An open lesson in biology on the topic "modern ideas about the origin of life on earth." Presentation on the origin of life on earth Presentation on the origin

MODERN CONCEPTS ABOUT THE ORIGIN OF LIFE

HYPOTHESES FOR THE ORIGIN OF LIFE ON EARTH

• To acquaint with the main hypotheses of the origin of life;
• Develop the ability to generalize, draw conclusions, work independently with popular science literature and a textbook;
• Show how views on the origin of life have changed as knowledge has accumulated.

• "Life is a mode of existence of protein bodies, the essential point of which is the constant exchange of substances with the external nature surrounding them, and with the cessation of this metabolism, life also ceases, which leads to the decomposition of the 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. STATION STATE THEORY

4. THEORY OF PANSPERMIA

5. THEORY OF BIOCHEMICAL EVOLUTION

divine world creation.

• Creationism (creation) –

religious and philosophical

concept in which everything

living beings and the planet itself

wholly 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 origin of life, considering it

the usual way of appearing

living beings from non-living

384-322 BC.

For example, Aristotle attributed the origin of lice 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 closet and a handful of wheat, and to start the process - human sweat.

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 covered with a cloth. The flies laid their eggs in the open vessels and the larvae of the flies appeared there, but there were no larvae in the closed vessels.

Thus, the impossibility of spontaneous generation of living organisms was finally proved.

L. Pasteur's experiment with flasks with curved necks

According to the steady state hypothesis

The earth did not come into existence

but has existed forever.

• The earth never came into being, but existed forever; it has always been capable of sustaining life, and if it has changed, it has changed very little; species have always existed. This hypothesis is sometimes called the hypothesis eternism(from lat. eternus- eternal).
• Put forward 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.

• The appearance of UFOs on Earth
• Rock paintings depicting objects similar to rockets and astronauts
• Encounters with aliens
• Findings of meteorites containing organic compounds

Theory of biochemical evolution 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 were 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 H 2 O

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 a young Earth. Under laboratory conditions, they subjected a mixture of carbon dioxide, ammonia, methane, hydrogen, and water to electrical discharges. During the experiment, biologically important organic compounds were obtained

In the Earth's atmosphere and in the waters

primary ocean

simple organic substances were formed from inorganic substances: amino acids, simple carbohydrates, alcohols, nitrogenous bases, fatty acids

Stanley Miller

The result is the synthesis of amino acids, urea, lactic acid

Electrical discharges (60000 V)

Pressure (nPa)

Temperature (+80˚С)

A mixture of gases (CO 2, CH 4, NH 3, H 2, water vapor)

the stage of chemical evolution is the synthesis of polypeptide proteins that could have been formed in the waters of the primary ocean.

Polypeptide proteins

amino acids

Properties of coacervates

• selectively absorb from environment substances
• Grow in size
• Not capable of self-reproduction

Coacervate drops

the emergence of a membrane, nucleic acid molecules capable of self-replication

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 proceeded millions of years. This is how the ancient world of RNA came into being. Mutations and recombinations in RNA populations have created an ever-increasing variety of this world.

In parallel, the links between RNA and the synthesis of polypeptides are evolving, ensuring their more reliable existence.

At the next stage, DNA arises, 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 RNA, 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 essential role in the process of differentiation of the organism, as well as its current life activity.

• Many of the theories that have been voiced today use almost the same data, but emphasize different aspects. Scientific theories can be super-fantastic on the one hand, super-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 strengths and weak sides, but none gives an exact answer to the question of the origin of life.

Spontaneous generation The hypothesis of spontaneous generation "was widespread in Ancient China, Babylon and Egypt as an alternative to creationism. After the impossibility of spontaneous generation of mice was proved by the end of the 17th century, atheists continued to believe in the spontaneous generation of bacteria. Disputes about whether or not bacteria can spontaneously arise from dirt continued until the second half of the 19th century. Only Louis Pasteur (1822-1895) experimentally proved the impossibility of spontaneous generation of bacteria. Back

Under what conditions is it possible for living organisms to appear? C. Darwin g "... the absence of living organisms." A.I. Oparin in 1924 "..lack of free oxygen in the atmosphere."

Stanley Miller apparatus. Stanley Miller and Sidney Fox designed an apparatus that contained the gases of the primary atmosphere. Through this mixture, they passed electrical discharges. Owls. scientists A. G. Pasynsky and T. E. Pavlovskaya (1956) showed the possibility of the formation of amino acids under ultraviolet irradiation gas mixture formaldehyde and ammonium salts

Under what conditions is it possible for living organisms to appear? Answer questions. 1. What processes on the ancient Earth led to the formation of a gaseous shell on it? 2. What is the composition of the primary atmosphere? 3. Why did the Earth cool down? 4. What substances accumulated in the ocean? 5. What, according to scientists, led to the appearance of organic compounds? 6. Why did the composition of substances in the ocean change?

Stages of the emergence of living organisms 1. Formation of amino acids and monomers for organic molecules 2. Formation of biopolymers, such as proteins, carbohydrates and fats, capable of forming complexes - coacervate drops. 3.Coacervates. 4. The emergence of the ability to self-reproduce (based on matrix synthesis)

Stages of the emergence of living organisms Model experiments conducted by A. I. Oparin and colleagues with coacervate drops released from an aqueous solution of various organic polymers showed that these systems have the ability to absorb various energy-rich substances from the solution surrounding them and, due to them, grow, increasing in sizes and weight.

Subject: "Modern ideas about the origin of life on Earth".

Target:

1. continue to form students' knowledge about the origin of life on Earth;
2. to acquaint with the main provisions of the modern theory of A.I. Oparina;
3. develop the ability to analyze the proposed information;

Equipment: Microsoft presentation Office PowerPoint "Modern ideas about the origin of life on Earth."

During the classes

1. Organizing time.

Greetings.

- Preparing the audience for work.

1. Motivation of educational activity.

Message about the topic and purpose of the lesson.

1. Checking students' knowledge.

Teacher : The problems of the origin and development of life on Earth have long attracted the attention of all philosophers and naturalists. What were the first views on the origin of life on Earth?

Student: a story about the first views on the origin of life on Earth using presentation materials.

Presentation. Slide number 3,4,5,6

Teacher: How did ideas about the origin of life develop later?

Student: Narrative of Francesco Redi's experience using an animated video clip.Presentation. Slide number 7

Teacher: So, for the first time an attempt was made to prove the failure of abiogenesis, the spontaneous generation of living organisms, but this did not destroy the idea of ​​the spontaneous generation of life. Who continued the development of F. Redi's ideas in the future?

Student: A story about the experience of Louis Pasteur using an animated video clip.Presentation. Slide #8

Teacher: So, after quite convincing experiments by F. Redi and L. Pasteur, the position of abiogenesis was finally refuted and the ideas of biogenesis were confirmed, which raised a number of new questions: how and when did life on Earth originally arise.

What hypotheses were formed about the initial appearance of life on Earth?

Student: In search of an answer to the question - "How and when did life arise on Earth?" The following main hypotheses have been formed:

1. Life on our planet is brought from outside, from the Universe -This is the panstpermia theory.

2. Life on Earth has always existed, but it has undergone various cataclysms -This is the steady state theory.

3. Life arose on Earth as a result of biochemical processes in the conditions of a still young planet. This modern hypothesis is calledtheory of biochemical evolution.

Presentation. Slide #9

Teacher: All these theories of the origin of life on Earth exist, each of them is interesting in its own way and deserves attention. But today we will discuss the latest, modern theory about the origin of life on Earth.

IX. Learning new material.

So, the topic of the lesson is "Modern ideas about the origin of life on Earth."

Purpose: to get acquainted with the main provisions of the modern theory of A.I. Oparin

(write the date and topic of the lesson in a notebook)

Presentation. Slide №10,11

Teacher: Modern views on the origin of life on Earth were formed during the first half of the 20th century. And a great contribution to the development of modern theory - the theory of the evolution of living matter was made by our domestic biochemist AI Oparin.

(Report about Oparin).Presentation. Slide #12

Teacher: Presentation. Slide #13

So, Oparin proposed a theory - the theory of the evolution of living matter, which was later supported by many scientists around the world. The main ideas of his theory are:

1. Initially, life arose in the oceans as a result of chemical evolution, i.e.. abiogenic;
2. The development of living matter and the emergence of a wide variety of life forms occurred in the process of biological evolution, i.e. biogenic.

How did life appear on Earth? Under what conditions did it form and develop?

Now I suggest that you carefully watch a video fragment about the origin of life on Earth, after watching which, you will have to fill out the table "Conditions for the emergence of life on Earth."

Viewing a video clip. Disk “Fundamentals of General Biology. Grade 9"

Teacher: Fill in the table "Conditions for the emergence of life on Earth"based on the material of the film and the textbook on pages 122-123

(filling in the table)

Table discussion.

Presentation. Slide #14

1. Fixing the material.

Presentation. Slide #15

1. What stages in the emergence of life on Earth did Oparin single out in his theory?
2. Is it now possible for life to form in a non-biological way?
3. Testing.

1. Summary of the lesson.

Presentation. Slide #16

Grading.

1. Homework.

1. § 33.
2. COMPLETE FIVE TESTS TO TEST YOUR KNOWLEDGE ON THE TOPIC.

General lesson on the topic: "Fundamentals of the doctrine of heredity and variability"

B-I

Part "A"

Choose one correct answer from the four given

1. Due to mitosis, the number of chromosomes in body cells:

1. doubled;
2. Reduced by half;
3. It turns out to be the same;
4. Changes with age.

1. In the process of cell division, the most significant transformations undergo:

1. Ribosomes;
2. Chromosomes;
3. Mitochondria;
4. Lysosomes

1. The egg nucleus of an animal contains 16 chromosomes, and the nucleus of the sperm of this animal:

1. 24; 2) 8; 3) 16; 4) 32

1. The totality of all external and internal signs of the body is:

1. Gene pool; 2) Genotype; 3) Phenotype; 4) DNA code

1. Human hair color is controlled by paired genes that are located on homologous chromosomes and are called:

1. dominant; 2) recessive 3) allelic; 4) linked

1. The predominant trait that appears in offspring hybrids is called:

1. dominant; 2) recessive; 3) hybrid; 4) mutant

1. Specify the genotype of a person, if according to the phenotype he is fair-haired and blue-eyed (recessive traits):

one). AABB; 2) AaBv 3) aavb 4) Aavb

1. When crossing guinea pigs with genotypes AAbb and aaBB, offspring will be obtained with the genotype:

1. AABv 2) AaVv; 3) AaBB; 4) aaBB

1. When crossing dogs with black and red hair, 5 puppies appeared, and all are black, which indicates the appearance of:

1. the Law of Independent Succession;
2. Rules of uniformity;
3. Intermediate nature of inheritance;
4. Sex-linked inheritance

1. If during monohybrid crossing in the second generation of hybrids, splitting according to the phenotype 1:2:1 is observed, then this is a consequence:

1. incomplete dominance;
2. Complete dominance;
3. Interaction of genes;
4. Linked inheritance

Part "B"

Choose multiple correct answers:

1. How is mitosis different from meiosis?

1. There are two successive divisions
2. One division occurs, consisting of four phases
3. Two daughter cells are formed, identical to the mother;
4. 4 haploid cells are formed;
5. Both homologous chromosomes and homologous chromatids diverge towards the poles.

1. Choose the correct statement:

1. A haploid organism may be heterozygous;
2. A haploid organism cannot have homologous chromosomes;
3. Gametes are heterozygous;
4. The law of purity of gametes is violated for diploin organisms;
5. In diploid organisms, the gene is represented by two alleles.

1. Set the sequence of phases in mitosis:

1. Prophase
2. Telophase
3. anaphase
4. metaphase

The origin of life on Earth The history of ideas about the origin of life. Modern ideas about the origin of life. Theories of the origin of protobiopolymers. Evolution of protobionts. The initial stages of biological evolution. The origin of life on Earth The history of ideas about the origin of life Theories of the origin of protobiopolymers. Evolution of protobionts. Representations of philosophers Modern ideas about the origin of life Initial stages of biological evolution. Formation of planetary systems Works of L. Pasteur Primary atmosphere of the Earth Theories of eternity of life Sources of energy and age of the Earth Theories of the origin of life Environmental conditions on the ancient Earth It is often argued that at present there are all the conditions for the emergence of primitive living beings that were once. But if now in any reservoir containing all the necessary ammonium salts and phosphates and accessible to light, heat, electricity, etc., a protein capable of further more and more complex transformations was chemically formed, then this protein would immediately be destroyed or absorbed, which was not possible in the period before the creation of living beings. Charles Darwin Representations of Ancient and Medieval Philosophers. The general level of knowledge in the ancient world was low, and the ideas that prevailed at that time were distinguished by their fantasticness. So, Empedocles (5th century BC) attributed to trees the ability to carry eggs. It is not surprising, therefore, that even such a prominent scientist as Aristotle (4th century BC) expressed similar views, absurd from our point of view. For example, Aristotle Works of L. Pasteur. The works of L. Pasteur were a turning point in the history of the doctrine of the origin of life. The question of spontaneous generation was resolved, and the principle "everything is from life" for all known creatures could be considered fair and not knowing not one exception. Along with this, old ideas about the origin and eternity of the theory of the origin of life reappeared. All religions, and in particular the Christian one, teach that plants, animals and people at the “creation of the world” were created by God about the same as they are now. Therefore, according to religious ideas, our planet was from the very beginning inhabited by the same species of living beings. The statement of the church was refuted by the great English scientist Charles Darwin. He was able to scientifically prove that all highly organized beings of our time descended from organisms that were more simply arranged, through evolution, that is, through sequential development. The study of fossil remains preserved in the earth's crust from living creatures that once inhabited our planet fully confirmed Darwin's teachings. The earth has not always been inhabited by the same species of living beings. Living beings arose as a result of the consistent development of relatively simple living organisms. The older the fossil remains of organisms, the simpler the structure of these organisms. How then did the primary organisms - the ancestors of all life on Earth - arise? Before such a question, Darwin himself stopped in thought. At the end of the last century, F. Engels suggested that such primitive living beings could arise only as a result of the development of lifeless matter. At the end of the last century, F. Engels suggested that such primitive living beings could arise only as a result of the development of lifeless matter. However, at that time, scientists could not yet imagine the successive steps in the development of inanimate matter into living organisms. This was possible only in the 20th century, when a sufficient amount of scientific information was accumulated. The history of carbon. The history of the formation of the Earth shows that during the formation of our planet and in the first periods of its existence, enormous quantities of the simplest organic substances arose on the surface of the globe. It is now generally accepted in astronomy that the Earth and other planets of the solar system were formed from a giant cloud of gas and dust matter. Such gas and dust matter exists in interstellar space even now. Astronomers have learned to determine its composition. It contains methane (CH4). Perhaps there are more complex hydrocarbons. When the particles of the gas and dust cloud united into large planets (Jupiter, Saturn), methane and other gases remained in the primary atmosphere of the formed planets. Astronomers are still detecting these gases there. And in the composition of the Earth - it is a relatively small planet - carbon remained only in the form of graphite and carbides (compounds of carbon with metals). From carbides, when they interact with water, hydrocarbons are formed, and water was also part of the Earth - in the form of hydrates of various rocks. Consequently, hydrocarbons and their simplest derivatives must inevitably have formed on Earth long before the appearance of living beings on it. From carbon to proteins. The age of the earth is determined by science different ways within 5 billion years, life has existed on it for more than 2 billion years. Thus, for the greatest period of its existence, our planet was lifeless. And hydrocarbons and the simplest organic substances that arose from them began to appear on the earth's surface from the very beginning of its formation. They served as the initial link in that long chain of transformations that eventually led to the emergence on the earth's surface, in its water shell and in the atmosphere of a large number of diverse and sometimes very complex substances. The very nature of hydrocarbons already contains the possibility of such transformations. But in order for them to occur, a sufficient influx of energy from the outside is needed. Such energy on the earth's surface was available in several forms: the radiant energy of the Sun, in particular ultraviolet light. The possibility of the formation of complex organic compounds under the conditions that were on the surface of the Earth in the initial periods of its existence can be proved even by direct laboratory experiments. Recently, the American researcher S. Miller artificially reproduced the conditions of the Earth's primary atmosphere: he passed quiet electrical discharges through a mixture of methane, hydrogen, ammonia, and water vapor. The result is amino acids - the main components of the protein molecule. The Indian scientist K. Bahadur in a similar experiment obtained amino acids by exposure to sunlight. This experience, by using ultraviolet rays, was significantly refined by our scientists at the Institute of Biochemistry. A. N. Bach of the Academy of Sciences of the USSR. The experiments of the Japanese scientist Sh. Akabori also showed how, under the conditions of the primary periods of the Earth's existence, protein-like substances could form from the combination of amino acids, more precisely, from their immediate predecessors. Age of the Earth The age of the Earth is determined by science in various ways within 5 billion years, life has existed on it for more than 2 billion years. Thus, for the greatest period of its existence, our planet was lifeless. And hydrocarbons and the simplest organic substances that arose from them began to appear on the earth's surface from the very beginning of its formation. They served as the initial link in that long chain of transformations that eventually led to the emergence on the earth's surface, in its water shell and in the atmosphere of a large number of diverse and sometimes very complex substances. The very nature of hydrocarbons already contains the possibility of such transformations. But in order for them to occur, a sufficient influx of energy from the outside is needed. Such energy on the earth's surface was available in several forms: the radiant energy of the Sun, in particular ultraviolet light, electrical discharges in the atmosphere, the energy of atomic decay of natural radioactive substances. The emergence of primary organisms When such protein-like substances arose on Earth, new stage in the development of matter - the transition from organic compounds to living beings. At first, organic substances were in the seas and oceans in the form of solutions. They didn't have any building, any structure. But when solutions of proteins or other similar organic compounds are mixed with each other, special semi-liquid ones are released from the solutions. Although coacervate droplets are liquid, they have a certain internal structure. Particles of matter in them are not arranged randomly, as in a solution, but with a certain regularity. With the formation of coacervates, the rudiments of organization appear, however, still very primitive and unstable. For the droplet itself, this organization is of great importance. Any coacervate droplet is capable of trapping certain substances from the solution in which it floats. They chemically attach themselves to the substances of the droplet itself. Thus, the process of creation, growth takes place in it. But in any drop, along with creation, decay is also observed. One or another of these processes, depending on FURTHER DEVELOPMENT OF LIFE. The structure of these primary living organisms was much more perfect than that of coacervate droplets. But still, it was incomparably simpler than even the simplest living beings today. Natural selection, which began in coacervate droplets, continued with the advent of life. Centuries, millennia passed, and the structure of living beings improved more and more, adapted to the conditions of existence. At the dawn of life, both plants and animals were the smallest single-celled creatures, similar to bacteria living in our time, blue-green algae, amoeba. A great event in the history of the consistent development of living nature was the emergence of multicellular organisms, that is, living beings consisting of many cells combined into one organism. Gradually, but much faster than before, living organisms became more complex and diverse. The end … Worked on the presentation: Student 10 3rd grade of gymnasium No. 13 Ibragimova Khazina