For the first time, the American scientist Stanley Miller managed to obtain organic molecules - amino acids - in laboratory conditions simulating those that were on the primitive Earth. Then these experiments became a sensation, and their author gained worldwide fame. He currently continues to conduct research in the field of prebiotic (before life) chemistry at the University of California. The installation on which the first experiment was carried out was a system of flasks, in one of which it was possible to obtain a powerful electric discharge at a voltage of 100,000 V. Miller filled this flask with natural gases - methane, hydrogen and ammonia, which were present in the atmosphere of the primitive Earth. The flask below contained a small amount of water, simulating the ocean. The electric discharge was close in strength to lightning, and Miller expected that under its influence the formation chemical compounds, which, once in the water, react with each other and form more complex molecules. The result exceeded all expectations. Having turned off the installation in the evening and returning the next morning, Miller discovered that the water in the flask had acquired a yellowish color. What emerged was a soup of amino acids, the building blocks of proteins. Thus, this experiment showed how easily the primary ingredients of life could be formed. All that was needed was a mixture of gases, a small ocean and a little lightning.
Other scientists are inclined to believe that the ancient atmosphere of the Earth differs from the one that Miller modeled, and most likely consisted of carbon dioxide and nitrogen. Using this gas mixture and Miller's experimental setup, chemists attempted to produce organic compounds. However, their concentration in water was as insignificant as if a drop of food coloring were dissolved in a swimming pool. Naturally, it is difficult to imagine how life could arise in such a dilute solution. If indeed the contribution of earthly processes to the creation of reserves of primary organic matter was so insignificant, then where did it even come from? Maybe from space? Asteroids, comets, meteorites and even particles of interplanetary dust could carry organic compounds, including amino acids. These extraterrestrial objects could provide sufficient amounts of water for the origin of life to enter the primordial ocean or small body of water. organic compounds. The sequence and time interval of events, starting from the formation of primary organic matter and ending with the appearance of life as such, remains and, probably, will forever remain a mystery that worries many researchers, as well as the question of what exactly is considered life.
The process of formation of the first organic compounds on Earth is called chemical evolution. She preceded biological evolution. The stages of chemical evolution were identified by A.I. Oparin.
Stage I– non-biological, or abiogenic (from the Greek u, un – negative particle, bios – life, genesis – origin). At this stage, chemical reactions took place in the Earth's atmosphere and in the waters of the primary ocean, saturated with various inorganic substances, under conditions of intense solar radiation. During these reactions, simple organic substances could be formed from inorganic substances - amino acids, simple carbohydrates, alcohols, fatty acid, nitrogenous bases.
Possibility of synthesis organic matter from inorganic in the waters of the primary ocean was confirmed in the experiments of the American scientist S. Miller and domestic scientists A.G. Pasynsky and T.E. Pavlovskaya.
Miller designed an installation in which a mixture of gases was placed - methane, ammonia, hydrogen, water vapor. These gases could have been part of the primary atmosphere. In another part of the apparatus there was water, which was brought to a boil. Gases and water vapor circulating in the apparatus under high pressure, were exposed to electrical discharges for a week. As a result, about 150 amino acids were formed in the mixture, some of which are part of proteins.
Subsequently, the possibility of synthesizing other organic substances, including nitrogenous bases, was experimentally confirmed.
Stage II- synthesis of proteins - polypeptides that could be formed from amino acids in the waters of the primary ocean.
Stage III– the appearance of coacervates (from the Latin coacervus - clot, heap). Protein molecules that are amphoteric certain conditions can spontaneously concentrate and form colloidal complexes, which are called coacervates.
Coacervate droplets are formed when two different proteins are mixed. A solution of one protein in water is transparent. When different proteins are mixed, the solution becomes cloudy, and under a microscope, drops floating in the water are visible. Such drops - coacervates could have arisen in the waters of the primordial ocean, where various proteins were located.
Some properties of coacervates are externally similar to the properties of living organisms. For example, they "absorb" from environment and selectively accumulate certain substances and increase in size. It can be assumed that substances inside the coacervates entered into chemical reactions.
Because the chemical composition"broth" in different parts The primary ocean was different, the chemical composition and properties of the coacervates were different. Competitive relationships for substances dissolved in the “broth” could have formed between coacervates. However, coacervates cannot be considered living organisms, since they lacked the ability to reproduce their own kind.
Stage IV– the emergence of nucleic acid molecules capable of self-reproduction.
Research has shown that short chains nucleic acids capable of doubling without any connection with living organisms - in a test tube. The question arises: how did the genetic code appear on Earth?
The American scientist J. Bernal (1901-1971) proved that minerals played a large role in the synthesis of organic polymers. It has been shown that a number of rocks and minerals - basalt, clay, sand - have information properties, for example, the synthesis of polypeptides can be carried out on clays.
Apparently, initially a “mineralogical code” arose on its own, in which the role of “letters” was played by aluminum, iron, and magnesium cations, alternating in various minerals in a certain sequence. Three-, four- and five-letter codes appear in minerals. This code determines the sequence of amino acids joining into a protein chain. Then the role of the information matrix passed from minerals to RNA, and then to DNA, which turned out to be more reliable for the transmission of hereditary characteristics.
However, the processes of chemical evolution do not explain how living organisms arose. The processes that led to the transition from nonliving to living were called biopoiesis by J. Bernal. Biopoiesis includes stages that must have preceded the appearance of the first living organisms: the appearance of membranes in coacervates, metabolism, the ability to reproduce themselves, photosynthesis, and oxygen respiration.
The appearance of the first living organisms could have been caused by the formation of cell membranes by the alignment of lipid molecules on the surface of coacervates. This ensured the stability of their shape. The inclusion of nucleic acid molecules in the coacervates ensured their ability to self-replicate. In the process of self-reproduction of nucleic acid molecules, mutations arose, which served as material for natural selection.
So, on the basis of coacervates, the first living beings could arise. They apparently were heterotrophs and fed on energy-rich, complex organic substances contained in the waters of the primordial ocean.
As the number of organisms increased, competition between them intensified, as reserves nutrients in ocean waters decreased. Some organisms have acquired the ability to synthesize organic substances from inorganic ones using solar energy or the energy of chemical reactions. This is how autotrophs arose, capable of photosynthesis or chemosynthesis.
The first organisms were anaerobes and obtained energy through oxygen-free oxidation reactions such as fermentation. However, the advent of photosynthesis led to the accumulation of oxygen in the atmosphere. The result was respiration, an oxygen-based, aerobic oxidation pathway that is about 20 times more efficient than glycolysis.
Initially, life developed in the ocean waters, since strong ultraviolet radiation had a detrimental effect on organisms on land. The appearance of the ozone layer as a result of the accumulation of oxygen in the atmosphere created the preconditions for living organisms to reach land.
There are currently several scientific definitions life, but they are all inaccurate. Some of them are so wide that inanimate objects such as fire or mineral crystals fall under them. Others are too narrow, and according to them, mules that do not give birth are not recognized as living.
One of the most successful defines life as a self-sustaining chemical system capable of behaving in accordance with the laws of Darwinian evolution. This means that, firstly, a group of living individuals must produce descendants similar to themselves, which inherit the characteristics of their parents. Secondly, in generations of descendants the consequences of mutations must manifest themselves - genetic changes that are inherited by subsequent generations and cause population variability. And thirdly, it is necessary for a system of natural selection to operate, as a result of which some individuals gain an advantage over others and survive in changed conditions, producing offspring.
What elements of the system were necessary for it to have the characteristics of a living organism? Big number biochemists and molecular biologists believe that RNA molecules had the necessary properties. Ribonucleic acids are special molecules. Some of them can replicate, mutate, thus transmitting information, and, therefore, they could participate in natural selection. True, they are not able to catalyze the replication process themselves, although scientists hope that in the near future an RNA fragment with such a function will be found. Other RNA molecules are involved in "reading" genetic information and transferring it to ribosomes, where the synthesis of protein molecules occurs, in which the third type of RNA molecules takes part.
Thus, the most primitive living system could be represented by RNA molecules doubling, undergoing mutations and being subject to natural selection. In the course of evolution, based on RNA, specialized DNA molecules emerged - the custodians of genetic information - and no less specialized protein molecules, which took on the functions of catalysts for the synthesis of all currently known biological molecules.
At some point in time, a “living system” of DNA, RNA and protein found shelter inside a sac formed by a lipid membrane, and this structure, more protected from external influences, served as the prototype of the very first cells that gave rise to the three main branches of life that are represented in modern world bacteria, archaea and eukaryotes. As for the date and sequence of appearance of such primary cells, this remains a mystery. In addition, according to simple probabilistic estimates for the evolutionary transition from organic molecules There is not enough time for the first organisms - the first simplest organisms appeared too suddenly.
For many years, scientists believed that it was unlikely that life could have emerged and evolved during the period when the Earth was constantly being hit by large comets and meteorites, a period that ended approximately 3.8 billion years ago. However, recently, in the oldest sedimentary rocks on Earth, found in southwestern Greenland, traces of complex cellular structures were discovered, the age of which is approximately at least, 3.86 billion years. This means that the first forms of life could have arisen millions of years before the bombardment of our planet by large cosmic bodies stopped. But then a completely different scenario is possible (Fig. 4). Organic matter fell to Earth from space along with meteorites and other extraterrestrial objects that bombarded the planet for hundreds of millions of years since its formation. Nowadays, a collision with a meteorite is a rather rare event, but even now, exactly the same compounds continue to arrive from space along with interplanetary material to Earth as at the dawn of life.
Space objects falling to Earth could have played a central role in the emergence of life on our planet, since, according to a number of researchers, cells similar to bacteria could have arisen on another planet and then reached Earth along with asteroids. One piece of evidence supporting the theory of extraterrestrial origins of life was found inside a meteorite shaped like a potato and named ALH84001. This meteorite was originally a piece of Martian crust, which was then thrown into space as a result of an explosion when a huge asteroid collided with the surface of Mars, which occurred about 16 million years ago. And 13 thousand years ago, after a long journey within solar system This fragment of Martian rock in the form of a meteorite landed in Antarctica, where it was recently discovered. A detailed study of the meteorite revealed rod-shaped structures resembling fossilized bacteria inside it, which gave rise to heated scientific debate about the possibility of life deep in the Martian crust. It will be possible to resolve these disputes no earlier than 2005, when the National Aeronautics and Space Administration of the United States of America will implement a program to fly an interplanetary spacecraft to Mars to take samples of the Martian crust and deliver samples to Earth. And if scientists manage to prove that microorganisms once inhabited Mars, then we can speak with a greater degree of confidence about the extraterrestrial origin of life and the possibility of life being brought from outer space.
includes4 verification work and 1 final test:
Test work on the topic
"The Origin of Life on Earth"
Part A Write down the numbers of the questions, next to them write down the letters of the correct answers.
1. Living things differ from non-living things:
a) the composition of inorganic compounds; b) the presence of catalysts;
c) interaction of molecules with each other; d) metabolic processes.
2. The first living organisms on our planet were:
a) anaerobic heterotrophs; b) aerobic heterotrophs;
c) autotrophs; d) symbiont organisms.
3. The essence of the theory of abiogenesis is:
4. The experiments of Louis Pasteur proved that it is not possible:
a) spontaneous generation of life; b) the emergence of living things only from living things; c) bringing in “seeds of life” from Space;
d) biochemical evolution.
5. Of the listed conditions, the most important for the emergence of life is:
a) radioactivity; b) availability liquid water; c) the presence of gaseous oxygen; d) mass of the planet.
6. Carbon is the basis of life on Earth, because. He:
a) is the most common element on Earth;
b) the first of chemical elements began to interact with water;
c) has a low atomic weight;
d) capable of forming stable compounds with double and triple bonds.
7. The essence of creationism is:
a) the origin of living things from non-living things; b) the origin of living things from living things;
c) the creation of the world by God; d) the introduction of life from Space.
8. When did the geological history of the Earth begin: a) over 6 billion; b) 6 million; c) 3.5 billion years ago?
9. Where did the first ones arise? inorganic compounds: a) in the bowels of the Earth; b) in the primary ocean; c) in the primary atmosphere?
10. What was the prerequisite for the emergence of the primary ocean: a) cooling of the atmosphere; b) land subsidence; c) the appearance of underground sources?
11. What were the first organic substances that arose in the waters of the ocean: a) proteins; b) fats; c) carbohydrates; d) nucleic acids?
12. What properties did preservatives have: a) growth; b) metabolism; c) reproduction?
13. What properties are inherent in the probiont: a) metabolism; b) growth; c) reproduction?
14. What type of nutrition did the first living organisms have: a) autotrophic; b) heterotrophic?
15. What organic substances arose with the advent of photosynthetic plants : a) proteins; b) fats; c) carbohydrates; d) nucleic acids?
16.
The emergence of which organisms created the conditions for the development of the animal world: a) bacteria; b) blue-green algae; c) green algae?
Part B Complete the sentences.
1. The theory postulating the creation of the world by God (Creator) –….
2. Prenuclear organisms that do not have a nucleus limited by a shell and organelles capable of self-reproduction - ....
3. Phase-separated system interacting with external environment type open system, – … .
4. The Soviet scientist who proposed the coacervate theory of the origin of life - ....
Part C Answer the question.
List the main provisions of the theory of A.I. Oparina.
Why are nucleic acid compounds with coacervate droplets considered the most important stage the origin of life?
Test work on the topic “Chemical organization of the cell”
Option 1
Test "Test yourself"
2. What chemical elements contained in the cell are
macroelements: a) oxygen; b) carbon; c) hydrogen; d) nitrogen; e) phosphorus; f) sulfur; g) sodium; h) chlorine; i) potassium; j) calcium; l) iron; m) magnesium; n) zinc?
3. What is the average proportion of water in a cell: a) 80%; b) 20%; in 1%?
What vital compound does iron include: a) chlorophyll; b) hemoglobin; c) DNA; d) RNA?
Which compounds are monomers of protein molecules:
6. What part of amino acid molecules distinguishes them from each other: a) radical; b) amino group; c) carboxyl group?
7. Through what chemical bond are amino acids connected to each other in a protein molecule of primary structure: a) disulfide; b) peptide; c) hydrogen?
8. How much energy is released when 1 g of protein is broken down: a) 17.6 kJ; b) 38.9 kJ?
9. What are the main functions of proteins: a) construction; b) catalytic; c) motor; d) transport; e) protective; f) energy; g) all of the above?
10. Which compounds in relation to water are lipids: a) hydrophilic; b) hydrophobic?
11. Where fats are synthesized in cells: a) in ribosomes; b) plastids; c) EPS?
12. What is the importance of fats for the plant body: a) membrane structure; b) energy source; c) thermoregulation?
13. As a result of what process are organic substances formed from
inorganic: a) protein biosynthesis; b)) photosynthesis; c) ATP synthesis?
14. Which carbohydrates are monosaccharides: a) sucrose; b) glucose; c) fructose; d) galactose; e) ribose; e) deoxyribose; g) cellulose?
15. What polysaccharides are characteristic of plant cells: a) cellulose; b) starch; c) glycogen; d) chitin?
What is the role of carbohydrates in an animal cell:
17. What is included in the nucleotide: a) amino acid; b) nitrogenous base; c) phosphoric acid residue; d) carbohydrate?
18. What kind of helix is a DNA molecule: a) single; b) double?
19. Which nucleic acid has the greatest length and molecular weight:
a) DNA; b) RNA?
Complete the sentences
Carbohydrates are divided into groups………………….
Fats are…………………
The bond between two amino acids is called……………
The main properties of enzymes are…………..
DNA performs the functions……………..
RNA performs the functions of……………..
1. The content of which four elements in the cell is especially high: a) oxygen; b) carbon; c) hydrogen; d) nitrogen; e) iron; e) potassium; g) sulfur; h) zinc; i) honey?
2. Which group of chemical elements makes up 1.9% of the wet weight
cells; a) organogens (carbon, hydrogen, nitrogen, oxygen); c) macroelements; b) microelements?
What vital compound does magnesium include: a) chlorophyll; b) hemoglobin; c) DNA; d) RNA?
What is the importance of water for cell life:
5. What are fats soluble in: a) in water; b) acetone; c) broadcast; d) gasoline?
6. What is the chemical composition of a fat molecule: a) amino acids; b) fatty acids; c) glycerin; d) glucose?
7. What is the importance of fats for the animal body: a) membrane structure; b) energy source; c) thermoregulation; d) source of water; d) all of the above?
How much energy is released when 1 g of fat is broken down: a) 17.6 kJ; b) 38.9 kJ?
What is formed as a result of photosynthesis: a) proteins; b) fats; c) carbohydrates?
11. What polysaccharides are characteristic of animal cells: a) cellulose; b) starch; c) glycogen; d) chitin?
12.What is the role of carbohydrates in a plant cell: a) construction; b) energy; c) transport; d) component of nucleotides?
13. How much energy is released during the breakdown of 1 g of carbohydrates: a) 17.6 kJ; b) 38.9 kJ?
How many of the known amino acids are involved in protein synthesis: a) 20; b) 23; c) 100?
In which cell organelles are proteins synthesized: a) in chloroplasts; b) ribosomes; c) in mitochondria; d) in EPS?
17. What is a nucleic acid monomer:
a) amino acid; b) nucleotide; c) a protein molecule?
18. What substances does ribose belong to: a) proteins; b) fats; c) carbohydrates?
19. What substances are included in DNA nucleotides: a) adenine; b) guanine; c) cytosine; d) uracil; e) thymine; f) phosphoric acid: g) ribose; h) deoxyribose?
II
. Complete the sentences
1. Carbohydrates are divided into groups………………….
2. Fats are…………………
3. The bond between two amino acids is called……………
4. The main properties of enzymes are…………..
5. DNA performs the functions……………..
6. RNA performs the functions of……………..
DECODER
Option #1
I a: 2-d, f, g, h, i, j, l, m; 3-a; 4-GB; 5-g; 6-a; 7-6; 8-a; 9-f; 10-6; 11-v; 12-a,b; 13-6; 14-b,c,d,f; 15-a,b; 16th century; 17-b,c,d; 18-6; 19-a.
Option No. 2
1-a,b,c,d; 2-6; 3-a; 4-d; 5-b,c,d; 6-b,c; 7-d; 8-6; 9-in; 10-a,b; 11th century; 12-a.b,d; 13-a; 14-a; 15-b; 16-b,c,d; 17-6; 18-v; 19-a.b.c,e,f,3.
1. monosaccharides, oligosaccharides, polysaccharides
2. esters of glycerol and higher fatty acids
3. peptide
4. specificity and rate dependence of catalysis depends on temperature, pH, substrate and enzyme concentration
5. storage and transmission of hereditary information
6. Messenger RNAs carry information about the structure of the protein from the RK to the site of protein synthesis; they determine the location of amino acids in protein molecules. Transfer RNAs deliver the amino acid to the site of protein synthesis. Ribosomal RNAs are part of ribosomes, determining their structure and functioning.
Test work on the topic “Structure and vital activity of cells”
Option 1
I. What features of a living cell depend on the functioning of biological membranes:
a) selective permeability; b) absorption and retention of water; c) ion exchange; d) isolation from the environment and connection with it; d) all of the above?
2. Through which parts of the membrane does water pass: a) lipid layer; b) protein pores?
3. Which cytoplasmic organelles have a single-membrane structure: a) outer cell membrane; b) ES; c) mitochondria; d) plastids; e) ribosomes; e) Golgi complex; g) lysosomes?
4. How is the cell cytoplasm separated from the environment: a) ES membranes (endoplasmic reticulum); b) the outer cell membrane?
How many subunits does a ribosome consist of: a) one; b) two; c) three?
What is included in ribosomes: a) proteins; b) lipids; c) DNA; d) RNA?
Which organelles are characteristic only of plant cells: a) ES; b) ribosomes; c) mitochondria; d) plastids?
Which of the plastids are colorless: a) leucoplasts; b) chloroplasts; c) chromoplasts?
11. Which organisms are characterized by a nucleus: a) prokaryotes; b) eukaryotes?
12. Which nuclear structure takes part in the assembly of ribosomal subunits: a) nuclear envelope; b) nucleolus; c) nuclear juice?
13. Which of the membrane components determines the property of selective permeability: a) proteins; b) lipids?
14. How do large protein molecules and particles pass through the membrane: a) phagocytosis; b) pinocytosis?
15. Which cytoplasmic organelles have a non-membrane structure: a) ES; b) mitochondria; c) plastids; d) ribosomes; d) lysosomes?
16. Which organelle connects the cell into a single whole, transports substances, participates in the synthesis of proteins, fats, complex carbohydrates: a) outer cell membrane; b) ES; c) Golgi complex?
17. In which nuclear structure does the assembly of ribosomal subunits take place: a) in the nuclear sap; b) in the nucleolus; c) in the nuclear envelope?
18. What function do ribosomes perform: a) photosynthesis; b) protein synthesis; c) synthesis of fats; d) ATP synthesis; d) transport function?
19. What is the structure of the ATP molecule: a) biopolymer; b) nucleotide; c) monomer?
20. In which organelles is ATP synthesized in a plant cell: a) in ribosomes; b) in mitochondria; c) in chloroplasts?
21. How much energy is contained in ATP: a) 40 kJ; b) 80 kJ; c) 0 kJ?
22. Why is dissimilation called energy metabolism: a) energy is absorbed; b) energy is released?
23. What does the assimilation process include: a) synthesis of organic substances with energy absorption; b) decomposition of organic substances with the release of energy?
24. What processes occurring in the cell are assimilative: a) protein synthesis; b) photosynthesis; c) lipid synthesis; d) ATP synthesis; d) breathing?
25. At what stage of photosynthesis is oxygen formed: a) dark; b) light; c) constantly?
26. What happens to ATP in the light stage of photosynthesis: a) synthesis; b) splitting?
27. What role do enzymes play in photosynthesis: a) neutralize; b) catalyze; c) split?
28. What type of nutrition does a person have: a) autotrophic; b) heterotrophic; c) mixed?
29. What is the function of DNA in protein synthesis: a) self-duplication; b) transcription; c) synthesis of tRNA and rRNA?
30. What does the information of one gene of a DNA molecule correspond to: a) squirrel; b) amino acid; c) gene?
31. Why corresponds to a triplet and RNA: a) amino acid; b) squirrel?
32. What is formed in the ribosome during protein biosynthesis: a) protein of tertiary structure; b) secondary structure protein; a) polypeptide chain?
Option 2
What molecules does a biological membrane consist of: a) proteins; b) lipids; c) carbohydrates; d) water; d) ATP?
Through which parts of the membrane do ions pass: a) lipid layer; b) protein pores?
Which cytoplasmic organelles have a double-membrane structure: a) ES; b) mitochondria; c) plastids; d) Golgi complex?
a) vegetable; b) animals?
Where are ribosomal subunits formed, a) in the cytoplasm; b) in the nucleus; c) in vacuoles?
In which cell organelles are ribosomes located?
7. Why are mitochondria called the energy stations of cells: a) carry out protein synthesis; b) ATP synthesis; c) synthesis of carbohydrates; d) ATP breakdown?
8. What organelles are common to plant and animal cells: a) ES; b) ribosomes; c) mitochondria; d) plastids? 9. Which plastids are orange-red in color: a) leucoplasts; b) chloroplasts; c) chromoplasts?
10. Which plastids store starch: a) leucoplasts; b) chloroplasts; c) chromoplasts?
11. Which nuclear structure carries the hereditary properties of the organism: a) nuclear membrane; b) nuclear juice; c) chromosomes; d) nucleolus?
12. What are the functions of the nucleus: a) storage and transmission of hereditary information; b) participation in cell division; c) participation in protein biosynthesis; d) DNA synthesis; e) RNA synthesis; e) formation of ribosomal subunits?
13. What are the internal structures of mitochondria called: a) grana; b) cristae; c) matrix?
14. What structures are formed by the inner membrane of the chloroplast: a) thylakoid grana; b) stromal thylakoids; c) stroma; d) cristae?
15. Which plastids have green color: a) leukoplasts; b) chloroplasts; c) chromoplasts?
16. Which plastids give color to flower petals, fruits, and autumn leaves:
a) leukoplasts; b) chloroplasts; c) chromoplasts?
17. With the appearance of what structure did the nucleus separate from the cytoplasm: a) chromosomes; b) nucleolus; c) nuclear juice; d) nuclear membrane?
18. What is the nuclear envelope: a) continuous envelope; b) porous shell?
19. What compounds are included in ATP: a) nitrogenous base; b) carbohydrate; c) three molecules of phosphoric acid; d) glycerin; d) amino acid?
20. In which organelles are ATP synthesized in an animal cell: a) ribosomes; b) mitochondria; c) chloroplasts?
21. As a result of what process occurring in mitochondria is ATP synthesized: a) photosynthesis; b) breathing; c) protein biosynthesis?
22. Why is assimilation called plastic exchange: a) organic substances are created; b) are organic substances broken down?
23. What does the dissimilation process include: a) synthesis of organic substances with energy absorption; c) decomposition of organic substances with the release of energy?
24. How is the oxidation of organic substances different in mitochondria?
from combustion of the same substances: a) release of heat; b) release of heat and synthesis of ATP; c) ATP synthesis; d) the oxidation process occurs with the participation of enzymes; e) without the participation of enzymes?
25. In which cell organelles does the process of photosynthesis take place: a) in mitochondria; b) ribosomes; c) chloroplasts; d) chromoplasts?
26. When which compound is broken down, free oxygen is released during photosynthesis:
a) C0 2; b) H 2 0; c) ATP?
27. Which plants create the greatest biomass and excrete most oxygen:
a) spore-bearing; b) seed; c) algae?
28. Which cell components are directly involved in protein biosynthesis: a) ribosomes; b) nucleolus; c) nuclear membrane; d) chromosomes?
29. Which nuclear structure contains information about the synthesis of one protein: a) DNA molecule; b) triplet of nucleotides; c) gene?
30. What components make up the body of the ribosome: a) membranes; b) proteins; c) carbohydrates; d) RNA; d) fats?
31. How many amino acids are involved in the biosynthesis of proteins, a) 100; b) 30; in 20?
32. Where complex structures of protein molecules are formed: a) in the ribosome; b) in the cytoplasmic matrix; c) in the channels of the endoplasmic reticulum?
Examination
Option 1:
1d; 2b; 3a, f, g; 4b; 5 B; 6a,d; 7b; 8g; 9a; 10b; 11b; 12b; 13b; 14a; 15g; 16b; 17b; 18b; 19b,c; 20b,c; 21b; 22b; 23a; 24a, b, c, d; 25b; 26 a; 27 a, b, c; 28b; 29b, c; 30a; 31a; 32c.
Option 2:
1a,b; 2a4 3b,c; 4a; 5 B; 6a,c,d,e; 7b; 8a,b,c; 9c; 10a; 11c; 12all; 13b; 14a,b; 15b; 16c; 17g; 18b; 19a,b,c: 20b; 21b; 22a; 23b; 24c,d; 25v; 26b; 26b; 28a,d; 29c; 30b,d; 31c; 32c.
Test work on the topic “Reproduction and development of organisms”
"Thaw out"
What's happened life cycle cells?
What are the different types of postembryonic development?
What is the structure of the blastula?
What functions do chromosomes perform?
What is mitosis?
What is cell differentiation?
What is the structure of the gastrula?
What germ layers are formed during embryonic development?
Name three Russian scientists who made a great contribution to the development of embryology.
List the stages of embryonic development of multicellular animals.
What is embryonic induction?
What are the advantages of indirect development over direct development?
What periods is it divided into? individual development organisms?
What is ontogeny?
What facts confirm that the embryo is an integral system?
What is the set of chromosomes and DNA in prophase 1 and prophase 2 of meiosis?
What is the reproductive period?
What is the set of chromosomes and DNA in metaphase 1 and metaphase 2 of meiosis?
What is the number of chromosomes and DNA during anaphase of mitosis and anaphase 2 of meiosis?
List the types of asexual reproduction.
List the stages of embryogenesis.
How many chromosomes and DNA will there be in cells during metaphase of mitosis and telophase of meiosis 2?
What is the vegetative pole in the blastula?
Name the types of chromosomes (by structure).
What are blastocoel and gastrocoel?
Formulate the biogenetic law.
What is cell specialization?
What is meiosis?
What is the number of chromosomes in cells at the beginning and end of mitosis?
What is stress?
List the phases of meiosis.
How many eggs and sperm are formed as a result of gametogenesis?
What are bivalents?
Who are primary and secondary cavity animals?
What is a neurula?
What periods does interphase consist of?
In what biological significance fertilization?
How does the second meiotic division end?
What is homeostasis?
What is sporulation?
In what biological meaning reproduction?
What is the importance of reproduction in nature?
What is a gastrula?
What parts does a bird's egg consist of?
What are the functions of a zygote?
How is regeneration expressed in highly organized animals and humans?
What germ layers are formed in multicellular animals at the gastrula stage?
List the phases of meiosis.
What stages do animals go through during development and metamorphosis?
What is direct and indirect development?
How does cleavage differ from mitotic division?
What stages are distinguished in post-embryonic human development?
What is amitosis?
What organs develop from the mesoderm in the human embryo?
What is the set of chromosomes and DNA in anaphase 1 and anaphase 2 of meiosis?
List the phases of mitosis.
What is animal embryonic development?
What is the number of chromosomes and DNA in cells in prophase of mitosis and anaphase 2 of meiosis?
What functions do the egg and sperm perform?
What is the structure of a chromosome?
How many chromosomes and DNA will there be in a cell at anaphase of mitosis and metaphase 1 of meiosis?
What happens to the cell in interphase?
List the main stages of egg formation.
What is regeneration?
What is the set of chromosomes and DNA in telophase 1 and telophase 2 of meiosis?
Who created the biogenetic law?
What is conjugation?
What are crossover chromosomes?
What does crossing over lead to?
How can we explain the differences in egg sizes between birds and humans?
What is the structure of the blastula?
In what phase of meiosis does conjugation occur and what is it?
What are the stages of oogenesis called?
In what phase of meiosis does crossing over occur and what is it?
What is the biological significance of crossing over?
From which germ layer does the human heart form?
How does the first meiotic division end?
Test "Test yourself"
1. What type of cell division is not accompanied by a decrease in the number of chromosomes: a) amitosis; b) meiosis; c) mitosis?
2. What set of chromosomes is obtained during mitotic division of a diploid nucleus: a) haploid; b) diploid?
3. How many chromatids are in a chromosome at the end of mitosis: a) two; b) alone?
4. Which division is accompanied by a reduction (decrease) in the number of chromosomes in a cell by half: a) mitosis; 6) amitosis; c) meiosis? 5. In what phase of meiosis does chromosome conjugation occur: a) in prophase 1; 6) in metaphase 1; c) in prophase 2?
6. Which method of reproduction is characterized by the formation of gametes: a) vegetative; b) asexual; c) sexual?
7. What set of chromosomes do sperm have: a) haploid; b) diploid?
8. In which zone during gametogenesis does meiotic cell division occur:
a) in the growth zone; 6) in the breeding zone; c) in the ripening zone?
9. Which part of the sperm and egg is the carrier of genetic information: a) membrane; b) cytoplasm; c) ribosomes; d) core?
10. The development of which germ layer is associated with the appearance of the secondary body cavity: a) ectoderm; b) mesoderm; c) endoderm?
11. Due to which germ layer the notochord is formed: a) ectoderm; b) endoderm; c) mesoderm?
Option 2
1. What division is typical for somatic cells: a) amitosis; b) mitosis; c) meiosis?
2. How many chromatids are in a chromosome at the beginning of prophase: a) one; b) two?
3. How many cells are formed as a result of mitosis: a) 1; b) 2; c) 3; d) 4?
4. As a result of what type of cell division four haploid cells are obtained:
a) mitosis; b) meiosis; c) amitosis?
What set of chromosomes does a zygote have: a) haploid; b) diploid?
What is formed as a result of oogenesis: a) sperm; b) egg; c) zygote?
7. Which method of reproduction of organisms arose later than all others in the process of evolution: a) vegetative; b) asexual; c) sexual?
9. Why is the stage of a two-layer embryo called gastrula:
a) looks like a stomach; b) has an intestinal cavity; c) has a stomach?
10. With the appearance of which germ layer does the development of tissues and organ systems begin:
a) ectoderm; b) endoderm; c) mesoderm?
11. Due to what germ layer is it formed? spinal cord: a) ectoderm; b) mesoderm; c) endoderm?
Examination
Option #1
1c ; 2b; 3b; 4c; 5a; 6c; 7a; 8c; 9g; 10b; 11v
Option No. 2
1b; 2b; 3b; 4b; 5 B; 6b; 7c; 8a; 9b; 10v; 11a.
Final testing
TEST WORK FOR THE COURSE
"General Biology" 10th grade
Option 1.
Instructions for students
The test consists of parts A, B, C. 60 minutes are allotted for completion. Read each task carefully and the suggested answer options, if any. Answer only after you understand the question and have considered all possible answers.
Complete the tasks in the order in which they are given. If any task gives you difficulty, skip it and try to complete the ones you are confident in the answers to. You can return to missed tasks if you have time.
One or more points are given for completing tasks of varying complexity. The points you receive for completed tasks are summed up. Try to complete as many tasks as possible and gain greatest number points.
We wish you success!
The process of formation of the first organic compounds on Earth is called chemical evolution. It preceded biological evolution. The stages of chemical evolution were identified by A.I. Oparin.
Stage I is non-biological, or abiogenic (from the Greek u, un - negative particle, bios - life, genesis - origin). At this stage, chemical reactions took place in the Earth's atmosphere and in the waters of the primary ocean, saturated with various inorganic substances, under conditions of intense solar radiation. During these reactions, from inorganic substances simple organic substances could be formed - amino acids, alcohols, fatty acids, nitrogenous bases.
The possibility of synthesizing organic substances from inorganic ones in the waters of the primary ocean was confirmed in the experiments of the American scientist S. Miller and domestic scientists A.G. Pasynsky and T.E. Pavlovskaya.
Miller designed an installation in which a mixture of gases was placed - methane, ammonia, hydrogen, water vapor. These gases could have been part of the primary atmosphere. In another part of the apparatus there was water, which was brought to a boil. Gases and water vapor circulating in the apparatus under high pressure were exposed to electrical discharges for a week. As a result, about 150 amino acids were formed in the mixture, some of which are part of proteins.
Subsequently, the possibility of synthesizing other organic substances, including nitrogenous bases, was experimentally confirmed.
Stage II - synthesis of proteins - polypeptides that could be formed from amino acids in the waters of the primary ocean.
Stage III - the appearance of coacervates (from the Latin coacervus - clot, heap). Protein molecules that are amphoteric, under certain conditions, can spontaneously concentrate and form colloidal complexes, which are called coacervates.
Coacervate droplets are formed when two different proteins are mixed. A solution of one protein in water is transparent. When different proteins are mixed, the solution becomes cloudy, and under a microscope, drops floating in the water are visible. Such drops—coacervates—could have arisen in the waters of the primordial ocean, where various proteins were located.
Some properties of coacervates are externally similar to the properties of living organisms. For example, they “absorb” from the environment and selectively accumulate certain substances and increase in size. It can be assumed that substances inside the coacervates entered into chemical reactions.
Since the chemical composition of the “broth” differed in different parts of the primordial ocean, the chemical composition and properties of the coacervates were not the same. Competitive relationships for substances dissolved in the “broth” could have formed between coacervates. However, coacervates cannot be considered living organisms, since they lacked the ability to reproduce their own kind.
Stage IV - the emergence of nucleic acid molecules capable of self-reproduction.
Research has shown that short chains of nucleic acids are capable of doubling without any connection with living organisms - in a test tube. The question arises: how did the genetic code appear on Earth?
The American scientist J. Bernal (1901-1971) proved that minerals played a large role in the synthesis of organic polymers. It has been shown that a number of rocks and minerals - basalt, clay, sand - have information properties, for example, the synthesis of polypeptides can be carried out on clays.
Apparently, initially a “mineralogical code” arose on its own, in which the role of “letters” was played by aluminum, iron, and magnesium cations, alternating in various minerals in a certain sequence. Three-, four- and five-letter codes appear in minerals. This code determines the sequence of amino acids joining into a protein chain. Then the role of the information matrix passed from minerals to RNA, and then to DNA, which turned out to be more reliable for the transmission of hereditary characteristics.
However, the processes of chemical evolution do not explain how living organisms arose. The processes that led to the transition from nonliving to living were called biopoiesis by J. Bernal. Biopoiesis includes stages that must have preceded the appearance of the first living organisms: the appearance of membranes in coacervates, metabolism, the ability to reproduce themselves, photosynthesis, and oxygen respiration.
The appearance of the first living organisms could have been caused by the formation of cell membranes by the alignment of lipid molecules on the surface of coacervates. This ensured the stability of their shape. The inclusion of nucleic acid molecules in the coacervates ensured their ability to self-replicate. In the process of self-reproduction of nucleic acid molecules, mutations arose, which served as material for.
So, on the basis of coacervates, the first living beings could arise. They apparently were heterotrophs and fed on energy-rich, complex organic substances contained in the waters of the primordial ocean.
As the number of organisms increased, competition between them intensified, as the supply of nutrients in the ocean waters decreased. Some organisms have acquired the ability to synthesize organic substances from inorganic ones using solar energy or the energy of chemical reactions. This is how autotrophs arose, capable of photosynthesis or chemosynthesis.
The first organisms were anaerobes and obtained energy through oxygen-free oxidation reactions such as fermentation. However, the advent of photosynthesis led to the accumulation of oxygen in the atmosphere. The result was respiration, an oxygen-based, aerobic oxidation pathway that is about 20 times more efficient than glycolysis.
Initially, life developed in the ocean waters, since strong ultraviolet radiation had a detrimental effect on organisms on land. The appearance of the ozone layer as a result of the accumulation of oxygen in the atmosphere created the preconditions for living organisms to reach land.
The situation was different on the surface of the Earth.
Here, the initially formed hydrocarbons must have entered into chemical reaction with the substances surrounding them, primarily with water vapor in the earth’s atmosphere. Hydrocarbons contain enormous chemical potential. Numerous studies by a number of chemists, especially the work of the Russian academician A. Favorsky and his school, show the exceptional ability of hydrocarbons for various chemical transformations. Of particular interest to us is the ability of hydrocarbons to add water to themselves relatively easily. There is no doubt that those hydrocarbons that primarily appeared on the earth's surface, for the most part, should have been combined with water. As a result of this, in earth's atmosphere new and varied substances were formed. Previously, hydrocarbon molecules were built from only two elements: carbon and hydrogen. But in addition to hydrogen, water also contains oxygen. Therefore, the molecules of the newly emerged substances already contained atoms of three different elements - carbon, hydrogen and oxygen. Soon they were joined by a fourth element - nitrogen.
In the atmosphere major planets(Jupiter and Saturn) we, along with hydrocarbons, can always detect another gas - ammonia. This gas is well known to us, since its solution in water forms what we call ammonia. Ammonia is a compound of nitrogen and hydrogen. This gas was present in significant quantities in the Earth’s atmosphere during the period of its existence that we are now describing. Therefore, hydrocarbons combined not only with water vapor, but also with ammonia. In this case, substances arose whose molecules were already built from four different elements - carbon, hydrogen, oxygen and nitrogen.
Thus, at the time we are describing, the Earth was a bare rocky ball, shrouded on the surface in an atmosphere of water vapor. In this atmosphere, in the form of gases, there were also those various substances that were obtained from hydrocarbons. We can rightfully call these substances organic substances, although they arose long before the first living beings appeared. In their structure and composition they were similar to some of the chemical compounds that can be isolated from the bodies of animals and plants.
The Earth gradually cooled, giving off its heat into the cold interplanetary space. Finally, the temperature of its surface approached 100 degrees, and then the water vapor of the atmosphere began to condense into droplets and rushed to the hot desert surface of the Earth in the form of rain. Powerful downpours poured onto the Earth and flooded it, forming the primary boiling ocean. Organic substances in the atmosphere were also carried away by these showers and passed into the waters of this ocean.
What was going to happen to them next? Can we reasonably answer this question? Yes, at present we can easily prepare these or similar substances, artificially obtain them in our laboratories from the simplest hydrocarbons. Let's take water solution these substances and leave it to stand at more or less high temperature. Will these substances then remain unchanged or will they undergo various types of chemical transformations? It turns out that even in those short time, during which we can conduct our observations in laboratories, organic substances do not remain unchanged, but are transformed into other chemical compounds. Direct experience shows us that in such aqueous solutions of organic substances such numerous and varied transformations occur that it is even difficult to briefly describe them. But the main thing general direction These transformations boil down to the fact that relatively simple small molecules of primary organic substances combine with each other in a thousand ways and thus form larger and larger and more complex molecules.
For clarification, I will give only two examples here. Back in 1861, our famous compatriot, chemist A. Butlerov, showed that if formaldehyde is dissolved in lime water and this solution is left to stand in a warm place, then after some time it will acquire a sweet taste. It turns out that under these conditions, six formaldehyde molecules combine with each other into one larger, more complex sugar molecule.
The oldest member of our Academy of Sciences, Alexey Nikolaevich Bakh on long time left an aqueous solution of formaldehyde to stand and potassium cyanide. At the same time, even more complex substances than Butlerov's. They had huge molecules and in their structure were close to proteins, the main constituent substances of any living organism.
There are dozens and hundreds of such examples. They undoubtedly prove that the simplest organic substances in the aquatic environment can easily be transformed into much more complex compounds such as sugars, proteins and other substances from which the bodies of animals and plants are built.
The conditions that were created in the waters of the primary hot ocean were not much different from the conditions reproduced in our laboratories. Therefore, at any point in the ocean of that time, in any drying puddle, the same complex organic substances that were obtained by Butlerov, Bach and in the experiments of other scientists should have formed.
So, as a result of the interaction between water and the simplest derivatives of hydrocarbons, through a series of successive chemical transformations, the material from which all living beings are currently built was formed in the waters of the primordial ocean. However, this was just construction material. In order for living beings - organisms - to arise, this material had to acquire the necessary structure, a certain organization. So to speak, it was only bricks and cement from which a building can be built, but it is not yet the building itself.
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