The process by which the cell nucleus or karyon divides is called karyokinesis. Mitosis cell division refers to karyokinesis. In 1879, Strasburger and Schleicher discovered the division of the nucleus and named it karyokinesis. Karyokinesis is divided into five stages. These are-

 

1. Prophage: The word Prophage is formed from the Greek words pro meaning origin and phage meaning condition.

Prophase is the first and longest phase of mitosis cell division. At this stage, the nucleus of the cell begins to increase in size. Dehydration of water between the chromosomes begins. Chromosomes increase in dye capacity. Chromosomes gradually shrink as CDK compounds phosphorylate proteins. As a result, the chromosomes become progressively shorter, thicker and more visible. At the end of this stage, each chromosome divides longitudinally without the centromere to form two chromatids. In the process of spiralization, the chromatids of the chromosome are stretched like two springs, becoming thicker and shorter. Phosphorylation of proteins causes the nuclear membrane or envelope and nucleolus to disintegrate. At this stage, the creation of the spindle machine begins.

2. Prometaphage: The word Prometaphage is composed of the Greek words pro meaning original, meta meaning middle and phage meaning stage. The stage between prophase and metaphase is called prometaphase.

In the prometaphase stage, the nuclear membrane and nucleolus completely disappear. Chromosomes become more compact, thicker and shorter. The spindle apparatus is formed from centrioles in animal cells and from microtubules in plant cells. Spindles are composed of proteins and are bipolar. The space between the spindle machines is called equator/equator/neutral/intermediate zone. Both poles are called polar regions. Spindle machines are of two types. Spindle fibers and attraction fibers. Spindle apparatuses that extend from one pole to another are called spindle fibers. The spindle apparatuses to which chromosomes are attached are called attraction fibers or chromosomal fibers or traction fibers. Attraction fibers attach to the pea protein at the kinetochore of the centromere. Chromosomes exhibit chromosomal dance by joining filaments. Aster filaments arise from centrioles at the two poles of the spindle apparatus in animal cells.

3. Metaphage: The word Metaphage is formed from the Greek words meta meaning middle and phage meaning state. Mitosis The intermediate stage of cell division is called metaphase.

Metaphase is a short-lived phase. In the process of condensation, the chromosomes become more compact, thicker and shorter. The coiling of chromosomes at this stage is called super coiling. Chromosomes are located at the equator. The arrangement of chromosomes in the equatorial region looks like a plate. It is called equatorial plate or metaphase plate. At the metaphase plate, the smaller chromosomes are arranged on the inside and the larger chromosomes on the outside. The process of arrangement of chromosomes at the equator is called metakinesis. At the end of metaphase, the centromere of each chromosome divides to form two daughter centromeres.

4. Anaphage: The word Anaphage is formed from the Greek words ana meaning motion and phage meaning state. Anaphase is the shortest phase. In this state, the chromosomes move toward each other’s poles, so it is called the motility phase.

During anaphase, the number of chromosomes in cells doubles that of the parent cell. Homozygous chromosomes produced from the same chromosome repel each other. Chromosomes are moved by the contraction of attraction fibers and elongation of the stem body. Chromosomes run at opposite poles. Half of the extraneous chromosomes run towards one pole and the other half towards the other pole. During polar movement, the centromere is the leader and the armature is the follower. Such poleward movement of chromosomes is called chromosomal movement or anaphase movement. In animal cells, the filaments join together to form interzonal fibers or stem bodies. The stem body helps the chromosomes to move towards the poles. Chromosomes are shaped like English letters V, L, J or I at the polar regions. Anaphase or the phase of motion is completed when the missing chromosomes reach the poles.

5. Telophage: The word Telophage is formed from the Greek words telo meaning end and phage meaning state. Telophase is the last stage of mitosis cell division. It is also called interphase.

Telophase is the opposite of prophase. Chromosomes are fixed at opposite poles. Water hydration begins between the chromosomes. As a result, the color or dye capacity of chromosomes decreases. In the process of de-condensation, the coils or patches of chromosomes open up, become narrower and longer and form the nucleoli. The structure of the spindle apparatus breaks down and gradually disappears. Nuclear membrane and nucleolus reappear. Each daughter nucleus has the same number of chromosomes as the mother nucleus. At the end of the telophase phase, cell plates in plant cells and cell membranes in animal cells are furrowed along the equator.

Endoplasmic reticulum is derived from the Greek word endo meaning inside, plasmic meaning plasma and reticulum meaning mesh. Endoplasmic reticulum means endoplasmic reticulum. Endoplasmic reticulum is a branched reticular hollow tube located in the cytoplasm of the cell. Small parts of the endoplasmic reticulum break off to form microsomes.

 

Discovery of endoplasmic reticulum

In 1897, scientist Gorniar observed the lattice-like structure in cells with the help of a light microscope and named them argestoplasm. In 1945, scientist Keith R. Porter and his colleagues Albert Claude and Ernest F. Fullam first discovered it from liver cells. Endoplasmic reticulum was named by scientist Keith R. Porter in 1953. In 1969, scientists Porter, Claude and Fullam described the detailed structure of endoplasmic reticulum from liver cells.

 

Elongation

Endoplasmic reticulum is found in almost all cells. They are most abundant in the liver, pancreas and endocrine glands. It extends from the nuclear membrane to the cell membrane. It is attached to the nuclear membrane. Mammalian red blood cells, spermatizoa, and sperm lack reticulum.

 

Types of endoplasmic reticulum

1. Smooth endoplasmic reticulum-SER : The endoplasmic reticulum that does not have ribosomes is called smooth endoplasmic reticulum or SER. It synthesizes lipids. It releases calcium during muscle contraction. Smooth endoplasmic reticulum is abundant in adipose cells, testes, adrenal cortex cells, muscle cells and liver cells.
2. Rough endoplasmic reticulum-RER : The endoplasmic reticulum that has ribosomes is called rough endoplasmic reticulum or RER. It synthesizes proteins. It stores calcium during muscle contraction. Rough endoplasmic reticulum contains tiny glyoxysome particles. These tiny glyoxysome particles are called microsomes. Pancreatic cells, liver cells, plasma cells and goblet cells have rough endoplasmic reticulum.

Physical structure of endoplasmic reticulum

There are three types of structure of endoplasmic reticulum. These are-

1. Lamellar or Cisternae: Endoplasmic reticulum that is long, cylindrical, unbranched and compressed is called cisternae. Their diameter is 40-50 millimicrons. Cisternae contain a glycoprotein called ribophorin. The cisternae are connected to each other with the help of ribophorin.
2. Vasicle: The endoplasmic reticulum that looks round or oval or blistered and surrounded by a membrane is called a vesicle. The vesicles are called microsomes. Their diameter is 25-50 mm. Vesicles are abundant in protein-synthesizing pancreatic cells.
3. Tubules: The endoplasmic reticulum which is long, cylindrical and branched is called tubules. Their diameter is 50-190 millimicrons. It stays connected. They have no ribosomes.

Chemical composition

The main chemical components of endoplasmic reticulum are proteins and lipids. It contains protein 60-70% and lipid 30-40%. Asymmetric lattice contains ATP and glyoxysomes. Besides, it contains 15 types of enzymes and co-enzymes. Enzymes are – glucose 6 phosphate, NADH diaphorase, active ATP-ase, glycosyl transferase, NADH cytochrome reductase, stearase, esterase, nucleotide diphosphatase, peptidase, fatty acyl CoA dehydrogenase etc.

 

Function of Endoplasmic Reticulum

1. Formation of intracellular skeleton: Endoplasmic reticulum extends like a net inside the cell and forms the intracellular skeleton. It provides cell strength.
2. Structure of the body: Endoplasmic reticulum acts as the structure of protoplasm.
3. Speed ​​of reaction: It increases the speed of chemical reaction. It increases biochemical activity in cells.
4. Substance transport: Endoplasmic reticulum forms the intracellular transport system. It acts as a transport pathway for various substances. It plays a major role in the transport of proteins produced in ribosomes.
5. Hydroxylating: Different types of drugs and toxic substances enter the body. The endoplasmic reticulum inactivates drugs and toxins in the hydroxylating process. As a result, the body gets rid of toxins.
6. Muscle contraction-dilation: It helps in muscle contraction-dilation.
7. Cell wall formation: It makes cellulose. Cellulose participates in making cell walls.
8. Chemical production: It produces lipids, hormones, phospholipids, steroids, glycoproteins, glycogen, vitamins and insulin.
9. Organelle formation: Endoplasmic reticulum participates in the formation of various organelles of the cell.
10. Protein synthesis: It synthesizes proteins. Proteins make up the body of organisms.
11. Cell distribution: The endoplasmic reticulum holds the cell membrane in place and distributes it uniformly.
12. As a container: It acts as a container for ribosomes and glyoxysomes.
13. Nuclear membrane formation: It participates in nuclear membrane formation in telophase.
14. Glucose production: Glucose is produced from glycogen in the process of glycogenolysis.
15. Formation of Spherosomes: Spherosomes are formed from smooth endoplasmic reticulum.
16. As a carrier: It acts as a carrier of proteins and lipids.
17. Neutralization: It neutralizes various toxic substances entering the cells.

The word Telophage is formed from the Greek words telo meaning end and phage meaning state. Telophase is the last stage of mitosis cell division. It is also called interphase.

Telophase is the opposite of prophase. Chromosomes are fixed at opposite poles. Water hydration begins between the chromosomes. As a result, the color or dye capacity of chromosomes decreases. In the process of de-condensation, the coils or patches of chromosomes open up, become narrower and longer and form the nucleoli. The structure of the spindle apparatus breaks down and gradually disappears. Nuclear membrane and nucleolus reappear. Each daughter nucleus has the same number of chromosomes as the mother nucleus. At the end of the telophase phase, cell plates in plant cells and cell membranes in animal cells are furrowed along the equator.

The word Anaphage is formed from the Greek words ana meaning motion and phage meaning state. Anaphase is the shortest phase. In this state, the chromosomes move toward each other’s poles, so it is called the motility phase.

During anaphase, the number of chromosomes in cells doubles that of the parent cell. Homozygous chromosomes produced from the same chromosome repel each other. Chromosomes are moved by the contraction of attraction fibers and elongation of the stem body. Chromosomes run at opposite poles. Half of the extraneous chromosomes run towards one pole and the other half towards the other pole. During polar movement, the centromere is the leader and the armature is the follower. Such poleward movement of chromosomes is called chromosomal movement or anaphase movement. In animal cells, the filaments join together to form interzonal fibers or stem bodies. The stem body helps the chromosomes to move towards the poles. Chromosomes are shaped like English letters V, L, J or I at the polar regions. Anaphase or the phase of motion is completed when the missing chromosomes reach the poles.

The word Metaphage is formed from the Greek words meta meaning middle and phage meaning state. Mitosis The intermediate stage of cell division is called metaphase.

Metaphase is a short-lived phase. In the process of condensation, the chromosomes become more compact, thicker and shorter. The coiling of chromosomes at this stage is called super coiling. Chromosomes are located at the equator. The arrangement of chromosomes in the equatorial region looks like a plate. It is called equatorial plate or metaphase plate. At the metaphase plate, the smaller chromosomes are arranged on the inside and the larger chromosomes on the outside. The process of arrangement of chromosomes at the equator is called metakinesis. At the end of metaphase, the centromere of each chromosome divides to form two daughter centromeres.

The word Prometaphage is composed of the Greek words pro meaning original, meta meaning middle and phage meaning stage. The stage between prophase and metaphase is called prometaphase.

In the prometaphase stage, the nuclear membrane and nucleolus completely disappear. Chromosomes become more compact, thicker and shorter. The spindle apparatus is formed from centrioles in animal cells and from microtubules in plant cells. Spindles are composed of proteins and are bipolar. The space between the spindle machines is called equator/equator/neutral/intermediate zone. Both poles are called polar regions. Spindle machines are of two types. Spindle fibers and attraction fibers. Spindle apparatuses that extend from one pole to another are called spindle fibers. The spindle apparatuses to which chromosomes are attached are called attraction fibers or chromosomal fibers or traction fibers. Attraction fibers attach to the pea protein at the kinetochore of the centromere. Chromosomes exhibit chromosomal dance by joining filaments. Aster filaments arise from centrioles at the two poles of the spindle apparatus in animal cells.

The word Prophage is formed from the Greek words pro meaning origin and phage meaning condition.

Prophase is the first and longest phase of mitosis cell division. At this stage, the nucleus of the cell begins to increase in size. Dehydration of water between the chromosomes begins. Chromosomes increase in dye capacity. Chromosomes gradually shrink as CDK compounds phosphorylate proteins. As a result, the chromosomes become progressively shorter, thicker and more visible. At the end of this stage, each chromosome divides longitudinally without the centromere to form two chromatids. In the process of spiralization, the chromatids of the chromosome are stretched like two springs, becoming thicker and shorter. Phosphorylation of proteins causes the nuclear membrane or envelope and nucleolus to disintegrate. At this stage, the creation of the spindle machine begins.

The process by which the cell nucleus or karyon divides is called karyokinesis. Mitosis cell division refers to karyokinesis. In 1879, Strasburger and Schleicher discovered the division of the nucleus and named it karyokinesis. Karyokinesis is divided into five stages.

Mitosis is derived from the Greek word Mitos meaning twisted thread. The process in which the nucleus and cytoplasm of the original cell divides to form two daughter cells and the chromosome number of the daughter cell is equal to the number of chromosomes of the mother cell is called mitosis. Because the number and quality of chromosomes of the offspring cells created in this process are similar to the mother cells, it is called equational division.

 

Discovery and naming

In 1973, the scientist Strasburger was the first to observe the creation of a nucleus from a nucleus. In 1873 Polish scientist Waclaw Mayzel observed cell division in frog, rabbit and cat corneas and described it in 1875. In 1855, the scientist Rudolf Virchow first explained that new cells are formed by division from previous cells. In 1879, scientist Snyder gave a complete description of the process of mitosis. Mitosis was named by scientist Walter Fleming in 1882. In 1960 Cockraum & Mac-Caulay explained the chemical nature of mitosis cell division. Scientist Walter Whitman called the division of cytoplasm as cytokinesis.

 

Mitosis is a characteristic of cell division

1. Mitosis Cell division occurs in body cells of organisms.
2. It occurs in haploid, diploid and polyploid cells.
3. In this process, two daughter cells are formed from each mother cell.
4. In this process the nucleus and chromosomes of the cell divide once.
5. The chromosome number of the resulting daughter cell is equal to the chromosome number of the mother cell.
6. Wound healing and necessary cell regeneration is done through mitosis cell division.
7. Mitosis cell division occurs in all unicellular and multicellular organisms.
8. In this process the division of the nucleus first and then the cytoplasm takes place.
9. The development and growth of various organs of the organism takes place in the process of mitosis.
10. Mitosis occurs in the formation and growth of the genitalia.
11. Mitosis occurs due to cytokines, steroids, lymphokines, EGF, PDGF etc.
12. The number of cells increases in the process of mitosis.
13. Mitosis causes the cell to increase in size.

Where does mitosis occur?

1. All embryonic cells divide into multicellular organisms by the process of mitosis.
2. The development and growth of various organs of the organism takes place in the process of mitosis.
3. All organelles in multicellular organisms divide by mitosis.
4. Mitosis takes place in the stem tip, root tip, embryonic root, flower bud, primary bud, developing leaf, cambium etc. region of the growing plant.
5. Mitosis occurs in the formation and growth of the genitalia.

 

Mitosis causes cell division

1. Mitosis cell division takes place to fill the wound in any part of the body.
2. Mitosis cell division occurs when the cell has more cytoplasm than nucleus.
3. Mitosis cell division occurs when the amount of DNA in the cell is high.
4. Mitosis accelerates cell division as protein synthesis occurs in the cell.
5. Mitosis Cell division occurs when there is more RNA than DNA in the cell.
6. Cell division is induced by cytokinins, steroids, lymphokines, EGF, PDGF etc.
7. Mitosis Cell division occurs to increase the number of cells.
8. Mitosis Cell division occurs to increase cell size.
9. Different types of metabolism take place in cells. Cell division is necessary for carrying out metabolism.
10. Nucleo-cytoplasmic ratio is maintained through cell division.

 

Why Mitosis is called Equivalent Division

Mitosis occurs in the body cells of organisms. Somatic cells have a diploid number of chromosomes. In this process two cells are formed from one cell. Both the cell nucleus and the chromosomes divide once in the process of mitosis. The resulting daughter cells resemble the mother cells. The chromosome number of the daughter cell is equal to the chromosome number of the mother cell. Hence, mitosis is called symmetrical division.

The word Mitochondria is formed from the Greek word mitos meaning thread and chondrion meaning grain. Mitochondria means filamentous grains. The energy producing organelles located in the cytoplasm are called mitochondria. It is called Power House as it provides the necessary energy for cells.

 

Discovery and naming of mitochondria

In 1850, the Swiss scientist A.V. Kolliker noticed tiny organelles in insect muscle cells and named them sarcosomes. He is called the discoverer of mitochondria. In 1882 W. Fleming observed filamentous mitochondria and named them Fila. In 1890, Altman named it Bioplast. Mitochondria was named by Carl Benda in 1898. In 1904, Frederick Mavis was the first to observe mitochondria in the plant cell Nymphaea alba. In 1957 scientist Philip Siekevitz coined the term Power House of the cell. Modern scientists call mitochondria semi-autonomous cells. They also called it electrosome. Mitochondria are also known as chondriosomes and plasmosomes. Mitochondria of birds’ flight muscles are called sarcosomes.

 

All true cells contain mitochondria. Stem cells, progenitor cells, and red blood cells do not contain mitochondria.

In shape it is round, rod, oval, star or coil shape.

Mitochondria make up 20% of cell volume. Mitochondria are typically 3-40 microns in length and 0.2-2.0 microns in diameter. Rod mitochondria are 9 microns in length and 0.5 microns in width. Circular mitochondria are 40-70 microns in length. Circular mitochondria are 0.2-2.0 microns in diameter.

 

Number of mitochondria

Each cell has an average of 300-400 mitochondria. Advanced plant cells contain 100-3000 mitochondria. Liver and kidney cells contain 1000 or more mitochondria. Human sperm has 20 mitochondria. A sea urchin egg has 140,000 mitochondria, an amphibian egg has 300,000, and an Amoeba has 500,000. Mammalian red blood cells do not contain mitochondria.

Origin of Mitochondria

There are three theories about the origin of mitochondria.

1. De novo origin: According to this theory, amino acids and lipids combine to form mitochondria. This doctrine is not accepted at present.
2. Cell membrane or endoplasmic origin: According to scientist Morison (1966), vesicles are formed from endoplasmic reticulum or cell membrane and mitochondria are formed from vesicles. This doctrine is now defunct.
3. Mitochondrial origin: According to this theory, during cell division, old mitochondria divide to form new mitochondria. The new mitochondria quickly change shape and move to other parts of the cell. It grows rapidly and divides to increase the number of cells to meet more energy.

Structure of Mitochondria

1. Membrane: Each mitochondrion is covered by a bilayered membrane. Outer cover and inner cover. The outer layer is called the outer layer and the inner layer is called the inner layer. The outer coat is smooth and the inner coat is rough. Each coat is 40–60 Å thick. The outer end of the mitochondrial membrane is called the H-face and the inner end is called the C-face. The outer membrane contains porin proteins and acts as a transporter. The space between the two membranes is called the perimitochondrial space. The distance of perimitochondrial space is 6-8 nm. It is composed of lipoproteins. It gives the mitochondria specific shape and protects them from external injury.
2. Chambers: Mitochondria have two types of chambers. Outer chamber and inner chamber. The compartment between the outer and inner envelope is called the outer compartment and the compartment between the inner envelope is called the endocompartment (70 Å wide). It is filled with various chemicals.
3. Matrix: The jelly-like substance inside the cell is called matrix. It is dense, homogenous and full of enzymes and co-enzymes.
4. CRISTIE: The inner membrane of the mitochondria folds inwards to form a number of finger-like extensions. It’s called Christy. The space between each cristae is called the intercristi space.
5. Oxysome or F1 Cells: Mitochondria have numerous fine granules like tennis bats on the inner envelope. These are called oxisomes or F1 cells. It consists of head, stem and base. There are two types of oxisomes. Sabrintak and Abrintak. The oxisomes which have a stalk are called stalked oxisomes and the oxisomes which do not have a stalk are called unstalked oxisomes. It has ATP-ase enzyme in its head.
6. ETS: Electron Transport System is abbreviated as ETS. It is called ETC (Electron Transport Chain). Christy has ETS on him. It transfers electrons from one place to another.
7. ATP-Synthases: All substances that synthesize ATP are called ATP-Synthases. Christy has spherical or oval ATP-synthases. It produces ATP.
8. mDNA: Each mitochondrion contains circular double-stranded DNA. These DNAs have their own characteristics. It is called mitochondrial DNA. It is self-reproducing. Human mDNA contains 37 genes.
9. Ribosomes: Mitochondria contain 70S ribosomes. It is called mitoribosomes. It synthesizes enzymes for cells.

 

Chemical structure of mitochondria

1. Protein: About 65% of the dry weight of mitochondria is protein. It contains both soluble and insoluble proteins.
2. Lipids: Mitochondria contain about 35% lipids. Of this, 90% are phospholipids and 10% are fatty acids and carotenoids. It contains glycerides 29%, lecithin and cephalin 4% and cholesterol 2%. Its inner membrane contains phospholipid called cardiolipin.
3. Pigments: Contains small amounts of carotenoids.
4. Nucleic acid: It contains DNA and RNA as nucleic acids. Each mitochondrion contains about 200 pieces of DNA. It contains 5% RNA.
5. Enzymes: It contains about 100 types of enzymes and co-enzymes.

 

Function of Mitochondria

1. Respiration Process: Krebs cycle and electron transport system of respiration process are completed in mitochondria. It is called mitochondrial respiration as it takes place in the mitochondria.
2. Energy production: ATP is produced in mitochondria. ATP is the source of energy.
3. Protein production: Mitochondria make proteins for the cell.
4. Nucleic acid production: It makes DNA and RNA. It plays a role in heredity.
5. Blood cell and hormone production: It helps in blood cell and hormone production.
6. Contains enzymes: It contains enzymes and co-enzymes required for respiration.
7. Ion balance: They maintain the correct concentration of calcium ions in different parts of the cell.
8. Metabolism: It metabolizes neurotransmitters and cholesterol or fat.
9. Control of apoptosis: Mitochondria control cell apoptosis.
10. Heredity: Mitochondria help in the formation of sperm and egg.
11. Energy regulation: It regulates the storage and release of energy in cells. ADP is converted into ATP and stored in the body by creating high energy bonds.
12. Cation storage: Mitochondria store Ca2+, S2+, Fe2+, Mn2+ etc.
13. Heat production: Mitochondria help in the production of excess heat in hibernating animals.
14. Production of chemical compounds: Mitochondria are capable of creating, breaking down and producing substances necessary for the cell. It produces compounds like cytochrome, ferridoxine, hemoglobin, chlorophyll, steroids, alkaloids etc.
15. Biosynthesis: It causes biosynthesis of iron and steroids in cells.
16. Transport: It is capable of active transport of calcium, potassium etc.
17. Disinfection: It participates in ammonia disinfection.
18. Pathogenesis: Mutations can occur in mitochondrial DNA that cause mitochondrial disorders. 100 such disorders are known. In old age, diseases like Parkinson’s, Alzheimer’s, type-1 diabetes etc. can occur. Proper health is dependent on the structure and function of mitochondria.