Metabolism and energy conversion. Features of energy metabolism

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MINISTRY OF EDUCATION OF THE SARATOV REGION

State Autonomous Professional Educational Institution of the Saratov Region

"Balashovsky College of Agricultural Mechanization"

Methodological development of a binary lesson

in the disciplines “Biology” and “Chemistry” on the topic:

“Metabolism and energy conversion in the cell”

Prepared by:

Kursakova S.N.

Grechishkina I.N.

Balashov 2015

1.Preface

2. Main part

3.Conclusion

4.Literature

1.Preface

Metabolism is the basis of cell life. Knowledge of metabolic processes in a cell makes it possible to understand how the cycle of substances occurs in nature, how plant biomass accumulates, which is the basis of nutrition for heterotrophic organisms, and to solve problems associated with providing food for most of the world's population.

All living organisms are open systems capable of actively organizing the flow of energy and matter from the outside.

Energy is necessary for the implementation of vital processes, but above all for the chemical synthesis of substances used to build and restore the structures of the cell and the body.

Today in the lesson we will look at metabolic processes, organic and inorganic substances that make up food products, and also consider the problem of providing food to the world's population.

2. Main part

Educational and methodological map of the lesson

Lesson topic: “Metabolism and energy conversion in the cell”

Type of lesson: binary lesson.

Lesson objectives:

Educational: study the types of metabolism in a cell, formulate the concepts of fats, proteins, carbohydrates, show the connection between the calorie content of foods and internal energy consumption.

Developmental: Improve the ability to analyze cause-and-effect relationships when explaining the essence of natural phenomena.

Educational: show how a person, learning the laws of nature, makes them work for the benefit of people.

Visual aids:

Stand "Photosynthesis"

Poster "ATP Energy Conversion"

Poster "Structure of a protein molecule."

Slides.

Reagent set

Handout: food packaging with calorie content indicated.

Progress of the lesson

2. Determining the degree of students’ readiness for the lesson.

3. Motivation of students’ cognitive activity

4. Recording the topic and lesson plan

Plan

2).Substances included in food products.

5.. Explanation of new material (method: explanatory and illustrative)

6. Consolidation of the studied material.

7. Homework

8. Final part

1. Organizational moment (greeting, marking absentees, checking students’ readiness for class)

1) Determining the degree of readiness of students for the lesson.

Testing method (see Appendix No.)

3.Motivation of cognitive activity.

Today we are teaching an unusual lesson called binary. All disciplines have a connection with each other and many topics complement each other

4.Record the topic and lesson plan

Plan

1).Plastic and energy metabolism in the cell

2).Substances included in food products.

3). The problem of providing the population with food

5. Explanation of new material (method: explanatory and illustrative)

Question No. 1 “Plastic and energy metabolism in the cell”

In previous lessons, we examined the structure of a cell, became acquainted with the functions of cell organelles, and noted that a cell contains both organic and inorganic compounds.

Today we will study how metabolism occurs in a cell, consider the properties of organic and inorganic substances.

Metabolism is the basis of cell life. Knowledge of metabolic processes in a cell makes it possible to understand how the cycle of substances occurs in nature, how plant biomass accumulates, which is the basis of nutrition for heterotrophic organisms, and to solve problems associated with providing food for most of the world's population.

All living organisms are open systems capable of actively organizing the flow of energy and matter from the outside.

Energy is necessary for the implementation of vital processes, but above all for the chemical synthesis of substances used to build and restore the structures of the cell and the body.

Now we will watch with you the film “Plastic and Energy Metabolism”. Pay attention to how complex organic substances are formed, and what happens when these compounds are broken down (Watching a filmstrip).

We got acquainted with two types of metabolism. Let's look at them in more detail.

Write down: “Plastic exchange”

Definition: synthesis reactions carried out with energy consumption form the basis of plastic exchange (or assimilation).

There are various forms of plastic metabolism: protein biosynthesis, chemosynthesis, photosynthesis.

Some forms of plastic metabolism are characteristic only of autotrophic organisms, and some are characteristic of both autotrophic and heterotrophic organisms.

Let's repeat which organisms we call autotrophic (guys' answer) and which heterotrophic (guys' answer). This is a form of plastic exchange called photosynthesis. Is it characteristic of heterotrophic or autotrophic organisms? (guys answer)

Let's look at how photosynthesis occurs.

To the stand . Photosynthesis consists of two phases: light and dark.

Graphic projector . In the light phase, a light quantum acts on the electrons of water and subjects it to photodecomposition.

H 2 O  H + +(OH) -

Hydroxyl ions give up their electrons to other molecules and become a free radical.

(OH) -  OH

Hydroxyl ions OH interact with each other resulting in the formation of water and oxygen:

4OH  2H 2 O+O 2

Light energy is used to synthesize ATP, ADP and phosphate.

That is, the energy that is needed in the dark phase accumulates.

In the dark phase, a number of reactions take place in which ATP molecules and H atoms participate

6СО 2 +24Н  С 6 Н 12 О 6 + 6Н 2 О

Glucose molecules combine with each other and form starch, which is stored as reserves.

This is how the energy of sunlight is converted into the energy of chemical bonds of complex organic compounds.

Write down what processes occur in the light and dark phases.

Now let's look at energy metabolism. Write down: "Energy exchange"

Definition: splitting reactions accompanied by the release of energy form the basis of energy metabolism or dissimilation.

The energy stage takes place in three stages. The end result is the oxidation of organic substances; the oxidation of glucose releases a large amount of energy

C 6 H 12 O 6 + 6 O 2  6 H 2 O + 6 CO 2 + ATP

Some of the energy released from nutrients is dissipated in the form of heat, and some is accumulated in energy-rich ATP molecules.

Poster.

ATP consists of the nitrogenous base adenine, a ribose carbon, and three phosphoric acid residues.

It is ATP that provides energy for all types of cellular functions: biosynthesis, mechanical work. In this case, ATP loses its phosphorus residue and turns into ADP. ATP is renewed extremely quickly; in humans, the lifespan of one ATP molecule is less than one minute.

Now let’s look at how the energy of food products is converted in the human body.

If plants have sunlight as their source of energy, then the only source of energy for the body is food.

The process of consuming energy and matter is called nutrition.

The energy supplied by the body with food is usually given in kilocalories.

The amount of energy released when the body absorbs a particular food product is called the calorie content of this product.

Here are samples of food packaging. On each one we see the calorie content of a given product.

Caloric content is measured in calories.

1 calorie – 4.19 J

1 kilocalorie – 1000 calories

A person actively spends energy in the process of life

Classes – 6000 J

Charging – 16000 J

Walking – 15000 J

Swimming - 30,000 J

We replenish this energy with food.

Food products contain organic substances:

Fats, proteins, carbohydrates. When these substances are broken down, a large amount of energy is released.

It is important for the body which groups of substances provide calorie intake. For normal human life, a certain ratio of organic and inorganic substances is necessary.

A chemistry teacher will tell you about the structure of these substances.

Question No. 2 “Substances included in food products”

Plant and animal cells have similar structures and chemical compositions. About 90 elements of D.M. Mendeleev’s periodic system were found in cells: oxygen 70%, carbon 18%, hydrogen 10%, nitrogen 3%, as well as Fe, K, S, P, Cl, Mg, Na, I, F and etc.

So, for example, N and S are part of protein, P is part of DNA and RNA, Mg is part of enzymes and chlorophyll.

Water takes up 80% of cell metabolism; it is tightly bound to proteins and forms water membranes around them. In living organisms, water not only dissolves substances, but also participates in hydrolysis reactions.

Organic substances include proteins, carbohydrates, and fats.

Squirrels - These are polymers, they consist of amino acids. Proteins in the cell account for 50-80% of the dry mass. They have a relative molecular weight. Amino acids contain two functional groups COOH and NH 2 , therefore proteins are amphoteric compounds. A protein macromolecule has a primary, secondary, tertiary and quaternary structure. In the human body, hydrolysis of proteins occurs (under the influence of enzymes, while amino acids enter the blood and enter the tissues and cells of the body, where proteins necessary for this organism are formed).

Fats – these are esters of the trihydric alcohol glycerol, higher carboxylic acids. They are contained in cells 5-15% of dry weight. Fats entering the human body undergo hydrolysis under the action of enzymes. The product of hydrolysis - glycerol and carboxylic acids are absorbed by the intestinal villi and again form the fat necessary for the body. Fats are sources of energy, when broken down 1g. 38.9 kJ of fat is released.

Carbohydrates - These are organic substances consisting of C and H 2 A. They are divided into three groups: monosaccharides (glucose and fructose), disaccharides (sucrose), polysaccharides (starch, cellulose). Glucose and fructose are highly soluble in water. Polysaccharides consist of monosaccharide residues and are insoluble in water. Carbohydrates play an important role in metabolism and energy in the human body. As the main component of food, carbohydrates supply most of the energy necessary for the functioning of organisms. Some carbohydrates are part of nucleic acids, carry out protein biosynthesis and transmit hereditary information.

Question No. 3 “The problem of providing the population with food”

Food products perform 3 functions in the human body:

1.Supply organisms with material for building their tissues and constantly renewing them;

2.Supply the body with the energy necessary for life and work;

3.Supply the body with substances that play an important role in regulating metabolism.

In the human body, nutrients undergo complex changes, as a result of which they are transformed into substances of the body itself, its cells and tissues, i.e. are assimilated. This process is called assimilation. Simultaneously with the creation of cells and tissues in the body, partial and destruction constantly occurs. The process of decay of substances that make up cells and tissues is called dissimilation and occurs with the release of energy spent on all types of work in the body.

Both processes are closely interconnected and are called metabolism.

The need for various nutrients and energy depends on gender, age and the nature of work activity. For the correct preparation of a diet, taking into account the nature and intensity of work activity.

Correct preparation of an individual diet is possible only with knowledge of the chemical composition of food products, which are divided into two groups: organic and inorganic. To provide the population with food, “artificial food” is used. The term “artificial food” means artificial production of food products, i.e. obtaining them by chemical reaction. When creating artificial food products, it is very important to select the smell and taste. Today they can synthesize any smell and create a menu for a good lunch: black caviar, salmon, chicken soup. Marmalade, juices

6. Consolidation

Choose the correct answer:

1.During the breathing process:

1. Oxygen is absorbed
2. Carbon dioxide is released
3. Carbon dioxide is absorbed

2. Oxygen released during photosynthesis is formed during the breakdown of:

1. Glucose
2. Water

1. The combination of simple substances into complex ones is called:

1. Metabolism
2. Assimilation
3. Metabolism

1. During the process of glycolysis in animal cells, the following is formed:

1. Glucose
2. Lactic acid
3. Starch

1. Assimilation processes include:

1. Photosynthesis
2. Breathing
3. Protein synthesis

7. Conclusion

Today in the lesson we looked at substances that supply the body with the energy necessary for life and work; they play an important role in the metabolism and energy in the cell. In the human body, nutrients undergo complex changes, as a result of which they are converted into substances of the body itself. The need for various nutrients and energy depends on gender, age and nature of work activity

Literature

1. Zakharov V.B.. General biology - M.: Bustard-2003.

2. Ridiger O.N. Biology - M.:AST-PRESS SCHOOL, 2003.

3. Gabrielyan O. S., Ostroumov I. G. Chemistry - M.: OIC “Academy”, 2008.

Remember from the textbook “Man and His Health” what metabolism and energy conversion in the body are. What two opposing processes does it consist of? Under the influence of what substances does the breakdown of nutrients occur in the body?

The basis of the life of a cell and an organism is metabolism and energy conversion. The exchange of its substances and the transformation of energy is the totality of all reactions of decay and synthesis occurring in a cell or in the entire organism, associated with the release or absorption of energy. Metabolism and energy conversion consists of two interrelated but opposite processes - assimilation and dissimilation (Fig. 53).

Rice. 53. Scheme of relationships between metabolism and energy conversion in a cell

Two sides of metabolism and energy conversion. Dissimilation (from the Latin dissimilation - destruction, release) is a set of reactions of decomposition and oxidation in living things of high molecular weight organic substances to low molecular weight organic and inorganic ones. During the process of dissimilation, the energy contained in the chemical bonds of organic molecules is released and stored in the form of ATP.

Dissimilation processes are respiration, fermentation, glycolysis. The main end products are water, carbon dioxide, ammonia, urea and lactic acid.

Assimilation (from the Latin assimilation - assimilation) is a set of reactions for the synthesis of high molecular weight organic substances from low molecular weight organic or inorganic substances. During the assimilation process, energy is absorbed, which is formed as a result of the breakdown of ATP. Thus, organic substances, such as carbohydrates, are synthesized in plant cells from carbon dioxide, water and mineral salts.

So, the main substance that ensures all metabolic processes in the cell is ATP. During the process of dissimilation, ATP molecules are synthesized and energy is stored in them. During the process of assimilation, ATP molecules disintegrate and the energy released during this process is spent on the synthesis of organic substances. All metabolic reactions of energy conversion in the cell are enzymatic - that is, they occur in the presence of enzymes.

Types of metabolism. The only source of energy on Earth is the Sun. Thanks to solar energy, the primary synthesis of organic substances from inorganic substances occurs - photosynthesis. The energy of the Sun is accumulated in synthesized organic substances, turning into the energy of chemical bonds. In the process of nutrition, organisms break down organic substances, and the energy released during this process is stored in ATP molecules. It is subsequently used in assimilation reactions.

According to the method of obtaining energy and synthesizing organic substances, all organisms are divided into autotrophic and heterotrophic (Fig. 54). Autotrophic organisms, or autotrophs (from the Greek autos - self and tropho - food, nutrition) synthesize organic substances from inorganic ones. Autotrophs include all green plants and cyanobacteria. Chemosynthetic bacteria also feed autotrophically, using energy released during the oxidation of inorganic substances, such as sulfur, iron, and nitrogen.

Rice. 54. Flow of substances and transformation of energy in the Earth’s biosphere

Heterotrophic organisms, or heterotrophs (from the Greek heteros - other and tropho - food, nutrition) use only ready-made organic substances. The source of energy for them is the energy stored in organic substances obtained from food and released during their breakdown and oxidation. Heterotrophs include all animals, fungi and most bacteria. With heterotrophic nutrition, the body absorbs organic substances in finished form and converts them into its own nutrients.

The processes of dissimilation among organisms also differ. Aerobic organisms, or aerobes (from the Greek aer - air and bios - life) require oxygen to function. Breathing for them is the main form of dissimilation. Energy-rich organic substances in the presence of oxygen are completely oxidized to energy-poor inorganic substances - carbon dioxide and water.

Anaerobic organisms, or anaerobes (from the Greek a, an - negative particle) do not need oxygen: their life processes can take place in an oxygen-free environment. Organic substances in this case are not completely broken down. Therefore, the products of their vital activity can be used by other organisms. For example, all lactic acid products are the result of the activity of anaerobic lactic acid bacteria.

Question 1. What is dissimilation? List its stages.
Dissimilation, or energy metabolism, is a set of reactions of cleavage of high-molecular compounds, which are accompanied by the release and storage of energy. Dissimilation in aerobic (oxygen-breathing) organisms occurs in three stages:
preparatory - the breakdown of high molecular weight compounds to low molecular weight ones without storing energy;
oxygen-free - partial oxygen-free breakdown of compounds, energy is stored in the form of ATP; oxygen - the final breakdown of organic substances to carbon dioxide and water, energy is also stored in the form of ATP.
Dissimilation in anaerobic (not using oxygen) organisms occurs in two stages: preparatory and oxygen-free. In this case, organic substances are not completely broken down and much less energy is stored.

Question 2. What is the role of ATP in cell metabolism?
Adenosine triphosphoric acid (ATP) consists of a nitrogenous base - adenine, a sugar - ribose and three phosphoric acid residues. The ATP molecule is very unstable and is capable of splitting off one or two phosphate molecules, releasing a large amount of energy, which is spent on ensuring all vital functions of the cell (biosynthesis, transmembrane transfer, movement, formation of an electrical impulse, etc.). The bonds in the ATP molecule are called macroergic.
The cleavage of the terminal phosphate from the ATP molecule is accompanied by the release of 40 kJ of energy.). In this case, ATP is converted into ADP. If the second phosphoric acid residue is eliminated, ADP is converted to AMP. All processes in living organisms that require energy are accompanied by the conversion of ATP molecules into ADP (or even AMP).
ATP synthesis occurs in mitochondria.

Question 3. What cell structures carry out ATP synthesis?
In eukaryotic cells, the synthesis of the bulk of ATP from ADP and phosphoric acid occurs in mitochondria and is accompanied by the absorption (storage) of energy. In plastids, ATP is formed as an intermediate product of the light stage of photosynthesis.

Question 4. Tell us about energy metabolism in a cell using the breakdown of glucose as an example.
Energy metabolism is usually divided into three stages. The first stage is Preparatory, also called digestion. It is carried out mainly outside the cells under the action of enzymes secreted into the cavity of the digestive tract. At this stage, large polymer molecules break down into monomers: proteins into amino acids, polysaccharides into simple sugars, fats into fatty acids and glycerol. In this case, a small amount of energy is released, which is dissipated in the form of heat.
Oxygen-free. As a result of glycolysis, one molecule of glucose is broken down into two molecules of pyruvic acid:
C 6 H 12 O 6<----->2C 3 H 4 0 3 .
The breakdown of one glucose molecule is accompanied by the formation of two ATP molecules. In this case, 60% of the released energy is converted into heat, and 40% is stored in the form of ATP. The breakdown of one glucose molecule produces 2 ATP molecules. Then, in anaerobic organisms, fermentation occurs - alcoholic (C 2 HC 5 OH - ethyl alcohol) or lactic acid (C 3 H 4 0 3 - lactic acid). In aerobic organisms, the third stage of energy metabolism begins.
Oxygen. This stage of catabolism requires the presence of molecular oxygen and is called respiration. The development of cellular respiration in aerobic microorganisms and in eukaryotic cells became possible only after molecular oxygen appeared in the Earth’s atmosphere as a result of photosynthesis. The addition of an oxygen step to the catalytic process provides cells with a powerful and efficient way to extract nutrients and energy from molecules.
Reactions of oxygen splitting, or oxidative catabolism, occur in special cell organelles - mitochondria, where molecules of pyruvic acid enter. After a number of terminations, the final products are formed - CO 2 and H 2 O, which then diffuse out of the cell. The overall equation for aerobic respiration looks like this:
C 6 H 12 O 6 + 6O 2 + 36H 3 PO 4 + 36ADP<----->6CO 2 + 6H 2 O + 36ATP.
Thus, the oxidation of two molecules of lactic acid produces 36 molecules of ATP. In total, during the second and third stages of energy metabolism, the breakdown of one glucose molecule produces 38 ATP molecules. Consequently, aerobic respiration plays the main role in providing the cell with energy.

And the transformation of energy. Energy metabolism

Remember!

What is metabolism?

What two interrelated processes does it consist of?

Where in the human body is the breakdown of most of the organic substances coming from food?

So, during the process of energy exchange, organic compounds are broken down and energy is stored, and during plastic exchange, energy is consumed and organic substances are synthesized. The reactions of energy and plastic exchange are inextricably linked, collectively forming a single process - metabolism and energy, or metabolism. Metabolism is continuously carried out in all cells, tissues and organs, maintaining the constancy of the internal environment of the body - homeostasis.

Energy exchange. Most organisms on our planet require oxygen to function. Such organisms are called aerobic. Energy metabolism in aerobes occurs in three stages: preparatory, oxygen-free and oxygen. In the presence of oxygen, organic substances are completely oxidized during respiration to carbon dioxide and water, as a result of which a large amount of energy is stored.

Anaerobic organisms able to survive without oxygen. For some of them, oxygen is generally destructive, so they live where there is no oxygen at all, such as the causative agent of tetanus. Others, so-called facultative anaerobes, can exist both without oxygen and in its presence. Energy metabolism in anaerobic organisms occurs in two stages: preparatory and oxygen-free, therefore organic substances are not completely oxidized and much less energy is stored.

Let us consider in more detail the three stages of energy metabolism (Fig. 49).

Preparatory stage. This stage takes place in the gastrointestinal tract and in the lysosomes of cells. Here, under the influence of digestive enzymes, high-molecular compounds break down into simpler, low-molecular compounds: proteins - into amino acids, polysaccharides - into monosaccharides, fats - into glycerol and fatty acids. The energy released during these reactions is not stored, but is dissipated as heat. Low molecular weight substances formed at the preparatory stage can be used by the body to synthesize its own organic compounds, i.e., enter into plastic metabolism or be broken down further in order to store energy.

Rice. 49. Stages of energy metabolism

Oxygen-free stage. The second stage occurs in the cytoplasm of cells, where further breakdown of simple organic substances occurs. The body does not use the amino acids formed at the first stage in the subsequent stages of dissimilation, because it needs them as material for the synthesis of its own protein molecules. Therefore, proteins are very rarely used to obtain energy, only when the remaining reserves (carbohydrates and fats) have already been exhausted. Typically, the most available source of energy in the cell is glucose.

The complex multi-stage process of oxygen-free breakdown of glucose at the second stage of energy metabolism is called glycolysis(from the Greek glycos - sweet and lysis - splitting).

As a result of glycolysis, glucose is broken down into simpler organic compounds (glucose C 6 H 12 O 6 - pyruvic acid C 3 H 4 O 3). This releases energy, 60% of which is dissipated as heat, and 40% is used for ATP synthesis. When one molecule of glucose is broken down, two molecules of ATP and two molecules of pyruvic acid are formed. Thus, at the second stage of dissimilation, the body begins to store energy.

The further fate of pyruvic acid depends on the presence of oxygen in the cell. If oxygen is present, then pyruvic acid enters the mitochondria, where it is completely oxidized to CO 2 and H 2 O and the third, oxygen stage of energy metabolism takes place (see below).

In the absence of oxygen, so-called anaerobic respiration occurs, which is often called fermentation. In yeast cells, during alcoholic fermentation, pyruvic acid (PVA) is converted into ethyl alcohol (PVA? Ethyl alcohol + CO 2).

During lactic acid fermentation, lactic acid is formed from PVC. This process can occur not only in lactic acid bacteria. During strenuous physical work, a lack of oxygen occurs in human muscle tissue cells, resulting in the formation of lactic acid, the accumulation of which causes a feeling of fatigue, pain and sometimes even cramps.

Oxygen stage. At the third stage, the products formed during the oxygen-free breakdown of glucose are oxidized to carbon dioxide and water. This releases a large amount of energy, a significant part of which is used for the synthesis of ATP. This process occurs in mitochondria and is called cellular respiration. During cellular respiration, the oxidation of two PVC molecules releases energy stored by the body in the form of 36 ATP molecules.

So, in the process of energy metabolism with the complete oxidation of one glucose molecule to carbon dioxide and water, 38 ATP molecules are formed (2 molecules in the process of glycolysis and 36 in the process of cellular respiration in mitochondria):

C 6 H 12 O 6 + 6O 2 + 38ADP + 38F? 6CO 2 + 6H 2 O + 38ATP

Under anaerobic conditions, the efficiency of energy metabolism is much lower - only 2 ATP molecules. Fermentation products (ethyl alcohol, lactic acid, butyric acid) still retain a lot of energy in their chemical bonds, i.e., the oxygen path of dissimilation is more energetically favorable. But historically, fermentation is a more ancient process. It could have been carried out even when there was no free oxygen in the atmosphere of the ancient Earth.

Review questions and assignments

1. What is dissimilation? List its stages.

2. What is the role of ATP in cell metabolism?

3. What cell structures carry out ATP synthesis?

4. Tell us about energy metabolism in a cell using the example of the breakdown of glucose.