then biological evolution is occur. 19

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