Category: Biology Second Paper

The word Protoplasm is derived from the Greek word Protos meaning origin and plasma. The translucent, sticky, colorless and jelly-like colloidal living matter inside the cell membrane is called protoplasm. It is called the physical basis of life or vivum fluidum as it performs all the functions of the organism.

The word Protoplast is formed from the Greek word Proto meaning origin and plasma meaning organization or matter. Protoplast means primitive matter. All parts of the cell except the cell wall are called protoplasts. German botanist Robert von Hanstein first used the term protoplast in 1880. According to I. K. Vasil (1980), the protoplast is the inner part of the cell wall that can be separated from the cell wall mechanically or by enzymes. Protoplasts that are produced artificially are called isolated protoplasts. Protoplast consists of two parts. Protoplasm and non-living matter.

1. Protection of living parts: The protoplasm of plant cells is surrounded by tough, thick and inert cell walls. Totally protects protoplasm from hostile environment. It protects the living part of the cell from external injury. As a result, the inner living parts are not damaged.
2. Shaping: It gives specific shape and form to each plant cell. As a result, the cells can be easily distinguished separately.
3. Stiffening: The cell wall is strong, firm and thick which gives strength to the cell.
4. Providing mechanical energy: It provides the required mechanical energy to the plant.
5. Transport: Cell wall contributes to the transport of water, mineral salts and food in the plant body. Acts as a conductor of extrinsic and intrinsic stimuli.
6. Absorption: The role of cell wall in absorption of water and mineral salts is undeniable. Because the main rom wall is semipermeable, pore water from the outside environment easily enters the mulrom.
7. Sensation: Sensation takes place through the cuticle and lenticels located in the cell wall. Cutin and suberin reduce the rate of respiration.
8. Immunity: The cell wall prevents microbes from entering the cell. Apart from this, if there is any bacteria on the cell wall, it will die due to salt like substance. As a result, the plant becomes disease resistant.
9. In paper and textile industry: As the cell wall contains cellulose, it is used as the main material of paper and textile industry. The demand for industrialization is increasing day by day.
10. Cell Separation: It separates two adjacent cells. As a result the separate entities of the two cells are maintained.
11. Intercellular communication: Two cells maintain intercellular communication through plasmodesmata located in the middle membrane.
12. Skeletal structure: Cell wall acts as a skeleton in the plant body.
13. As a source of nutrition: Herbivorous animals like goat, cow, sheep, buffalo, dumba, camel, deer, giraffe, rabbit, guinea pig etc. have cellulose digesting enzymes in their bodies. Cellulose-containing cell walls therefore act as a source of nutrients for animals. But as the human body does not have cellulose digesting (cellulase) enzyme, it is not used as food.

 

1. Madhyaparda: Madhyaparda is composed of pectic acid (more), calcium pectate, magnesium pectate, propectin etc.
2. Primary wall: Primary wall is composed of cellulose, hemicellulose, glycoprotein, xyloglucan etc.
3. Secondary wall: Secondary wall is composed of cellulose, lignin, suberin, cutin, tannin, wax, calcium oxalate etc. Hemicellulose contains xylan, araban and galactan. Hemicellulose called xyloglucan acts as a crosslink in the cell wall structure.
Cell wall consists of 40% cellulose, 20% hemicellulose, 30% pectin and 10% glycoprotein. The cell walls of higher plants contain cellulose and polysaccharides, the cell walls of bacteria contain peptidoglycan and mucoproteins, the cell walls of fungi contain chitin, the cell walls of algae contain polysaccharides and glycoproteins, the cell walls of diatoms contain silicic acid and the cell walls of archaea contain glycoproteins, pseudopeptidoglycans and polysaccharides.

Cellulose is the main chemical component of plant cells. Cellulose is formed from β-D glucose with six carbons. A cellulose chain is formed by 1000-3000 molecules of cellulose. A mycelium is formed by 100 cellulose chains. Each mycelium is 10 nm in diameter. A microfibril is formed by 20 mycelia. The diameter of the microfibrils is 250 angstroms. Again, 250 microfibrils join together to form a macrofibril. Its diameter is 0.4 micron. Each macrofibril contains 500,000 molecules of cellulose. It is the main structural unit of the cell wall. It creates a web-like texture. Between the macrofibrils are microcapillaries. Many macrofibrils join together to form fibers. Fibers are clearly visible in the cell wall.

Each cell wall has three distinct layers. These are-

1. Median Membrane: Two adjacent cells connected by a cement membrane is called median membranous. It is continuous and single-layered. Sometimes the primary wall is not formed on the median membrane. As a result narrow holes are formed. This hole is called a coupe or pit. Two pits facing each other are called pit pairs or pit pairs. The middle membrane of pit pair is called pit membrane. Pit membrane has very fine pores. Through these pores there are tiny pores. The filaments are called plasmodesmata. Scientist Tangle discovered it. The mesenchyme contains more pectic acid. It also contains pectin and protopectin. It acts as a common membrane between the two cells. Phragmosomes accumulate at the equator of the cell during the telophase phase of cell division. Later, pectin accumulates with phragosomes to form the membranous membrane.
2. Primary wall: The first layer that forms above the mesentery is called the primary wall. It is thin, fragmented and monolayered. Its thickness is 1-3 microns. Primary walls are not formed in the cell well area. It is composed of microfibrils. Its chemical components are cellulose, hemicellulose, glycoprotein, pectin, lignin etc. Parenchyma, collenchyma and mesophyll are only primary walls in bananas.
3. Secondary wall: The layer formed above the primary wall is called secondary wall. It is three-layered, segmented and 5-10 microns thick. Its outer layer is partially thin, the middle layer is slightly thicker and the inner layer is thinner. Secondary walls are not formed in the cusp region. It is composed of cellulose, hemicellulose, lignin, suberin, cutin, wax, tannin, calcium oxalate, silica, inorganic salts etc. Cells that are metabolically active (dividing cells) do not have secondary walls. Only permanent cells consist of tracheids, vessels, fibers etc. secondary wall. It is impermeable to water and gas. It gives shape to the cell and protects the organism from external injury.

Cell wall is a unique feature of plant cells. Due to the accumulation of various substances on the cell wall, its ornamentation can be circular, spiral, stepped, reticular, etc.

The hard, thick and dead covering outside the cell membrane of plant cells is called cell wall. It indicates cell boundaries. In 1665, Robert Hooke first observed the cell wall. In 1804, Carl Rudolf & F. Link proved that plant cells have cell walls. Cell wall is a unique feature of plant cells. The cell wall is formed at the beginning of the telophase phase of mitosis cell division. Animal cells, pollen and gametes do not have cell walls.

A cell in which all the parts or organelles of an organism are present is called an ideal cell. A plant cell is a typical cell. It consists of cell wall, cell membrane and protoplasm. Protoplasm contains nucleus and cytoplasm. Cytoplasm contains all the organelles. The organelles in the cytoplasm are called cytoplasmic organelles.

Sperm, egg, red blood cell, white blood cell, goblet cell, liver cell, fibroblast, seratium, fat cell, osteocyte, choanocyte, chromatophore, muscle cell, nerve cell etc. are animal cells.