What is a cell? Definition, Functions & types | FAQ

Structural, functional and biological units of all living things. It is made up of all living cells and each cell is self-contained. All cells contain cytoplasm, which is surrounded by a cell membrane, and contains cytoplasm, such as proteins and nucleic acids. They range in size from 1–100 micrometers (10–6). The cells can be seen under a microscope. According to the number of cells in an organism, they are classified as unicellular (e.g., bacteria) and multicellular (e.g., plants, animals, etc.). The number of cells varies according to the species of plants and animals. Su in the human body. There are 1 trillion cells.

When scientist Robert Hooke saw a thin slice of Bucha under a microscope in 1665, he saw microscopic cups in the cut. He named these cups 'cells'. Butch is made from the bark of an tree. The hooks that Hooke saw were Plant cell in tree trunks. In 1839, Schneiden and Schwann theorized that all living things are made up of cells, that in all living things the cells are a unit of the structure and function of these living things, and that new cells are formed from pre-existing cells.

All cells show some similar properties. For example, cells breathe, cells need food, cells excrete wastes, cells grow, and cells die. Nutrients, oxygen and carbon dioxide are exchanged from the cell surface.

Although there are differences in the size of living things in the same creation, the size of their cells is the same. For example, elephants and rats differ in body size. This is because the number of cells in an elephant's body is higher than the number of cells in a rat's body. Also, the liver of an elephant is larger than the liver of a rat because the number of cells in the liver of an elephant is higher than the number of cells in the liver of a rat. Cell size does not increase beyond a certain limit. This is because as the size of the cell increases, so does the ratio of cell surface to volume. A high ratio of cell surface to volume is essential for cell function. This is because the cells receive nutrients through the surface, oxygen and carbon dioxide are exchanged, and waste is expelled.

What is a cell? Definition, Functions & types | FAQ


What is Cell ?
  1. The cell is the anatomical and functional unit of living organisms and often has the ability to spontaneously regenerate. It is that small organized form of various substances in which all those actions are collectively called as life.
  2. The English word for cell is derived from the Latin word 'cellula' which means 'a small room'. Some living organisms like bacteria are made up of a single cell, they are called unicellular organisms whereas some living organisms like human body are made up of many cells, they are called multicellular organisms. Robert Hooke discovered the cell in 185 AD.
  3. In 1939, Schleiden and Schwann introduced cell theory according to which the body of all living beings is made up of one or more cells and all cells originate from a pre-existing cell.
  4. All biological functions of living organisms occur within cells. Within the cells, there are essential genetic information that controls the functions of the cell and the information is transferred to the next generation of cells.
  5. The proper study of cells is called Cytology or Cell Biology.

Types of Cell : 

There are two types of cells
1. Eukaryotic cells - 1) pant cell 2) animal cell
2. Prokaryotic cell

Prokaryotic cells are often independent, whereas eukaryotic cells are found in multicellular organisms. The prokaryotic cell has no clear nucleus. The centrioles are scattered in the cell fluid. This type of cell is found in bacteria and blue-green algae. Eukaryotic cell types are found in all high-grade plants and animals. All eukaryotic cells have an organized nucleus that is covered by a covering.

Cells are living and perform all the functions that live animals do. Their shape is minimal and the shape is spherical, oval, columnar, porous, flagellate, polygonal etc. They are surrounded by an object like jelly. This coating is called cell membrane or cell membrane. This membrane is selectively permeable, which means that this membrane allows a substance (molecule or ion) to freely cross, crossing a limited amount. It is sometimes called 'plasma membrane'. The following structures are found within it:
(1) nucleus
(2) Cell Membrane
(3) Golgi complex or Golgi apparatus
(4) Vacuoles
(5) endoplasmic sac
(6) chromosome (parent) and genes
(7) ribosome And centrosome
(8) salts

Except for some special differences, the structure of all types of cells, plant and animal cells is almost the same. They are made up of both living and non-living units. There are three main parts of a normal cell or typical cell, cytoplasm, cytoplasm and nucleus. The cytoplasm is the outermost covering or enclosure of the cell. In the plant cell, the cell wall and cell membrane combine to form cytoplasm.

Read : Animal Cell Structure and Functions

Structure of Cell :

There are two types of cells, protoplasmic cells and visual cells.

Stem cells: Stem cells are found in living organisms, i.e. bacteria. For the first time on Earth, protozoan life was produced. The nucleus cells are smaller than the visual nuclei and are 0.5–20 मीटरm (10–6) in length. The nucleus cells do not have a nucleus membrane but a nucleus-like nucleus. It is called a virtual nucleus or nucleoid; It contains genetic information in the form of DNA molecules. Cells contain only ribosomes, which are used to make proteins. The progenitor cells divide in a bifurcated manner. The main parts of this cell are the myocardium and the cytoplasm.

Cortex: The cell membrane is surrounded by protoplasmic cells. There is a cell wall outside this covering. Some bacteria have a capsule outside the cell wall. These sheaths shape the cell and protect it.

Cellulose: Cellulose contains chromosomes made up of DNA and some fragments of DNA separately. Cells also contain glycolysis and protein synthesis.

The nucleus accumbens is made up of a protein called flagellin. Kashabhika is used for cell movement and sensation. All protoplasmic cells contain a number of microscopic membranes, except for a few. They are used for movement and for cellular contact during reproduction.

Visual nucleus cells: The living proximal nuclei in the protista, fungi, flora and fauna. The nucleus of the focal cells is membrane-like and is prominently visible under a microscope. Hence they are called ‘optical cells’. These cells are 10—100 micrometers (10–6) in length. The focal cells are 15 times wider than the primordial cells. 1000 times larger. These cells are made up of the membranes and cytoplasm.

Cytoplasm: The myocardium of visual cells is similar to that of myocardial cells. The cells of protista organisms and living organisms have only a cell membrane, but no cell wall. The cell wall of the living organism of red algae and green algae, fungi, and plants in the Protista world. Many focal cells have phagocytosis or phagocytosis which are used for movement and sensation of temperature change, chemical change touch.

Cytoplasm of visual cell : The cytoplasm of visual cells consists of cytoplasm and cell organs. The cell nucleus is surrounded by a double sheath that contains DNA molecules in the form of chromosomes. In cytoplasm, intracellular reticulum, ribosomes, gallbladder system, fibroblasts, vacuoles, lymphocytes, peroxisomes, stellar centers, microtubules, chloroplasts Mitochondria etc.


Intracellular components: Overall, the internal and extracellular components of stem cells and visual cells are considered here. The differences between these two cells in terms of their constituents are recorded when informing each component.

Cell membrane: This biological membrane encloses the cytoplasm in the cell. In animals, the mesentery is the outer layer of the cell, while between the plant cells and the progenitor cells there is a cell wall around the mesentery. Normally the cell membrane is made up of a double layer of phospholipids, thereby protecting the cell from the surrounding environment and protecting it. The cytoplasm contains different molecules of proteins, and they act as conductors and pumps for different molecules to enter or exit the cells. Cell membranes are mercury for hemispherical or selective substances, meaning they allow a substance (molecule or ion) to pass through, allow, or block a limited amount of it. The cell membrane contains a number of receptor proteins, which identify molecules that carry out signals, such as hormones.

Cellular Skeleton: In both prototypical and visual centrifugal cells, the skeletal skeleton is useful for maintaining the size of cells, keeping cell membranes in place, helping in cell proliferation when extracellular material enters, cell separation after cell division, and cell growth and movement. The cytoplasm of optical cells is made up of microscopic or microscopic, mesenteric and microtubules. A large number of proteins are attached to these components and proteins perform the functions of holding the components of the cell together, keeping the fibers in a line as well as in one direction. The microfiber contains a protein called actin, while the microtubule contains a protein called tubulin, the mesentery contains more than one protein.

Genetic material: Visual cells contain two types of genetic material, DNA and RNA. Biological information about living things is stored symbolically in the form of DNA sequences. RNA is used to carry information (m-RNA), for the function of receptors (r-RNA), as well as for the synthesis of amino acids in protein production (t-RNA).

In stem cells, the genetic material is in one place in the cytoplasm. It is called the nucleus. The nucleus accumbens contains the genetic material divided into chromosomes in the nucleus and a small number of fibers and chloroplasts.

In human cells, the genetic material is between the nucleus and the fibroblast. The human genome is divided into 46 chromosomes. Of these, 22 pairs are of cognate chromosomes, while 1 pair is of sex chromosome. The chromosomes in the fibers are coarse in size and differ from the chromosomes in the nucleus. They are mainly involved in energy production and the function of t-RNA.


Cell organs: Just as each organ in the human body performs a specific function, so do the cell organs perform one or more functions. Cells contain many types of organs; Some cell organs, such as cell nuclei, gallbladder systems, etc., are single in number, while fibrous cells, chloroplasts, peroxisomes, lymphocytes, Mitochondria etc., are more numerous in number. Cells contain gelatin-like cellular fluid in which cell membranes float. Both protoplasmic cells and visceral cells have cell membranes, but the progenitor cell membranes are not membrane-bound.

Read : Plant Cell Structure and Functions


Components of Cells :

Nucleus: It regulates all the activities in the cell like a control room. The membrane around the nucleus separates the nucleus from the cytoplasm. The fluid in the nucleus is called nucleus fluid. Its components are different from cytoplasm. The nucleus contains chromosomes and nuclei. Chromosomes are thread-like, microscopic structures made up of chromatin. Each chromosome contains a DNA molecule and a histone protein. Genetic traits are transmitted from one generation to the next through chromosomes. Fragments of specific lengths of DNA in a chromosome are called genes. Since the DNA in the cell is in the form of chromatin, the chromosomes do not appear under a microscope; Chromosomes can be seen under a microscope if pigment is used during cell division (see: chromosomes). The nucleus contains ribosomes, RNA and proteins. Ribosomes are formed in the nucleus. In proinflammatory cells, genetic processes or DNA processes occur in the cytoplasm.

Mitochondria:
It was discovered in 1890 AD by a scientist named Altman. It is a very important composition found in cytoplasm which is scattered in cytoplasm. Altman named it Bioblast and Benda named mitochondria. Its shape and shape are variable. It is scattered in the cytoplasm in the form of particles (chondriomits), filaments, chondriconts and balls. Each mitochondria is surrounded by an outer membrane and an innermost membrane, and in the middle of it is a fluidized cavity, called the mitochondrial cavity. From the inner membrane of the mitochondria, many amplitudes emerge and hang in the mitochondrial cavity matrix (Cristae). F1 particles or oxysomes are found on Christie's surface. The mitochondria are called the power house of the cell to generate energy. This is called the energy house of the cell because of the 36 ATP molecules that are formed by the breakdown of one glucose molecule, 34 ATP (during the Krebs cycle) are formed in the mitochondria.

Read : Mitochondria structure & Functions


Fibroblasts and chlorophylls: Fibroblasts are the energy-producing centers of cells. The number of fibroblasts in a cell can range from 100 to 10,000. There are two layers of membrane around the fiber. The outer layer is round and the inner layer is rounded. The DNA in a fiber is different from the DNA in a nucleus. The fibers in the cell come only from the female gamete. The dissociation of pyruvic acid, which is produced in the cytoplasm by the vicissitudes in the fibroblasts, leads to the breakdown of pyruvic acid. This action is called oxidative phosphorylation (Krebs cycle). This action produces carbon dioxide and water and releases energy. The released energy is stored in the form of ATP. Fibroblasts, like these progenitor cells, multiply in a bifurcated manner.

Chlorophylls are found only in plant cells and absent in Animal cell and are the main centers of photosynthesis.

Intracellular reticulum: This reticulum formed by a single membrane carries the substance produced in the cell to the specific place. There are two types of mesh, granular and smooth; There are ribosomes on the granular lattice. The proteins formed in the ribosome are released into the cytoplasm from the endocrine glands. Calcium ions are transported through a smooth intracellular lattice.

Golgi system: This system is located near the center and is made up of a single layer panel. This information was given by the scientist Golji. The system is like a moving bush stacked on top of one another. The functions of the gallbladder system are to collect the proteins formed in the cell, to cover them and to expel them from the cell in the form of vesicles.

Lysosome: Lysosomes are round. They break down excess or worn-out cell membranes through their digestive tract, as well as feeding on bacteria and viruses. It was discovered by Christian de duve in 1958 AD. It is very microscopic cells that are found in the form of small vesicles. There is a thin membrane around it. It is very small and pouch-like in shape. It contains enzymes that have the ability to dissolve or destroy organisms.
When the cell is damaged due to interruption of cellular metabolism, the lysosomes burst and the enzymes present in it digest their own cells. This results in cell death. Hence, it is also called suicide bag. It digests large particles and foreign substances entering the cell.
It cleans the cell by securing the broken parts of endocytic materials and organs. It protects against bacteria and viruses.

Peroxisomes: These membranes are membranes that contain perforations that inactivate toxins produced in the body.

Stellar body: Most cells have a stellar body near the nucleus. It has two constellations. During cell division, these star nuclei separate and help to form fibers.

Vacuoles: Vacuoles is paneled and separates waste. Unicellular organisms, such as amoebae, have a vacuole for contraction, which acts like a pump and expels water from the cell if the water is too high. The vacuoles of plant cells and fungal cells are larger in size than the vacuoles of animal cells. Vacancies in plants store water.

Ribosomes: Ribosomes float freely in the nucleus of both cells and in the form of microscopic particles in the cytoplasm or are attached to the endothelial network. Ribosomes play an important role in protein production. It was discovered by Palade in 1955 AD. These are particles that are visible only through electron microscopes. These endoplasmic membranes are adjacent to the surface of the membranes or are scattered singly or in clusters in cytoplasm. Such ribosomes, which are found in clusters, are called polyribosomes or polysome. These compositions are protein and RNA. (RNA). The ribosome participates in protein synthesis.


Extracellular components of cell :
Many cells have certain structures outside the cell membrane. They are not protected from the external environment as they do not have a semicircle. Also, their constituents are embedded inside the cells to form them.

Cell wall: There are many types of protoplasm as well as visual center cells. The function of the cell wall is to protect the cell from its environment, from mechanical shock, from chemical elements, and to surround the cell membrane. In different types of cells, the cell wall is made up of different substances; The cell wall of plant cells is composed of cellulose, the cell wall of fungi is composed of chitin, and the cell wall of bacteria is composed of peptidoglycone.

The nucleus accumbens contains a gelatinous capsule surrounding the mesentery and the cell wall. In pneumococcal, meningococcal species, the capsule is composed of polysaccharide, Bacillus atherosclerosis polypeptide, or streptococcus bacteria, hyaluronic acid.

Flagella : The movement of cells by these senses. Some are long and thread-like and are made up of proteins. Some of the bacteria originate from the cytoplasm and protrude beyond the mesentery and cell wall. The cells of the focal cells are of different types.

Pilli: Also known as 'Rome'. They are thin, thin, and hairy, with bacteria on the surface. Through them the bacteria take refuge.



Functions Of cell


Immunization: When cell division occurs, two progenitor cells are formed. Cell division leads to the proliferation of multicellular organisms, while the proliferation of unicellular organisms occurs. The progenitor cells divide in a bifurcated manner, while the visceral cells divide in a molecular manner, eventually dividing into a cytoplasm and dividing into cells. The meiosis of a dicotyledonous cell divides into four monocotyledonous cells. In multicellular organisms, such monocotyledonous cells are called gamete cells, and when they combine, new diploid cells are formed. DNA replication or DNA replication is formed only when cell division occurs by point division or by bifurcation method.

Cell division occurs twice during meiosis, DNA replication occurs only once. This occurs before DNA antimicrobial division () occurs. During meiosis (ⅠⅠ), DNA replication does not occur when cell division occurs a second time. Proteins are also needed for DNA replication.

Growth and metabolism:
Metabolic functions take place in cells. In this process, nutrients are processed in each cell. In catabolism, complex molecules are broken down into simple molecules by the cell to generate energy, and in the process of metabolism, complex molecules are formed by the cell and other biological functions take place. For example, complex sugars consumed by living organisms can be converted into glucose. After entering the cell, glucose decomposes to form ATP molecules, which store energy and can be used for physiological functions.

Protein production:
Cells have the ability to make new proteins, which are needed to regulate cellular activity. In this process, proteins are formed by the synthesis of amino acids according to the signaling information stored in DNA or RNA molecules (see: Proteins → Protein synthesis).

Movement:
Algae move to find food or to get rid of predators. For this, they use Kashabhika. In multicellular organisms, cells move from one place to another to heal wounds, to fight off pathogens, and to prevent the spread of diseases such as cancer. For example, white blood cells accumulate in the wound area to prevent infection by microorganisms and to heal the wound. Cell movements require many proteins such as receptors, clusters, binding, adhesions, stimuli, and so on.

In multicellular organisms, the cells are adapted to their function and the cells are named accordingly. For example, mammals have different types of skin cells, muscle cells, nerve cells, blood cells, stem cells, fibroblasts, etc. Although different types of cells have different forms and functions, they are genetically identical or similar. Most different types of cells originate from a single complete cell, the zygote (the fertilized egg before differentiation), which develops into hundreds of different types of cells.

Reproduction : Another important function of the cell is the reproduction.

Read : Reproduction definition, types-and importance


Frequently Asked Questions 


1. Do cells also commit suicide?
Answer: Yes! Cells also commit suicide. When cells are damaged due to external or internal causes, they protect the whole body by destroying themselves. The process of self-destructing of cells in this way is called apoptosis.

The cells made to do any specific work in the body become unnecessary after the work is finished, so their destruction is good for the body.
Cells whose DNA is damaged for some reason die on their own. That means she commits suicide. If such bad cells start living and start dividing cells, they can also turn into cancer cells.

Similarly, when virus divides from our cell and prepares to spread the disease, then suddenly our virus sick cells die. Together, the viruses also end. In this way, the body is protected from disease.

2. Robert Hook discovered a dead cell, but do you know who is credited with the discovery of a living cell?
Answer: The living cell was discovered in 1674 by Dutch scientist Antoine van Leuwenhoek. They are also credited with the discovery of protozoa, bacteria and sperm cells.

3. Who discovered the mitochondria that produce energy inside the cell?
Answer: Albert von Kolliker was discovered in 1857 by mitochondria.

4. Who gave the cell theory?
Answer: Cell theory was formulated in 1838 by Theodore Schwann and Matthias Jacob Schleiden.

5. What is a cell study called?
Answer: The study of a cell is called cytology. The structure and function of the cell is studied under this science.

6. What is the name of world's smallest cell?
Answer: The world's smallest cell is considered 'Mycoplasma'. Its size is about 10 micrometers. The sperm cell is considered to be the smallest cell in the human body.

7. Who is considered the world's largest cell?
Answer: The largest cell in the world is considered the egg of an ostrich bird. The largest cell in the human body is considered the ovum.

8. What are the main types of cells?
Answer: There are mainly two types of cells
Prokaryotic Cell: This is a cell in which the nucleus is not found in the middle. Organisms with this type of cell are very small in size. Like - different types of bacteria

Eukaryotic Cell: The nucleus is found in the middle of this cell. These types of cells are larger in size than an acentric cell and their structure is also complex. This type of cell is found in humans and plants.


9. What is a vesicle?
Answer : A vesicle is a membrane-enclosed small organ inside the cell, which contains various types of fluid. The vesicles form during exocytosis and endocytosis. On the other hand, liposomes are formed artificially. The membrane that surrounds the vesicle is a phospholipid bilayer. Unilamellar liposomes have a single phospholipid boiler around the vesicle. Multimalar liposomes are enclosed by two phospholipid bilayers. Vesicles can fuse with the plasma membrane as well as organelles in the cell to release their contents.

10. what are lysosomes
Answer : Lysosomes are an important type of vesicles involved in digestion. Food vacuoles are associated with lysosomes, which contain enzymes to digest food. Lysosomes are also involved in phagocytosis. On the other hand, lysosomes destroy damaged organs in the process known as autophagy.

11. what is a vacuole
Answer : A vacuole is a type of vesicle that contains mostly water. Vacuole is a distinctive feature of plant cells, but it can also be found in animal cells, bacterial cells, protists, and fungal cells. It contains organic compounds including enzymes and inorganic compounds in addition to water. The vacuole is formed by the fusion of several vesicles. The size and shape of a vacuole varies depending on the requirements of the cell.

12. what is cell wall
Answer : A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible.

Cell Wall Function
  1. Gives the cell a definite shape and structure.
  2. Provides structural support.
  3. Protection against infection and mechanical stress.
  4. Separates interior of the cell from the outer environment.


13. what is a cell in biology
Answer : (What is Cell: Cell Biology Definition) - Cell is the anatomical and functional unit of the body of organisms. It is a small organized form of various forms. Which has all those actions, which we collectively call 'life'.