Category: Biology Second Paper

Spherical, cylindrical and sac-like objects in the cytoplasm of cells are called Golgibodies. Golgi is a small cell unit called Golgisome. Golgi bodies are called Golgi apparatus, Golgi field, Golgi complex, Golgi apparatus, dictyosomes, idiosomes, lipochondria, carbohydrate factories etc. It is also known as cell traffic police and packaging center. It can be stained with osmium tetroxide. In 1898, the Italian physician Camillo Golgi discovered it from owl and cat nerve cells. For this he was awarded the Nobel Prize in 1906. In 1954, Dalton and Felix reported the electron microscopic structure of Golgibodies. The porous structure of the corpus callosum is called fenestration.

Position of golgi body

In animal cells, Golgibodies are clustered near the nuclear membrane. Hundreds of Golgibodies are scattered in plant cells. A species of Paramoeba has 2 golibodies. Liver cells contain 50 and secretory cells have more. Spores of bacteria, fungi, fungi, mosses, ferns, and red blood cells of mammals do not contain glycoproteins.

Number of Golgibodies

Hundreds of Golgibodies are distributed individually in plant cells. Golgibodies are one or more in algal cells. Its number is several hundreds in the root cells of Bhutra.

Origin of Golgi body

Golgibodies probably originate from the smooth endoplasmic reticulum. According to the scientist Navikoff (1962), the Golgi body originates from the endoplasmic reticulum. According to scientist Buch (1965), the Golgi body originates from the nuclear membrane. According to the scientist Danieli (1966), Golgibody originated from cell membrane.

Physical structure of Golgibody

There are three types of structure of Golgibody. These are-

1. Cisternae : All the gills which are narrow, long, cylindrical and parallel are called Cisternae. Its diameter is 0.5-1.0 micron. Its lumen or cavity is 500-1000 nanometers wide. 3-8 cisternae are clustered together. Each cluster is called a dictyosomes. The part of the dictyosomes facing the plasma membrane is called the trans-phase and the part facing the center of the cell is called the cis-face. All organizations are held together by intercisternal material. The number of cisternae is 3-7 in animal cells and 10-20 in plant cells. There are three types of cisterns. These are-

(i) Trans-cisterna : The last part of the trans-face is called transcisterna.

(ii) Cess-Cisterna : The terminal part of the sess-face is called the sess-cisterna.

(iii) Medial Cisterna : The middle part is called medial cisterna.

2. Vacuole: Those cells that look like spherical sacs are called vacuoles. It is the transformed part of the cistern. It is filled with granular material.
3. Vasicle : A small sac-like golibody is called a vesicle. It is located in clusters. Trans-faces and vesicles join together to form the trans-golgi network (TGN). Again, cis-faces and vesicles join to form the cis-golgi network (CGN).

 

Chemical structure of golgi body

Composed of lipoproteins that coat the corpuscles. It contains 60% protein and 40% lipid. That is, the ratio of lipid and protein is 4:6 or 2:3. It contains various enzymes, carotenoids, fatty acids, vitamin-C and vitamin-K. Golgibody enzymes are glycosyl transferase, glucose-6 phosphatase, acid phosphatase, hydrolase, transferase, NADH cytochrome reductase, thiamine pyrophosphatase, ATP-ase, ADP-ase, TTP-ase, CTP-ase etc.

Golgibodies called traffic police

Different types of proteins and lipids are produced in cells. Golgibodies bind these proteins and lipids to the membrane. It is then converted into lipoproteins. Lipoproteins are taken up by cisternae. Enters the medial cisterna from the cis-cisterna. From the medial cisterna comes the trans cisterna. Transports from the trans cisterna to the plasma membrane or cell membrane. Finally, lipoproteins are released. Hence Goljibodi is called traffic police.

 

Function of golgi body

1. Traffic Police: Golgibodies bind proteins and lipids produced in cells. It is then converted into lipoproteins. Releases lipoproteins out of cells. Hence Goljibodi is called traffic police.
2. Carbohydrate Factories: Synthesize and secrete complex polysaccharides in Golgibody cells. This is why the Golgibody is called a carbohydrate factory.
3. Cell wall formation: Golgibodies form hemicellulose microfibrils. These elements form the plant cell wall. Cell wall is a unique feature of plant cells.
4. Formation of Cell Membranes: Golgibodies help in the formation of cell membranes. Cell membrane controls the movement of various substances.
5. Formation of cell plates: It forms cell plates during cell division. Cell plates join together to form the cell wall.
6. Glycosylation: Linking proteins to sugars to produce glycols. The process by which glycols are produced is called glycosylation.
7. Acrosome Formation: Golgibodies form the acrosome of sperm. Acrosome provides energy to the sperm.
8. Lysosome formation: Golgibodies help in the formation of lysosomes. Lysosomes cause autolysis.
9. Storage function: It stores food items. It stores protein and vitamin-C.
10. Chemical secretion: Cell metabolites are secreted. Helps in secretion of water, enzymes, proteins and hormones.
11. Melanin production: Melanin is produced from the Golgi body of mammary cancer and tumor cells.
12. Enzyme production: Golgibodies produce enzymes to generate ATP. ATP provides energy for cells.
13. Production of chemical substances: Galactose, silicic acid, pectin, polysaccharides etc. are produced from sugars.
14. Detoxification: It destroys many toxins or toxins in the cells. As a result, the body gets rid of toxins.
15. Side chain formation: Golgibodies attach side chains to oligosaccharides of glycoproteins in plant cells.
16. Excretion of water: Golgibody excretes water from cells.

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.

 

Process of mitosis cell division

Mitosis Cell division is completed in two stages. Karyokinesis and cytokinesis

 

Karyokinesis

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.

The word Lysosome is formed from the Greek words Lyso meaning digestive and soma meaning substance. Lysosme means digester. The microscopic organelles located in the cytoplasm of cells that contain digestive enzymes and digest food are called lysosomes. This is called cell stomach.

 

Discovery of lysosomes

In 1953, scientist Perner discovered lysosomes from the endosperm of seeds. In 1955, Belgian cytologist Christian de Duve observed it in animal cells and named it lysosome. He was awarded the Nobel Prize in Physiology and Medicine in 1974 for this discovery. In 1960, scientist Nevi Coft described the microscopic structure of lysosomes. In 1964, scientist Christina L Martin observed lysosomes in the fungus Neurospora. In 2016, Japanese scientist William Osumi discovered the autophagy technique of cells.

 

Expansion of lysosomes

Almost all animal cells contain lysosomes. Lysosomes are most abundant in white blood cells, liver cells, lung cells, kidney cells, etc. RBC, yeast and most plant cells do not contain lysosomes. Recently lysosomes have been discovered in plant cells. Lysosomes in plant cells are called Spherosome or Oleosome. Lysosomes are found in onion seeds, bhutra and tobacco cells. Lysosomes have been found in some thallophytes plants.

 

Origin of lysosomes

Lysosomes originate from endoplasmic reticulum and Golgibodies. Lysosomes are formed by the end of the cyst of the Golgi body.

Types of lysosomes

There are two types of lysosomes. Primary lysosomes and secondary lysosomes. Lysosomes that arise from Golgibodies are called primary lysosomes. Primary lysosomes fuse to form secondary lysosomes.

 

Physical structure of lysosome

Lysosomes are small spherical or circular organelles. A large number of hydrolytic enzymes are enveloped to form lysosomes. Each lysosome is surrounded by a two-layered membrane. But the coating of Spherosome or Oleosome is multi-layered. The coating is made up of lipoproteins. Lysosomes are the largest in kidney cells. Their diameter is 0.2-0.8 millimicron. Its vacuoles are filled with fluid. Lysosome coat contains stabilizers and labilizers. Stabilizer maintains the stability of the lysosomal membrane. As a result cortisone, cholesterol, heparin etc. cannot be released. That is, the stabilizer does not allow the enzyme to leave the lysosome. Labilizer disrupts the stability of the lysosomal membrane. As a result, testosterone, progesterone, vitamin-A, vitamin-B, vitamin-K etc. can be released. That is, the labilizer allows the enzyme to escape from the lysosome.

 

Chemical structure of lysosomes

Lysosomes contain 40-50 types of enzymes. The main enzymes are – nuclease (DNA-ase, RNA-ase), acid phosphatase, aryl phosphatase, acid lipase, phospholipase, esterase, sucrase, sulfatase, dextronase, lysozyme, collagenase etc. Enzymes work in acidic environment. Its coat is composed of lipids and proteins. It contains a small amount of sugar.

Chemical structure of lysosomes

Lysosomes contain 40-50 types of enzymes. The main enzymes are – nuclease (DNA-ase, RNA-ase), acid phosphatase, aryl phosphatase, acid lipase, phospholipase, esterase, sucrase, sulfatase, dextronase, lysozyme, collagenase etc. Enzymes work in acidic environment. Its coat is composed of lipids and proteins. It contains a small amount of sugar.

Function of lysosome

1. Enzyme content: Lysosomes contain 40-50 types of enzymes. Nuclease (DNA-ase, RNA-ase), acid phosphatase, aryl phosphatase, acid lipase, phospholipase, esterase, sucrase, sulfatase, dextronase, lysozyme, collagenase etc. Enzymes are active in acidic environment.
2. Intracellular Metabolism: Lysosomes participate in the intracellular metabolism of cells.
3. Germ-eating: Germs are eaten by the process of pinocytosis and phagocytosis.
4. Autolysis: During acute digestion, the cell wall ruptures and enzymes are released to destroy other organelles. This is called autolysis.
5. Suicide Squad: Autolysis destroys useless body cells. Finally the whole body is destroyed. So it is called suicidal bag or squad.
6. Cell Division: Lysosomes stimulate mitosis in cell division. Helps break down the nuclear membrane.
7. Hormone secretion: It helps in hormone secretion.
8. Metabolism: Lysosomes play a role in the transformation of organisms. Extinction of body parts, especially the frog’s tail.
9. Heterophagy: Enzymes in lysosomes oxidize food and bacteria. This process is called heterophagy.
10. Metabolism: Enzymes in lysosomes convert proteins into dipeptides and sugars into monosaccharides. They produce keratin for cells.
11. Enzyme action: Spermlysin (hyaluronidase) enzyme is secreted from sperm lysosomes. Spermlysin dissolves the ovum wall to form the entrance. It binds the dissolving enzymes so that other cells are protected.
12. Body Defense: Lysosomes in white blood cells help in body defense.
13. Keratin production: Lysosomes produce keratin for the cells.
14. Bone formation: Enzymes released from lysosomes play a special role during bone formation from cartilage.
15. Cell membrane destruction: Golgibodies help in cell and nuclear membrane breakdown. It contains phosphatase enzyme which dissolves tissue.
16. Diseases: Nuclease enzyme released from lysosome causes blood cancer and thyroxine hormone causes hepatitis and polynephritis. Cartilage wears down in rheumatoid arthritis due to the action of lysosomal enzymes. Lysosomal enzymes cause about 20 types of congenital diseases. These diseases are called storage diseases.

 

Lysosomes are called suicidal bags

In hostile environment, intense feeding occurs. At this time the lysosome wall ruptures and the enzymes come out. This enzyme destroys other small parts of the cell. This process is called autophagy. Thus all cells can be digested. This is called autolysis. Lysosomal nuclease enzymes (DNA-ase, RNA-ase) cause blood cancer and thyroxine hormone causes hepatitis and polynephritis. Lysosome enzymes cause about 20 types of congenital diseases or storage diseases. As a result, all cells can be destroyed. For these reasons, lysosomes are called suicidal sacs.

 

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.