Download the presentation of the hypothesis of the origin of life on earth. Basic hypotheses of the origin of life on earth

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2 mutually exclusive points of view

• Biogenesis – “living from living”
• Abiogenesis – “living from non-living”

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Creationism hypothesis

• Creationism (from the English creation - creation) - considers the emergence of life as a manifestation of the will of God. This is stated in the Bible and other holy books
• This theory was put forward by Archbishop Ussher in 1650

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• The creationism hypothesis is outside the field of scientific research (since it is irrefutable)
• It is impossible to prove by scientific methods both that God did not create life and that God created it)

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Spontaneous generation of life

The hypothesis of spontaneous generation was widespread in Egypt, Babylon, China, and also spread in the Middle Ages.

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Proponents of this hypothesis believed that living things could arise from non-living things with the help of some kind of “living force.”

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Francesco Redi

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Louis Pasteur

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Stationary state of life

• According to this hypothesis, the Earth never came into being, but existed forever; she always was
• Capable of supporting life, and if it changed, it was very slight.

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Panspermia hypothesis

In its basic form, the panspermia hypothesis was proclaimed by the German scientist G. Richter in 1865. In his opinion, life on Earth did not arise from inorganic substances, but was brought from other planets.

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Cosmic origin of life

However, questions immediately arose about how possible such a transfer of life from one planet to another was.

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• The authors of biochemical evolution are A.I. Oparin and D. Haldane.
• The transition from chemical evolution to biological evolution required the obligatory emergence of individual phase-separated systems capable of interacting with the surrounding environment.

Biochemical hypothesis

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Biochemical hypothesis

Coacervate droplets can be considered the most promising models in this hypothesis.

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1. The essence of abiogenesis consists in: a) the origin of living things from non-living things; b) the origin of living things from

living; c) the creation of the world by God; d) the bringing of life from Space.

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2. The experiments of Louis Pasteur proved the possibility of: a) spontaneous generation of life; b) the appearance of a living thing only

from living things; c) the introduction of “seeds of life” from Space; d) biochemical evolution.

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3. Of the listed conditions, the most important for the emergence of life is:

a) radioactivity; b) the presence of water; c) the presence of an energy source; d) the mass of the planet.

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4. The panspermia hypothesis implies: a) Divine creation of the worldb) cosmic generation

lifec) the emergence of life from coacervatesd) the stationary state of living things

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• Phenomenon of life.
• creationism;
• biogenesis hypothesis;
• panspermia hypothesis;
• Oparin-Haldane hypothesis;
• Bibliography.
• Origin of life on Earth

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What is life?

Life is a way of existence of protein bodies, and this way of existence consists essentially in the constant self-renewal of the chemical parts of these bodies.

Living bodies existing on Earth are open, self-regulating and self-reproducing systems built from biopolymers - proteins and nucleic acids

• F. Engels
• M.V.Volkenshtein

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Phenomenon of life

In the 20th century, numerous attempts were made to define life, reflecting the versatility of this process.

All definitions contained the following postulates reflecting the essence of life:

• life is a special form of movement of matter;
• life is the metabolism and energy in the body;
• life is vital activity in the body;
• life is self-reproduction in the body, which is ensured by the transfer of genetic information from generation to generation

Origin of life on Earth

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Theories of the origin of life on Earth

Creationism

• Vitalism (spontaneous generation)
• Panspermia
• Steady State Theory
• Biochemical evolution
• Biogenesis - the origin of living things from living things
• Abiogenesis – the origin of living things from non-living things

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Origin of life on Earth

Hypotheses about the origin of life on Earth

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Main hypotheses of the origin of life

• Creationism

Life arose as the result of a divine creative act.

Michelangelo Buanarroti: "The Creation of Adam"

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Spontaneous origin of life hypothesis

Living creatures can repeatedly appear from inanimate matter: fish from silt, worms from soil or meat, mice from rags, etc.

Ancient engravings: on the left - the transformation of fruits into fish and birds; on the right - into the ducks.

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Origin of life on Earth

Hypotheses about the origin of life on Earth

2. Biogenesis hypothesis

From ancient times to the middle of the 17th century. Scientists had no doubt about the possibility of the spontaneous origin of life. All living beings arise from nonliving matter:

• fish - from silt;
• worms - from the soil;
• mice - from rags;
• flies - from rotten meat;
• fruits are birds.

Aristotle, studying eels, found that they are born from “sausages of silt formed from the friction of adult fish on the bottom

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Biogenesis hypothesis

The first blow to the idea of ​​spontaneous generation came from the experiments of the Italian scientist Francesco Redi, who in 1668 proved the impossibility of spontaneous generation of flies in rotting meat.

However, it was only in 1862 that the French scientist Louis Pasteur finally refuted the hypothesis of the spontaneous generation of life. The works of L. Pasteur made it possible to assert that the principle “Every living thing is from living things” is valid for all known organisms on our planet, but they did not resolve the question of the origin of life

Louis Pasteur

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1862

Louis Pasteur

Pasteur conducts an experiment with boiled broth in a sealed flask from which an s-shaped tube was removed. The broth is sterile.

Pasteur removes the tube and after some time life appears in the broth

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Panspermia hypothesis

An alternative was the concept of panspermia, associated with the names of such outstanding scientists as G. Helmholtz, W. Thompson (Lord Kelvin), S. Arrhenius, V.I. Vernadsky. These researchers believed that life was as eternal and ubiquitous as matter, and its germs were constantly traveling through space; Arrhenius, in particular, proved through calculations the fundamental possibility of transferring bacterial spores from planet to planet under the influence of light pressure; It was also assumed that the substance of the Earth at the time of its formation from the gas and dust cloud was already “infected” with the “embryos of life” that were part of the latter.

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All attempts to discover living beings outside the Earth have not yielded positive results. Repeatedly appearing reports of the discovery of traces of life on meteorites are based either on the erroneous interpretation of some bacteria-like inorganic inclusions, or on the contamination of “heavenly stones” by terrestrial microorganisms.

In addition, the panspermia hypothesis does not solve the question of the origin of life in general, but only explains the emergence of life on Earth

Meteorite from Mars. NASA experts said that forms similar to bacteria were found in its cracks. However, after a thorough check, we found out that this is due to the method of electron microscopy and treatment of preparations with gold.

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Steady State Hypothesis

Earth and life have always existed, forever. Species have always existed, but they could become extinct or change in number.

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OPARIN-HALDAIN THEORY 1924-1928

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Stages of the emergence of life on the planet (according to Oparin):

• Living cell
• Protobionts
• Coacervates

Complex organic compounds (proteins, lipids, carbohydrates, nucleic acids)

Simple organic compounds (amino acids, sugars, etc.)

Simple inorganic compounds (H₂O, CO₂, N₂, NH₃), metal ions, mineral acids

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Geophysical stage

"Big Bang".

• Formation of the Solar System
• Formation of the Earth's shells

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• A set of conditions on the primordial Earth
• Quite high surface temperature of the planet
• Active volcanic activity
• Lightning electrical discharges
• Ultraviolet radiation
• The result of their influence
• Synthesis of organic substances from inorganic compounds occurring in an aqueous environment

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Abiogenic synthesis of organic compounds

• 1953 S. Miller and G. Ury synthesized organic compounds from inorganic ones under artificial conditions.
• Various organic compounds were formed in the aqueous phase: urea, lactic acid and some amino acids

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Theory of biochemical evolution

Conditions - the age of the Earth is 5-7 billion years, then on the surface of the Earth there is more than 4000°C, then the water in the primary atmosphere became less than 100°C and formed the World Ocean.

"Reducing" primary atmosphere: H2, NH3, CH4,CO2, H2O

1 – abiogenic synthesis; synthesis of biological monomers has been experimentally proven

2 – synthesis of biopolymers (nucleic acids, polypeptides, etc.), formation of coacervates

3 – reproduction of molecules based on template synthesis – RNAs self-replicate, have a tertiary structure, and have catalytic activity

4 – double-stranded DNA provides more accurate replication and repair

5 – appearance of coacervates covered with an outer membrane

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Evolution of probionts

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Scheme of the emergence of eukaryotesTheory of symbiogenesis

1. Ancestral prokaryotic cells

2. Pre-eukaryotic cell with a separate nucleus

3. Aerobic bacterium (mitochondrion precursor)

4. Cyanobacteria (chloroplast precursor)

6. Mitochondria

7. Chloroplast

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Biological stage

• Multicellular eukaryotes
• Colonial organisms
• Unicellular eukaryotes
• Prokaryotes Prokaryotes
• heterotrophs autotrophs
• Probionts
• Coacervates

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Disadvantages of the Oparin-Haldane hypothesis:

• how there was a qualitative leap from nonliving to living. The probability of random formation of a protein molecule, depending on the complexity of the protein, is approximately 10-500 – 10-300;
• Self-production of nucleic acids requires enzyme proteins, and protein synthesis requires nucleic acids.

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Modern ideas about the origin of life on Earth.

In 1947, the English scientist John Bernal formulated the hypothesis of biopoiesis. He identified three main stages in the formation of life: the abiogenic emergence of organic monomers (chemical), the formation of biological polymers (prebiological) and the emergence of the first organisms (biological)

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Biopoiesis hypothesis

• Stage of chemical evolution: abiogenic synthesis of organic monomers in the conditions of the primary atmosphere.
• Duration: many millions and hundreds of millions of years
• Biological stage of evolution:
• formation of diverse groups of living organisms
• Stage of prebiological evolution: polymerization reactions.
• The formation of a protein-nucleic acid complex (coacervates, hypercycles, probionts, progenotes) took place.

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Conclusion

• So, there are 5 main hypotheses about the origin of life on Earth. Each of them has its strengths and weaknesses, but none gives an accurate answer to the question of the origin of life.
• The most convincing hypothesis is biochemical evolution, but it will never be fully proven.

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Determine the correctness of judgments

1. Coacervates are the first living organisms on Earth.

2. The temperature of the Earth at the time of formation reached 1000˚C.

3. The composition of the primary atmosphere included gases: methane, ammonia, nitrogen, water vapor.

4. Coacervates are not able to absorb substances from the surrounding solution

5. At present, spontaneous generation of living organisms is impossible on Earth.

6. Condensation of water vapor began during the cooling period of the planet.

7. Coacervates are liquid bubbles surrounded by protein films.

8. The first living organisms on Earth were heterotrophs.

9. The formation of organic substances was facilitated by the absence of an ozone screen in the atmosphere.

10. The sequence of protein formation is ammonia  amines  amino acids  proteins.

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Bibliography

• Yablokov A.V., Yusufov A.G. Evolutionary doctrine (Darwinism): Textbook. for biol. specialist. universities – 3rd ed. – M.: Higher. school, 1989.
• Agapova O. V., Agapov V. I. Lectures on the concepts of modern natural science. University course. – Ryazan, 2000.
• Gorelov A. A. Concepts of modern natural science. – M.: Mysl, 1997.
• Concepts of modern natural science. Series "Textbooks and teaching aids". – Rostov n/d, 1997.
• Dubnischeva G.D. Concepts of modern natural science: Textbook. for students universities / Ed. M. F. Zhukova. – Novosibirsk: UKEA, 1997.
• Vernadsky V.I. The beginning and eternity of life. – M.: Republic, 1989.
• Selye G. From dream to discovery. – M., 1987. Pp. 32.
• Soviet encyclopedic dictionary. - M.: Sov. encyclopedia, 1982.
• Marx K. and Engels F., Soch., 2nd ed., vol. 20. M.: Mysl, 1965.
• "Biological picture of the world."

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• Alexander Ivanovich Oparin (Materials for the biobibliography of scientists of the USSR, series of biochemistry, issue 3). M.; L., 1949. P. 5.
• Oparin A.I. Life, its nature, origin and development. M., 1960. P. 12.
• Rudenko A.P. Evolutionary catalysis and the problem of the origin of life // Interaction of methods of natural sciences in the knowledge of life. M., 1976 P. 220.