Scientific theories of the origin of life on Earth.

According to the panspermia hypothesis, life is brought from space either in the form of spores of microorganisms, or by deliberately populating the planet with intelligent aliens from other worlds. There is no direct evidence in favor of the cosmic origin of life. Space, however, along with volcanoes, could be a source of low-molecular organic compounds, the solution of which served as a medium for the development of life.

According to the second hypothesis, life arose on Earth when a favorable set of physical and chemical conditions developed that made possible the abiogenic formation of organic substances from inorganic ones.

In the middle of the last century, L. Pasteur finally proved the impossibility of spontaneous generation of life under present conditions. Oparin and Haldane suggested that under the conditions that took place on the planet several billion years ago, the formation of living matter was possible. These conditions included the presence of a reducing atmosphere, water, energy sources, acceptable temperature, and the absence of other living beings.

Scientific definition of the essence of life. properties of the living. Levels of organization of the living.

The first scientific definition of life was given by Friedrich Engels in Dialectics of Nature in 1898. Life is a mode of existence of protein molecules, the essential point of which is the constant exchange of substances with the environment. With the cessation of metabolism, life ceases.

properties of the living.

self-reproduction

self-renewal

Self-regulation

Integrity and discreteness

Metabolism is a process of assimilation and dissimilation.

Heredity is the property of living organisms to pass on their traits to their offspring.

Variability is the property of changing under the influence of the environment.

Movement is the property of moving in space.

Irritability is the property of responding with various reactions to environmental influences.

Levels of organization of the living:

Microbiosystem: (-molecular – subcellular – cellular)

Mesobiosystem: (-tissue - organ - organism)

Macrobiosystem: (-population-species - biogeocenotic - biospheric)

Metabolism. The concept of assimilation and dissimilation. Types of metabolism.

Metabolism is a set of chemical transformations that ensure growth, vital activity, and reproduction in living organisms.

Assimilation (plastic exchange or anabolism) is an endothermic process of the synthesis of high-molecular organic substances, accompanied by the absorption of energy. Occurs in the cytoplasm.

Dissimilation (energy metabolism or catabolism) - energy is released. The breakdown of substances in the cell to simple, non-specific compounds. It starts in the cytoplasm and ends in the mitochondria.

Types of metabolism:

Protein

carbohydrate

The process of converting external substances into energy and a set of reactions that result in the formation of complex organic substances necessary for the life of an organism is called metabolism or metabolism. The main metabolic processes are assimilation and dissimilation, which are closely interconnected.

Metabolism

Metabolism occurs at the cellular level, but begins with the process of digestion and respiration. Organic compounds and oxygen are involved in the metabolism.

Nutrients enter the gastrointestinal tract with food, and already in the oral cavity begin to break down. As a result of digestion, the molecules of substances enter the bloodstream through the intestinal villi and are carried to each cell. Oxygen enters the lungs during breathing and is also carried by the blood stream.

Assimilation and dissimilation in metabolism are two interrelated processes running in parallel:

• assimilation or anabolism - a set of processes for the synthesis of organic substances with energy consumption;
• dissimilation or catabolism - the process of decomposition or oxidation, as a result of which simpler organic substances and energy are formed.

Dissimilation is called energy exchange, because. the main goal of the process is to obtain energy. Assimilation is called plastic exchange, because. The energy released as a result of dissimilation goes to the construction of the organism.

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Cellular exchange

The processes of assimilation and dissimilation of substances occurring in the cell play an important role for the whole organism. Energy is obtained from incoming substances in the mitochondria or cytoplasm. During dissimilation, ATP molecules (adenosine triphosphate) are formed. It is a universal source of energy that is involved in further metabolic processes. The course of catabolism on the example of starch breakdown is described in the table.

Dissimilation	Where is happening	Result
Preparatory	digestive tract	Breakdown of proteins, fats, carbohydrates that enter the body into simpler compounds: Proteins - to amino acids; Fats - to fatty acids and glycerol; Complex carbohydrates (starch) - to glucose
glycolysis	in the cytoplasm	Anoxic breakdown of glucose to pyruvic acid with the formation of energy. Most (60%) of the energy is dissipated as heat, the rest (40%) is used to form two ATP molecules. In the future, without access to oxygen, pyruvic acid turns into lactic acid.
intracellular respiration	in mitochondria	Breakdown of lactic acid with the participation of oxygen. Carbon dioxide is formed - the end product of decomposition

The composition of ATP includes:

• adenine is a nitrogenous base;
• ribose is a monosaccharide;
• three residues of phosphoric acid.

Rice. 1. ATP formula.

ATP is a macroergic compound and, upon hydrolysis (interaction with water), releases a significant amount of energy that goes to the restoration and development of the body, maintaining body temperature, and also participates in chemical reactions in the process of assimilation. From simpler substances in the course of anabolism, complex substances characteristic of a given organism are synthesized.

Assimilation examples:

• cell growth;
• tissue renewal;
• muscle formation;
• wound healing.

Rice. 2. The process of metabolism.

Metabolic processes are regulated by hormones. For example, adrenaline shifts the metabolism towards dissimilation, and insulin - towards assimilation.

Autotrophs and heterotrophs

All living organisms, depending on the method of nutrition, are divided into autotrophs and heterotrophs. Autotrophs include plants and some bacteria that synthesize organic substances from inorganic substances. Such organisms independently create all the substances necessary for life.

In plants, the process of assimilation is called photosynthesis. Sunlight is used as an energy source for the synthesis of organic substances, not ATP.

Heterotrophs are organisms that use ready-made organic compounds to obtain energy and maintain life. Heterotrophs include all animals, fungi, most bacteria, and parasitic plants. Organic substances with food enter the body, where the processes of anabolism and catabolism begin to release energy and obtain the necessary substances.

"Introduction to General Biology and Ecology. Grade 9". A.A. Kamensky (gdz)

Assimilation and dissimilation are opposite metabolic processes

Question 1. Why is the Sun the main source of energy on Earth?
Any living cell, carrying out diverse processes of synthesis and decay of substances, is similar to the most complex chemical plant. For the normal course of these chemical processes, a constant exchange of substances between the cell and the environment is necessary, as well as a constant transformation of energy in the cell. Proteins, fats, carbohydrates, vitamins, microelements obtained from outside are used by cells for the synthesis of the compounds they need, the construction of cellular structures. However, the synthesis of substances requires energy. The main source of energy for living organisms is the Sun.

Question 2. Why is assimilation impossible without dissimilation, and vice versa?
From the food components entering the cell, under the action of biological catalysts, enzymes, new molecules are synthesized to replace the consumed substances, to build organelles. The whole set of reactions of biological synthesis of substances in a cell (biosynthesis) is called assimilation, or plastic exchange.
Obviously, the synthesis of any substances is impossible without the expenditure of energy. Assimilation reactions occur especially intensively in a growing, developing cell. The most important of these reactions are protein synthesis and photosynthesis. How does a cell get energy for biosynthesis reactions? Along with the processes of synthesis of new substances in cells, there is a constant decay of complex organic substances stored during assimilation. With the participation of enzymes, these molecules break down to simpler compounds; this releases energy. Most often, this energy is stored in the form of adenosine triphosphate (ATP). Further, the energy of ATP is used for various needs of the cell, including for biosynthesis reactions. The set of reactions of decomposition of the substances of the cell, accompanied by the release of energy, is called dissimilation.
Assimilation and dissimilation are opposite processes: in the first case, substances are formed, in the second they are destroyed. But they are closely interconnected and impossible without each other. After all, if complex substances are not synthesized and stored in the cell, then there will be nothing to decay when energy is needed. And if the substances do not decay, then where to get the energy for the synthesis of the necessary substances?
Thus, assimilation and dissimilation are two sides of a single process of metabolism and energy, called metabolism (gr. metabole - transformation).

Question 3. Could any living creatures survive on Earth if the Sun went out?
The sun is a source of energy for plants, which, thanks to chlorophyll, synthesize organic substances. Animals, fungi and bacteria use this organic matter to obtain the energy of ATP, which they use to synthesize the necessary compounds and build cells. Without solar energy, they could not exist. Many species of bacteria capable of synthesizing the organic compounds they need from inorganic ones at the expense of the energy of chemical oxidation reactions occurring in the cell are chemotrophs. The substances captured by the bacterium are oxidized, and the resulting energy is used for the synthesis of complex organic molecules from CO 2 and H 2 O. This process is called chemosynthesis.
The most important group of chemosynthetic organisms are nitrifying bacteria. Exploring them, S.N. Vinogradsky in 1887 discovered the process chemosynthesis. Nitrifying bacteria, living in the soil, oxidize the ammonia formed during the decay of organic residues to nitrous acid. Other types of bacteria are able to use the energy of many other oxidation-reduction reactions (sulfur bacteria, iron bacteria, etc.). Microorganisms whose metabolism does not depend on solar energy could well survive if the Sun went out.

All cells and living organisms are open systems, that is, they are in a state of constant exchange of energies and substances with the environment. There are open systems in inanimate nature, but their existence is qualitatively different from living organisms. Consider the following example: a burning piece of native sulfur is in a state of exchange with the environment. When it burns, O 2 is absorbed, and SO 2 and energy (in the form of heat) are released. However, at the same time, a piece of sulfur, as a physical body, collapses, loses its primary structure.

For living organisms, however, exchange with the environment is a condition for maintaining, maintaining their structural organization through self-renewal of all substances and components of which they are composed.

Metabolism (metabolism)- a set of processes occurring in living organisms (consumption, transformation, accumulation and release of substances and energy) that ensure their vital activity, development, growth, reproduction. In the process of metabolism, splitting and synthesis of molecules that make up cells occur; renewal of cellular structures and intercellular substance.

Metabolism is based on interrelated processes of assimilation (anabolism) and dissimilation (catabolism). During assimilation (plastic exchange), complex substances are synthesized from simple ones. It is thanks to this that all organic substances are created in the cell, which are necessary for the construction of its structural components, enzyme systems, etc. Assimilation is always carried out with the expenditure of energy.

In the course of dissimilation (energy metabolism), complex organic substances are broken down into simpler or inorganic ones. In this case, energy is released, which is consumed by the cell to perform various processes that ensure its vital activity (synthesis and transport of substances, mechanical work, etc.).

All living organisms can be divided into two groups: autotrophs and heterotrophs, which differ in sources of energy and necessary substances to ensure their vital activity.

Autotrophs- organisms that synthesize organic compounds from inorganic substances using the energy of sunlight (as phototrophs - plants, cyanobacteria) or energy obtained from the oxidation of mineral (inorganic) substances (such as chemotrophs - sulfur bacteria, iron bacteria, etc.). Consequently, they are able to independently create the substances required for their life activity.

DISSIMILATION AND ASSIMILATION

DISSIMILATION AND ASSIMILATION

(from Latin dissimilis - dissimilar and assimilis - similar) - mutually opposite processes that ensure the continuous life of living organisms in unity; flow in the body continuously, simultaneously, in close interconnection and constitute two sides of a single metabolic process. D. and a. form a complex system consisting of a chain of interconnected biochemical. reactions, each of which individually is only chemical, but to-rye in unity constitute, which has a biological. nature. The contradiction of D. and a. defines dynamic. balance of the living body. As open (see Life), it must, constantly acquiring, just as continuously spend the acquired energy, so that it does not increase.

D and with with and m and l I c and I - the process of splitting in a living organism organic. substances into simpler compounds - leads to the release of energy necessary for all vital processes of the body. A s and m and l i c and i - the process of assimilation of organic. substances entering, and assimilation of their organic. substances characteristic of a given organism, comes with the use of energy released during the processes of dissimilation. At the same time, compounds with high energy (macroergic) are formed (synthesized), to-rye become a source of energy released during dissimilation.

The dissimilation of nutrients entering the body, mainly proteins, fats and carbohydrates, begins with their enzymatic breakdown into simpler compounds - intermediate metabolic products (peptides, amino acids, glycerol, fatty acids, monosaccharides), from which the body synthesizes (assimilates ) organic compounds necessary for its life. All processes of D. and a. flow in the body as a whole. See Metabolism, Life and lit. with these articles.

I. Weisfeld. Moscow.

Philosophical Encyclopedia. In 5 volumes - M .: Soviet Encyclopedia. Edited by F. V. Konstantinov. 1960-1970 .

See what "DISSIMILATION AND ASSIMILATION" is in other dictionaries:

- (lat. assimilatio, from assimilare to liken). Equation, assimilation, for example, in phonetics, assimilation of neighboring sounds to one another; in physiology, the assimilation of substances absorbed by animals, substances of their own body. Dictionary of foreign words, ... ...

- [lat. dissimilatio dissimilarity] lingv. a change that destroys the similarity and likeness of sounds in a word. Dictionary of foreign words. Komlev N.G., 2006. dissimilation (lat. dissimilatio dissimilarity) 1) otherwise, catabolism is the breakdown of complex organic ... ... Dictionary of foreign words of the Russian language

- (from Latin assimilatio reproduction), anabolism, the process during which more complex ones (polysaccharides, nucleic acids, proteins, etc.) are synthesized from simpler substances, similar to the components of this organism and necessary for it ... ... Ecological dictionary

The term assimilation (lat. assimilation) is used in several areas of knowledge: Assimilation (biology) is a set of synthesis processes in a living organism. Assimilation (linguistics) likening the articulation of one ... Wikipedia

- (lat. dissimilatio dissimilarity). Replacement of one of two identical or similar sounds with another, less similar in terms of articulation to the one that remained unchanged. Like assimilation, dissimilation can be progressive or regressive.

I A change that breaks the similarity, the similarity of the same or similar sounds in a word or in neighboring words; dissimilarity (in linguistics). Ant: assimilation I II f. The breakdown in the body of complex organic substances, cells, tissues, etc. (in biology) ... Modern explanatory dictionary of the Russian language Efremova

- (lat. assimilatio likening). Assimilation of one sound to another in articulation and acoustic relations (cf .: dissimilation). Assimilation occurs in vowels with vowels, in consonants with consonants ... Dictionary of linguistic terms

I Assimilation (from lat. assimilatio) assimilation, merging, assimilation. II Assimilation (ethnographic) merger of one people with another with the loss of one of them of their language, culture, national identity. In many countries in... ...

I Dissimilation (from Latin dissimilis dissimilar) in biology, the opposite of assimilation (See Assimilation) side of metabolism (See Metabolism), which consists in the destruction of organic compounds with the transformation of proteins, nucleic ... ... Great Soviet Encyclopedia