Cell biology of living organisms studies prokaryotes that do not have a nucleus (nucleus, core). Which organisms are characterized by the presence of a nucleus? The nucleus is the central organelle.
In contact with
Important! The main function of the cell nucleus is the storage and transmission of hereditary information.
Structure
What is the core? What parts does the nucleus consist of? Components listed below are part of core:
- Nuclear envelope;
- Nucleoplasm;
- Karyomatrix;
- Chromatin;
- Nucleols.
Nuclear envelope
Karyolemma consists of two layers- external and internal, separated by a perinuclear cavity. The outer membrane communicates with rough endoplasmic tubules. The fibrillar proteins of the core of the nuclear substance are attached to the inner shell. Between the membranes there is a perinuclear cavity formed by the mutual repulsion of ionized organic molecules with similar charges.
The karyolemma is penetrated by a system of openings - pores formed by protein molecules. Through them, ribosomes, the structures in which protein synthesis occurs, as well as messenger RNAs penetrate the cytoplasmic reticulum.
Intermembrane pores are tubules filled with. Their walls are formed by specific proteins - nucleoporins. The diameter of the hole allows the cytoplasm and the contents of the nucleus to exchange small molecules. Nucleic acids, as well as high molecular weight proteins, are not able to independently flow from one part of the cell to another. For this purpose, there are special transport proteins, the activation of which occurs with energy costs.
High molecular weight compounds move through pores with the help of karyopherins. Those that transport substances from the cytoplasm to the nucleus are called importins. Movement in the opposite direction is carried out by exportins. In what part of the nucleus is the RNA molecule located? She travels throughout the cell.
Important! High-molecular substances cannot independently penetrate through the pores from the core to and from the core.
Nucleoplasm
Represented by karyoplasm- a gel-like mass located inside a two-layer shell. Unlike the cytoplasm, where pH >7, the environment inside the nucleus is acidic. The main substances that make up the nucleoplasm are nucleotides, proteins, cations, RNA, H2O.
Karyomatrix
What components make up the core? It is formed by fibrillar proteins of a three-dimensional structure - lamins. Plays the role of a skeleton, preventing deformation of the organoid under mechanical stress.
Chromatin
This main substance, represented by a set of chromosomes, some of which are in an activated state. The rest are packed in compacted blocks. Their opening occurs during division. What part of the nucleus contains the molecule we know as DNA? consist of genes, which are parts of a DNA molecule. They contain information that transmits hereditary characteristics to new generations of cells. Therefore, this part of the nucleus contains a DNA molecule.
In biology they distinguish the following types of chromatin:
- Euchromatin. Appears as filamentous, despiralized, non-staining formations. It exists in the resting nucleus during the interphase between cycles of cell division.
- Heterochromatin. Non-activated spiralized, easily stained regions of chromosomes.
Nucleols
The nucleolus is the most compacted structure that makes up the nucleus. It has predominantly round shapes, however, there are segmented ones, like leukocytes. The nucleus of the cells of some organisms does not have nucleoli. In other cores there may be several of them. The substance of the nucleoli is represented by granules, which are subunits of ribosomes, as well as fibrils, which are RNA molecules.
Nucleolus: structure and functions
Nucleols are represented by the following structural types:
- Reticular. Typical for most cells. It is characterized by a high concentration of compacted fibrils and granules.
- Compact. Characterized by a multiplicity of fibrillar accumulations. Found in dividing cells.
- Annular. Characteristic of lymphocytes and connective tissue cells.
- Residual. Prevails in cells where the division process does not occur.
- Separated. All components of the nucleolus are separated, plastic actions are impossible.
Functions
What function does the kernel perform? Nucleus is characterized by the following responsibilities:
- Transfer of hereditary characteristics;
- Reproduction;
- Programmed death.
Storage of genetic information
Genetic codes are stored in chromosomes. They differ in shape and size. Individuals of different species have different numbers of chromosomes. The complex of characteristics characteristic of the repositories of hereditary information of a given species is called a karyotype.
Important! A karyotype is a set of characteristics characteristic of the chromosomal composition of organisms of a given species.
There are haploid, diploid, and polyploid sets of chromosomes.
The cells of the human body contain 23 types of chromosomes. The egg and sperm contain a haploid, that is, a single set of them. During fertilization, the stores of both cells combine, forming a double - diploid set. Cells of cultivated plants have a triploid or tetraploid karyotype.
Storage of genetic information
Transmission of hereditary characteristics
What vital processes occur in the nucleus? Gene coding is transmitted during the process of reading information, which results in the formation of messenger (messenger) RNA. Exportins excrete ribonucleic acid through nuclear pores into the cytoplasm. Ribosomes use genetic codes to synthesize proteins needed by the body.
Important! Protein synthesis occurs in cytoplasmic ribosomes based on encoded genetic information delivered by messenger RNA.
Reproduction
Prokaryotes reproduce simply. Bacteria have a single DNA molecule. In the process of division she copies herself attaching to the cell membrane. The membrane grows between the two junctions and two new organisms are formed.
In eukaryotes there are amitosis, mitosis and meiosis:
- Amitosis. Nuclear division occurs without cell fragmentation. Binuclear cellae are formed. During the next division, polynuclear formations may appear. What organisms are characterized by such reproduction? Aging, non-viable, and tumor cells are susceptible to it. In some situations, amitotic division to form normal cells occurs in the cornea, liver, cartilaginous textures, and also in the tissues of some plants.
- Mitosis. In this case, nuclear fission begins with its destruction. A cleavage spindle is formed, with the help of which paired chromosomes are separated to different ends of the cell. Replication of the carriers of heredity occurs, after which two nuclei are formed. After this, the spindle is dismantled and a nuclear membrane is formed, which divides one cell into two.
- Meiosis. A complex process in which nuclear division occurs without duplication of diverged chromosomes. Characteristic for the formation of germ cells - gametes that have a haploid set of carriers of heredity.
Programmed Doom
Genetic information provides for the life span of the cell, and after the allotted time, it starts the process of apoptosis (Greek - leaf fall). Chromatin condenses and the nuclear membrane is destroyed. The cella disintegrates into fragments limited to the plasma membrane. Apoptotic bodies, bypassing the stage of inflammation, are absorbed by macrophages or neighboring cells.
For clarity, the structure of the core and the functions performed by its parts are presented in the table
| Core element | Structural features | Functions performed |
| Shell | Double layer membrane | Distinguishing the contents of the nucleus and cytoplasm |
| Pores | Holes in the shell | Export - import RNA |
| Nucleoplasm | Gel-like consistency | Medium for biochemical transformations |
| Karyomatrix | Fibrillar proteins | Support structure, protect against deformation |
| Chromatin | Euchromatin, heterochromatin | Storage of genetic information |
| Nucleola | Fibrils and granules | Ribosome production |
Appearance
The shape is determined by the configuration of the membrane. The following types of nuclei are noted:
- Round. The most common one. For example, most of the lymphocyte is occupied by the nucleus.
- Elongated. The horseshoe-shaped nucleus is found in immature neutrophils.
- Segmented. Partitions form in the shell. Segments attached to each other are formed, such as in a mature neutrophil.
- Branched. Found in the nuclei of arthropod cells.
Number of Cores
Depending on the functions they perform, cellas may have one or more cores or not have them at all. The following types of cells are distinguished:
- Non-nuclear. The formed components of the blood of higher animals are erythrocytes, platelets are carriers of important substances. To make room for hemoglobin or fibrinogen, the bone marrow produces these elements nuclear-free. They are not able to divide and die off after the programmed time has passed.
- Single core. This is the case with most cells of living organisms.
- Binuclear. Liver hepatocytes perform a dual function - detoxification and production. Heme is synthesized, which is necessary for the production of hemoglobin. For these purposes, two cores are required.
- Multi-core. Muscle myocytes perform a colossal amount of work; additional nuclei are required to perform it. For the same reason, the cells of angiosperms are polynuclear.
Chromosomal pathologies
Many diseases are the result of disorders associated with abnormalities in chromosomal composition. The most well-known symptom complexes are:
- Down. Caused by the presence of an extra twenty-first chromosome (trisomy).
- Edwards. An extra eighteenth chromosome is present.
- Patau. Trisomy 13.
- Turner. The X chromosome is missing.
- Klinefelter. Characterized by extra X or Y chromosomes.
Ailments caused by a disorder in the functioning of the constituent parts of the nucleus are not always associated with chromosomal abnormalities. Mutations that affect individual nuclear proteins cause the following diseases:
- Laminopathy. Manifested by premature aging.
- Autoimmune diseases. Lupus erythematosus is a diffuse lesion of connective tissue textures, multiple sclerosis is the destruction of the myelin sheaths of nerves.
Important! Chromosomal abnormalities lead to severe diseases.
Core structure
Biology in pictures: Structure and functions of the nucleus
Conclusion
The cell nucleus has a complex structure and performs vital functions. It is a repository and transmitter of hereditary information, controls the synthesis of proteins and the processes of cell division. Chromosomal abnormalities are the causes of severe diseases.
The genetic information of a eukaryotic cell is stored in a special double-membrane organelle - the nucleus. It contains more than 90% of DNA.
Structure
The concept of what a nucleus is in biology and what functions it performs was strengthened in the scientific community only at the beginning of the 19th century. However, the nucleus was first observed in salmon cells by naturalist Antonie van Leeuwenhoek back in the 1670s. The term was proposed by botanist Robert Brown in 1831.
The nucleus is the largest organelle of the cell (up to 6 microns), which consists of three parts:
- double membrane;
- nucleoplasm;
- nucleolus.
Rice. 1. Internal structure of the nucleus.
The nucleus is separated from the cytoplasm by a double membrane that has pores through which selective transport of substances into the cytoplasm and back occurs. The space between the two membranes is called perinuclear. The inner membrane is lined from the inside with a nuclear matrix, which plays the role of a cytoskeleton and provides structural support for the nucleus. The matrix contains the nuclear lamina, which is responsible for the formation of chromatin.
Under the membrane shell there is a viscous liquid called nucleoplasm or karyoplasm.
It contains:
- chromatin, consisting of protein, DNA and RNA;
- individual nucleotides;
- nucleic acids;
- proteins;
- water;
- ions.
According to the density of chromatin twisting can be of two types:
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- euchromatin - decondensed (loose) chromatin in a non-dividing nucleus;
- heterochromatin - condensed (tightly twisted) chromatin in the dividing nucleus.
Some of the chromatin is always in a twisted state, and some is in a free state.
Rice. 2. Chromatin.
Heterochromatin is usually called a chromosome. Chromosomes are clearly visible under a microscope during mitotic cell division. The set of characteristics of chromosomes (size, shape, number) is called a karyotype. The karyotype includes autosomes and gonosomes. Autosomes carry information about the characteristics of a living organism. Gonosomes determine sex.
The outer membrane passes into the endoplasmic reticulum or reticulum (ER), forming folds. On the surface of the ER membrane there are ribosomes responsible for protein biosynthesis.
The nucleolus is a dense structure without a membrane. Essentially, this is a compacted area of nucleoplasm with chromatin. Consists of ribonucleoproteins (RNP). Here the synthesis of ribosomal RNA, chromatin and nucleoplasm occurs. The nucleus may contain several small nucleoli. The nucleolus was first discovered in 1774, but its functions became known only by the middle of the twentieth century.
Rice. 3. Nucleolus.
Mammalian red blood cells and plant sieve tube cells do not contain a nucleus. Striated muscle cells contain several small nuclei.
Functions
The main functions of the kernel are:
- control of all cell life processes, including protein synthesis;
- synthesis of some proteins, ribosomes, nucleic acids;
- storage of genetic material;
- transfer of DNA to subsequent generations during division.
A cell without a nucleus dies. However, cells with a transplanted nucleus regain viability by receiving the genetic information of the donor cell.. Total ratings received: 189.
The Linux kernel contains over 13 million lines of code and is one of the largest open source projects in the world. So what is the Linux kernel and what is it used for?
The kernel is the lowest level of software that interacts with the computer hardware. It is responsible for the interaction of all applications running in user space down to the physical hardware. Also allows processes known as services to receive information from each other using the IPC system.
Types and versions of the kernel
You already know what the Linux kernel is, but what types of kernels are there? There are various methods and architectural considerations when creating kernels from scratch. Most kernels can be one of three types: monolithic kernel, microkernel, and hybrid. The Linux kernel is a monolithic kernel, while the Windows and OS X kernels are hybrid. Let's take an overview of these three types of kernels.
Microkernel
Microkernels implement an approach in which they only manage what they are supposed to: CPU, memory, and IPC. Almost everything else on the computer is treated as an accessory and handled in user mode. Microkernels have the advantage of portability; they can be used on other hardware, and even another operating system, as long as the OS attempts to access the hardware in a compatible manner.
Microkernels are also very small in size and are more secure since most processes run in user mode with minimal privileges.
pros
- Portability
- Small size
- Low memory consumption
- Safety
Minuses
- Hardware accessible via drivers
- Hardware is slower because drivers run in user mode
- Processes must wait their turn to receive information
- Processes cannot access other processes without waiting
Monolithic core
Monolithic kernels are the opposite of microkernels because they cover not only the processor, memory and IPC, but also include things like device drivers, file system management, I/O system. Monolithic kernels give better access to hardware and enable better multitasking because if a program needs to get information from memory or another process, it doesn't have to wait in a queue. But this can cause some problems, because many things are performed in superuser mode. And this can harm the system if done incorrectly.
Pros:
- More direct access to hardware
- Easier exchange of data between processes
- Processes respond faster
Minuses:
- Big size
- Takes up a lot of RAM
- Less secure
Hybrid core
Hybrid kernels can choose what to work with in user mode and what in kernel space. Often device and file system drivers are in user space, while IPC and system calls are in kernel space. This solution takes the best of both worlds, but requires more work from OEMs. Because all responsibility for the drivers now lies with them.
pros
- Ability to choose what will work in kernel and user space
- Smaller in size than a monolithic core
- More flexible
Minuses
- May work slower
- Device drivers are released by manufacturers
Where are the kernel files stored?
Where is the Linux kernel located? The kernel files of Ubuntu or any other Linux distribution are located in the /boot folder and are called the vmlinuz version. The name vmlinuz comes from the Unix era. In the sixties, kernels were usually called simply Unix; in the 90s, Linux kernels were also called Linux.
When virtual memory was developed to facilitate multitasking, the letters vm appeared in front of the file name to indicate that the kernel supported this technology. For some time the kernel was called vmlinux, but then the image no longer fit in the boot memory and was compressed. After this, the last letter x was changed to z to indicate that zlib compression was used. This particular compression is not always used; sometimes you can find LZMA or BZIP2, so some kernels are simply called zImage.
The version number consists of three digits, the version number of the Linux kernel, your version number and patches or fixes.
The /boot package contains not only the Linux kernel, but also files such as initrd.img and system.map. Initrd is used as a small virtual disk that fetches and executes the actual kernel file. The System.map file is used to manage memory while the kernel is not yet loaded, and configuration files can specify which kernel modules are included in the kernel image when built.
Linux kernel architecture
Since the Linux kernel is a monolithic structure, it is larger and much more complex than other types of kernels. This design feature attracted much controversy in the early days of Linux and still carries some of the design flaws inherent in monolithic kernels.
But to get around these shortcomings, the Linux kernel developers did one thing - kernel modules that can be loaded at runtime. This means you can add and remove kernel components on the fly. This can go beyond adding hardware functionality, you can run server processes, enable virtualization, and completely replace the kernel without a reboot.
Imagine being able to install a Windows update package without having to constantly reboot.
Kernel modules
What if Windows already had all the drivers you needed by default, and you could only enable the ones you needed? This is exactly the principle that Linux kernel modules implement. Kernel modules, also known as loadable modules (LKMs), are essential for keeping the kernel running with all the hardware without using up all the RAM.
The module extends the functionality of the base kernel for devices, file systems, and system calls. Loadable modules have a .ko extension and are usually stored in the /lib/modules/ directory. Thanks to its modular nature, you can customize the kernel very easily by installing and loading modules. Automatic loading or unloading of modules can be configured in configuration files or unloaded and loaded on the fly using special commands.
Third-party, proprietary, closed-source modules are available on some distributions such as Ubuntu, but they are not shipped by default and must be installed manually. For example, the developers of the NVIDIA video driver do not provide source code, but instead they have compiled their own modules in the .ko format. Although these modules appear to be free, they are not free. That's why they are not included in many distributions by default. The developers believe that there is no need to pollute the kernel with proprietary software.
Now you are closer to answering the question what is the Linux kernel. The core is not magic. It is very necessary for the operation of any computer. The Linux kernel is different from OS X and Windows because it includes all the drivers and does a lot of things supported out of the box. Now you know a little more about how your software works and what files are used to do it.
Core I
Core
cellular, an obligatory, along with the cytoplasm, component of the cell in protozoa, multicellular animals and plants, containing chromosomes and the products of their activity. Based on the presence or absence of nitrogen in cells, all organisms are divided into eukaryotes (See Eukaryotes) and prokaryotes (See Prokaryotes). The latter do not have a formed ego (its shell is missing), although deoxyribonucleic acid (DNA) is present. The main part of the cell's hereditary information is stored in the nucleus; The genes contained in chromosomes play a major role in the transmission of hereditary characteristics in a number of cells and organisms. Ya is in constant and close interaction with the cytoplasm; it synthesizes intermediary molecules that transfer genetic information to the centers of protein synthesis in the cytoplasm. Thus, the ego controls the synthesis of all proteins and, through them, all physiological processes in the cell. Therefore, experimentally obtained nuclear-free cells and cell fragments always die; when transplanted into such cells, their viability is restored. I. was first observed by the Czech scientist J. Purkynė (1825) in a chicken egg; Yarn was described in plant cells by the English scientist R. Brown (1831-33), and in animal cells by the German scientist T. Schwann (1838-39). Usually there is only one nucleus in a cell, located near its center, and has the appearance of a spherical or ellipsoidal bubble ( figures 1-3, 5, 6
). Less often Y. is incorrect ( figure 4
) or complex shapes (for example, Ya. leukocytes, Macronucleus s ciliates). Bi- and multinucleate cells are not uncommon, usually formed by nuclear division without division of the cytoplasm or by the fusion of several mononuclear cells (the so-called symplasts, for example, striated muscle fibers). Ya sizes vary from Core 1 µm(in some protozoa) up to Core 1 mm(some eggs). The nucleus is separated from the cytoplasm by the nuclear envelope (NE), consisting of 2 parallel lipoprotein membranes 7-8 thick nm, between which there is a narrow perinuclear space. Nuclear weapons are permeated with pores with a diameter of 60-100 nm, at the edges of which the outer membrane of the nuclear weapon passes into the inner one. The frequency of pores varies in different cells: from units to 100-200 per 1 µm 2 surface of the I. Along the edge of the pore there is a ring of dense material - the so-called annulus. In the lumen of the pore there is often a central granule with a diameter of 15-20 nm, connected to the annulus by radial fibrils. Together with the pores, these structures constitute a pore complex, which apparently regulates the passage of macromolecules through the nuclear system (for example, the entry of protein molecules into the nuclear system, the exit of ribonucleoprotein particles from the nuclear system, etc.). The outer membrane of the NE in places passes into the membranes of the endoplasmic reticulum (See Endoplasmic reticulum); it usually carries protein-synthesizing particles - ribosomes .
The internal membrane of the nucleus sometimes forms invaginations into the depths of the nucleus. The contents of the nucleus are represented by nuclear juice (karyolymph, karyoplasm) and formed elements immersed in it - chromatin, nucleoli, etc. Chromatin is more or less loosened in the non-dividing nucleus the material of chromosomes, the DNA complex with proteins - the so-called deoxyribo-nucleoprotein (DNP). It is detected using the Feulgen color reaction for DNA ( figures 1 and 8
). During cell division (see Mitosis), all chromatin is condensed into chromosomes; at the end of mitosis, most of the chromosome sections are loosened again; these regions (called euchromatin) contain mostly unique (non-repeating) genes. Other regions of the chromosomes remain dense (so-called heterochromatin); they contain mostly repeating DNA sequences. In a non-dividing cell, most of the euchromatin is represented by a loose network of DNP fibrils with a thickness of 10 - 30 nm, heterochromatin - dense clumps (chromocenters), in which the same fibrils are tightly packed. Some euchromatin can also transform into a compact state; such euchromatin is considered inactive in relation to RNA synthesis. Chromocenters usually border the nuclear center or nucleolus. There is evidence that DNP fibrils are anchored on the inner membrane of the nuclear reactor. In a non-dividing cell, DNA synthesis (replication) occurs, which is studied by recording DNA precursors (usually thymidine) included in the cell, labeled with radioactive isotopes. It has been shown that along the length of chromatin fibrils there are many sections (so-called replicons), each with its own starting point for DNA synthesis, from which replication spreads in both directions. Due to DNA replication, the chromosomes themselves double. In nuclear chromatin, the genetic information encoded in DNA is read through the synthesis of matrix, or information, RNA molecules on DNA (see. Transcription), as well as molecules of other types of RNA involved in protein synthesis. Special regions of chromosomes (and, accordingly, chromatin) contain repeating genes that encode ribosomal RNA molecules; in these places, cells rich in ribonucleoproteins (RNP) are formed nucleoli, the main function of which is the synthesis of RNA, which is part of the ribosomes. Along with the components of the nucleolus, there are other types of RNA particles in the nucleus. These include perichromatin fibrils with a thickness of 3-5 nm and perichromatin granules (PG) with a diameter of 40-50 nm,
located at the boundaries of zones of loose and compact chromatin. Both of them probably contain messenger RNA in combination with proteins, and PGs correspond to its inactive form; release of PG from the cell into the cytoplasm through the pores of the cell was observed. There are also interchromatin granules (20-25 nm), and sometimes thick (40-60 nm) RNP threads twisted into balls. In the nuclei of amoebas there are RNP threads twisted into spirals (30-35 nm x 300 nm); the helices can extend into the cytoplasm and probably contain messenger RNA. Along with DNA and RNA-containing structures, some cells contain purely protein inclusions in the form of spheres (for example, in the cells of growing eggs of many animals, in the cells of a number of protozoa), bundles of fibrils or crystalloids (for example, in the nuclei of many tissue cells of animals and plants, macronuclei of a number of ciliates). Phospholipids, lipoproteins, and enzymes (DNA polymerase, RNA polymerase, a complex of enzymes of the membrane of the egg, including adenosine triphosphatase, etc.) were also found in the egg. Various special types of eggs are found in nature: giant growing eggs. eggs, especially fish and amphibians; Cells containing giant polytene chromosomes (see Polythenia), for example, in the cells of the salivary glands of dipteran insects; compact, devoid of nucleoli, spermatozoa and micronuclei
ciliates, completely filled with chromatin and not synthesizing RNA; Ya., in which chromosomes are constantly condensed, although nucleoli are formed (in some protozoa, in a number of insect cells); Ya., in which there was a two- or multiple increase in the number of sets of chromosomes (Polyploidy; figures 7, 9
). The main method of cell division is mitosis, which is characterized by the duplication and condensation of chromosomes, the destruction of cell chromosomes (with the exception of many protozoa and fungi) and the correct separation of sister chromosomes into daughter cells. However, the cells of some specialized cells, especially polyploid ones, can divide by simple ligation (see Amitosis). Highly polyploid eggs can divide not only into 2, but also into many parts, and also bud ( figure 7
). In this case, separation of entire chromosome sets can occur (so-called genome segregation). Lit.: Guide to cytology, vol. 1, M. -L., 1965; Raikov I.B., Karyology of protozoa, L., 1967; Robertis E., Novinsky V., Saez F.,. Cell biology, trans. from English, M., 1973; Chentsov Yu. S., Polyakov V. Yu., Ultrastructure of the cell nucleus, M., 1974; The nucleus, ed. A. J. Dalton, F, Haguenau, N. Y. - L., 1968; The cell nucleus, ed. N. Busch, v. 1-3, N. Y. - L., 1974. I. B. Raikov. Scheme of the ultrastructure of the liver cell nucleus: zones of compact (cx) and loose (px) chromatin; nucleolus (yak) with intranucleolar chromatin (vx), perichromatin fibrils (arrows), perichromatin (pg) and interchromatin (ig) granules; ribonucleoprotein thread coiled into a ball (k); core shell (yao) with pores (n). function TO(X,at), specifying the integral transformation which translates the function f(y) into the function φ ( X). The theory of such transformations is related to the theory of linear integral equations (See Integral equations). a spherical solid impact projectile in smoothbore artillery. From the middle of the 14th century. They were made of stone, from the 15th century. iron, then cast iron (for large-caliber guns) and lead (for small-caliber guns). From the 16th century incendiary “red-hot” weapons were used. In the 17th century. Hollow explosive shells (grenades) filled with gunpowder became widespread. In the 2nd half of the 19th century. Due to the replacement of smooth-bore guns with rifled ones, they fell out of use.
Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .
Synonyms:Antonyms:
See what “Kernel” is in other dictionaries:
The atomic nucleus is the positively charged massive central part of an atom, consisting of protons and neutrons (nucleons). daughter nucleus a nucleus formed as a result of the disintegration of the mother nucleus. mother nucleus atomic nucleus experiencing... ... Nuclear energy terms
Noun, s., used. compare often Morphology: (no) what? kernels, what? core, (I see) what? core, what? core, what? about the core; pl. What? kernels, (no) what? cores, what? cores, (I see) what? kernels, what? kernels, what are you talking about? about nuclei 1. The core is the internal,... ... Dmitriev's Explanatory Dictionary
KERNEL, cores, many. cores, cores, cores, cf. 1. The inner part of the fruit is in a hard shell. Walnut kernel. 2. only units. Internal, middle, central part of something (special). Wood core. Core of the earth (geol.). Ovule nucleus (bot.). Comet nucleus... ... Ushakov's Explanatory Dictionary
Wed. kernel, core, core, very middle, inside a thing, its interior or middle depth; concentrated essence, essence, basis; solid, strong, or most importantly, important, essential; | round body, ball. From these two meanings other meanings are derived: Son... Dahl's Explanatory Dictionary
- (nucleus), an obligatory part of the cell in plural. unicellular and all multicellular organisms. Based on the presence or absence of formed self in the cells, all organisms are divided into eukaryotes and prokaryotes, respectively. Basic the differences lie in the degree... ... Biological encyclopedic dictionary
core- NUCLEUS1, a, mn nuclei, nuclei, nuclei. The inner part of the fruit, enclosed in a hard shell. The kernel of a walnut is very similar in appearance to the brain of a mammal. CORE2, a, pl nuclei, nuclei, cf The internal central part of an object (consisting of ... ... Explanatory dictionary of Russian nouns
Cm … Synonym dictionary
A; pl. cores, cores, cores; Wed 1. The inner part of a fruit (usually a nut), enclosed in a hard shell. * And the nuts are not simple: All the shells are golden, The kernels are pure emerald (Pushkin). Don’t crack the nut, don’t eat the kernel (Sequel). 2. Internal,... ... encyclopedic Dictionary