The structure of an animal cell and the functions of organelles. Structure of eukaryotic cells

We invite you to familiarize yourself with the materials and.

: cellulose membrane, membrane, cytoplasm with organelles, nucleus, vacuoles with cell sap.

The presence of plastids is the main feature plant cell.

Functions of the cell membrane- determines the shape of the cell, protects against factors external environment.

Plasma membrane- a thin film, consisting of interacting molecules of lipids and proteins, delimits the internal contents from the external environment, ensures the transport of water, minerals and organic substances into the cell by osmosis and active transport, and also removes waste products.

Cytoplasm- the internal semi-liquid environment of the cell, in which the nucleus and organelles are located, provides connections between them, and participates in basic life processes.

Endoplasmic reticulum- a network of branching channels in the cytoplasm. It is involved in the synthesis of proteins, lipids and carbohydrates, and in the transport of substances. Ribosomes are bodies located on the ER or in the cytoplasm, consisting of RNA and protein, and are involved in protein synthesis. EPS and ribosomes are a single apparatus for the synthesis and transport of proteins.

Mitochondria- organelles delimited from the cytoplasm by two membranes. They oxidize organic matter and are synthesized ATP molecules with the participation of enzymes. Increase in the surface of the inner membrane on which enzymes are located due to cristae. ATP is an energy-rich organic substance.

Plastids(chloroplasts, leucoplasts, chromoplasts), their content in the cell is the main feature plant organism. Chloroplasts are plastids containing the green pigment chlorophyll, which absorbs light energy and uses it to synthesize organic substances from carbon dioxide and water. Chloroplasts are separated from the cytoplasm by two membranes, numerous outgrowths - grana on the inner membrane, in which chlorophyll molecules and enzymes are located.

Golgi complex- a system of cavities delimited from the cytoplasm by a membrane. The accumulation of proteins, fats and carbohydrates in them. Carrying out the synthesis of fats and carbohydrates on membranes.

Lysosomes- bodies delimited from the cytoplasm by a single membrane. The enzymes they contain accelerate the breakdown of complex molecules into simple ones: proteins into amino acids, complex carbohydrates into simple ones, lipids into glycerol and fatty acids, and also destroy dead parts of the cell and entire cells.

Vacuoles- cavities in the cytoplasm filled with cell sap, a place of accumulation of reserve nutrients, harmful substances; they regulate the water content in the cell.

Core - main part cells covered on the outside with two membranes, permeated with pores nuclear envelope. Substances enter the core and are removed from it through the pores. Chromosomes are carriers of hereditary information about the characteristics of an organism, the main structures of the nucleus, each of which consists of one DNA molecule combined with proteins. The nucleus is the site of DNA, mRNA, and rRNA synthesis.

Availability outer membrane, cytoplasm with organelles, nuclei with chromosomes.

Outer or plasma membrane- delimits the contents of the cell from environment(other cells, intercellular substance), consists of lipid and protein molecules, provides communication between cells, transport of substances into the cell (pinocytosis, phagocytosis) and out of the cell.

Cytoplasm- the internal semi-liquid environment of the cell, which provides communication between the nucleus and organelles located in it. The main life processes take place in the cytoplasm.

Cell organelles:

1) endoplasmic reticulum (ER)- a system of branching tubules, participates in the synthesis of proteins, lipids and carbohydrates, in the transport of substances in the cell;

2) ribosomes- bodies containing rRNA are located on the ER and in the cytoplasm and participate in protein synthesis. EPS and ribosomes are a single apparatus for protein synthesis and transport;

3) mitochondria- “power stations” of the cell, delimited from the cytoplasm by two membranes. The inner one forms cristae (folds), increasing its surface. Enzymes on the cristae accelerate the oxidation of organic substances and the synthesis of energy-rich ATP molecules;

4) Golgi complex- a group of cavities delimited by a membrane from the cytoplasm, filled with proteins, fats and carbohydrates, which are either used in vital processes or removed from the cell. The membranes of the complex carry out the synthesis of fats and carbohydrates;

5) lysosomes- bodies filled with enzymes accelerate the breakdown of proteins into amino acids, lipids into glycerol and fatty acids, polysaccharides into monosaccharides. In lysosomes, dead parts of the cell, whole cells, are destroyed.

Cellular inclusions- accumulations of reserve nutrients: proteins, fats and carbohydrates.

Core- the most important part of the cell. It is covered with a double-membrane shell with pores, through which some substances penetrate into the nucleus, and others enter the cytoplasm. Chromosomes are the main structures of the nucleus, carriers of hereditary information about the characteristics of the organism. It is transmitted during the division of the mother cell to daughter cells, and with germ cells to daughter organisms. The nucleus is the site of DNA, mRNA, and rRNA synthesis.

Exercise:

Explain why organelles are called specialized cell structures?

Answer: organelles are called specialized cell structures, since they perform strictly defined functions, hereditary information is stored in the nucleus, ATP is synthesized in mitochondria, photosynthesis occurs in chloroplasts, etc.

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Cell structure. The main parts and organelles of the cell, their structure and functions.

A cell is an elementary unit of structure and vital activity of all organisms, possessing its own metabolism, capable of independent existence, self-reproduction and development.
Cell organelles are permanent cellular structures, cellular organs that ensure the performance of specific functions during the life of the cell - storage and transmission of genetic information, transfer of substances, synthesis and transformation of substances and energy, division, movement, etc.
Chromosomes are nucleoprotein structures in the nucleus of a eukaryotic cell, in which the most of hereditary information and which are intended for its storage, implementation and transmission.

2. Name the main components of cells.
Cytoplasm, nucleus, plasma membrane, mitochondria, ribosomes, Golgi complex, endoplasmic reticulum, lysosomes, microtubules and microfilaments.

3. Give examples of non-nuclear cells. Explain the reason for their non-nuclear status. How does the life of nuclear-free cells differ from cells with a nucleus?
Prokaryotes are microbial cells that contain chromatin instead of a nucleus, which contains hereditary information.
In eukaryotes: mammalian erythrocytes. In place of the nucleus, they contain hemoglobin and, therefore, the binding of O2 and CO2 increases, the oxygen capacity of the blood - gas exchange in the lungs and tissues proceeds more efficiently.

4. Complete the diagram “Types of organelles by structure.”

5. Fill out the table “Structure and functions of cell organelles.”

7. What are they? cellular inclusions? What is their purpose?
These are accumulations of substances that the cell either uses for its needs or releases into the external environment. These can be protein granules, drops of fat, grains of starch or glycogen located directly in the cytoplasm.

Eukaryotic and prokaryotic cells. Structure and functions of chromosomes.
1. Define the concepts.
Eukaryotes are organisms whose cells contain one or more nuclei.
Prokaryotes are organisms whose cells do not have a formed nucleus.
Aerobes are organisms that use energy metabolism air oxygen.
Anaerobes are organisms that do not use oxygen in energy metabolism.

3. Fill out the table “Comparison of prokaryotic and eukaryotic cells.”

4. Draw a schematic diagram of the chromosome structure of prokaryotic and eukaryotic cells. Label their basic structures.
What do the chromosomes of eukaryotic and prokaryotic cells have in common and how do they differ?
In prokaryotes, DNA is circular, has no envelope, and is located right in the center of the cell. Sometimes bacteria do not have DNA, but RNA instead.
In eukaryotes, DNA is linear, located in chromosomes in the nucleus, covered with an additional membrane.
What these cells have in common is that genetic material represented by DNA located in the center of the cell. The function is the same - storage and transmission of hereditary information.

6. Why do scientists believe that prokaryotes are the most ancient organisms on our planet?
Prokaryotes are the simplest and most primitive organisms in structure and life activity, however, they easily adapt to almost any conditions. This allowed them to populate the planets and give rise to other, more advanced organisms.

2. Representatives of which kingdoms of living nature consist of eukaryotic cells?
Fungi, plants and animals are eukaryotes.

The science that studies the structure and function of cells is called cytology.

Cell- elementary structural and functional unit alive.

Cells, despite their small size, are very complex. The internal semi-liquid contents of the cell are called cytoplasm.

Cytoplasm is internal environment cells where they pass various processes and the components of the cell - organelles (organelles) are located.

Cell nucleus

The cell nucleus is the most important part cells.
The nucleus is separated from the cytoplasm by a shell consisting of two membranes. The core shell contains numerous pores in order to various substances could enter from the cytoplasm into the nucleus, and vice versa.
The internal contents of the kernel are called karyoplasma or nuclear juice. Located in the nuclear juice chromatin And nucleolus.
Chromatin is a strand of DNA. If a cell begins to divide, then the chromatin threads are tightly wound into a spiral around special proteins, like threads on a spool. Such dense formations are clearly visible under a microscope and are called chromosomes.

Core contains genetic information and controls the life of the cell.

Nucleolus is a dense round body inside the core. Typically, there are from one to seven nucleoli in the cell nucleus. They are clearly visible between cell divisions, and during division they are destroyed.

The function of the nucleoli is the synthesis of RNA and proteins, from which special organelles are formed - ribosomes.
Ribosomes participate in protein biosynthesis. In the cytoplasm, ribosomes are most often located on rough endoplasmic reticulum. Less commonly, they are freely suspended in the cytoplasm of the cell.

Endoplasmic reticulum (ER) participates in the synthesis of cell proteins and transport of substances within the cell.

A significant part of the substances synthesized by the cell (proteins, fats, carbohydrates) is not consumed immediately, but through the EPS channels enters for storage in special cavities laid in peculiar stacks, “cisterns,” and delimited from the cytoplasm by a membrane. These cavities are called Golgi apparatus (complex). Most often, the cisterns of the Golgi apparatus are located close to the cell nucleus.
Golgi apparatus takes part in the transformation of cell proteins and synthesizes lysosomes- digestive organelles of the cell.
Lysosomes They are digestive enzymes, “packed” into membrane vesicles, budded and distributed throughout the cytoplasm.
The Golgi complex also accumulates substances that the cell synthesizes for the needs of the whole organism and which are removed from the cell to the outside.

Mitochondria- energy organelles of cells. They convert nutrients into energy (ATP) and participate in cell respiration.

Mitochondria are covered with two membranes: the outer membrane is smooth, and the inner one has numerous folds and projections - cristae.

Plasma membrane

For the cell to be unified system, it is necessary that all its parts (cytoplasm, nucleus, organelles) are held together. For this purpose, in the process of evolution, it developed plasma membrane, which, surrounding each cell, separates it from the external environment. The outer membrane protects the internal contents of the cell - the cytoplasm and nucleus - from damage, maintains a constant shape of the cell, ensures communication between cells, selectively allows necessary substances into the cell and removes metabolic products from the cell.

The structure of the membrane is the same in all cells. The basis of the membrane is a double layer of lipid molecules, in which numerous protein molecules are located. Some proteins are located on the surface of the lipid layer, others penetrate both layers of lipids through and through.

Special proteins form the finest channels through which potassium, sodium, calcium ions and some other ions of small diameter can pass into or out of the cell. However, larger particles (nutrient molecules - proteins, carbohydrates, lipids) cannot pass through membrane channels and enter the cell using phagocytosis or pinocytosis:

• At the point where the food particle touches the outer membrane of the cell, an invagination is formed, and the particle enters the cell, surrounded by a membrane. This process is called phagocytosis (plant cells on top of the outer cell membrane covered with a dense layer of fiber (cell membrane) and cannot capture substances by phagocytosis).
• Pinocytosis differs from phagocytosis only in that in this case the invagination of the outer membrane captures not solid particles, but droplets of liquid with substances dissolved in it. This is one of the main mechanisms for the penetration of substances into the cell.

Cell organelles, also known as organelles, are specialized structures the actual cells responsible for various important and vital necessary functions. Why “organelles” after all? It’s just that here these cell components are compared with the organs of a multicellular organism.

What organelles make up the cell?

Also, sometimes organelles mean only the permanent structures of the cell that are located in it. For the same reason, the cell nucleus and its nucleolus are not called organelles, just as cilia and flagella are not organelles. But the organelles that make up the cell include: complex, endoplasmic reticulum, ribosomes, microtubules, microfilaments, lysosomes. In fact, these are the main organelles of the cell.

If we're talking about about animal cells, their organelles also include centrioles and microfibrils. But the number of organelles of a plant cell still includes only plastids characteristic of plants. In general, the composition of organelles in cells can differ significantly depending on the type of cell itself.

Drawing of the structure of a cell, including its organelles.

Double membrane cell organelles

Also in biology, there is such a phenomenon as double-membrane cell organelles, these include mitochondria and plastids. Below we will describe their inherent functions, as well as all other main organelles.

Functions of cell organelles

Now let’s briefly describe the main functions of organelles animal cell. So:

• The plasma membrane is a thin film around the cell consisting of lipids and proteins. A very important organelle that transports water, minerals and organic substances into the cell, removes harmful waste products and protects the cell.
• Cytoplasm is the internal semi-liquid environment of the cell. Provides communication between the nucleus and organelles.
• The endoplasmic reticulum is also a network of channels in the cytoplasm. Accepts Active participation in the synthesis of proteins, carbohydrates and lipids, and transports nutrients.
• Mitochondria are organelles in which organic substances are oxidized and ATP molecules are synthesized with the participation of enzymes. Essentially, mitochondria are a cell organelle that synthesizes energy.
• Plastids (chloroplasts, leucoplasts, chromoplasts) - as we mentioned above, are found exclusively in plant cells, in general their presence is main feature plant organism. They play very important function For example, chloroplasts, which contain the green pigment chlorophyll, are responsible for the phenomenon in a plant.
• The Golgi complex is a system of cavities delimited from the cytoplasm by a membrane. Carry out the synthesis of fats and carbohydrates on the membrane.
• Lysosomes are bodies separated from the cytoplasm by a membrane. The special enzymes they contain accelerate the breakdown of complex molecules. The lysosome is also an organelle that ensures protein assembly in cells.
• - cavities in the cytoplasm filled with cell sap, a place of accumulation of reserve nutrients; they regulate the water content in the cell.

In general, all organelles are important, because they regulate the life of the cell.

Basic cell organelles, video

And finally, a thematic video about cell organelles.