The emergence of life. Presentation - the origin of life on earth Modern ideas about the origin of life on earth presentation
Slide 2
Lesson Objectives:
- To acquaint with the main hypotheses of the origin of life;
- Show how the views on the origin of life have changed with the accumulation of knowledge.
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Friedrich Engels
"Life is a way of existence of protein bodies, the essential moment of which is a constant exchange of substances with the external nature surrounding them, and with the termination of this metabolism, life also stops, which leads to the decomposition of protein"
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Hypotheses about the origin of life
- The origin of the living from the living
- The origin of the living from the non-living
- Abiogenesis
- Biogenesis
Slide 5
Aristotle
"Nature makes the transition from lifeless objects to animals with such a smooth sequence, placing between them creatures that live without being animals, that between neighboring groups, due to their close proximity, you can hardly notice the difference."
Slide 6
Spontaneous generation of Bernakel geese
This goose grows on fragments of a pine tree, rushing through the depths of the sea. Initially, it looks like a droplet of resin. It attaches with its beak to a tree and provides a hard shell for safety, in which it lives calmly and carefree. After a while, feathers grow on the goose, and then it descends from a piece of bark into the water and begins to swim. And one day it flaps its wings and flies away.
Slide 7
Van Helmont (1577-1644)
described how, in three weeks, he created mice.
All you need to do this is a dirty shirt, a dark wardrobe and a handful of wheat, and for the process to begin - human sweat.
Slide 8
Theophrastus Paracelsus
Homunculus recipe
“Take a well-known human liquid and leave it to rot first in a sealed pumpkin, then in a horse's stomach for forty days, until it begins to live, move and swarm, which is easy to notice. The result is not at all like a person, it is transparent and without a body. But if then daily, secretly and carefully, with prudence, nourish it with human blood and keep it for forty weeks in the constant and uniform warmth of a horse's stomach, then a real living child will occur, having all the limbs, like a child born of a woman, but only very vertically challenged».
Slide 9
Francesco Redi (1626-1698)
- conclusion: flies sit on rotting meat and lay larvae in it, as a result of which new flies are born.
- They are born, not appear by themselves.
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Joseph Needham (1713-1781)
Found bacteria in a tightly closed flask with meat broth using a microscope
CONCLUSION: Microorganisms can spontaneously generate
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Vitalism (from Latin vitalis - vital, life-giving, alive)
- "Life force" is present everywhere
- It is enough just to "breathe" it, and the inanimate will become alive
Slide 12
Lazzaro Spallanzani (1729-1799)
- Conducted an experiment: boiled meat broth for an hour, sealed the elongated neck of the flask. Microorganisms did not appear in the sealed flask.
- CONCLUSION: The high temperature has destroyed all forms of living things, and without them nothing living can arise.
Slide 13
Louis Pasteur
Slide 14
Creationism
- everything that exists in the Universe, including life, was created by a single Power - the Creator as a result of several acts of supernatural creation in the past.
- The created species were excellently organized from the very beginning and endowed with the ability to vary somewhat within certain boundaries.
- This hypothesis is adhered to by the followers of almost all the most widespread religious teachings.
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Stationary hypothesis
- The earth never arose, but existed forever; she was always able to maintain life, and if she changed, then very little; species have always existed as well. This hypothesis is sometimes called the hypothesis of eternism (from the Latin eternus - eternal).
- Nominated by the German scientist W. Preyer in 1880
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Panspermia hypothesis
- life on Earth did not arise from inorganic substances, but was brought in from other planets.
- LIFE EXISTS FOREVER AND IS TRANSFERRED FROM PLANET TO PLANET BY METEORITES.
Views and hypotheses about the origin of life on Earth
Biology 9th grade
Vlasov school
Teacher:
Ostanina G.M.
“Oh, solve for me the riddle of life, a painful ancient riddle, over which so many heads, - heads in caps painted with hieroglyphs, heads in turbans and black berets, heads in wigs and thousands of other poor human heads ... "
G. Heine.
Van Helmont. “Put some grains in a pot, plug it with a dirty shirt and wait. What will happen? In twenty-one days, mice will appear: they will be born from the fumes of caked grain and a dirty shirt. "
Problematic issues
How did life begin on Earth?
What are the views and hypotheses about the origin of life on Earth?
Which one is the most convincing?
What is life?
Living properties:
the ability to move, the ability to grow and develop, metabolism, respiration, nutrition, irritability, reproduction, cellular structure.
Life is a process of existence complex systemsconsisting of large organic molecules and inorganic substances and capable of self-reproduction, self-development and maintenance of their existence as a result of the exchange of energy and matter with the environment.
A hypothesis is an assumption that has insufficient evidence.
Theory is views with solid evidence.
Origin of life hypotheses
Hypothesis name
Supporters of the hypothesis
Divine creation of the world
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Origin of life hypotheses
Hypothesis name
Supporters of the hypothesis
Ideas about the origin of life
Creationism - Divine Creation of the World
Creationism - lat. the word creatio - creation
Life on earth was created by the Creator, God once, organisms, well organized and endowed with the ability to change.
Slide number 11
Origin of life hypotheses
Hypothesis name
Supporters of the hypothesis
Ideas about the origin of life
Slide number 12
Aristotle (384–322 BC) wrote that frogs and
insects start
in moist soil.
Plato spoke of
spontaneous generation of living
creatures from earth to
the process of decay.
Slide number 13
In the Middle Ages, it was "possible" to observe the emergence of living things, such as insects, worms, eels, mice, in the decaying or decaying remains of organisms
Spontaneous generation of lambs
Spontaneous generation
Bernakel geese
Slide number 14
Francesco Redi (1626-1697)
Francesco Redi (1626-1697)
In 1668 Redi conducted an experiment with
vessels in which they were placed
dead snakes on which appeared
fly larvae.
Conclusion: what life
may arise
only from
previous life.
Slide number 15
Anthony van Leeuwenhoek
Anthony van Leeuwenhoek
(1632-1723) examined under a microscope the simplest
Conclusion: Tiny organisms, or "animals", descend from their own kind.
Lazzaro Spallanzani
(1729-1799) Experiments with sterilized meat broth.
Conclusion: impossibility of spontaneous generation of microorganisms.
Slide number 16
Louis Pasteur (1822-1895) French microbiologist
Pasteur's experiment with curved S-necked flasks
Conclusion: living organisms originate only from other living organisms.
Slide number 17
Origin of life hypotheses
Hypothesis name
Supporters of the hypothesis
Ideas about the origin of life
The hypothesis of spontaneous origin of life
Aristotle,
Plato,
Francesco Redi, Anthony van Leeuwenhoek,
Lazzaro Spallanzani, Louis Pasteur
Living organisms arise spontaneously; either inorganic compounds or decaying organic residues can serve as a source of origin.
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Origin of life hypotheses
Hypothesis name
Supporters of the hypothesis
Ideas about the origin of life
Slide number 19
Origin of life hypotheses
Hypothesis name
Supporters of the hypothesis
Ideas about the origin of life
Stationary hypothesis
Hypothesis of eternism (from Latin eternus - eternal).
The earth has never arisen, but has existed forever and has always been able to support life. The species of animals and plants have always existed as well.
Slide number 20
Origin of life hypotheses
Hypothesis name
Supporters of the hypothesis
Ideas about the origin of life
Slide number 21
German scientist G. Richter in 1865 expressed the idea of \u200b\u200bthe cosmic (extraterrestrial) origin of life
Slide number 22
Scientists J. Thomson and G. Helmholtz are of the opinion that the spores of bacteria and other organisms could have been brought to the Earth with meteorites.
Slide number 23
Nobel Prize laureate English biophysicist F. Crick believes that life was brought to Earth by accident or deliberately by cosmic bodies or aliens.
Slide number 24
Origin of life hypotheses
Hypothesis name
Supporters of the hypothesis
Ideas about the origin of life
Panspermia hypothesis - cosmic origin of life
Panspermia - (from the Greek pan - all, everyone and sperma - seed)
G. Richter, J. Thomson, G. Helmholtz, F. Crick
Life on Earth was brought accidentally or intentionally by space bodies or space aliens.
Slide number 25
Origin of life hypotheses
Hypothesis name
Supporters of the hypothesis
Ideas about the origin of life
Biochemical evolution hypothesis,
or "coacervate hypothesis".
Slide number 26
Biochemical evolution
Oparin A.I.
(1894–1980)
In 1924, Aleksandr Ivanovich Oparin, a Russian biologist and biochemist, who created the theory of the origin of life on Earth from abiotic components, suggested that with powerful electrical discharges in the primary earth's atmosphere, which 4-4.5 billion years ago consisted of ammonia, methane , carbon dioxide and water vapor, the simplest organic compounds necessary for the emergence of life could arise.
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J. Haldane
(1892–1964) In 1929, the English scientist-naturalist John Haldane, an English biologist (geneticist, evolutionist, physiologist, biochemist, biometrist), popularizer and philosopher of science, came to a similar conclusion, independently of AI Oparin.
One of the founders of modern population, mathematical, molecular and biochemical genetics, as well as synthetic theory evolution.
Slide number 28
The Oparin-Haldane hypothesis asserts that life on Earth arose abiogenically (“living from non-living”).
MODERN CONCEPTS OF THE BEGINNING OF LIFE
HYPOTHESES OF THE ORIGIN OF LIFE ON EARTH
- To acquaint with the main hypotheses of the origin of life;
- Develop the ability to generalize, draw conclusions, independently work with popular science literature and textbooks;
- Show how the views on the origin of life have changed with the accumulation of knowledge.
- "Life is a way of existence of protein bodies, the essential moment of which is a constant exchange of substances with the external nature surrounding them, and with the termination of this metabolism, life also stops, which leads to the decomposition of protein"
There are quite a few theories of the origin of life on Earth, they can be divided into groups
1. CREATIONISM
2. THEORY OF SELF GENERATION
3. THEORY OF STATIONARY STATE
4 THEORY OF PANSPERMIA
5. THEORY OF BIOCHEMICAL EVOLUTION
Divine world creation.
- Creationism (creation) –
religious-philosophical
a concept in which everything
living beings and the planet itself
whole created by God.
The hypothesis of creationism is outside the field of scientific research, since it is irrefutable: it is impossible to scientifically prove, both that God did not create life, and that God created it.
Spontaneous generation of life
- For millennia
people believed in spontaneous
the birth of life, considering it
the usual way of appearing
living beings from non-living
384-322 BC.
For example, Aristotle attributed lice origin from meat, earthworms - from the silt of ponds.
described how, in three weeks, he created mice.
For this, all you need is:
a dirty shirt, a dark wardrobe and a handful of wheat, and human sweat to start the process.
Francesco Redi 1626 -1698 Italian naturalist and physician.
He conducted an experiment with vessels in which he put meat, left some of the vessels open, others closed with a cloth. In the open vessels the flies laid their testicles and the larvae of the flies appeared there, in the closed vessels there were no larvae.
Thus, the impossibility of spontaneous generation of living organisms was finally proved.
L. Pasteur's experiment with flasks with curved necks
According to the stationary state hypothesis
The earth did not arise
but existed forever.
- The earth never arose, but existed forever; she was always able to maintain life, and if she changed, then very little; species have always existed as well. This hypothesis is sometimes called the hypothesis eternism (from lat. eternus - eternal).
- Nominated by the German scientist W. Preyer in 1880
Panspermia theory It has
Panspermia theory It is believed that life on Earth was brought from the outside with meteorites, comets or even UFOs
- UFO appearance on Earth
- Rock carvings depicting objects similar to rockets and astronauts
- Meetings with aliens
- Finds of meteorites containing organic compounds
Biochemical evolution theory has the largest number of supporters among modern scientists
Alexander Ivanovich Oparin
In 1924 A. I. Oparin in his work "The Origin of Life" put forward coacervate hypothesis, according to which initial stages chemical evolution have been associated with the formation of protein structures.
Subsequently, the PRIMARY atmosphere of the Earth was again formed from heavier volcanic gases
It consisted of
water vapor Н 2 О
carbon dioxide CO 2
ammonia NH 3
methane CH 4
In 1924 the Russian scientist A.I. Oparin proposed the first concept of chemical evolution
In 1953, American scientists G. Urey and S. Miller synthesized amino acids, nucleic acids and simple sugars under conditions close to the atmosphere of the young Earth. Under laboratory conditions, they exposed a mixture of carbon dioxide, ammonia, methane, hydrogen, and water to electrical discharges. Biologically important organic compounds were obtained during the experiment
In the atmosphere of the Earth and in the waters
primary ocean
from inorganic substances formed simple organic matter: amino acids, simple carbohydrates, alcohols, nitrogenous bases, fatty acids
Stanley Miller
The result is the synthesis of amino acids, urea, lactic acid
Electrical discharges (60,000 V)
Pressure (n Pa)
Temperature (+ 80˚С)
Gas mixture (CO 2, CH 4, NH 3, H 2, water vapor)
the stage of chemical evolution is the synthesis of proteins-polypeptides that could have formed in the waters of the primary ocean.
Proteins-polypeptides
amino acids
Properties of coacervates
- Selectively absorb from environment substances
- Increase in size
- Not capable of self-replication
Coacervate drops
the emergence of a membrane, nucleic acid molecules capable of self-reproduction
Probionts
- English biochemist, geneticist and physiologist. The author of the hypothesis about “ primary broth ", one of the founders of population genetics
Hypotheses of abiogenesis: hypothesis of biochemical evolution
Evolution at the level of RNA molecules in coacervates was millions of years ... This is how the ancient world of RNA came into being. Mutations and recombinations in RNA populations have created increasing diversity in this world.
In parallel, the evolution of bonds between RNA and the synthesis of polypeptides is taking place, ensuring their more reliable existence.
At the next stage, DNA appears, their double-stranded structure ensures stability and accurate replication (doubling).
New discoveries of RNA functions
The discovery of new functions of RNA, or rather the so-called small RNAs, has become a major scientific event. In 2003, new evidence was found that RNA molecules are not just intermediaries between DNA and proteins in the process of protein synthesis. There are more and more arguments in favor of the fact that RNAs are able to regulate ("turn on / off") certain genes, thereby playing crucial role in the process of differentiation of the organism, as well as its current life.
- Many of the theories that have been voiced today use almost the same data, but emphasize different aspects. Scientific theories can be over-fantastic on the one hand, over-skeptical on the other. Theological considerations also find their place within this framework, depending on the religious views of their authors. Each of the hypotheses has its own strengths and weak sides, but none gives a precise answer to the question of the origin of life.
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Purpose of the lesson: To form a system of knowledge among students about different views on the origin of life on Earth.
Lesson objectives:
I. Educational:
- Show the role of experiment in solving scientific disputes about the origin of life.
- Train to analyze the main scientific hypotheses about the origin of life.
II. Developing:
- Continue to develop the desire for independent cognitive activity.
- Continue the formation of formal-logical skills of explanation, concretization, definition, generalization.
III. Educational:
- Intellectual - to continue the formation of the scientific worldview.
- Environmental - consolidation of knowledge about the relationship between living and inanimate nature.
- Moral - the formation of knowledge and beliefs of students about human responsibility for maintaining the integrity of the biosphere of our planet.
Motivation:
The origin of life on our planet is the subject of centuries-old discussions, in which more than one generation of mankind took part. This is an interesting area of \u200b\u200bknowledge that has scientific, philosophical and ideological significance, and still attracts the attention of researchers in various fields.
The study of various theories about the origin of life on Earth is necessary to form a holistic view of the historical path of development of living nature, the formation of a scientific worldview.
Students should know:
- The main provisions of theories about the origin of life;
- Contemporary views about the origin of life on Earth (theory of biochemical evolution).
Students should be able to:
- To uncover key provisions basic theories about the origin of life on Earth;
- Describe the experiments of F. Redi, L. Spallanzani, L. Pasteur, S. Miller, reveal their significance for solving the question of the origin of life;
- To reveal the main provisions of modern ideas about the origin of life on Earth (the theory of biochemical evolution);
- Formulate the main provisions of the theory of A.I. Oparin.
Lesson equipment:
- lesson plan;
- abstract;
- handout;
- tasks for control;
- presentation;
- notebook;
- multimedia projector;
- screen.
Interdisciplinary connections:
a) physics (device devices, physical phenomena);
b) chemistry (composition of the atmosphere, chemicals);
c) history (development of science);
d) philosophy (the formation of a scientific worldview);
e) foreign language (translation of terms).
Literature for the teacher:
- Sivoglazov V.I., Agafonov I.B. General biology 10-11. - M .: Bustard, 2005
- Sivoglazov V.I., Sukhova T.S., Kozlova T.A. General biology. Teacher's guide. - M .: AIRIS PRESS, 2004
- Sukhova T.S. Biology lesson. Developmental education technology. - M .: Ventana-Graf, 2001
Literature for students:
1. Sivoglazov V.I., Agafonov I.B. General biology 10-11.– M .: Bustard, 2005
Activity timeline:
1. Organizational moment
Greetings, checking those present according to the list, wishes successful work in class.
2. Control of the initial level of knowledge (standards of correct answers are indicated in brackets)
Objectives:
- Determine the level of knowledge of students.
- Adjust the difficulty level of new material submission.
1.What are the main features (criteria) that can distinguish a living object from a nonliving one?
(Unity chemical composition living organisms, metabolism, irritability, growth, reproduction, development, adaptation to the environment, self-regulation).
2. Where and when did the first living organisms appear? What were they like? (The first organisms appeared about 3 billion years ago in the aquatic environment, they were unicellular prokaryotes, fed on the organic matter of the ocean, anaerobes.)
3. What stages in the development of plants on Earth can you name? (unicellular, multicellular; occurrence of photosynthesis, sexual process; landfall, development of terrestrial vegetation.)
4. What stages in the development of animals on Earth can you name? (Single-celled, colonial, multicellular; the appearance of the sexual process; the appearance of invertebrates and vertebrates; access to land; the complication in the structure due to the terrestrial lifestyle.)
5. What substances are included in living organisms?
(Inorganic (water, mineral salts) and organic (amino acids, proteins, fats, carbohydrates, etc.))
3. Studying new material (explanation of new material is accompanied by a presentation, the text contains slide numbers)
3.1. Formulation of the problem
Life has existed on Earth for billions of years. It fills every corner of our planet.
From ancient times to our time, a huge number of hypotheses about the origin of life have been expressed. The specificity of the living determines a number of questions that must be answered, solving the problem of the origin of life:
- How did life originate and develop on our planet?
- How did the cell - a structural unit of living things arise?
- How did all the substances and structures specific to living come about?
- How was the existing metabolism formed? Etc.
We have to get acquainted with the hypotheses of the origin of life, analyze them and form an idea of \u200b\u200bhow life arose and developed on Earth.
3.2. Development of ideas about the origin of life on Earth (slide number 1)
Since time immemorial, the origin of life has been a mystery to humanity. From the moment of his appearance, thanks to labor, a person begins to stand out among other living beings.
But the ability to ask oneself the question "where are we from?" man receives relatively recently - 7-8 thousand years ago.
Until this time, man hardly separated himself from other animals (man was both a hunter and a kind of game), but gradually he began to delimit himself from nature with his inner spiritual world. The first primitive forms of belief in unreal, supernatural or divine forces appeared 35-40 thousand years ago.
3.3. Basic theories of the origin of life on Earth (Slide number 2)
According to this theory, life arose as a result of some supernatural event in the past, which most often means a divine creation. The idea of \u200b\u200bthe creation of the world as a “creative act” of God arose, and this myth underlies all religions.
"These are the facts - living things can arise not only as a result of the mating of animals, but also the decomposition of the soil ... Some plants develop from seeds, while others spontaneously arise under the action of the forces of nature from the decaying earth or certain parts of plants ..."
However, with the advent of Christianity, especially in the Middle Ages, the theory of spontaneous generation came under the yoke of the Church. She was considered an attribute of witchcraft and a manifestation of the devil. However, it continued to exist.
At the turn of the XVI-XVII centuries. Van Helmont (1579-1644) described an experiment in which he managed to get mice from dirty linen and wheat placed in a dark cabinet. Van Helmont considered human sweat to be the active origin of the mouse. (Slide number 5)- to biogenesis concept (from the Greek “bios” - life, “genesis” - origin). (Slide number 6)
In 1668. the Italian physician Francesco Redi (1626-1698) proved that the white worms found in meat are fly larvae; if the meat or fish are covered while they are fresh and the access of flies is prevented, although they will rot, they will not produce worms. From this F. Redi concluded that the living only originated from the living). (Slide number 7)In 1765, Lazzardo Spallanzani (1729-1799) boiled meat and vegetable broths and immediately sealed them. After a few days, he examined the decoctions and found no signs of life. From this, he concluded that the high temperature destroyed all living things, and nothing new could arise. (Slide number 8)
J. Needham - supporter vitalism (from Latin vita - life), explained the negative results obtained by L. Spallanzani by the fact that he subjected his infusions to too harsh processing, as a result of which their "vitality" was destroyed. (Slide number 9)According to the vitalists, "life force" is present everywhere. It is enough just to “inhale” it, and the inanimate will become alive.
In 1862, the great French scientist Louis Pasteur (1822-1895) published his observations on the problem of arbitrary spontaneous generation. He argues that the sudden emergence ("spontaneous generation") of microbes in various types of rotting tinctures or extracts is not the emergence of life. Rotting and fermentation is the result of the vital activity of microorganisms introduced from the outside. His research finally destroyed the age-old prejudices about spontaneous spontaneous generation.
Fig. 1. L. Pasteur's experience in flasks with S-shaped necks:
1 - a flask with sugared yeast water; after sterilization and cooling, it remains sterile for a long time;
2 - the same flask 48 hours after removing the bent neck; the growth of microorganisms is observed. (slides No. 10,11)
- Stationary state theory (Slide number 12)
If you follow this theory, the Earth has existed forever, never arising, was always able to support life, and any changes on it were completely insignificant. This theory currently does not stand up to criticism.
- Panspermia theory (Slide number 13)
In the V century. BC. Greek philosopher Anaxagoras expressed the idea of \u200b\u200bcosmic seeding - panspermia(from the Greek “pan” - everything and “sperma” - the seed). According to his teaching, life arose from a seed that exists "always and everywhere." According to this theory, the embryos of life are carried to Earth by meteorites or cosmic dust. This theory does not offer any mechanism for the origin of life, simply putting forward the postulate of its extraterrestrial origin. It is argued that life could arise repeatedly at different times and in different places in the universe.
4. Modern ideas about the origin of life
(Slide 14)The modern theory of the origin of life is based on the idea that biological molecules could arise in the distant geological past in an inorganic way.
The most widespread in the twentieth century. received the theory of biochemical evolution, proposed independently of each other by the Russian chemist A.I. Oparin (1894 - 1980) and the English biologist D. Haldane (1892 - 1964).
- Biochemical evolution theory (Slide number 15)
Stage 1 - the abiogenic emergence of organic monomers Our planet emerged about 4.6 billion years ago. The gradual compaction of the planet was accompanied by the release of a huge amount of heat, radioactive compounds decayed, a stream of hard ultraviolet radiation emanated from the Sun. After 500 million years, the Earth began to slowly cool down. The formation of the earth's crust was accompanied by active volcanic activity. It is believed that the primary atmosphere consisted primarily of ammonia, water, methane, carbon monoxide and carbon dioxide. The lack of oxygen gave it its reducing properties. On May 3, 1924, at a meeting of the Russian Botanical Society, the young scientist A.I. Oparin expressed the opinion that in the conditions of the primary atmosphere of the Earth, which is significantly different from the current one, synthesis of all the precursor substances necessary for the origin of life could occur.
Under such conditions, organic matter could be created much easier and could be stored without decaying for a long time. AI Oparin believed that complex substances could be synthesized from simpler ones in ocean conditions. The energy required for the reactions was brought in by solar radiation, since the protective ozone shield did not yet exist; synthesis also took place under conditions of lightning discharges.
Conditions on the primeval earth (slides No. 16,17):
The variety of simple compounds found in the ocean and the large time scales suggest the possibility of accumulation in the ocean of a large amount of organic matter, which formed a "primary soup" in which life could arise.
Formation scheme of "primary broth"
This theory was confirmed in the experiments of S. Miller carried out in 1953. (Slide 18)
Fig. 2. Scheme of S. Miller's device:
1 - reaction flask; 2 - tungsten electrodes; 3 - spark discharge; 4 - a flask with boiling water; 5 - fridge; 6 - trap; 7 - tap through which the gas mixture is fed into the apparatus
Through a gas mixture containing methane, ammonia, molecular hydrogen and water vapor, that is, imitating the atmospheric composition of the primitive Earth, he passed electrical discharges, and then analyzed the resulting reaction products. Tungsten electrodes were mounted in a reaction flask containing a mixture of gases. Spark discharges with a voltage of 60,000 V were passed for a week. In another flask (small), the water was kept boiling. Water vapor passed through the reaction flask and condensed in a refrigerator. In the process of circulation, they captured the reaction products from the reaction flask and transferred them into a trap, where they were concentrated. When identifying the reaction products, organic compounds were found: urea, lactic acid and some amino acids.
Stage 2 - the formation of biological polymers and coacervates (Slide number 19)
A.I. Oparin believed that proteins play a decisive role in the transformation of non-living things into living things. Protein molecules formed complexes with molecules of the surrounding water. The merger of such complexes with each other led to their separation from the aquatic environment, formed coacervates(from Latin “coacervus” - a clot). Coacervate drops were capable of: exchanging substances with the environment, accumulating various compounds. The absorption of metal ions by coacervates led to the formation of enzymes. Proteins in coacervates protected nucleic acids from the damaging effects of ultraviolet radiation. In the drops themselves, further chemical transformations of the substances that got there took place. On the border of drops with external environment lipid molecules lined up, forming a primitive membrane that increased the stability of the entire system.
Stage 3 - the formation of membrane structures and primary organisms (probionts) Around the coacervates rich in organic compounds, layers of lipids have arisen, separating the coacervate from the surrounding aquatic environment. Lipids were transformed in the course of evolution into the outer membrane, which significantly increased the viability and stability of organisms. This is how probionts arose - primitive heterotrophic organisms that fed on the organic matter of the primary broth. It happened 3.5 - 3.8 billion years ago. Chemical evolution is over.
The essence of A.I. Oparin can be formulated in the form of three postulates:
1. Life is one of the stages of the evolution of the Universe. 2. The emergence of life is a natural result of the chemical evolution of carbon compounds. 3. For the transition from chemical evolution to biological evolution, the formation and natural selection of integral, isolated from the environment, but constantly interacting with it, multi-molecular systems, which were called probionts, are necessary.
Conclusions. (Slide number 20)
Slide 1
KSU "Zyryanovsk Agricultural College" ORIGIN AND INITIAL STAGES OF LIFE ON THE EARTHSlide 2
Lesson objectives: Educational: students should -know the conditions and stages of the emergence of life on Earth in the course of biochemical evolution. - to understand that life, as a way of existence, is unique - to be able to compare and analyze various hypotheses, to correctly define them by their essential characteristics. - apply the knowledge gained when working with diagrams, tables. Developing: develop - the ability to compare, analyze, draw conclusions; skills in working with information, tables, diagrams. Educating: students should: - show such qualities as composure, responsibility, attentiveness. - to foster interest and a positive attitude towards biological science and the search for a comprehensive theory on the problem of the origin of life on Earth.
Slide 3
“Oh, solve for me the riddle of life, a painful ancient riddle over which so many heads have been beating - heads in hats painted with hieroglyphs, heads in turbans and black berets, heads in wigs and thousands of other poor human heads ...” G. Heine ...
Slide 4
Problematic questions How did life on Earth come about? What are the views and hypotheses about the origin of life on Earth? Which one is the most convincing?
Slide 5
Life is ... "nutrition, growth and decrepitude" Aristotle "persistent uniformity of processes with different external influences" G. Treviranus "a set of functions that resist death" M. Bichat "chemical function" A. Lavoisier "complex chemical process"I.P. Pavlov" a special, very complex form of motion of matter "A.I.Oparin
Slide 6
"Life is a way of existence of protein bodies, the essential moment of which is a constant exchange of substances with the external nature surrounding them, and with the cessation of this metabolism, life also stops, which leads to the decomposition of protein" Friedrich Engels (November 28, 1820 - August 5, 1895, London) - German philosopher, one of the founders of Marxism, friend, associate and co-author of Karl Marx
Slide 7
"Living bodies that exist on Earth are open, self-regulating and self-reproducing systems built of biopolymers - proteins and nucleic acids" Mikhail Vladi mirovich Volkenshtein (10 (23) October 1912, St. Petersburg - 18 February 1992, Moscow) - Soviet physicochemist and biophysicist, corresponding member of the Russian Academy of Sciences.
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"Life is a phase-separate form of existence of functioning autocatalysts capable of chemical mutations and undergoing a fairly long evolution due to natural selection" Valentin Nikolaevich Parmon (born April 18, 1948, Brandenburg) - Russian scientist. Specialist in the field of catalysis and photocatalysis, chemical kinetics.
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Criteria are the main properties of living organisms. - the complexity and high degree of organization of living things - metabolism and energy. - the unity of the chemical composition - discreteness (discontinuity, separation). - irritability - growth of organisms - development. - self-reproduction (reproduction). - the ability to self-regulation.
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Life is a complex of properties: metabolism, the ability to grow and develop, reproduce their own kind, irritability and mobility.
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A hypothesis is an assumption that has insufficient evidence. Theory is views with solid evidence. Biogenesis is a scientific theory that explains the emergence of life only as a result of the vital activity of living organisms. Abiogenesis is a scientific theory that explains the emergence of life through the gradual formation of organic compounds from inorganic ones. Protobionts are primitive organisms that first appeared on Earth. Coacervates are clots in the form of a multimolecular drop with an outer thin aqueous shell. Evolution is an irreversible historical development of living nature. Autotrophs - (ancient Greek αὐτός - itself + τροφή - food) are organisms that synthesize organic substances from inorganic ones. Heterotrophs - (ancient Greek ἕτερος - "different", "different" and τροφή - "food") - organisms that use for nutrition only or mainly organic substances produced by autotrophs. New concepts
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Both the Earth and life are created by the Highest Mind (God) ABIOGENESIS Life arose repeatedly as a result of spontaneous generation. Main points of view on the origin of life on Earth BIOGENESIS Living organisms appeared on the Earth 3.5 billion years ago in the course of biochemical evolution. Life was brought from space along with meteorites, then - evolution. The earth has existed forever, has always been able to support life; if changed, then very little (hypothesis of eternal life)
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Hypotheses of the origin of life № Name of the hypothesis Supporters of the hypothesis Conceptions about the origin of life 1. Creationism - Divine creation of the world Creationism - lat. wordcreatio - creation
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Life was created by the Supreme Mind (God, Creator). Creationist hypothesis. However, the victory of the theory of biogenesis led to another problem. For the emergence of one living being, another living organism is needed. Where did the first living organism come from? In other words, how and when did life first appear on Earth? In the theories of the formation of the Earth and the solar system, the emergence of life on Earth, there are many "white spots".
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Panspermia hypothesis (from the Greek "pan" - everything, "sperma" - seed) Anaxagoras (500-428 BC) - ancient Greek philosopher, mathematician and astronomer, the founder of the Athenian philosophical school. In the V century. BC. expressed the idea of \u200b\u200bspace sowing - panspermia: life arose from a “seed” that exists “always and everywhere”, “the embryos of life” are brought to Earth by meteorites or cosmic dust ... However, the victory of the theory of biogenesis led to another problem. For the emergence of one living being, another living organism is needed. Where did the first living organism come from? In other words, how and when did life first arise on Earth? In the theories of the formation of the Earth and the Solar system, the emergence of life on Earth, there are many "white spots".
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Eustace Liebig (1803-1873), a German chemist, put forward and formulated the panspermia hypothesis: life is transferred from planet to planet by meteorites. "Seeds of life", getting to a new planet and finding favorable conditions here, multiply, giving rise to evolution from the simplest forms to complex ones. Panspermia hypothesis Supporters of the panspermia hypothesis: Vernadsky Vl. Yves. (1863-1945) Svante Arrhenius (1859-1927)
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The theory of a stationary state, or ... He considered the incandescent masses of the emerging globe as giant living organisms with their own special metabolism. The cooled masses fell out of the circle of life and constituted an inorganic nature. Hypothesis Of eternal life In 1880 it was put forward by the German scientist W. Preyer.
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Vitalism (from Lat. Vitalis - vital, life-giving, alive) "Life force" is present everywhere, you just need to "breathe" it, and the inanimate will become alive
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In the Middle Ages, it was "possible" to observe the emergence of living things, such as insects, worms, eels, mice, in decaying or decaying remains of organisms It was believed that there are trees, from the fruits of which, falling to the ground, birds are formed, from those that fell into the water - fish ... Spontaneous generation of lambs Spontaneous generation of Bernakel geese SELF-GENERATION OF LIFE
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The Belgian physician Van Helmont (1579-1644) proposed a recipe for the birth of mice: “Put grain in a pot, plug it with a dirty shirt and wait. What will happen? After 21 days, mice will appear: they will be born from the vapors of caked grain and a dirty shirt ... "Hypothesis of spontaneous generation Aristotle (384 - 322 BC), who is called the founder of biology, wrote that" frogs and insects start in a damp soil ... "In Europe up to the middle of the XVI century. obscurantism prevailed, an intolerant attitude towards the development of sciences, especially natural sciences. Alchemy flourished at this time. Among the alchemists there were many naive and ignorant people, but there were others - excellent scientists, whose names have gone down in history. Among them are the Belgian physician Van Helmont and the Swiss physician Paracelsus, the greatest reformer of the Renaissance, the father of modern medicine. Alchemists dreamed of finding the Philosopher's Stone and getting gold. But there were others ... Having set their tables with cans, retorts, erected stills and other devices, they boiled, distilled, insisted, filtered ... Everything that came to hand was poured into the flasks. We tried our best. Some called for God's help, others were ready to give their souls to the devil, just to see how some tadpole, frog, or mouse would be wrapped in a flask. Alas, nothing worked. Apparently, the whole point is in the recipe. Van Helmont got down to business.
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“Take a well-known human liquid (urine), leave it to rot first, sealed in a pumpkin, then in a horse's stomach for 40 days, until it begins to live, move and swarm, which is easy to notice ... then daily, secretly and carefully, with prudence, feed it with human blood and maintain for 40 weeks in the constant and uniform warmth of the stomach, then a real living child will occur, having all the limbs, like a child born of a woman, but only of very small stature. " Alchemists called such a little man from a test tube HOMUNCULUS (homunculus) Theophrastus Paracelsus (1493 - 1541). The Swiss physician, alchemist, wrote: Paracelsus also proposed his recipe. It's too small to mess around with getting mice, frogs, scorpions. If we get down to business, then so that a homunculus appears in the test tube. You, who have not studied Latin, do not understand this word. But you have heard the word "homo" more than once - a person. The diminutive of the word "man" - "little man", and in Latin - "homunculus". But "homunculus" was called fantastic creature , which should have been created in the laboratory, even if it be a giant. Homunculus is the memory of dreamers who dreamed of creating living things from non-living things. The great magician in his dimly lit laboratory with a vaulted ceiling, tables lined with flasks of colored liquids, alembics and retorts. On the walls - bunches of bats, shabby, moth-eaten stuffed animals and birds. There is a crocodile under the ceiling. He writes the recipe: “Take the famous human liquid. (urine) leave it to rot first in a sealed pumpkin, then in a horse's stomach for forty days, until it begins to live, move and swarm, which is easy to notice. The result is not at all like a person, it is transparent and without a body. But if then daily, secretly and carefully, with prudence, feed it with human blood and keep it for forty weeks in the constant and uniform warmth of a horse's stomach, then a real living child will occur, having all the limbs, like a child born of a woman, but only very small growth ". Pouring the "well-known human liquid" into a pumpkin is easy, then pouring it into a horse's stomach will not be difficult either. But “to nourish carefully and with prudence” that invisible and transparent that should be buried in a rotting liquid is not very easy. There are so many loopholes in the recipe that you can always get away with. Let's imagine that an alchemist apprentice enters his laboratory, bows respectfully to the Master and speaks with trembling. Disciple. Master, I did everything that is written in your recipe. But I didn't succeed! Paracelsus. Yes? And did you do everything exactly? Disciple. Yes, Master. Paracelsus. No, no and NO! You didn't follow all the instructions! Have you been prudent and careful? Did you give the liquid enough to rot? Did you pour it from the pumpkin into your stomach in time? Have you kept a secret? The student lowers his head. Yes, about the secret - he could not resist, boasted in the tavern to his comrades that soon an "unborn" man would appear in his laboratory. Paracelsus. Well? Confess! Disciple. You're right, Master. Again the unhappy disciple fills the pumpkin and waits. Every day he looks: rotting or not rotting. In due time, it pours the decayed liquid into the horse's stomach, turning his nose to the side. It smells very unpleasant. Yes, Paracelsus cleverly fooled everyone. New "creators" of fantastic stories appeared. Nobody knew where worms, flies, frogs, snails came from. Why do they sometimes appear in huge numbers? Nobody saw their birth, their eggs, their development. Here is the conclusion: they spontaneously originated from dirt, rotting parts of plants, animals, but you never know from what. However, skeptics appeared who did not believe in anyone or anything. Sometimes they tried to protest. But ... (pause) the authority of the Greek scientists and the wisest of them - Aristotle was unshakable. Who dares to contradict him! A menacing cry was immediately heard.
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Redi took 4 wide-necked pots, put a dead snake in one, some fish in the other, eels in the third, a piece of veal in the fourth, and closed them tightly. Then I put the same in 4 other pots, leaving them open. Soon the meat and fish in the open vessels became fermented, and it was possible to see how flies freely fly into the vessels and fly out of them. There were not a single worm in the closed pots, although many days have passed since the experiment was started. The experiments of Francesco REDI, 1668 “Flies are not born from rotting meat. Worms don't start spontaneously in rotting meat. They hatch from the testicles laid there by flies ... ”1668. Redi took four wide-necked pots, placed a dead snake in one of them, some fish in the other, Arno eels in the third, and a piece of veal in the fourth, closed them tightly and sealed them. Then he put the same in four other pots, leaving them open. Thus, the scientist decided to control the course of his experiment. It was mid-June outside the window. Soon the meat and fish in the open vessels became fermented, and one could see how flies freely fly into the vessels and fly out of them. In the closed pots, not a single worm was found, although many days have passed since the experiment was started. Redi: “Flies are not born from rotting meat. Worms don't start spontaneously in rotting meat. They emerge from the testicles laid there by flies. " It was a brilliant experiment. Redi proved the impossibility of spontaneous generation of flies. His data confirmed the idea that "life can arise only from a previous life." By striking a blow to the theory of abiogenesis, Redi laid the foundation for the theory of biogenesis.
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Lazzaro Spallanzani, Italian abbot, mathematician and naturalist: "... One has only to solder the bottles and boil the infusion for an hour - and not a single microbe will appear there, no matter how long the infusion stands ..." Ideas of biogenesis: Ideas of abiogenesis Georges-Louis Leclerc, Comte de Buffon, French writer, naturalist, biologist, mathematician, artist: "... Microbes arise from tinctures and gravies! .." ... And microbes must have parents! .. 1729 - 1799 1707 - 1788 On the origin of microorganisms, scientists were divided into two camps , some argued that microorganisms self-generate, others argued that spontaneous generation is impossible. The Frenchman Buffon and the Irishman Nidgem were representatives of one camp, the other was represented by the Italian Abbot Lazzaro Spallanzani.
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I can make infusions from peas and almonds, yellow foliage leaves, or a carnation flower. And the composition of the animals will be the same everywhere. But only on condition that all infusions are prepared in the same water. A simple conclusion follows from this: animalcules fall along with water. There is nothing surprising. Indeed, in nature, these crumbs live in water: swamp, pond, lake, sea and even well. And when they dry, they die. Refutation of spontaneous generation ... MM Terekhovsky 1740-1796 Spallanzani's ally was the Russian scientist Martyn Matveyevich Terekhovsky. In dozens of books you can read about the dispute between Spallanzani and Buffon and Nidgem, but you can rarely find the name of Terekhovsky, our compatriot, who experimentally proved the impossibility of spontaneous generation almost simultaneously with Spallanzani. At the University of Strasbourg, Terekhovsky wrote and defended his work "Zoological and physiological dissertation on the liqueur chaos of Linnaeus." "Pouring chaos" is a little understandable name for us. "Chaos" in his system of animals Linnaeus called the section to which he attributed the most diverse creatures that have one common property - the smallest size. For example, ciliates, the very name of which comes from the Latin "infusion, liqueur". Terekhovsky, unlike Spallanzani, did not argue with Buffon. He worked only with ciliates and flagellates, which after a while appear in infusions from seeds, fruits and herbs. But where do they come from? Terekhovsky. The reason is in the water. I can make infusions from peas and almonds, yellow foliage leaves, or a carnation flower. And the composition of the animals will be the same everywhere. But only on condition that all infusions are prepared in the same water. A simple conclusion follows from this: animalcules fall along with water. There is nothing surprising. Indeed, in nature, these crumbs live in water: swamp, pond, lake, sea and even well. And when they dry, they die. There was another way for these crumbs to get into the infusions - the air. However, the doctor decided that this probability was too small. The water was the most suspicious. Terekhovsky began to experiment with water. Terekhovsky. To begin with, I will take clean water - raw and boiled, pour it into the vessels and leave them open. I'll see what happens. So, animalculi appeared in a vessel with raw water, but they are not in boiled water. Add raw water to a vessel with boiled water. So, now there are "cute crumbs" in it. Consequently, they get into infusions with raw water! I will also do the following experiment: I will heat one jar of animals above 35 ° C, and I will freeze the other. What happens? In both banks, animals died. Now I will leave the vessels with cooled and melted water for a long time. The animals did not appear! So, I'll boil the grass, fill it with raw and boiled water. Now the animals have appeared in a can of raw water. And in a jar with boiled them there are not, although it stood for many days. And if I brew tea, why not infusion? But no one wound up in it either. There is no spontaneous generation! Terekhovsky made many experiments. The result was the same. Animalculi appeared in infusions made with raw water and when raw water was added to the decoction after cooling. Now you and I know what could have happened in a different way - cysts of protozoa could get into vessels with boiled water from the air. But this did not happen: the vessels were in the rooms, and the cysts of protozoa, in contrast to the spores of microbes, are very small in clean air - 1–2 per cubic meter of air. However, at the time of Terekhovsky, they simply did not know anything about protozoan cysts, and for his time he convincingly proved that animalculi do not arise in infusions. The Paris Academy of Sciences decided to put an end to these disputes and appointed a prize for the final experimental solution of the problem, saying that "no ambiguities in the formulation of experiments should obscure their results." Pasteur, the famous "germ hunter", having learned about the competition, set to work. Pasteur. Fools! They think that if there are no microbes in the air, then they are not there. No matter how it is! I'll prove it to them! It’s not difficult. I will take a glass tube and put a piece of cotton in it. I attach a pump to one end of the tube, put the other in the window and begin to suck in the outside air. Four hours passed, the cotton wool in the tube darkened. I will rinse it in a watch glass and squeeze it over another. I will do this operation several times. The cotton wool became clean, all the dust from it was washed off. Well, let's see, let's see what is in the flush from the fleece. I will place a drop of water on a glass slide and examine its contents under a microscope. Here are fungal spores, mold spores, microbes and their spores! Now I had to learn how to catch microbes. Pasteur is an excellent microbiologist. The scientist poured nutrient solutions into the cones and boiled them. Then he heated the neck of the flask, pulled it into a long tube and sealed the tip. With such a flask it was possible to start hunting. Going out into the courtyard, Pasteur broke off the sealed tip. Air rushed into the flask and carried microbes and their spores there. After that Pasteur sealed the neck again. Pasteur. So it is, the microbes that got into the flask multiplied. This can be seen by the cloudy cloud formed on the surface of the broth. Oh, these are clouds of germs! Pasteur did not stop there. Now he needed to find out which air contains more microbes. Flasks in hand, he wandered through the Parisian garbage dumps. Then he stumbled over the roots and stumps of trees in the forest, elm in swamps, wandered along the seashore, climbed high mountains, even climbed the glaciers of Mont Blanc. Everywhere he opened and sealed flasks. And then in the laboratory he was engaged in accounting: under the microscope he kept a careful record of microbes. Pasteur. Well, it is, microbes are everywhere. True, in some places there are a lot of them, in others there are few. There are the fewest of them in the air of glaciers. And I didn’t always manage to catch a single microbe here. So the first part of the problem was solved - microbes and their spores were flying in the air everywhere and could get anywhere. But the second part was much more difficult - to prove that it is the microbes, getting from the air into the flask, are misleading the researchers. The well-known rule "Warm up the air, kill the microbes in it" is no good. Even Needham argued that heated air is not suitable for life, so spontaneous generation does not occur in it. The air cannot be warmed up, which means that microbes can remain in it, and ... the tale of the white bull begins. How to solve this problem? What barrier to put on the path of microbes into the flask? Pasteur was lucky. He met a man who gave good advice... This is how the famous "Pasteur flask" appeared. The neck in such a flask is elongated into a long tube and curved, like a swan's neck. Pasteur put new series experiments: in flasks poured various nutrient media (yeast solution with added sugar, sugar beet juice, pepper infusion, urine), prepared under normal conditions. Above the fire, he pulled the neck of the flask into a long tube, with tweezers pulled the tip of the elongated neck down, and then up. The result was a bend. The liquid boiled in the flask for several minutes. During boiling, steam escaped freely through the long narrow end of the flask. After the flask was cooled, the nutrient solutions remained clear. At first glance, it may seem that microbes could enter the cooling flask in the usual way - through the neck, along with air. In fact, all the dust and microbes from the air settle in the humid places of the tube bend and do not get to the nutrient solution. If, after a few months of storing the infusion in such an open flask, break off the curved neck, then various microorganisms will very quickly appear in the infusion. Pasteur. See? No spontaneous generation! The flask contains both nutrient solution and air! Where is your generating power? Where is spontaneous generation? Show it to me. Pouchet and his associates - two professors from Toulouse - stuffed sealed Pasteur flasks with boiled hay infusion into their pockets and climbed into the mountains. The results of the expedition showed that microbes always appeared in the flasks. Even in air samples taken from Mount Mladetta, which is significantly higher than Mont Blanc. Pouche. Monsieur Pasteur! Well, is there spontaneous generation or not? Pasteur did not doubt the purity of his experiments and doubted the accuracy of the experiments of Pouchet and his supporters. He, who had experienced many different environments, did not want to repeat all the work and also check the hay infusion. Why waste precious time on nonsense? Pasteur. Let the commission figure it out! And he will find the error Pouchet. The Academy of Sciences decided in its own way. Commission? A commission has been appointed. But to understand Pouchet's experiments? No! The solution is as follows: in the presence of the members of the commission, Pasteur and Pouchet must stage their experiments. Pouchet refused. Perhaps he doubted his research. There were also rumors that the commission found fault with the French scientist, having previously preferred Pasteur. What really happened is beyond us. But Pouchet refused, and the commission issued a verdict: Pasteur's experiments are convincing. However, 10 years later in England, doctor Bastian conducted a new series of experiments with hay infusion. And indeed, microbes appeared in the flasks each time, although the experimenter exactly reproduced Pasteur's experiment. So what, Pasteur was wrong, is Pouchet right? Pasteur. I thought Pouchet got it wrong. But Bastian has a similar result ... Anyway, something is wrong here! We need to find a reason. Pasteur also solved this riddle. Both Pouchet and Bastian were wrong: there was no spontaneous generation in the hay infusion. In this case, microbes got into the infusion not from the air. They were present in the hay from which the infusion was prepared. There is such a microbe - "hay stick". The spores of this microbe do not die when boiling, maintaining a temperature of 100 C. Therefore, simply boiled hay infusion is teeming with hay bacillus spores. As long as the flask is sealed, there is no oxygen in it, microbes do not develop. But it is worth breaking off the neck of the flask, air passes into it, and microbes begin to multiply. This is what Pouchet and Bastian observed. Pasteur found a hay stick and figured out how to kill it: you need to boil the infusion for at least 20 minutes at a temperature of 120 C and at high pressure in closed vessels. To achieve such conditions, Pasteur invented what is now called an "autoclave". Autoclaves are now used to sterilize medical instruments. And then the objections of Pouchet and Bastian were refuted. Pasteur. My prize! And he got it. The dispute, which lasted hundreds of years, ended with the victory of the theory of biogenesis. This was in 1862.
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