1. What fat-like substances do you know?

Cholesterol, esters, waxes, etc.

2. What foods are high in fat?

The source of fat are vegetable oils, meat, fish, eggs, milk and dairy products, chocolate, nuts.

3. What is the role of fats in the body?

Fats in living organisms are the main type of reserve substances and the main source of energy.

Questions

1. What substances are lipids?

Lipids are a large group of fat-like substances that are insoluble in water.

2. What is the structure of most lipids?

Most lipids are composed of high molecular weight fatty acids and the trihydric alcohol glycerol.

3. What functions do lipids perform?

One of the functions of lipids is energy. In vertebrates, approximately half of the energy consumed by cells at rest comes from fat oxidation.

Fats can also be used as a source of water (when 1 g of fat is oxidized, more than 1 g of water is formed).

Due to their low thermal conductivity, lipids perform protective functions, that is, they serve to insulate organisms. For example, in many vertebrates, the subcutaneous fat layer is well expressed, which allows them to live in cold climates, while in cetaceans it also plays another role - it contributes to buoyancy.

Lipids also perform a building function, since their insolubility in water makes them the most important components of cell membranes.

Lipids have a regulatory function. Many hormones (eg, adrenal cortex, sex hormones) are derivatives of lipids.

4. What cells and tissues are richest in lipids?

Cells of seeds of some plants and adipose tissue of animals are richest in lipids.

Tasks

After analyzing the text of the paragraph, explain why many animals before winter, and migratory fish before spawning, tend to accumulate more fat. Give examples of animals and plants in which this phenomenon is most pronounced. Is excess fat always good for the body? Discuss this problem in class.

Many animals store food in their bodies. It's a good way to get through tough times.

Hibernating mammals such as marmots eat huge amounts of nuts and other calorie-rich foods in the fall. Although their metabolism slows down in winter, they need energy to keep their body alive.

Before hibernation, hedgehogs and brown bears, as well as all bats, get significantly fatter.

Winter hibernation of brown bears is a slight stupor. In nature, in the summer, a bear accumulates a thick layer of subcutaneous fat and, immediately before the onset of winter, settles in its lair for hibernation. Usually the lair is covered with snow, so it is much warmer inside than outside. During hibernation, the accumulated fat reserves are used by the bear's body as a source of nutrients, and also protect the animal from freezing.

Whales accumulate a thick layer of blubber under their skin during summer hunting in the food-rich waters of the Arctic and Antarctic. This fat, which makes up almost half of their weight, provides the whales with energy for the winter, which they spend in food-poor waters in tropical regions.

In fish, stored fat is a source of energy during spawning.

However, these reserves should not affect the mobility of the animal too much, so that it does not become a victim of enemies.

In humans, excess fats form fat depots and the body can always use them as a source of energy during cooling, during fasting, during heavy physical exertion. It is important to remember that consuming excessive amounts of fat leads to cardiovascular disease, as well as to being overweight.

Lesson summary

Pedagogy and didactics

The sequence of amino acids in the composition of the polypeptide chain represents the primary structure of the protein. It is unique to any protein and determines its shape, properties and function. This helix is ​​the secondary structure of the protein.

Lesson 5. Lipids. The composition and structure of proteins 1.3-1.4

1. Lipids

Lipids. (from Greek lipos fat) an extensive group of fat-like substances that are insoluble in water. The content of lipids in different cells varies greatly: from 23 to 5090% in the cells of seeds of some plants and adipose tissue of animals.

Lipids are present in all cells without exception, performing specific biological functions.

Fats the simplest and most abundant lipids play an important role asenergy source.With the complete breakdown of 1 g of fat to end products, 38.9 kJ of energy is released. Fats consist of three residues of high molecular weight fatty acids and the trihydric alcohol glycerol (Fig. 4). When oxidized, they provide more than twice as much energy as carbohydrates.

Fats are the main formenergy storagein a cage. In vertebrates, approximately half of the energy consumed by cells at rest comes from fat oxidation.

Fats can also be used as a source of water (when 1 g of fat is oxidized, more than 1 g of water is formed). This is especially valuable for arctic and desert animals that live in conditions of free water deficiency.

Due to their low thermal conductivity, lipids performprotective features,i.e., they serve for thermal insulation of organisms. For example, many vertebrates have a well-defined subcutaneous fat layer, which allows them to live in cold climates, while in cetaceans it also plays another role - it contributes to buoyancy.

Lipids perform andbuilding function,since insolubility in water makes them the most important components of cell membranes.

Many hormones (eg, adrenal cortex, genital) are derivatives of lipids. Therefore, lipids haveregulatory function.

2. Composition and structure of proteins.

Among organic matter proteins, or proteins the most numerous, most diverse and of paramount importance biopolymers. They account for 5080% of the dry mass of the cell.

Protein molecules are large, which is why they are calledmacromolecules. Proteins differ from each other in number (from one hundred to several thousand), composition and sequence of monomers. Protein monomers are amino acids (Fig. 5). An endless variety of proteins is created by varying the combination of just 20 amino acids. In addition to carbon, oxygen, hydrogen and nitrogen, amino acids may contain sulfur. Each amino acid has its own name, special structure and properties. Their general formula can be represented as follows:

An amino acid molecule consists of two parts identical for all amino acids, one of which is an amino group ( NH2 ) with basic properties, the other carboxyl group (COOH) with acidic properties. The part of the molecule called the radical ( R ), different amino acids have different structures. The presence of basic and acidic groups in one amino acid molecule determines their high reactivity. Through these groups, amino acids are combined to form a protein. In this case, a water molecule appears, and the released electrons form a peptide bond. That is why proteins are called polypeptides.

Protein molecules can have different spatial configurations, and four levels of structural organization are distinguished in their structure (Fig. 6).

The sequence of amino acids in a polypeptide chain isprimary structuresquirrel. It is unique to any protein and determines its shape, properties and functions.

Most proteins have the form of a spiral as a result of the formation of hydrogen bonds between CO- and NH-rpynna mi different amino acid residues of the polypeptide chain. Hydrogen bonds are weak, but in combination they provide a fairly strong structure. This spiralsecondary structure squirrel.

Tertiary structurethree-dimensional spatial "packing" of the polypeptide chain. The result is a bizarre, but specific configuration for each protein globule.

The strength of the tertiary structure is provided by various bonds that arise between amino acid radicals.Quaternary structurenot typical for all proteins. It arises as a result of the combination of several macromolecules with a tertiary structure into a complex complex. For example, human blood hemoglobin is a complex of four protein macromolecules (Fig. 7).

This complexity of the structure of protein molecules is associated with a variety of functions inherent in these biopolymers. Violation of the natural structure of the protein is called denaturation (Fig. 8). It can occur under the influence of temperature, chemicals, radiant energy and other factors.

With a weak impact, only the quaternary structure disintegrates, with a stronger one, the tertiary one, and then the secondary one, and the protein remains in the form of a polypeptide chain. This process is partially reversible: if the primary structure is not destroyed, then the denatured protein is able to restore its structure. It follows that all structural features of a protein macromolecule are determined by its primary structure. Except simple proteins consisting only of amino acids, there are also complex proteins which may contain carbohydrates(glycoproteins), fats (lipoproteins), nucleic acids(nucleoproteins) and etc.

The role of proteins in cell life is enormous. Modern biology has shown that the similarity and difference of organisms is determined, ultimately, by a set of proteins. The closer organisms are to each other in a systematic position, the more similar their proteins are.

Board card:

1. What molecules make up fats?
2. What is the main function of fats?
3. How much energy is released when fat is oxidized compared to carbohydrates?
4. What is the building function of lipids?
5. What is the regulatory function of lipids?
6. Write down the general formula of an amino acid.
7. What determines the primary structure of a protein?
8. What is the secondary structure of a protein?
9. What are the tertiary and quaternary structures of a protein?
10. What is denaturation?

Cards for writing work:

1. Definition or essence of the term: 1. Lipids. 2. Fats. 3. Proteins. 4. Amino acids. 5. Peptide bond. 6. Protein structures. 7. Denaturation.
2. Lipids and their importance.
3. The structure of proteins.
4. Structures of protein molecules.

Computer testing

**Test 1 . What molecules make up fats?

1. Amino acids.
2. Glycerin.
3. high molecular weight fatty acids.
4. Nucleotides.

Test 2 . What is the main function of fats?

1. Construction.
   1. Reserve.
   2. Energy.
   3. Storage of genetic information.

**Test 3 . The main functions of lipids:

1. Construction. 5. Storage of genetic information.
2. Reserve. 6. The main source of energy for the cell.
3. Regulatory. 7. Water source.
4. Thermal insulation.

Test 4 What molecules make up proteins?

1. Amino acids.
2. Glycerin.
3. fatty acids.
4. Nucleotides.

Test 5

1. Basic.
2. Acid.

Test 6 . What are the properties of a carboxyl group?

1. Basic.
2. Acid.

Test 7 . A peptide bond is formed:

1. between carboxyl groups of adjacent amino acids.
2. Between the amino groups of adjacent amino acids.
3. Between the carboxyl group of one amino acid and the amino group of another.
4. Between the carboxyl group of one amino acid and the radical of another.

Test 8 . The sequence of amino acids in a polypeptide:

1. The primary structure of a protein.
2. Secondary structure of a protein.
3. Tertiary structure of a protein.

**Test 9 . Helix of amino acids held by hydrogen bonds:

1. The primary structure of a protein.
2. Secondary structure of a protein.
3. Tertiary structure of a protein.
4. Quaternary structure of the protein.

Test 10 . The configuration of the polypeptide in the form of a globule:

1. The primary structure of a protein.
2. Secondary structure of a protein.
3. Tertiary structure of a protein.
4. Quaternary structure of the protein.

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>> Lipids

Lipids

1. What fat-like substances do you know?
2. What foods are high in fat?
3. What is the role of fats in the body?

Fats are the main form of storage of lipids in the cell. In vertebrates, approximately half of the energy consumed by cells at rest comes from fat oxidation. Fats can also be used as a source water(when 1 g of fat is oxidized, more than 1 g of water is formed). This is especially valuable for arctic and desert animals that live in conditions of free water deficiency.
Due to their low thermal conductivity, lipids perform protective functions, that is, they serve for thermal insulation. organisms. For example, in many vertebrates, the subcutaneous fat layer is well expressed, which allows them to live in cold climates, while in cetaceans it also plays another role - it contributes to buoyancy.

Lipids also perform a building function, since their insolubility in water makes them the most important components of cell membranes.

Many hormones (eg, adrenal cortex, sex hormones) are derivatives of lipids. Therefore, lipids have a regulatory function.

Lipids. Fats. Hormones. Functions of lipids: energy, storage, protective, building, regulatory.

1. What substances are lipids?
2. What is the structure of most lipids?
3. What functions do lipids perform?
4. What cells and tissues richest in lipids?

Kamensky A. A., Kriksunov E. V., Pasechnik V. V. Biology Grade 9
Submitted by readers from the website

Lesson content Lesson outline and support frame Lesson presentation Accelerative methods and interactive technologies Closed exercises (for teacher use only) Assessment Practice tasks and exercises, self-examination workshops, laboratory, cases level of complexity of tasks: normal, high, olympiad homework Illustrations illustrations: video clips, audio, photographs, graphics, tables, comics, multimedia essays chips for inquisitive cribs humor, parables, jokes, sayings, crossword puzzles, quotes Add-ons external independent testing (VNT) textbooks main and additional thematic holidays, slogans articles national features glossary other terms Only for teachers

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-1.jpg" alt="(!LANG:>lipids">!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-2.jpg" alt="(!LANG:> Lipids are a group of water-insoluble organic compounds that"> Липиды – сборная группа нерастворимых в воде органических соединений, которые могут быть извлечены из клеток органическими растворителями (эфиром, хлороформом, бензолом).!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-3.jpg" alt="(!LANG:> Lipids Simple lipids (higher fatty"> Липиды Простые липиды (высшие жирные Сложные кислоты + спирт) липиды Воски (ВЖК + Фосфолипиды Гликолипиды Жиры (ВЖК + спирт одноатомные (ВЖК+ спирт + (ВЖК + глицерин) + фосфат) спирты) углевод)!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-5.jpg" alt="(!LANG:> Fatty acids have: 1) the same for all"> Жирные кислоты имеют: 1) одинаковую для всех кислот группировку - карбоксильную группу (–СООН) 2) R - радикал, которым они отличаются друг от друга. Радикал представляет собой цепочку из различного количества (от 14 до 22) группировок –СН 2–!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-6.jpg" alt="(!LANG:> Sometimes a fatty acid radical contains one or more double bonds (–CH =CH–)"> Иногда радикал жирной кислоты содержит одну или несколько двойных связей (–СН=СН–) Ø Если в жирной кислоте имеются двойные связи, то такую жирную кислоту называют ненасыщенной. Ø Если жирная кислота не имеет двойных связей, ее называют насыщенной.!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-7.jpg" alt="(!LANG:> If saturated fatty acids predominate in triglycerides, then at 20°С they are solid;"> Если в триглицеридах преобладают насыщенные жирные кислоты, то при 20°С они - твердые; их называют жирами, они характерны для животных клеток. (искл. – рыбий жир) Если в триглицеридах преобладают ненасыщенные жирные кислоты, то при 20 °С они - жидкие; их называют маслами, они характерны для растительных клеток. (искл. кокосовое масло)!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-8.jpg" alt="(!LANG:> 3 carboxylic acid triglyceride glycerol">!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-9.jpg" alt="(!LANG:>The density of triglycerides is lower than that of water, so they float in water , are"> Плотность триглицеридов ниже, чем у воды, поэтому в воде они всплывают, находятся на ее поверхности.!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-11.jpg" alt="(!LANG:> By origin, waxes can be divided into 1 - animals: bee wax is produced by bees ; woolen (lanolin)"> По происхождению воски можно разделить на 1 - животные: пчелиный вырабатывается пчёлами; шерстяной (ланолин) предохраняет шерсть и кожуживотных от влаги, засорения и высыхания; спермацетдобывается из спермацетового масла кашалотов; 2 – растительные: воски покрывают тонким слоем листья, стебли, плоды и защищают их от размачивания водой, высыхания, вредных микроорганизмов, иногда в качестве резервных липидов входят в состав семян (т. н. «масло» жожоба)!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-13.jpg" alt="(!LANG:> Phospholipids are triglycerides in which one fatty acid residue is replaced by"> Фосфолипиды - триглицериды, у которых один остаток жирной кислоты замещен на остаток фосфорной кислоты. Принимают участие в формировании клеточных мембран.!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-14.jpg" alt="(!LANG:> Glycolipids are triglycerides in which one fatty acid residue is replaced by"> Гликолипиды - триглицериды, у которых один остаток жирной кислоты замещен на углевод. Принимают участие в формировании клеточных мембран.!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-15.jpg" alt="(!LANG:> Lipoproteins are complex substances formed as a result of the combination of lipids and proteins.">!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-16.jpg" alt="(!LANG:>Lipoids are fat-like substances. These include carotenoids (photosynthetic pigments) , steroid hormones"> Липоиды - жироподобные вещества. К ним относятся каротиноиды (фотосинтетические пигменты), стероидные гормоны (половые гормоны, минералокортикоиды, глюкокортикоиды), гиббереллины (ростовые вещества растений), жирорастворимые витамины (А, D, Е, К), холестерин, камфора и т. д.!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-17.jpg" alt="(!LANG:>Lipid functions">!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-18.jpg" alt="(!LANG:> Function Examples and Explanations The main function of triglycerides. When"> Функция Примеры и пояснения Основная функция триглицеридов. При Энергетическая расщеплении 1 г липидов выделяется 38, 9 к. Дж. Фосфолипиды, гликолипиды и липопротеины Структурная принимают участие в образовании клеточных мембран.!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-19.jpg" alt="(!LANG:> Fats and oils are a reserve nutrient"> Жиры и масла являются резервным пищевым веществом у животных и растений. Важно для животных, впадающих в холодное время года в спячку или совершающих Запасающая длительные переходы через местность, где нет источников питания. Масла семян растений необходимы для обеспечения энергией проростка.!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-20.jpg" alt="(!LANG:> Layers of fat and fat capsules provide cushioning for internal"> Прослойки жира и жировые капсулы обеспечивают амортизацию внутренних органов. Защитная Слои воска используются в качестве водоотталкивающего покрытия у растений и животных.!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-21.jpg" alt="(!LANG:> Subcutaneous fat"> Подкожная жировая клетчатка препятствует оттоку тепла в окружающее пространство. Важно Теплоизоляционная для водных млекопитающих или млекопитающих, обитающих в холодном климате.!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-22.jpg" alt="(!LANG:> Gibberellins regulate plant growth. Sexual"> Гиббереллины регулируют рост растений. Половой гормон тестостерон отвечает за развитие мужских вторичных половых признаков. Половой гормон эстроген отвечает за развитие женских вторичных половых Регуляторная признаков, регулирует менструальный цикл. Минералокортикоиды (альдостерон и др.) контролируют водно-солевой обмен. Глюкокортикоиды (кортизол и др.) принимают участие в регуляции углеводного и белкового обменов.!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-23.jpg" alt="(!LANG:> When 1 kg is oxidized Fat source is released 1, 1"> При окислении 1 кг Источник жира выделяется 1, 1 метаболической воды кг воды. Важно для обитателей пустынь.!}

Src="https://present5.com/presentation/3/18119840_229819868.pdf-img/18119840_229819868.pdf-24.jpg" alt="(!LANG:> Fat-soluble vitamins A, D, E, K are"> Жирорастворимые витамины A, D, E, K являются кофакторами ферментов, т. е. сами по Каталитическая себе эти витамины не обладают каталитической активностью, но без них ферменты не могут выполнять свои функции.!}

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Biology The science of life is one of the oldest sciences. Humans have accumulated knowledge about living organisms for thousands of years. As knowledge was accumulated, biology was differentiated into independent sciences (botany, zoology, microbiology, genetics, etc.). The importance of borderline disciplines, linking biology with other sciences - physics, chemistry, mathematics, etc., is growing more and more. As a result of integration, biophysics, biochemistry, space biology, etc. have arisen.

At present, biology is a complex science, formed as a result of differentiation and integration of different disciplines.

In biology, various research methods are used: observation, experiment, comparison, etc.

Biology studies living organisms. They are open biological systems that obtain energy and nutrients from the environment. Living organisms respond to external influences, contain all the information they need for development and reproduction, and are adapted to a particular habitat.

All living systems, regardless of the level of organization, have common features, and the systems themselves are in continuous interaction. Scientists distinguish the following levels of organization of living nature: molecular, cellular, organismal, population-species, ecosystem and biospheric.

Chapter 1

The molecular level can be called the initial, the deepest level of organization of the living. Every living organism consists of molecules of organic substances - proteins, nucleic acids, carbohydrates, fats (lipids), called biological molecules. Biologists are studying the role of these important biological compounds in the growth and development of organisms, the storage and transmission of hereditary information, metabolism and energy conversion in living cells, and in other processes.

In this chapter you will learn

What are biopolymers;

What is the structure of biomolecules;

What are the functions of biomolecules;

What are viruses and what are their features.

§ 4. Molecular level: general characteristics

1. What is a chemical element?

2. What is called an atom and a molecule?

3. What organic substances do you know?

Any living system, no matter how complex it may be organized, manifests itself at the level of functioning of biological macromolecules.

By studying living organisms, you learned that they are made up of the same chemical elements as non-living ones. Currently, more than 100 elements are known, most of them are found in living organisms. The most common elements in living nature include carbon, oxygen, hydrogen and nitrogen. It is these elements that form the molecules (compounds) of the so-called organic matter.

All organic compounds are based on carbon. It can enter into bonds with many atoms and their groups, forming chains that differ in chemical composition, structure, length and shape. Molecules are formed from groups of atoms, and from the latter more complex molecules differ in structure and function. These organic compounds that make up the cells of living organisms are called biological polymers or biopolymers.

Polymer(from Greek. polys- numerous) - a chain consisting of numerous links - monomers, each of which is relatively simple. A polymer molecule can consist of many thousands of interconnected monomers, which can be the same or different (Fig. 4).

Rice. 4. Scheme of the structure of monomers and polymers

The properties of biopolymers depend on the structure of their molecules: on the number and variety of monomeric units that form the polymer. All of them are universal, as they are built according to the same plan in all living organisms, regardless of species.

Each type of biopolymer has a specific structure and function. Yes, the molecules proteins are the main structural elements of cells and regulate the processes occurring in them. Nucleic acids participate in the transfer of genetic (hereditary) information from cell to cell, from organism to organism. Carbohydrates and fats are the most important sources of energy necessary for the life of organisms.

It is at the molecular level that the transformation of all types of energy and metabolism in the cell takes place. The mechanisms of these processes are also universal for all living organisms.

At the same time, it turned out that the diverse properties of biopolymers, which are part of all organisms, are due to various combinations of just a few types of monomers that form many variants of long polymer chains. This principle underlies the diversity of life on our planet.

The specific properties of biopolymers are manifested only in a living cell. Isolated from cells, biopolymer molecules lose their biological essence and are characterized only by the physicochemical properties of the class of compounds to which they belong.

Only by studying the molecular level, one can understand how the processes of the origin and evolution of life on our planet proceeded, what are the molecular foundations of heredity and metabolic processes in a living organism.

The continuity between the molecular and the next cellular level is ensured by the fact that biological molecules are the material from which supramolecular - cellular - structures are formed.

Organic substances: proteins, nucleic acids, carbohydrates, fats (lipids). Biopolymers. Monomers

Questions

1. What processes do scientists study at the molecular level?

2. What elements prevail in the composition of living organisms?

3. Why are molecules of proteins, nucleic acids, carbohydrates and lipids considered as biopolymers only in a cell?

4. What is meant by the universality of biopolymer molecules?

5. How is the variety of properties of biopolymers that are part of living organisms achieved?

Tasks

What biological patterns can be formulated based on the analysis of the text of the paragraph? Discuss them with class members.

§ 5. Carbohydrates

1. What substances related to carbohydrates do you know?

2. What role do carbohydrates play in a living organism?

3. As a result of what process are carbohydrates formed in the cells of green plants?

Carbohydrates, or saccharides, is one of the main groups of organic compounds. They are part of the cells of all living organisms.

Carbohydrates are made up of carbon, hydrogen and oxygen. They got the name "carbohydrates" because most of them have the same ratio of hydrogen and oxygen in the molecule as in the water molecule. The general formula for carbohydrates is C n (H 2 0) m.

All carbohydrates are divided into simple, or monosaccharides, and complex, or polysaccharides(Fig. 5). Of the monosaccharides, the most important for living organisms are ribose, deoxyribose, glucose, fructose, galactose.

Rice. 5. The structure of the molecules of simple and complex carbohydrates

Di- and polysaccharides formed by combining two or more monosaccharide molecules. So, sucrose(cane sugar), maltose(malt sugar) lactose(milk sugar) - disaccharides formed by the fusion of two monosaccharide molecules. Disaccharides are similar in properties to monosaccharides. For example, both hornyu are soluble in water and have a sweet taste.

Polysaccharides are made up of a large number of monosaccharides. These include starch, glycogen, cellulose, chitin and others (Fig. 6). With an increase in the amount of monomers, the solubility of polysaccharides decreases and the sweet taste disappears.

The main function of carbohydrates is energy. During the breakdown and oxidation of carbohydrate molecules, energy is released (with the breakdown of 1 g of carbohydrates - 17.6 kJ), which ensures the vital activity of the body. With an excess of carbohydrates, they accumulate in the cell as reserve substances (starch, glycogen) and, if necessary, are used by the body as an energy source. Enhanced breakdown of carbohydrates in cells can be observed, for example, during seed germination, intense muscular work, and prolonged fasting.

Carbohydrates are also used as building material. Thus, cellulose is an important structural component of the cell walls of many unicellular organisms, fungi and plants. Due to its special structure, cellulose is insoluble in water and has high strength. On average, 20-40% of plant cell wall material is cellulose, and cotton fibers are almost pure cellulose, which is why they are used to make fabrics.

Rice. 6. Scheme of the structure of polysaccharides

Chitin is part of the cell walls of some protozoa and fungi; it is also found in certain groups of animals, such as arthropods, as an important component of their external skeleton.

Complex polysaccharides are also known, consisting of two types of simple sugars that alternate regularly in long chains. Such polysaccharides perform structural functions in the supporting tissues of animals. They are part of the intercellular substance of the skin, tendons, cartilage, giving them strength and elasticity.

Some polysaccharides are part of cell membranes and serve as receptors, ensuring that cells recognize each other and their interaction.

Carbohydrates, or saccharides. Monosaccharides. Disaccharides. Polysaccharides. Ribose. Deoxyribose. Glucose. Fructose. Galactose. Sucrose. Maltose. Lactose. Starch. Glycogen. Chitin

Questions

1. What is the composition and structure of carbohydrate molecules?

2. What carbohydrates are called mono-, di- and polysaccharides?

3. What functions do carbohydrates perform in living organisms?

Tasks

Analyze Figure 6 "Scheme of the structure of polysaccharides" and the text of the paragraph. What assumptions can you make based on a comparison of the structural features of the molecules and the functions performed by starch, glycogen and cellulose in a living organism? Discuss this question with your classmates.

§ 6. Lipids

1. What fat-like substances do you know?

2. What foods are high in fat?

3. What is the role of fats in the body?

Lipids(from Greek. lipos- fat) - an extensive group of fat-like substances that are insoluble in water. Most lipids consist of high molecular weight fatty acids and the trihydric alcohol glycerol (Fig. 7).

Lipids are present in all cells without exception, performing specific biological functions.

Fats- the simplest and most widespread lipids - play an important role as energy source. When oxidized, they provide more than twice as much energy as carbohydrates (38.9 kJ for the breakdown of 1 g of fat).

Rice. 7. The structure of the triglyceride molecule

Fats are the main form lipid storage in a cage. In vertebrates, approximately half of the energy consumed by cells at rest comes from fat oxidation. Fats can also be used as a source of water (when 1 g of fat is oxidized, more than 1 g of water is formed). This is especially valuable for arctic and desert animals that live in conditions of free water deficiency.

Due to their low thermal conductivity, lipids perform protective functions, i.e., serve for thermal insulation of organisms. For example, many vertebrates have a well-defined subcutaneous fat layer, which allows them to live in cold climates, while in cetaceans it plays another role - it contributes to buoyancy.

Lipids perform and building function, since their insolubility in water makes them essential components of cell membranes.

Many hormones(eg, adrenal cortex, genital) are derivatives of lipids. Therefore, lipids have regulatory function.

Lipids. Fats. Hormones. Lipid functions: energy, storage, protective, building, regulatory

Questions

1. What substances are lipids?

2. What is the structure of most lipids?

3. What functions do lipids perform?

4. What cells and tissues are richest in lipids?

Tasks

After analyzing the text of the paragraph, explain why many animals before winter, and migratory fish before spawning, tend to accumulate more fat. Give examples of animals and plants in which this phenomenon is most pronounced. Is excess fat always good for the body? Discuss this problem in class.

§ 7. Composition and structure of proteins

1. What is the role of proteins in the body?

2. What foods are rich in proteins?

Among organic matter squirrels, or proteins, are the most numerous, most diverse and of paramount importance biopolymers. They account for 50–80% of the dry mass of the cell.

Protein molecules are large, which is why they are called macromolecules. In addition to carbon, oxygen, hydrogen, and nitrogen, proteins can contain sulfur, phosphorus, and iron. Proteins differ from each other in number (from one hundred to several thousand), composition and sequence of monomers. Protein monomers are amino acids (Fig. 8).

An endless variety of proteins is created by different combinations of just 20 amino acids. Each amino acid has its own name, special structure and properties. Their general formula can be represented as follows:

An amino acid molecule consists of two parts identical for all amino acids, one of which is an amino group (-NH 2) with basic properties, the other is a carboxyl group (-COOH) with acidic properties. The part of the molecule called the radical (R) has a different structure for different amino acids. The presence of basic and acidic groups in one amino acid molecule determines their high reactivity. Through these groups, amino acids are combined to form a protein. In this case, a water molecule appears, and the released electrons form peptide bond. That is why proteins are called polypeptides.

Rice. 8. Examples of the structure of amino acids - monomers of protein molecules

Protein molecules can have different spatial configurations - protein structure, and four levels of structural organization are distinguished in their structure (Fig. 9).

The sequence of amino acids in a polypeptide chain is primary structure squirrel. It is unique to any protein and determines its shape, properties and functions.

Most proteins have the form of a helix as a result of the formation of hydrogen bonds between CO and NH groups of different amino acid residues of the polypeptide chain. Hydrogen bonds are weak, but in combination they provide a fairly strong structure. This spiral is secondary structure squirrel.

Tertiary structure- three-dimensional spatial "packing" of the polypeptide chain. As a result, a bizarre, but specific configuration for each protein arises - globule. The strength of the tertiary structure is provided by various bonds that arise between amino acid radicals.

Rice. 9. Scheme of the structure of a protein molecule: I, II, III, IV - primary, secondary, tertiary, quaternary structures

Quaternary structure not typical for all proteins. It arises as a result of the combination of several macromolecules with a tertiary structure into a complex complex. For example, human blood hemoglobin is a complex of four protein macromolecules (Fig. 10).

This complexity of the structure of protein molecules is associated with a variety of functions inherent in these biopolymers.

Violation of the natural structure of the protein is called denaturation(Fig. 11). It can occur under the influence of temperature, chemicals, radiant energy and other factors. With a weak impact, only the quaternary structure disintegrates, with a stronger one, the tertiary one, and then the secondary one, and the protein remains in the form of a polypeptide chain.

Rice. 10. Scheme of the structure of the hemoglobin molecule

This process is partially reversible: if the primary structure is not destroyed, then the denatured protein is able to restore its structure. It follows that all structural features of a protein macromolecule are determined by its primary structure.

Except simple proteins, consisting only of amino acids, there are also complex proteins, which may include carbohydrates ( glycoproteins), fats ( lipoproteins), nucleic acids ( nucleoproteins) and etc.

The role of proteins in cell life is enormous. Modern biology has shown that the similarity and difference of organisms is ultimately determined by a set of proteins. The closer organisms are to each other in a systematic position, the more similar their proteins are.

Rice. 11. Protein denaturation

Proteins, or proteins. Simple and complex proteins. Amino acids. Polypeptide. Primary, secondary, tertiary and quaternary structures of proteins

Questions

1. What substances are called proteins or proteins?

2. What is the primary structure of a protein?

3. How are secondary, tertiary and quaternary protein structures formed?

4. What is protein denaturation?

5. On what basis are proteins divided into simple and complex?

Tasks

Did you know that egg white is made up mostly of proteins. Think about the change in the structure of the protein in a boiled egg. Give other examples known to you when the structure of a protein can change.

§ 8. Functions of proteins

1. What is the function of carbohydrates?

2. What functions of proteins do you know?

Proteins perform extremely important and diverse functions. This is possible largely due to the diversity of forms and composition of the proteins themselves.

One of the most important functions of protein molecules is construction (plastic). Proteins are part of all cell membranes and cell organelles. Mostly protein consists of the walls of blood vessels, cartilage, tendons, hair and nails.

Of great importance catalytic, or enzymatic, protein function. Special proteins - enzymes are capable of accelerating biochemical reactions in the cell by tens and hundreds of millions of times. About a thousand enzymes are known. Each reaction is catalyzed by a specific enzyme. You will learn more about this below.

motor function perform special contractile proteins. Thanks to them, cilia and flagella move in protozoa, chromosomes move during cell division, muscles contract in multicellular organisms, and other types of movement in living organisms are improved.

It is important transport function proteins. So, hemoglobin carries oxygen from the lungs to the cells of other tissues and organs. In muscles, in addition to hemoglobin, there is another gas-transport protein - myoglobin. Serum proteins promote the transfer of lipids and fatty acids, various biologically active substances. Transport proteins in the outer membrane of cells carry various substances from the environment into the cytoplasm.

Specific proteins do protective function. They protect the body from the invasion of foreign proteins and microorganisms and from damage. Thus, antibodies produced by lymphocytes block foreign proteins; fibrin and thrombin protect the body from blood loss.

Regulatory function inherent in proteins hormones. They maintain constant concentrations of substances in the blood and cells, participate in growth, reproduction and other vital processes. For example, insulin regulates blood sugar levels.

Proteins also have signaling function. Proteins are embedded in the cell membrane that can change their tertiary structure in response to the action of environmental factors. This is how signals are received from the external environment and information is transmitted to the cell.

Proteins can perform energy function, being one of the sources of energy in the cell. With complete breakdown of 1 g of protein to final products, 17.6 kJ of energy is released. However, proteins are rarely used as an energy source. Amino acids released during the breakdown of protein molecules are used to build new proteins.

Functions of proteins: building, motor, transport, protective, regulatory, signaling, energy, catalytic. Hormone. Enzyme

Questions

1. What explains the diversity of protein functions?

2. What functions of proteins do you know?

3. What role do hormone proteins play?

4. What is the function of enzyme proteins?

5. Why are proteins rarely used as an energy source?

§ 9. Nucleic acids

1. What is the role of the nucleus in the cell?

2. With what organelles of the cell is the transmission of hereditary traits associated?

3. What substances are called acids?

Nucleic acids(from lat. nucleus– nucleus) were first found in the nuclei of leukocytes. Subsequently, it was found that nucleic acids are contained in all cells, not only in the nucleus, but also in the cytoplasm and various organelles.

There are two types of nucleic acids - deoxyribonucleic(abbreviated DNA) and ribonucleic(abbreviated RNA). The difference in names is due to the fact that the DNA molecule contains a carbohydrate. deoxyribose, and the RNA molecule ribose.

Nucleic acids are biopolymers made up of monomers. nucleotides. Monomers-nucleotides of DNA and RNA have a similar structure.

Each nucleotide consists of three components connected by strong chemical bonds. it nitrogenous base, carbohydrate(ribose or deoxyribose) and phosphoric acid residue(Fig. 12).

Part DNA molecules There are four types of nitrogenous bases: adenine, guanine, cytosine or thymine. They determine the names of the corresponding nucleotides: adenyl (A), guanyl (G), cytidyl (C), and thymidyl (T) (Fig. 13).

Rice. 12. Scheme of the structure of nucleotides - monomers of DNA (A) and RNA (B)

Each DNA strand is a polynucleotide consisting of several tens of thousands of nucleotides.

The DNA molecule has a complex structure. It consists of two helically twisted chains, which are connected to each other along the entire length by hydrogen bonds. This structure, which is unique to DNA molecules, is called double helix.

Rice. 13. DNA nucleotides

Rice. 14. Complementary connection of nucleotides

During the formation of the DNA double helix, the nitrogenous bases of one strand are arranged in a strictly defined order against the nitrogenous bases of the other. In this case, an important regularity is revealed: the thymine of the other chain is always located against the adenine of one chain, and cytosine is always located against the guanine, and vice versa. This is due to the fact that the nucleotide pairs adenine and thymine, as well as guanine and cytosine, strictly correspond to each other and are additional, or complementary(from lat. complementum addition) to each other. The rule itself is called principle of complementarity. In this case, two hydrogen bonds always appear between adenine and thymine, and three between guanine and cytosine (Fig. 14).

Therefore, in any organism, the number of adenyl nucleotides is equal to the number of thymidyl, and the number of guanyl nucleotides is equal to the number of cytidyl. Knowing the sequence of nucleotides in one strand of DNA, the principle of complementarity can be used to establish the order of nucleotides in another strand.

With the help of four types of nucleotides in DNA, all information about the body is recorded, which is inherited by the next generations. In other words, DNA is the carrier of hereditary information.

DNA molecules are mainly found in the nuclei of cells, but a small amount is found in mitochondria and plastids.

The RNA molecule, unlike the DNA molecule, is a polymer consisting of a single chain of much smaller sizes.

RNA monomers are nucleotides consisting of a ribose, a phosphoric acid residue, and one of the four nitrogenous bases. The three nitrogenous bases - adenine, guanine and cytosine - are the same as those of DNA, and the fourth is uracil.

The formation of the RNA polymer occurs through covalent bonds between the ribose and the phosphoric acid residue of adjacent nucleotides.

There are three types of RNA, differing in structure, size of molecules, location in the cell and functions performed.

Ribosomal RNA (rRNA) are part of ribosomes and participate in the formation of their active centers, where the process of protein biosynthesis takes place.

Transfer RNAs (tRNA) - the smallest in size - transport amino acids to the site of protein synthesis.

Informational, or matrix, RNA (mRNA) are synthesized in a section of one of the chains of the DNA molecule and transmit information about the protein structure from the cell nucleus to the ribosomes, where this information is realized.

Thus, various types of RNA represent a single functional system aimed at the implementation of hereditary information through protein synthesis.

RNA molecules are found in the nucleus, cytoplasm, ribosomes, mitochondria and plastids of the cell.

Nucleic acid. Deoxyribonucleic acid, or DNA. Ribonucleic acid, or RNA. Nitrogenous bases: adenine, guanine, cytosine, thymine, uracil, nucleotide. Double helix. Complementarity. Transfer RNA (tRNA). Ribosomal RNA (rRNA). Messenger RNA (mRNA)

Questions

1. What is the structure of a nucleotide?

2. What is the structure of a DNA molecule?

3. What is the principle of complementarity?

4. What is common and what are the differences in the structure of DNA and RNA molecules?

5. What types of RNA molecules do you know? What are their functions?

Tasks

1. Plan your paragraph.

2. Scientists have found that a fragment of a DNA chain has the following composition: C-G G A A T T C C. Using the principle of complementarity, complete the second chain.

3. During the study, it was found that in the studied DNA molecule, adenines make up 26% of the total number of nitrogenous bases. Count the number of other nitrogenous bases in this molecule.