It is known that most living beings consist of water in free or bound form by 70 percent or more. Where does it come from so much, where is it localized? It turns out that each cell in its composition has up to 80% water, and only the rest falls on the mass of dry matter.
And the main "water" structure is just the cytoplasm of the cell. This is a complex, heterogeneous, dynamic internal environment, with the structural features and functions of which we will get acquainted further.
Protoplast
This term is used to denote the entire internal content of any eukaryotic smallest structure, separated by a plasma membrane from its other "colleagues". That is, this includes the cytoplasm - the internal environment of the cell, the organelles located in it, the nucleus with nucleoli and genetic material.
What organelles are located inside the cytoplasm? This is:
- ribosomes;
- mitochondria;
- EPS;
- Golgi apparatus;
- lysosomes;
- cell inclusions;
- vacuoles (in plants and fungi);
- cell center;
- plastids (in plants);
- cilia and flagella;
- microfilaments;
- microtubules.
The nucleus, separated by a karyolemma, with nucleoli and DNA molecules, also contains the cytoplasm of the cell. In the center it is in animals, closer to the wall - in plants.
Thus, the structural features of the cytoplasm will largely depend on the type of cell, on the organism itself, its belonging to the kingdom of living beings. In general, it occupies all the free space inside and performs a number of important functions.
Matrix, or hyaloplasm
The structure of the cytoplasm of a cell consists primarily of its division into parts:
- hyaloplasm - permanent liquid part;
- organelles;
- inclusions are structure variables.
Matrix, or hyaloplasm, is the main internal component, which can be in two states - ash and gel.
Cytosol is a cell cytoplasm that has a more liquid aggregate character. The cytogel is the same, but in a denser state, rich in large molecules of organic substances. The general chemical composition and physical properties of the hyaloplasm are expressed as follows:
- colorless, viscous colloidal substance, quite thick and slimy;
- has a clear differentiation in terms of structural organization, howeverdue to mobility, can easily change it;
- from the inside is represented by a cytoskeleton or microtrabecular lattice, which is formed by protein filaments (microtubules and microfilaments);
- on parts of this lattice all the structural parts of the cell as a whole are located, and due to microtubules, the Golgi apparatus and the ER, a message occurs between them through the hyaloplasm.
Thus, hyaloplasm is an important part that provides many functions of the cytoplasm in the cell.
Composition of the cytoplasm
If we talk about the chemical composition, then the share of water in the cytoplasm accounts for about 70%. This is an average value, because some plants have cells in which up to 90-95% of water. Dry matter represented by:
- proteins;
- carbs;
- phospholipids;
- cholesterol and other nitrogen-containing organic compounds;
- electrolytes (mineral s alts);
- inclusions in the form of glycogen droplets (in animal cells) and other substances.
The general chemical reaction of the medium is alkaline or slightly alkaline. If we consider how the cytoplasm of the cell is located, then such a feature should be noted. The part is collected at the edge, in the region of the plasmalemma, and is called ectoplasm. The other part is oriented closer to the karyolemma, is called the endoplasm.
The structure of the cell cytoplasm is determined by special structures - microtubules and microfilaments, so we will consider them in more detail.
Microtubules
Hollowsmall elongated particles up to several micrometers in size. Diameter - from 6 to 25 nm. Due to too meager indicators, a complete and capacious study of these structures is not yet possible, however, it is assumed that their walls consist of the protein substance tubulin. This compound has a chain helically twisted molecule.
Some functions of the cytoplasm in the cell are performed precisely due to the presence of microtubules. So, for example, they are involved in building the cell walls of fungi and plants, some bacteria. In animal cells, they are much less. Also, it is these structures that carry out the movement of organelles in the cytoplasm.
Microtubules themselves are unstable, capable of quickly disintegrating and forming again, being renewed from time to time.
Microfilaments
Sufficiently important elements of the cytoplasm. They are long filaments of actin (globular protein), which, intertwining with each other, form a common network - the cytoskeleton. Another name is microtrabecular lattice. This is a kind of structural features of the cytoplasm. Indeed, it is thanks to such a cytoskeleton that all organelles are held together, they can safely communicate with each other, substances and molecules pass through them, and metabolism is carried out.
However, it is known that the cytoplasm is the internal environment of the cell, which is often capable of changing its physical data: becoming more liquid or viscous, changing its structure (transition from sol to gel and vice versa). In this regard, microfilaments are a dynamic, labile part, capable ofquickly rebuild, change, disintegrate and form again.
Plasma membranes
The presence of well-developed and normally functioning numerous membrane structures is important for the cell, which also constitutes a kind of structural features of the cytoplasm. After all, it is through the plasma membrane barriers that molecules, nutrients and metabolic products, gases for respiration processes, and so on are transported. That is why most organelles have these structures.
They, like a network, are located in the cytoplasm and delimit the internal contents of their hosts from each other, from the environment. Protect and protect against unwanted substances and harmful bacteria.
The structure of most of them is similar - a fluid-mosaic model, which considers each plasmalemma as a biolayer of lipids, penetrated by different protein molecules.
Since the functions of the cytoplasm in the cell are primarily a transport message between all its parts, the presence of membranes in most organelles is one of the structural parts of the hyaloplasm. In a complex, all together, they perform common tasks to ensure the life of the cell.
Ribosome
Small (up to 20 nm) rounded structures, consisting of two halves - subunits. These halves can exist both together and separated for some time. The basis of the composition: rRNA (ribosomal ribonucleic acid) and protein. The main localization of ribosomes in the cell:
- nucleus and nucleoli wherethe formation of the subunits themselves on the DNA molecule;
- cytoplasm - ribosomes here are finally formed into a single structure, uniting the halves;
- membranes of the nucleus and endoplasmic reticulum - ribosomes synthesize protein on them and immediately send it inside the organelles;
- mitochondria and chloroplasts of plant cells synthesize their own ribosomes inside the body and use the produced proteins, that is, in this respect they exist autonomously.
The functions of these structures are the synthesis and assembly of protein macromolecules, which are spent on the vital activity of the cell.
Endoplasmic reticulum and Golgi apparatus
Numerous network of tubules, tubules and vesicles, forming a conducting system inside the cell and located throughout the cytoplasm, is called the endoplasmic reticulum, or reticulum. Its function corresponds to the structure - ensuring the interconnection of organelles with each other and transporting nutrient molecules to organelles.
The Golgi complex, or apparatus, performs the function of accumulating the necessary substances (carbohydrates, fats, proteins) in a system of special cavities. They are limited from the cytoplasm by membranes. Also, it is this organoid that is the site of the synthesis of fats and carbohydrates.
Peroxisomes and lysosomes
Lysosomes are small, rounded structures resembling fluid-filled vesicles. They are very numerous and distributed in the cytoplasm, where they move freely within the cell. Their main task is the dissolution of foreign particles,that is, the elimination of "enemies" in the form of dead sections of cellular structures, bacteria and other molecules.
The liquid content is saturated with enzymes, so lysosomes take part in the breakdown of macromolecules to their monomer units.
Peroxisomes are small oval or round organelles with a single membrane. Filled with liquid content, including a large number of different enzymes. They are one of the main consumers of oxygen. They perform their functions depending on the type of cell in which they are located. Myelin synthesis is possible for the sheath of nerve fibers, and they can also carry out the oxidation and neutralization of toxic substances and various molecules.
Mitochondria
These structures are not in vain called the power (energy) stations of the cell. After all, it is in them that the formation of the main energy carriers occurs - the molecules of adenosine triphosphoric acid, or ATP. In appearance, they resemble beans. The membrane that separates the mitochondria from the cytoplasm is double. The internal structure is highly folded to increase the surface area for ATP synthesis. The folds are called cristae, they contain a large number of different enzymes to catalyze the synthesis processes.
Most of all mitochondria have muscle cells in animals and humans, since they require a high content and energy consumption.
Cyclose phenomenon
The movement of the cytoplasm in the cell is called cyclosis. It consists of several types:
- oscillatory;
- rotary, or circular;
- striated.
Any movement is necessary to ensure a number of important functions of the cytoplasm: the full movement of organelles inside the hyaloplasm, the uniform exchange of nutrients, gases, energy, and the removal of metabolites.
Cyclose occurs in both plant and animal cells, with no exceptions. If it stops, then the body dies. Therefore, this process is also an indicator of the vital activity of beings.
Thus, we can conclude that the cytoplasm of an animal cell, plant cell, any eukaryotic cell is a very dynamic, living structure.
The difference between the cytoplasm of animal and plant cells
Actually, there are few differences. The general plan of the building, the functions performed are completely similar. However, there are still some discrepancies. So for example:
- The cytoplasm of plant cells contains more microtubules that take part in the formation of their cell walls than microfilaments. Animals do the opposite.
- Cell inclusions in the cytoplasm of plants are grains of starch, while in animals they are drops of glycogen.
- The plant cell is characterized by the presence of organelles that are not found in animals. These are plastids, vacuole and cell wall.
In other respects, both structures are identical in composition and structure of the cytoplasm. The number of certain elemental links may vary, but their presence is mandatory. Therefore, the value of the cytoplasm in the cell asplants and animals are equally great.
The role of the cytoplasm in the cell
The value of the cytoplasm in the cell is great, if not to say that it is decisive. After all, this is the basis in which all vital structures are located, so it is difficult to overestimate its role. We can formulate several main points that reveal this meaning.
- It is it that unites all the constituent parts of the cell into one complex unified system that carries out the processes of life smoothly and collectively.
- Thanks to water, the cytoplasm in the cell acts as a medium for numerous complex biochemical interactions and physiological transformations of substances (glycolysis, nutrition, gas exchange).
- This is the main "capacity" for the existence of all cell organelles.
- Using microfilaments and tubules, it forms the cytoskeleton, binding organelles and allowing them to move.
- It is in the cytoplasm that a number of biological catalysts are concentrated - enzymes, without which no biochemical reaction occurs.
Summarizing, I must say the following. The role of the cytoplasm in the cell is practically the key, since it is the basis of all processes, the environment of life and the substrate for reactions.
