The principle of compartmentation. Cellular compartment Compartment biology
Functions
Within compartments surrounded by a lipid bilayer, different values of κ may exist and different enzymatic systems may function. The principle of compartmentalization allows a cell to perform different metabolic processes simultaneously.
The cytosol of mitochondria contains an oxidative environment in which NADH is oxidized to NAD +.
The quintessence of the principle of compartmentalization can be considered the Golgi apparatus, in the dictyosomes of which various enzymatic systems operate, carrying out, for example, different stages of post-translational modification of proteins.
Classification
Three main cellular compartments are classified:
- Nuclear compartment containing the nucleus
- Space of the cisterns of the endoplasmic reticulum (transitioning into the nuclear lamina)
- Cytosol
Prokaryotes
In any cell there are two general microcompartments separated by a unitary membrane - cytoplasmic and exoplasmic. Bacteria with a gram-negative morphotype also have a third general microcompartment - the periplasmic one, which is located between the cytoplasmic membrane and the outer membrane. Pinevich A. V. Microbiology: Biology of Prokaryotes, Volume I, St. Petersburg State University Publishing House, 2006.
Sometimes a specialized microcompartment is located in several general compartments at once, that is, it has mixed localization. One example of this is undulopodia.
see also
Notes
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See what “Compartmentalization” is in other dictionaries: compartmentalization - The presence in the imaginal discs of insects of non-overlapping groups of cells (compartments, or polyclones), occupying a certain position in the disc and developing along their “own” cellular path; the development of each compartment is under ...
Technical Translator's Guide
and genetics. Dictionary. Compartmentalization Official terminology
This term has other meanings, see Broadcast. Translation (from Latin translatio translation) is the process of protein synthesis from amino acids on a matrix of informational (messenger) RNA (mRNA, mRNA), carried out by a ribosome.... ... Wikipedia
Compartments are divided into two main groups - general and specialized. The functions they perform are also divided into general and specialized.
General microcompartments are necessary for the life of the cell, since fundamental functions are carried out on their basis. For example, the functions of storage, reproduction and processing of gene sequences, as well as the functions of biogenesis of cellular structures, transport and metabolism.
In any cell there are two general microcompartments separated by a unitary membrane - cytoplasmic and exoplasmic. Bacteria with a gram-negative morphotype also have a third general microcompartment - the periplasmic one, which is located between the cytoplasmic membrane and the outer membrane.
Within the cytoplasmic general microcompartment there are multiple general microcompartments that lack their own membrane boundary. These include translation organelles - ribosomes, as well as post-transcriptional and post-translational processing organelles similar in size - dergadosomes, chaperonins and proteasomes.
Specialized microcompartments perform adaptive functions, and their presence in the cell does not serve as a condition for maintaining viability.
Specialized microcompartments are located inside the general microcompartments; accordingly, they are divided into
- cytoplasmic compartments
- periplasmic compartments
- exoplasmic compartments
Sometimes a specialized microcompartment is located in several general compartments at once, that is, it has mixed localization. One example of this is the rotating flagellum.
see also
Links
Pinevich A.V. Microbiology: Biology of Prokaryotes, Volume I, St. Petersburg State University Publishing House, 2006
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High orderliness of the internal contents of a eukaryotic cell is achieved by compartmentation its volume is divided into “cells” that differ in the details of their chemical (enzyme) composition. Compartmentation promotes the spatial separation of substances and processes in the cell.
The currently accepted point of view is that the membrane is composed of bimolecular layer of lipids. The hydrophobic regions of their molecules are turned towards each other, and the hydrophilic ones are located on the surface of the layer. Varied protein molecules embedded in this layer or placed on its surfaces.
Due to the compartmentation of cellular volume in a eukaryotic cell, a division of functions between different structures is observed. At the same time, various structures naturally interact with each other.
8. Structure of a eukaryotic cell: surface apparatus, protoplasm (nucleus and cytoplasm).
The main part of the cell surface apparatus is the plasma or biological membrane (cytoplasmic membrane). Cell membrane- the most important component of the living contents of a cell, built according to a general principle. Several models of the structure have been proposed. According to the fluid mosaic model proposed in 1972 by Nicholson and Singer, membranes include a bimolecular layer of phospholipids, which includes protein molecules. Lipids are water-insoluble substances whose molecules have two poles: hydrophilic and hydrophobic. In a biological membrane, the lipid molecules of two parallel layers face each other with their hydrophobic ends. And the hydrophilic poles remain outside, which form hydrophilic surfaces. On the surface of the membrane, outward and inward, proteins are located in a CONTINUOUS layer; there are 3 groups of them: peripheral, submerged (semi-integral), penetrating (integral). Most membrane proteins are enzymes. Immersed proteins form a biochemical conveyor on the membrane, where the transformation of substances occurs. The position of the buried proteins is stabilized by peripheral proteins. Penetrating proteins ensure the transfer of substances in two directions: through the membrane into the cell and back. There are two types: carriers and channel-formers. Channel formers line a pore filled with water through which dissolved inorganic substances pass from one side of the membrane to the other. On the outer surface of the plasma membrane in an animal cell, protein and lipid molecules are associated with branched carbohydrate chains, forming the glycocalyx, the supramembrane, nonliving layer, a waste product of the cell. Carbohydrate chains act as receptors (intercellular recognition - friend or foe). The cell acquires the ability to specifically respond to external influences. The supramembrane layer in bacteria contains murein, and in plants it contains cellulose or pectin. Under the plasma membrane on the cytoplasmic side there is a cortical (surface) layer and intracellular fibrillar structures that provide the mechanical stability of the membrane.
Cell nucleus consists of a membrane, nuclear juice, nucleolus and chromatin. Functional role nuclear envelope consists in the isolation of the genetic material (chromosomes) of a eukaryotic cell from the cytoplasm with its numerous metabolic reactions, as well as the regulation of bilateral interactions between the nucleus and the cytoplasm. The nuclear envelope consists of two membranes separated by a perinuclear (perinuclear) space. The latter can communicate with the tubules of the cytoplasmic reticulum.
The basis nuclear juice, or matrix, make up proteins. Nuclear sap forms the internal environment of the nucleus, and therefore plays an important role in ensuring the normal functioning of the genetic material.
Nucleolus represents the structure in which formation and maturation occurs ribosomal RNA (rRNA). Such areas in metaphase chromosomes look like narrowings and are called secondary constrictions.
Chromatin structures in the form of clumps, scattered in the nucleoplasm are an interphase form of existence of cell chromosomes.
IN cytoplasm distinguish between the main substance (matrix, hyaloplasm), inclusions and organelles. Basic substance of the cytoplasm fills the space between the plasmalemma, nuclear envelope and other intracellular structures. The most important proteins are represented by enzymes of glycolysis, sugar metabolism, nitrogenous bases, amino acids and lipids.
The main substance of the cytoplasm should be considered in the same way as a complex colloidal system capable of transitioning from a sol-like (liquid) state to a gel-like state. In the process of such transitions, work is done.
9. Surface apparatus of the cell. Structure and functions. Biological membranes. Their structure and functions. Transport of substances: active and passive.
The surface apparatus of cells consists of 3 subsystems - the plasma membrane, the supra-membrane complex (glycocalyx or cell wall) and submembranous musculoskeletal apparatus.
Its main functions are determined by its border position and include:
1) barrier (discriminating) function;
2) the function of recognizing other cells and components of the intercellular substance;
3) receptor function, including interaction with signaling molecules
4) transport function;
5) the function of cell movement through the formation of pseudo-, filo- and lamellipodia).
Biological membranes They delimit the cytoplasm from the environment, and also form the shells of nuclei, mitochondria and plastids. They form a labyrinth of endoplasmic reticulum and stacked flattened vesicles that make up the Golgi complex. Membranes form lysosomes, large and small vacuoles of plant and fungal cells, and pulsating vacuoles of protozoa. All these structures are compartments (compartments) intended for certain specialized processes and cycles.
Plasma membrane or plasmalemma, is the most constant, basic, universal membrane for all cells. It is a thin film covering the entire cell
Phospholipid molecules are arranged in two rows - with hydrophobic ends inward, hydrophilic heads towards the internal and external aqueous environment. In some places, the bilayer (double layer) of phospholipids is penetrated through and through by protein molecules (integral proteins). Inside such protein molecules there are channels - pores through which water-soluble substances pass. Other protein molecules penetrate the lipid bilayer halfway on one side or the other (semi-integral proteins). There are peripheral proteins on the surface of the membranes of eukaryotic cells. Lipid and protein molecules are held together due to hydrophilic-hydrophobic interactions.
The functions of biological membranes are as follows:
1. Barrier. They delimit the contents of the cell from the external environment and the contents of organelles from the cytoplasm.
2. Transport. They ensure the transport of substances into and out of the cell, from the cytoplasm to organelles and vice versa.
3. Receptor. They act as receptors (receiving and converting signals from the environment, recognizing cell substances, etc.).
4. Stabilizing.
5. Regulatory.
Transport of substances:
The flow of substances through the membrane depends on the size of the substance. Small molecules pass through active and passive transport; the transport of macromolecules and large particles is carried out through the formation of membrane vesicles by endocytosis and exocytosis. Passive transport - (without energy) diffusion along a concentration gradient; facilitated diffusion through a channel in the membrane formed by proteins. Active transport (ATP energy consumption) with the participation of carrier proteins against a concentration gradient.
Endocytosis is the transport of macromolecules through the plasmalemma. According to the aggregative state of the absorbed substance, they are isolated pinocytosis(capture and transport of fluid or compounds dissolved in fluid by the cell) and phagocytosis(capture and transport of solid particles). Phagocytosis and pinocytosis also refer to active transport. Phagocytosis– absorption of solids by the cell organic matter. Once near the cell, the solid particle is surrounded by membrane outgrowths, or membrane depressions are formed under it. As a result, the particle is enclosed in a membrane vesicle - a phagosome - inside the cell.
Pinocytosis- This is the process of absorption by a cell of small drops of liquid with high molecular weight substances dissolved in it. It is carried out by capturing these droplets by outgrowths of the cytoplasm. The captured droplets are immersed in the cytoplasm and absorbed there.
10. Protoplasm. Organization and functions. The role of changes in the aggregative state of the cytoplasm in the life of the cell (sol–gel transitions). Concept of biocolloid.
Protoplasm is the contents of a living cell, including its nucleus and cytoplasm.
Interacting with environment, the cell behaves as an integral structure.
The properties of protoplasm are attributed an important role in functional unification structural components and cell compartments. In general, it is usually considered as a special multiphase colloidal system or biocolloid.
An important role in the functional unification of the structural components and compartments of the cell belongs to the properties of living protoplasm. In general, it is usually considered as a special multiphase colloidal system, or biocolloid. Biocolloid differs from banal colloidal systems in the complexity of the dispersed phase. It is based on macromolecules, which are present either in dense, microscopically visible structures (organelles), or in a dispersed state, close to solutions or loose network-like structures such as gels.
Being a colloidal solution in the physicochemical sense, a biocolloid, due to the presence of lipids and large particles, simultaneously exhibits the properties of an emulsion and a suspension, respectively. Various “impurities” settle on the vast surfaces of macromolecules, which leads to a change in the aggregative state of protoplasm.
Between the extreme poles of the organization of protoplasm in the form of viscous gels and solutions there are transition states. During these transitions, work is performed, as a result of which various intracellular transformations are carried out - the formation of membranes, the assembly of microtubules or microfilaments from subunits, the release of secretions from the cell, a change in the geometry of protein molecules, leading to inhibition or enhancement of enzymatic activity. A feature of the biocolloid is also that under physiological conditions the transitions of protoplasm from one state of aggregation to another (due to the presence of a special enzymatic mechanism) are reversible.
This property of a biocolloid provides the cell with the ability, in the presence of energy, to repeatedly perform work in response to stimuli.