With over 13 million lines of code, the Linux kernel 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's 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

What is the Linux kernel you already know, but what are the types of kernels? There are various ways and architectural considerations when building 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 review these three kinds of kernels.

microkernel

Microkernels take an approach in which they manage only what they have to: CPU, memory, and IPC. Almost everything else in the computer is treated as accessories and handled in user mode. Microkernels have the advantage of portability, they can be used on different hardware, and even different operating systems, as long as the OS tries to access the hardware in a compatible way.

Microkernels are also very small and more secure because most processes run in user mode with minimal privileges.

pros

• Portability
• small size
• Low memory consumption
• Safety

Minuses

• Hardware available through drivers
• Hardware is slower because drivers are running 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 CPU, memory, and IPC, but also include things like device drivers, filesystem management, and I/O. Monolithic kernels give you better access to hardware and better multitasking because if a program needs to get information from memory or another process, it won't have to wait in a queue. But this can cause some problems, because a lot of things are done in superuser mode. And it can harm the system if it behaves incorrectly.

Pros:

• More direct access to hardware
• Easier communication between processes
• Processes respond faster

Minuses:

• Big size
• Takes up a lot of RAM
• Less safe

hybrid core

Hybrid kernels can choose what to work with in user mode and what in kernel space. Often device drivers and filesystems 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. Since all responsibility for the driver now lies with them.

pros

• Ability to choose what will work in kernel and user space
• Smaller than a monolithic core
• More flexible

Minuses

• May run 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 vmlinuz-version. The name vmlinuz comes from the Unix era. In the 60s, kernels were 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 a while the kernel was called vmlinux, but then the image no longer fit in boot memory and was compressed. After that, the last letter x was changed to z to indicate that zlib compression was used. This compression is not always used, sometimes you can find LZMA or BZIP2, so some kernels simply call zImage.

The version numbering consists of three digits, the version number of the Linux kernel, your version number, and patches or fixes.

In the /boot package, you can find not only the Linux kernel, but also files such as initrd.img and system.map. The 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 has not yet loaded, and configuration files can specify which kernel modules are included in the kernel image when it is built.

Linux kernel architecture

Since the Linux kernel has a monolithic structure, it is larger and much more complex than other types of kernels. This design feature attracted a lot of 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 developers of the Linux kernel have done one thing - kernel modules that can be loaded at runtime. This means that you can add and remove kernel components on the fly. Everything can go beyond adding hardware functionality, you can run server processes, enable virtualization, and completely replace the kernel without rebooting.

Imagine being able to install a Windows update package without the need for constant reboots.

Kernel modules

What if Windows already had all the drivers you need by default, and you could only enable the ones you need? This principle is implemented by Linux kernel modules. Kernel modules, also known as loadable modules (LKMs), are essential to keep the kernel running on all hardware without consuming all of the RAM.

The module extends the functionality of the base kernel for devices, file systems, system calls. Loadable modules have a .ko extension and are usually stored in the /lib/modules/ directory. Due to its modular nature, you can very easily customize the kernel 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, closed-source, proprietary modules are available in some distributions, such as Ubuntu, but they are not supplied by default and must be installed manually. For example, the NVIDIA video driver developers do not provide the 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. Therefore, they are not included in many distributions by default. Developers believe that it is not necessary to pollute the kernel with non-free software.

Now you are closer to the answer to the question of 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 that are supported out of the box. Now you know a little more about how your software works and what files it uses.

Probably, every user who is little familiar with a computer has come across a bunch of incomprehensible characteristics when choosing a central processor: process technology, cache, socket; sought advice from friends and acquaintances competent in the matter of computer hardware. Let's look at the variety of all possible parameters, because the processor is the most important part of your PC, and understanding its characteristics will give you confidence in the purchase and further use.

CPU

The processor of a personal computer is a microcircuit that is responsible for performing any operations with data and controls peripheral devices. It is contained in a special silicon case called a crystal. The abbreviation is used for abbreviation - CPU(CPU) or CPU(from the English Central Processing Unit - central processing unit). In today's computer hardware market, there are two competing corporations, Intel and AMD, which are constantly in the race for the performance of new processors, constantly improving the technological process.

Process technology

Process technology is the size used in the manufacture of processors. It determines the size of the transistor, the unit of which is nm (nanometer). Transistors, in turn, form the internal basis of the CPU. The bottom line is that continuous improvement in manufacturing techniques allows you to reduce the size of these components. As a result, much more of them are placed on the processor chip. This helps to improve the performance of the CPU, so the process technology used is always indicated in its parameters. For example, the Intel Core i5-760 is made according to the 45 nm process technology, and the Intel Core i5-2500K is made according to the 32 nm process technology, based on this information, one can judge how modern the processor is and outperforms its predecessor in performance, but when choosing it is necessary to take into account a number of other options.

Architecture

Also, processors are characterized by such a characteristic as architecture - a set of properties inherent in a whole family of processors, as a rule, produced for many years. In other words, the architecture is their organization or the internal design of the CPU.

Number of Cores

Core- the most important element of the central processor. It is a part of the processor capable of executing a single instruction stream. The cores differ in cache size, bus frequency, manufacturing technology, etc. Manufacturers assign new names to them with each subsequent technical process (for example, the AMD processor core is Zambezi, and Intel is Lynnfield). With the development of processor manufacturing technologies, it became possible to place more than one core in one package, which significantly increases the performance of the CPU and helps to perform several tasks simultaneously, as well as use several cores in programs. Multi-core processors will be able to handle archiving, video decoding, the operation of modern video games, etc. faster. For example, Intel's Core 2 Duo and Core 2 Quad processor lines, which use dual-core and quad-core CPUs, respectively. At the moment, processors with 2, 3, 4 and 6 cores are widely available. Most of them are used in server solutions and are not required by an ordinary PC user.

Frequency

In addition to the number of cores, performance is affected by clock frequency. The value of this characteristic reflects the performance of the CPU in the number of cycles (operations) per second. Another important characteristic is bus frequency(FSB - Front Side Bus) demonstrating the speed at which data is exchanged between the processor and the computer's peripherals. The clock frequency is proportional to the bus frequency.

socket

In order for the future processor to be upgraded compatible with the existing motherboard, you need to know its socket. The socket is called connector, in which the CPU is installed on the computer motherboard. The socket type is characterized by the number of pins and the processor manufacturer. Different sockets correspond to certain types of CPU, so each socket accepts a certain type of processor. Intel uses the LGA1156, LGA1366, and LGA1155 socket, while AMD uses AM2+ and AM3.

Cache

Cache- the amount of memory with a very high access speed, necessary to accelerate the access to data that is constantly in memory with a lower access speed (RAM). When choosing a processor, keep in mind that increasing the size of the cache improves the performance of most applications. The CPU cache is distinguished by three levels ( L1, L2 and L3), located directly on the processor core. Data from RAM gets into it for higher processing speed. It is also worth considering that for multi-core CPUs, the amount of L1 cache for one core is indicated. The second-level cache performs similar functions, differing in lower speed and larger volume. If you intend to use the processor for resource-intensive tasks, then a model with a large amount of second-level cache will be preferable, given that the total amount of L2 cache is indicated for multi-core processors. The most powerful processors such as AMD Phenom, AMD Phenom II, Intel Core i3, Intel Core i5, Intel Core i7, Intel Xeon are equipped with L3 cache. The third level cache is the least fast, but it can be up to 30 MB.

Energy consumption

The power consumption of the processor is closely related to the technology of its production. With a decrease in the nanometers of the process technology, an increase in the number of transistors and an increase in the clock frequency of processors, there is an increase in the power consumption of the CPU. For example, Intel's Core i7 processors require up to 130 or more watts. The voltage supplied to the core clearly characterizes the power consumption of the processor. This setting is especially important when choosing a CPU for use as a multimedia center. Modern processor models use various technologies that help combat excessive power consumption: built-in temperature sensors, automatic voltage and frequency control systems for processor cores, and power-saving modes with low CPU load.

Additional features

Modern processors have acquired the ability to work in 2 and 3-channel modes with RAM, which significantly affects its performance, and also support a larger set of instructions, raising their functionality to a new level. GPUs process video on their own, thereby offloading the CPU, thanks to the technology DXVA(from the English DirectX Video Acceleration - video acceleration by the DirectX component). Intel uses the above technology turbo boost to dynamically change the CPU clock frequency. Technology Speed ​​Step manages CPU power consumption depending on processor activity, and Intel Virtualization Technology creates a virtual environment in hardware to use multiple operating systems. Also, modern processors can be divided into virtual cores using technology Hyper Threading. For example, a dual-core processor is able to split the clock speed of one core into two, which contributes to high processing performance with four virtual cores.

Thinking about the configuration of your future PC, do not forget about the video card and its GPU(from the English Graphics Processing Unit - graphic processing device) - the processor of your video card, which is responsible for rendering (arithmetic operations with geometric, physical objects, etc.). The higher the frequency of its core and the frequency of memory, the less will be the load on the central processor. Gamers should pay special attention to the GPU.

Many biochemical reactions and processes take place in every living cell. To control them, as well as to regulate many vital factors, a special structure is needed. What is a nucleus in biology? What makes it effective in its task?

What is a nucleus in biology. Definition

The nucleus is the essential structure of any cell in the body. What is a core? In biology, it is an essential component of every organism. The nucleus can be found both in unicellular protozoa and in highly organized representatives of the eukaryotic world. The main function of this structure is the storage and transmission of genetic information, which is also contained here.

After the egg is fertilized by the sperm, the two haploid nuclei fuse. After the fusion of germ cells, a zygote is formed, the nucleus of which already carries a diploid set of chromosomes. This means that the karyotype (the genetic information of the nucleus) already contains copies of both the mother's and father's genes.

Core Composition

What is the characteristic of the core? Biology carefully studies the composition of the nuclear apparatus, since this can give impetus to the development of genetics, breeding and molecular biology.

The nucleus is a two-membrane structure. Membranes are an extension that is necessary for the transport of formed substances from the cell. The contents of the nucleus is called the nucleoplasm.

Chromatin is the main substance of the nucleoplasm. The composition of chromatin is diverse: here are primarily nucleic acids (DNA and RNA), as well as proteins and many metal ions. DNA in the nucleoplasm is ordered in the form of chromosomes. It is the chromosomes that double during division, after which each of their sets passes into daughter cells.

There are two main types of RNA in the nucleoplasm: mRNA and rRNA. formed in the process of transcription - reading information from DNA. The molecule of such ribonucleic acid later leaves the nucleus and subsequently serves as a template for the formation of new proteins.

Ribosomal RNA is produced in special structures called nucleoli. The nucleolus is built from the end sections of chromosomes formed by secondary constrictions. This structure can be seen under a light microscope as a compact spot on the nucleus. Ribosomal RNAs, which are synthesized here, also enter the cytoplasm and then, together with proteins, form ribosomes.

Functions are directly affected by the composition of the kernel. Biology as a science studies the properties of chromatin to better understand the processes of transcription and cell division.

Kernel functions. Biology of processes in the nucleus

The first and most important function of the nucleus is the storage and transmission of hereditary information. The nucleus is a unique cell structure, since it contains most of the human genes. The karyotype can be haploid, diploid, triploid, and so on. The ploidy of the venom depends on the function of the cell itself: gametes are haploid, while somatic cells are diploid. The endosperm cells of angiosperms are triploid, and, finally, many varieties of seed crops have a polyploid set of chromosomes.

Transfer to the cytoplasm from the nucleus occurs during the formation of mRNA. During transcription, the desired karyotype genes are read, and as a result, messenger or messenger RNA molecules are synthesized.

Also, heredity is manifested during cell division by mitosis, meiosis or amitosis. In each case, the kernel performs its specific function. For example, in the prophase of mitosis, the shell of the nucleus is destroyed and highly compacted chromosomes enter the cytoplasm. However, in meiosis, chromosome crossing-over occurs before the destruction of the membrane in the nucleus. And in amitosis, the nucleus is completely destroyed and makes a small contribution to the fission process.

In addition, the nucleus is indirectly involved in the transport of substances from the cell due to the direct connection of the membrane with the EPS. That's what a nucleus is in biology.

Shape of nuclei

The nucleus, its structure and functions may depend on the shape of the membrane. The nuclear apparatus can be rounded, elongated, in the form of blades, etc. Often the shape of the nucleus is specific to individual tissues and cells. Single-celled organisms differ in the type of nutrition, life cycle, and at the same time, the forms of the membrane of the nuclei also differ.

Diversity in the shape and size of the nucleus can be seen in the example of leukocytes.

• The neutrophil nucleus may or may not be segmented. In the first case, they speak of a horseshoe-shaped nucleus, and this shape is characteristic of young cells. A segmented nucleus is the result of the formation of several partitions in the membrane, resulting in the formation of several parts interconnected.
• In eosinophils, the nucleus has a characteristic dumbbell shape. In this case, the nuclear apparatus consists of two segments connected by a partition.
• Almost the entire volume of lymphocytes is occupied by a huge nucleus. Only a small part of the cytoplasm remains on the periphery of the cell.
• In the glandular cells of insects, the nucleus may have a branched structure.

The number of nuclei in one cell can be different

Not always in the cell of the body there is only one nucleus. Sometimes it is necessary to have two or more nuclear devices to perform several functions simultaneously. Conversely, some cells can do without a nucleus at all. Here are some examples of unusual cells in which there is more than one nucleus or none at all.

1. Red blood cells and platelets. These blood cells transport hemoglobin and fibrinogen, respectively. In order for one cell to be able to accommodate the maximum amount of matter, it lost its nucleus. This feature is not typical for all representatives of the animal world: frogs have huge erythrocytes with a pronounced nucleus in their blood. This shows the primitiveness of this class in comparison with more developed taxa.

2. Liver hepatocytes. These cells contain two nuclei. One of them regulates the purification of blood from toxins, and the other is responsible for the formation of heme, which will later become part of the hemoglobin of the blood.

3. Myocytes of striated skeletal tissue. Muscle cells are multinucleated. This is due to the fact that they are actively involved in the synthesis and breakdown of ATP, as well as the assembly of proteins.

Features of the nuclear apparatus in protozoa

For example, consider two types of protozoa: ciliates and amoeba.

1. Infusoria-shoe. This representative of unicellular organisms has two nuclei: vegetative and generative. Since they differ in both function and size, this feature is called nuclear dualism.

The vegetative nucleus is responsible for the daily life of the cell. It regulates the processes of its metabolism. The generative nucleus is involved in cell division and in conjugation, a sexual process in which genetic information is exchanged with individuals of the same species.

Diseases

Many genetic diseases are associated with abnormalities in the set of chromosomes. Here is a list of the most famous deviations in the genetic apparatus of the nucleus:

• Down syndrome;
• siddrome Patau;
• Klinefelter's syndrome;
• Shereshevsky-Turner syndrome.

The list goes on, and each of the diseases is distinguished by the serial number of a pair of chromosomes. Also, such diseases often affect the sex X and Y chromosomes.

Conclusion

The nucleus plays an important role in It regulates biochemical processes, is a repository of hereditary information. The transport of substances from the cell, the synthesis of proteins are also associated with the functioning of this central structure of the cell. That's what a nucleus is in biology.

The word "core" means the core of something, having the shape of a ball. However, the meaning of this concept may be different, depending on the area in which it is applied. So, in mathematics, biology, computer science and other areas, the kernel can characterize different things. In this article, we will talk about what a core is and how this concept is used in different areas.

Nucleus in biology

In biology, the concept of "core" can also have different meanings. Firstly, even from the course of botany, we should know that this is the name of the core of seeds or fruits, which is placed in a shell. In addition, the inner part of the tree trunk is also called the core, although the term “heartwood” is most often used in this case.

In neurophysiology, this term characterizes the accumulation of gray matter in a specific area of ​​the central nervous system, which is responsible for the implementation of certain functions.

It should also be said about such a concept as the cell nucleus, which is a component of the cell that contains genetic information, that is, DNA molecules. It performs the most important functions of storage and transmission of hereditary information. It is in the cell nucleus that the functioning and reproduction of this material also takes place.

Core in computer science

Other meanings

In nuclear physics, there is the concept of “atomic nucleus”, which defines the central part of the atom. It is in this part that the bulk of it is concentrated. The atomic nucleus consists of neutral neutrons and positively charged protons bound together by a powerful force. Such nuclei are often called nuclides.

Another term - the core of the Earth, implies the central part of our planet, which can also be called the geosphere. The core of the Earth is usually divided into internal and external. The inner core is often referred to as solid and the outer core as liquid.

The nucleus of a comet is its solid part. It has a relatively small size. Such a core consists of cosmic dust, ice and volatile compounds in the form of methane, carbon and others. Some studies suggest that the comet's nucleus may consist of iron, stone, or a mixture of both.

There is also the concept of “sports core”, which means a sports projectile in the form of a metal ball, designed for pushing.

The cannonball is an ancient artillery shell, which is a spherical body. Cannonballs are one of the first projectiles to be used in firearms. They were used to destroy wooden structures and defeat living enemy forces.

The nucleus of the cell is the central organelle, one of the most important. Its presence in the cell is a sign of the high organization of the body. A cell that has a well-formed nucleus is called a eukaryotic cell. Prokaryotes are organisms consisting of a cell that does not have a formed nucleus. If we consider in detail all its components, we can understand what function the cell nucleus performs.

Core structure

1. Nuclear shell.
2. Chromatin.
3. Nucleoli.
4. Nuclear matrix and nuclear juice.

The structure and functions of the cell nucleus depend on the type of cells and their purpose.

nuclear envelope

The nuclear envelope has two membranes - outer and inner. They are separated from each other by the perinuclear space. The shell has pores. Nuclear pores are necessary so that various large particles and molecules can move from the cytoplasm to the nucleus and vice versa.

Nuclear pores are formed by the fusion of the inner and outer membranes. The pores are rounded openings having complexes, which include:

1. A thin diaphragm covering the opening. It is pierced by cylindrical channels.
2. Protein granules. They are located on both sides of the diaphragm.
3. Central protein granule. It is associated with peripheral granules fibrils.

The number of pores in the nuclear envelope depends on how intensively synthetic processes take place in the cell.

The nuclear envelope consists of outer and inner membranes. The outer one passes into the rough EPR (endoplasmic reticulum).

Chromatin

Chromatin is the most important substance in the cell nucleus. Its functions are the storage of genetic information. It is represented by euchromatin and heterochromatin. All chromatin is a collection of chromosomes.

Euchromatin are parts of chromosomes that are actively involved in transcription. Such chromosomes are in a diffuse state.

Inactive sections and whole chromosomes are condensed clumps. This is heterochromatin. When the state of the cell changes, heterochromatin can turn into euchromatin, and vice versa. The more heterochromatin in the nucleus, the lower the rate of synthesis of ribonucleic acid (RNA) and the lower the functional activity of the nucleus.

Chromosomes

Chromosomes are special formations that appear in the nucleus only during division. The chromosome consists of two arms and a centromere. According to their form they are divided into:

• Rod-shaped. Such chromosomes have one large arm and the other small.
• Equal-shouldered. They have relatively equal shoulders.
• Diverse. The arms of the chromosome are visually different from each other.
• With secondary straps. Such a chromosome has a non-centromeric constriction that separates the satellite element from the main part.

In each species, the number of chromosomes is always the same, but it is worth noting that the level of organization of the organism does not depend on their number. So, a person has 46 chromosomes, a chicken has 78, a hedgehog has 96, and a birch has 84. Largest number chromosomes has the fern Ophioglossum reticulatum. It has 1260 chromosomes per cell. The male ant of the species Myrmecia pilosula has the smallest number of chromosomes. It has only 1 chromosome.

It was by studying the chromosomes that scientists understood what the functions of the cell nucleus are.

Chromosomes are made up of genes.

Gene

Genes are sections of deoxyribonucleic acid (DNA) molecules that encode certain compositions of protein molecules. As a result, the body manifests one or another sign. The gene is inherited. Thus, the nucleus in the cell performs the function of transferring genetic material to the next generations of cells.

Nucleoli

The nucleolus is the densest part that enters the nucleus of the cell. The functions that it performs are very important for the entire cell. Usually has a rounded shape. The number of nucleoli varies in different cells - there may be two, three, or none at all. So, in the cells of crushing eggs there are no nucleoli.

The structure of the nucleolus:

1. granular component. These are granules that are located on the periphery of the nucleolus. Their size varies from 15 nm to 20 nm. In some cells, HA may be evenly distributed throughout the nucleolus.
2. Fibrillar component (FC). These are thin fibrils, ranging in size from 3 nm to 5 nm. FC is the diffuse part of the nucleolus.

Fibrillar centers (FCs) are low-density fibril regions, which, in turn, are surrounded by high-density fibrils. The chemical composition and structure of PCs are almost the same as those of the nucleolar organizers of mitotic chromosomes. They include fibrils up to 10 nm thick, which contain RNA polymerase I. This is confirmed by the fact that the fibrils are stained with silver salts.

Structural types of nucleoli

1. Nucleolonemic or reticular type. It is characterized by a large number of granules and dense fibrillar material. This type of nucleolus structure is characteristic of most cells. It can be observed both in animal cells and in plant cells.
2. Compact type. It is characterized by a small severity of nucleonoma, a large number of fibrillar centers. It is found in plant and animal cells, in which the process of protein and RNA synthesis is actively taking place. This type of nucleoli is characteristic of actively proliferating cells (tissue culture cells, plant meristem cells, etc.).
3. Ring type. In a light microscope, this type is visible as a ring with a bright center - a fibrillar center. The average size of such nucleoli is 1 µm. This type is typical only for animal cells (endotheliocytes, lymphocytes, etc.). In cells with this type of nucleoli, the level of transcription is rather low.
4. Residual type. In cells of this type of nucleoli, RNA synthesis does not occur. Under certain conditions, this type can turn into reticular or compact, i.e., be activated. Such nucleoli are characteristic of the cells of the prickly layer of the skin epithelium, normoblast, etc.
5. segregated type. In cells with this type of nucleoli, rRNA (ribosomal ribonucleic acid) synthesis does not occur. This happens if the cell is treated with some kind of antibiotic or chemical. The word "segregation" in this case means "separation" or "isolation", since all components of the nucleoli are separated, which leads to its reduction.

Almost 60% of the dry weight of the nucleoli is protein. Their number is very large and can reach several hundred.

The main function of the nucleoli is the synthesis of rRNA. The embryos of ribosomes enter the karyoplasm, then through the pores of the nucleus they seep into the cytoplasm and onto the endoplasmic reticulum.

Nuclear matrix and nuclear juice

The nuclear matrix occupies almost the entire nucleus of the cell. Its functions are specific. It dissolves and evenly distributes all nucleic acids in the interphase state.

The nuclear matrix, or karyoplasm, is a solution that includes carbohydrates, salts, proteins and other inorganic and organic substances. It contains nucleic acids: DNA, tRNA, rRNA, mRNA.

In the state of cell division, the nuclear envelope dissolves, chromosomes form, and the karyoplasm mixes with the cytoplasm.

The main functions of the nucleus in the cell

1. informative function. It is in the nucleus that all the information about the heredity of the organism is located.
2. Inheritance function. Thanks to the genes that are located on the chromosomes, the body can pass on its traits from generation to generation.
3. Union function. All organelles of the cell are united into one whole precisely in the nucleus.
4. regulation function. All biochemical reactions in the cell, physiological processes are regulated and coordinated by the nucleus.

One of the most important organelles is the cell nucleus. Its functions are important for the normal functioning of the whole organism.