The chemical structure of the cell. Cell structure. The chemical composition of the cell. Macro- and microelements
Video lesson 2: Structure, properties and functions of organic compounds The concept of biopolymers
Lecture: The chemical composition of the cell. Macro- and microelements. The relationship of the structure and functions of inorganic and organic substances
The chemical composition of the cell
It has been found that about 80 chemical elements are constantly contained in the cells of living organisms in the form of insoluble compounds and ions. All of them are divided into 2 large groups according to their concentration:
macronutrients, the content of which is not lower than 0.01%;
trace elements - the concentration of which is less than 0.01%.
In any cell, the content of microelements is less than 1%, macroelements, respectively, more than 99%.
Macronutrients:
Sodium, potassium and chlorine - provide many biological processes - turgor (internal cellular pressure), the appearance of nerve electrical impulses.
Nitrogen, oxygen, hydrogen, carbon. These are the main components of the cell.
Phosphorus and sulfur are important components of peptides (proteins) and nucleic acids.
Calcium is the basis of any skeletal formations - teeth, bones, shells, cell walls. Also involved in muscle contraction and blood clotting.
Magnesium is a component of chlorophyll. Participates in the synthesis of proteins.
Iron is a component of hemoglobin, is involved in photosynthesis, determines the performance of enzymes.
trace elements contained in very low concentrations, are important for physiological processes:
Zinc is a component of insulin;
Copper - participates in photosynthesis and respiration;
Cobalt is a component of vitamin B12;
Iodine is involved in the regulation of metabolism. It is an important component of thyroid hormones;
Fluorine is a component of tooth enamel.
Imbalance in the concentration of micro and macro elements leads to metabolic disorders, the development of chronic diseases. Lack of calcium - the cause of rickets, iron - anemia, nitrogen - deficiency of proteins, iodine - a decrease in the intensity of metabolic processes.
Consider the relationship of organic and inorganic substances in the cell, their structure and functions.
Cells contain a huge number of micro and macromolecules belonging to different chemical classes.
Inorganic substances of the cell
Water. Of the total mass of a living organism, it makes up the largest percentage - 50-90% and takes part in almost all life processes:
thermoregulation;
capillary processes, as it is a universal polar solvent, affects the properties of the interstitial fluid, the intensity of metabolism. In relation to water, all chemical compounds are divided into hydrophilic (soluble) and lipophilic (soluble in fats).
The intensity of metabolism depends on its concentration in the cell - the more water, the faster the processes occur. Loss of 12% of water by the human body - requires restoration under the supervision of a doctor, with a loss of 20% - death occurs.
mineral salts. Contained in living systems in dissolved form (having dissociated into ions) and undissolved. Dissolved salts are involved in:
transport of substances across the membrane. Metal cations provide a "potassium-sodium pump" by changing the osmotic pressure of the cell. Because of this, water with substances dissolved in it rushes into the cell or leaves it, carrying away unnecessary ones;
the formation of nerve impulses of an electrochemical nature;
muscle contraction;
blood clotting;
are part of proteins;
phosphate ion is a component of nucleic acids and ATP;
carbonate ion - maintains Ph in the cytoplasm.
Insoluble salts in the form of whole molecules form the structures of shells, shells, bones, teeth.
The organic matter of the cell
Common feature of organic substances- the presence of a carbon skeletal chain. These are biopolymers and small molecules of a simple structure.
The main classes found in living organisms:
Carbohydrates. There are various types of them in cells - simple sugars and insoluble polymers (cellulose). In percentage terms, their share in the dry matter of plants is up to 80%, animals - 20%. They play an important role in the life support of cells:
Fructose and glucose (monosugar) - are quickly absorbed by the body, are included in metabolism, and are a source of energy.
Ribose and deoxyribose (monosugar) are one of the three main components of DNA and RNA.
Lactose (refers to disaccharides) - synthesized by the animal body, is part of the milk of mammals.
Sucrose (disaccharide) - a source of energy, is formed in plants.
Maltose (disaccharide) - provides seed germination.
Also, simple sugars perform other functions: signaling, protective, transport.
Polymeric carbohydrates are water-soluble glycogen, as well as insoluble cellulose, chitin, and starch. They play an important role in metabolism, carry out structural, storage, protective functions.
lipids or fats. They are insoluble in water, but mix well with each other and dissolve in non-polar liquids (not containing oxygen, for example, kerosene or cyclic hydrocarbons are non-polar solvents). Lipids are needed in the body to provide it with energy - when they are oxidized, energy and water are formed. Fats are very energy efficient - with the help of 39 kJ per gram released during oxidation, you can lift a load weighing 4 tons to a height of 1 m. Also, fat provides a protective and heat-insulating function - in animals, its thick layer helps to keep warm in the cold season. Fat-like substances protect the feathers of waterfowl from getting wet, provide a healthy shiny appearance and elasticity of animal hair, and perform an integumentary function on plant leaves. Some hormones have a lipid structure. Fats form the basis of the structure of membranes.
Proteins or proteins
are heteropolymers of biogenic structure. They consist of amino acids, the structural units of which are: amino group, radical, and carboxyl group. The properties of amino acids and their differences from each other determine the radicals. Due to amphoteric properties, they can form bonds with each other. A protein can be made up of a few or hundreds of amino acids. In total, the structure of proteins includes 20 amino acids, their combinations determine the variety of forms and properties of proteins. About a dozen amino acids are essential - they are not synthesized in the animal body and their intake is provided by plant foods. In the gastrointestinal tract, proteins are broken down into individual monomers used for the synthesis of their own proteins.
Structural features of proteins:
primary structure - amino acid chain;
secondary - a chain twisted into a spiral, where hydrogen bonds are formed between the turns;
tertiary - a spiral or several of them, folded into a globule and connected by weak bonds;
quaternary does not exist in all proteins. These are several globules connected by non-covalent bonds.
The strength of structures can be broken and then restored, while the protein temporarily loses its characteristic properties and biological activity. Irreversible is only the destruction of the primary structure.
Proteins perform many functions in the cell:
acceleration of chemical reactions
(enzymatic or catalytic function, each of which is responsible for a specific single reaction);
transport - the transfer of ions, oxygen, fatty acids through cell membranes;
protective- such blood proteins as fibrin and fibrinogen are present in the blood plasma in an inactive form, at the site of wounds under the action of oxygen form blood clots. Antibodies provide immunity.
structural– peptides are partly or are the basis of cell membranes, tendons and other connective tissues, hair, wool, hooves and nails, wings and outer coverings. Actin and myosin provide contractile activity of muscles;
regulatory- proteins-hormones provide humoral regulation;
energy - during the absence of nutrients, the body begins to break down its own proteins, disrupting the process of its own vital activity. That is why, after a long hunger, the body cannot always recover without medical help.
Nucleic acids. There are 2 of them - DNA and RNA. RNA is of several types - informational, transport, ribosomal. Opened by the Swiss F. Fischer at the end of the 19th century.
DNA is deoxyribonucleic acid. Contained in the nucleus, plastids and mitochondria. Structurally, it is a linear polymer that forms a double helix of complementary nucleotide chains. The idea of its spatial structure was created in 1953 by the Americans D. Watson and F. Crick.
Its monomeric units are nucleotides, which have a fundamentally common structure of:
phosphate groups;
deoxyribose;
nitrogenous base (belonging to the purine group - adenine, guanine, pyrimidine - thymine and cytosine.)
In the structure of a polymer molecule, nucleotides are combined in pairs and complementary, which is due to the different number of hydrogen bonds: adenine + thymine - two, guanine + cytosine - three hydrogen bonds.
The order of nucleotides encodes the structural amino acid sequences of protein molecules. A mutation is a change in the order of nucleotides, since protein molecules of a different structure will be encoded.
RNA is ribonucleic acid. Structural features of its difference from DNA are:
instead of thymine nucleotide - uracil;
ribose instead of deoxyribose.
Transfer RNA - this is a polymer chain, which is folded in the plane in the form of a clover leaf, its main function is to deliver amino acids to ribosomes.
Matrix (information) RNA is constantly formed in the nucleus, complementary to any section of DNA. This is a structural matrix; on the basis of its structure, a protein molecule will be assembled on the ribosome. Of the total content of RNA molecules, this type is 5%.
Ribosomal- Responsible for the process of composing a protein molecule. Synthesized in the nucleolus. It is 85% in the cage.
ATP is adenosine triphosphate. This is a nucleotide containing:
3 residues of phosphoric acid;
As a result of cascade chemical processes, respiration is synthesized in mitochondria. The main function is energy, one chemical bond in it contains almost as much energy as is obtained by oxidizing 1 g of fat.
The cells that form the tissues of plants and animals vary considerably in shape, size and internal structure. However, all of them show similarities in the main features of the processes of vital activity, metabolism, in irritability, growth, development, and the ability to change.
Biological transformations occurring in a cell are inextricably linked with those structures of a living cell that are responsible for the performance of a single or other function. Such structures are called organelles.
Cells of all types contain three main, inextricably linked components:
- the structures that form its surface: the outer membrane of the cell, or the cell membrane, or the cytoplasmic membrane;
- cytoplasm with a whole complex of specialized structures - organelles (endoplasmic reticulum, ribosomes, mitochondria and plastids, Golgi complex and lysosomes, cell center), which are constantly present in the cell, and temporary formations called inclusions;
- nucleus - separated from the cytoplasm by a porous membrane and contains nuclear juice, chromatin and nucleolus.
Cell structure
The surface apparatus of the cell (cytoplasmic membrane) of plants and animals has some features.
In unicellular organisms and leukocytes, the outer membrane ensures the penetration of ions, water, and small molecules of other substances into the cell. The process of penetration of solid particles into the cell is called phagocytosis, and the entry of droplets of liquid substances is called pinocytosis.
The outer plasma membrane regulates the exchange of substances between the cell and the external environment.
In eukaryotic cells there are organelles covered with a double membrane - mitochondria and plastids. They contain their own DNA and protein-synthesizing apparatus, multiply by division, that is, they have a certain autonomy in the cell. In addition to ATP, a small amount of protein is synthesized in mitochondria. Plastids are characteristic of plant cells and multiply by division.
| Cell types | The structure and functions of the outer and inner layers of the cell membrane | ||
|---|---|---|---|
| outer layer (chemical composition, functions) |
inner layer - plasma membrane |
||
| chemical composition | functions | ||
| plant cells | Made up of fiber. This layer serves as the framework of the cell and performs a protective function. | Two layers of protein, between them - a layer of lipids | Limits the internal environment of the cell from the external and maintains these differences |
| animal cells | The outer layer (glycocalix) is very thin and elastic. Consists of polysaccharides and proteins. Performs a protective function. | Too | Special enzymes of the plasma membrane regulate the penetration of many ions and molecules into the cell and their release into the external environment. |
Single-membrane organelles include the endoplasmic reticulum, the Golgi complex, lysosomes, various types of vacuoles.
Modern means of research have allowed biologists to establish that, according to the structure of the cell, all living beings should be divided into organisms "non-nuclear" - prokaryotes and "nuclear" - eukaryotes.
Prokaryotic bacteria and blue-green algae, as well as viruses, have only one chromosome, represented by a DNA molecule (less often RNA), located directly in the cytoplasm of the cell.
| Major organoids | Structure | Functions |
|---|---|---|
| Cytoplasm | Internal semi-liquid medium of fine-grained structure. Contains a nucleus and organelles |
|
| EPS - endoplasmic reticulum | The system of membranes in the cytoplasm "forming channels and larger cavities, ER is of 2 types: granular (rough), on which many ribosomes are located, and smooth |
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| Ribosomes | Small bodies with a diameter of 15-20 mm | Carry out the synthesis of protein molecules, their assembly from amino acids |
| Mitochondria | They have spherical, filiform, oval and other shapes. There are folds inside the mitochondria (length from 0.2 to 0.7 microns). The outer cover of mitochondria consists of 2 membranes: the outer one is smooth, and the inner one forms outgrowths-crosses on which respiratory enzymes are located. |
|
| Plastids - characteristic only of plant cells, there are three types: | double membrane cell organelles | |
| chloroplasts | They are green, oval in shape, limited from the cytoplasm by two three-layer membranes. Inside the chloroplast are the faces where all the chlorophyll is concentrated | Use the light energy of the sun and create organic substances from inorganic |
| chromoplasts | Yellow, orange, red or brown, formed as a result of the accumulation of carotene | Give different parts of plants a red and yellow color |
| leucoplasts | Colorless plastids (found in roots, tubers, bulbs) | They store spare nutrients. |
| Golgi complex | It can have a different shape and consists of cavities delimited by membranes and tubules extending from them with bubbles at the end |
|
| Lysosomes | Round bodies about 1 µm in diameter. They have a membrane (skin) on the surface, inside of which there is a complex of enzymes | Perform a digestive function - digest food particles and remove dead organelles |
| Organelles of cell movement |
|
|
| Cell inclusions | These are non-permanent components of the cell - carbohydrates, fats and proteins. | Spare nutrients used in the life of the cell |
| Cell Center | Consists of two small bodies - centrioles and centrosphere - a compacted area of the cytoplasm | Plays an important role in cell division |
Eukaryotes have a great wealth of organelles, have nuclei containing chromosomes in the form of nucleoproteins (a complex of DNA with a histone protein). Eukaryotes include most modern plants and animals, both unicellular and multicellular.
There are two levels of cellular organization:
- prokaryotic - their organisms are very simply arranged - they are unicellular or colonial forms that make up the kingdom of shotguns, blue-green algae and viruses
- eukaryotic - unicellular colonial and multicellular forms, from protozoa - rhizomes, flagellates, ciliates - to higher plants and animals that make up the kingdom of plants, the kingdom of fungi, the kingdom of animals
| Major organelles | Structure | Functions |
|---|---|---|
| Nucleus of plant and animal cells | Round or oval shape | |
| The nuclear envelope consists of 2 membranes with pores |
|
|
| Nuclear juice (karyoplasm) - a semi-liquid substance | The environment in which the nucleoli and chromosomes are located | |
| Nucleoli are spherical or irregular | They synthesize RNA, which is part of the ribosome | |
| Chromosomes are dense, elongated or filamentous formations that are visible only during cell division. | Contain DNA, which contains hereditary information that is passed down from generation to generation |
All organelles of the cell, despite the peculiarities of their structure and functions, are interconnected and "work" for the cell as a single system in which the cytoplasm is the link.
Special biological objects, occupying an intermediate position between animate and inanimate nature, are viruses discovered in 1892 by D.I. Ivanovsky, they currently constitute the object of a special science - virology.
Viruses reproduce only in the cells of plants, animals and humans, causing various diseases. Viruses have a very simple structure and consist of a nucleic acid (DNA or RNA) and a protein coat. Outside the host cells, the viral particle does not show any vital functions: it does not feed, does not breathe, does not grow, does not multiply.
From the course of botany and zoology youknow that the bodies of plants and the bellynyh are built from cells. organismHumans are also made up of cells.Due to the cellular structureorganism, its growth is possible, oncereproduction, organ repairand fabrics and other forms of activity ness.
The shape and size of cells depend on the function performed by the organ.The main instrument for studyingcell structure is microosprey The light microscope allowsconsider a cell with an increase of up to about three thousand times;an electron microscope in which a stream of electrons is used instead of light - hundreds of thousands of times.Cytology deals with the study of the structure and functions of cells (from the Greek."cytos" - cell).
Cell structure.
Each cell is made up of a cytoplasm and a nucleus, andoutside it is covered with a membrane,delimiting one cell fromneighboring. Spacebetween the membranes of neighboring cellsfilled with liquid intercellular substance. The main function of the meme branes is that through it moving various substancescell to cell and soexchange of substances takes placein the manner of cells and intercellular space society.
Cytoplasm - viscous semi-liquid some substance. The cytoplasm contains a number of the smallest structures of the cell - organelles, who perform timespersonal features. Consider the mostimportant of the organelles: mitochondrii, network of tubules, ribosomes, cleexact center, core.
Mitochondria are short schenye bodies with internal featherssmall towns. They form a substance rich in energy, necessaryfor processes taking place inATP cell. It has been observed that the more activethe cell works, the more it contains mitochondria.
A network of tubules permeates the entire cytoplasm. Through these channels comes the movement of substances and mustacheconnection is established between organs ladies.
Ribosomes - dense bodiescontaining protein and ribonucleic acid acid. They are the place of proteins.
The cell center is formed bodies that are involved in the businesscells. They are located near the core.
Nucleus is a body that isis an obligatory partcells. During cell deletionthe structure of the nucleus changes. Whencell division ends, nucleusreturns to the previous stateniyu. There is a special substance in the nucleus - chromatin, from which before dividing cells form filamentous bodies - chromosomes. For cells ha racially constant amount of chromosom of a certain shape. In cage kah of the human body contains 46chromosomes, and in germ cells 23.
The chemical composition of the cell. Clet the ki of the human body are made up ofvarious chemical compoundsof inorganic and organicnature. to inorganic substancesyou cells include water and salt.Water makes up to 80% of the mass of cellski. It dissolves substancesworking in chemical reactions:transports nutrients,removes waste products from the cellharmful compounds. mineralsalts - sodium chloride, sodium chlorideliya, etc. - play an important role in the distribution of water between cellsand intercellular substance. Separate nye chemical elements, such aslike oxygen, hydrogen, nitrogen, sulfur,iron, magnesium, zinc, iodine, phosphorus, participate in the creation of vital ny organic compounds. Organic compounds image up to 20-30% of the mass of each cell. Among organic compoundsthe most important are carbohydratedy, fats, proteins and nucleic acids.
Carbohydrates made up of carbon, road and oxygen. to carbohydrates fromrushing glucose, animal collapse small - glycogen. many carbohydrates highly soluble in water and arebeing the main sources of energy for the implementation of all vitalprocesses. With the breakdown of 1 g of carbohydrates17.6 kJ of energy is released.
Fats formed by the same chemistrieschemical elements, as carbondy. Fats are insoluble in water. They areare part of cell membranes.Fats also serve as a reservesource of energy in the body. Atcomplete breakdown of 1 g of fat38.9 kJ of energy is expected.
Squirrels are the mainsubstances of the cell. Proteins are the mostcomplex of those found in naturede organic substances, although withare made up of relatively smallnumber of chemical elements - ylerod, hydrogen, oxygen, nitrogen,sulfur. Very often included in the composition of the proteindit phosphorus. The protein molecule haslarge sizes and presents withbattle chain consisting of dozens andhundreds of simpler compounds - 20 types amino acids.
Proteins serve as the main buildingbody material. They are participatingyut in the formation of cell membraneski, nuclei, cytoplasm, organelles.Many proteins act as an acceleratorcarriers of the flow of chemical reactionstsy - enzymes. Biochemicalprocesses can take place in a cellke only in the presence of specialenzymes that speed up the chemochemical transformations of substances into honeycombsnot a million times.
Proteins have a variety of structuresion. Only in one cellup to 1000 different proteins are produced.
When proteins are broken down in the bodyreleased about the samethe amount of energy, as in the breakdown of carbohydrates - 17.6 kJ per 1 g.
Nucleic acids form is in the cell nucleus. Related to thistheir name (from the Latin "nucleus" -nucleus). They are made up of carbon, acid lor, hydrogen and nitrogen and phosphorus. Nucleinew acids are of two types - deoxyribonucleic (DNA) and ribonucleic (RNA). DNA is found sya mainly in the chromosomes of cells. DNA determines the composition of cellular proteins ki and transmission of hereditarysigns and properties from parents tolanguor. RNA functions are associated witheducation characteristic of this protein cells.
From the course of botany and zoology, you know that the bodies of plants and animals are built from cells. The human body is also made up of cells. Thanks to the cellular structure of the body, its growth, reproduction, restoration of organs and tissues, and other forms of activity are possible.
The shape and size of cells depend on the function performed by the organ. The main instrument for studying the structure of the cell is a microscope. A light microscope makes it possible to view a cell at a magnification of up to about three thousand times; an electron microscope in which a stream of electrons is used instead of light - hundreds of thousands of times. Cytology deals with the study of the structure and functions of cells (from the Greek "cytos" - cell).
| |
Cytoplasm- viscous semi-liquid substance. The cytoplasm contains a number of the smallest structures of the cell - organelles, which perform different functions. Consider the most important of the organelles: mitochondria, a network of tubules, ribosomes, a cell center, a nucleus.
Mitochondria- short thickened bodies with internal partitions. They form a substance rich in energy necessary for the processes occurring in the ATP cell. It has been observed that the more actively a cell works, the more mitochondria it contains.
network of tubules pervades the entire cytoplasm. Through these tubules, substances move and a connection is established between organelles.
Ribosomes- dense bodies containing protein and ribonucleic acid. They are the site of protein formation.
Cell Center formed by bodies that are involved in cell division. They are located near the core.
Nucleus- this is a little body, which is an obligatory component of the cell. During cell division, the structure of the nucleus changes. When cell division ends, the nucleus returns to its previous state. There is a special substance in the nucleus - chromatin, from which, before cell division, filamentous bodies are formed - chromosomes. Cells are characterized by a constant number of chromosomes of a certain shape. The cells of the human body contain 46 chromosomes, and the germ cells have 23.
The chemical composition of the cell. The cells of the human body are composed of a variety of chemical compounds of inorganic and organic nature. The inorganic substances of the cell include water and salts. Water makes up to 80% of the cell mass. It dissolves substances involved in chemical reactions: it carries nutrients, removes waste and harmful compounds from the cell. Mineral salts - sodium chloride, potassium chloride, etc. - play an important role in the distribution of water between cells and intercellular substance. Separate chemical elements, such as oxygen, hydrogen, nitrogen, sulfur, iron, magnesium, zinc, iodine, phosphorus, are involved in the creation of vital organic compounds. Organic compounds form up to 20-30% of the mass of each cell. Among organic compounds, carbohydrates, fats, proteins and nucleic acids are of the greatest importance.
Carbohydrates are made up of carbon, hydrogen and oxygen. Carbohydrates include glucose, animal starch - glycogen. Many carbohydrates are highly soluble in water and are the main sources of energy for all life processes. With the breakdown of 1 g of carbohydrates, 17.6 kJ of energy is released.
Fats are formed by the same chemical elements as carbohydrates. Fats are insoluble in water. They are part of cell membranes. Fats also serve as a reserve source of energy in the body. With the complete breakdown of 1 g of fat, 38.9 kJ of energy is released.Squirrels are the basic substances of the cell. Proteins are the most complex organic substances found in nature, although they consist of a relatively small number of chemical elements - carbon, hydrogen, oxygen, nitrogen, sulfur. Very often, phosphorus is included in the composition of the protein. The protein molecule is large and is a chain consisting of tens and hundreds of simpler compounds - 20 types of amino acids.
Proteins serve as the main building material. They are involved in the formation of cell membranes, nuclei, cytoplasm, organelles. Many proteins act as accelerators for chemical reactions - enzymes. Biochemical processes can occur in a cell only in the presence of special enzymes that accelerate the chemical transformations of substances hundreds of millions of times.
Proteins have a variety of structures. Only in one cell there are up to 1000 different proteins.
When proteins break down in the body, approximately the same amount of energy is released as when carbohydrates are broken down - 17.6 kJ per 1 g.
Nucleic acids are formed in the cell nucleus. Their name is connected with this (from the Latin "nucleus" - the core). They are composed of carbon, oxygen, hydrogen and nitrogen and phosphorus. Nucleic acids are of two types - deoxyribonucleic (DNA) and ribonucleic (RNA). DNA is found mainly in the chromosomes of cells. DNA determines the composition of cell proteins and the transfer of hereditary traits and properties from parents to offspring. The functions of RNA are associated with the formation of proteins characteristic of this cell.
Basic terms and concepts: