Protoplasm: Definition, Structure & Biological Importance

Protoplasm refers to the living substance which makes up a cell. Biologists tend to speak about the cell nucleus and the cytoplasm

It is surrounded in plant cells by a cell wall. The entire cell of animal cells is made of protoplasm, surrounded by a cell membrane. In living organisms, the protoplasm consists of around 75–80 percent water

Hugo von Mohl first used the word "protoplasm" in 1846 to describe the substance in plant cells besides the cell wall, the cell nucleus and the vacuole

Protoplasm Definition

In general, the word protoplasm is used to refer to the living parts of a cell. However, the term protoplasm is not widely used these days, since it was originally used to indicate that a cell comprises only two elements, a nucleus and a plain, homogeneous cytoplasm.

We now realize the cytoplasm is very complex, and it contains complicated organelles. Nevertheless, we now refer to the protoplasm outside of the nucleus as the cytoplasm in eukaryotes, such as plants and animals, and the protoplasm inside the nucleus as nucleoplasm. In prokaryotes the content of a cell is called the cytoplasm collectively.

Structure of Protoplasm and its Components

Structural, it comprises 3 parts, like

1) Plasma/cell membrane

2) Cytoplasm 

3) Nucleus

Component of Protoplasm

The major component of a protoplasm is the cytoplasm that exists in eukaryotes between the cell membrane and the nucleus. The cytoplasm is responsible for maintaining an environment which will allow the various organelles within it to perform their functions.

The nucleus is the second part to make up the protoplasm. It contains a cell, or organism's genetic material. It also has a role to play in controlling cell activity. In addition, the nucleus is the place where ribosomes are produced, which are essential for the creation of proteins in the cell.

Features of Protoplasm

The protoplasm is the living material of the cell. It is primarily composed of biomolecules like nucleic acids, proteins, lipids, and carbohydrates. It also holds inorganic salts and molecules of water. The protoplasm is surrounded by the membrane of the cells.

• The protoplasm refers to the materials contained within the cell membrane, i.e. the prokaryotic cytoplasm, since prokaryotes do not have a distinct nucleus and other cytoplasmic organelles.

• The protoplasm extends to the periplasm region between the cytoplasmic membrane and the outer membrane in certain prokaryotes, especially the Gram-negative bacteria.

•  This region contains a gel-like material called periplasm, which is a part of the Gram-negative bacteria protoplasm.

• The protoplasm consists of two major divisions in eukaryotes: the cytoplasm, and the nucleoplasm (cell nucleus).

• The cytoplasm is the eukaryotic cell's jelly-like material. Except for the nucleus it consists of the cytosol, the vesicles, the cytoskeleton, the inclusions and the organelles.

Thus, a eukaryotic cell's cytoplasm is that cell part between the cell membrane and the nuclear envelope. The material inside the nuclear envelope is known as nucleoplasm. Essential nucleoplasm is the nucleus protoplasm.

Functions of Protoplasm

It performs all the essential lifelong procedures. Its procedures include nutrients and oxygen, transforming food into living matter, ejecting used substances, renewing their worn parts and producing new cells themselves. All protoplasm functions are discussed in detail.

Reproduction

Cells divide to form identical daughter cells; the protoplasm nucleus function, e.g. the angiosperm meristematic region. A cell helps with the mitosis (in more evolved organisms) and meiosis processes in reproduction.

Irritability

The living protoplasm responds to stimuli, e.g. responds to light by retinal cells in the eye. It is the protoplasm's ability to respond to stimuli, and is an aspect of life itself that disappears with cell death.

Chemical

Most of these roles are performed within the cell, e.g. in mitochondrial respiration. Organisms need the energy required to perform various chemical reactions. The energy in plants comes from the photosynthesis process, while in the animals the energy comes from respiration.

Structure and Support

Some cells, such as collenchyma and sclerenchyma, are present to provide structural support, but all cells generally provide the structural basis of all organisms as well.

Excretion

Cells should get rid of excretory waste; they normally spread through the cell membrane out of the cell. It requires imbibing compounds that may be assimilated or otherwise used by the cells in metabolism. It is a process by which material is extruded by a cell. These materials may be useful (secretion) or useless (excretion) products, such as digestive enzymes and hormones, urine and sweat etc.

Transport

Cells produce the nutrients used in the chemical dissimilar procedure that takes place within them. A waste product is produced as a result of those processes. Then, cells work to get rid of that waste. In this way, the small molecules like oxygen, carbon dioxide, and ethanol pass by diffusion through the cell membrane. That method is called passive transportation. That method is called passive transportation. On the other hand, the larger molecules such as the proteins and polysaccharides enter and exit the cell via active transport.

Metabolism

A cell is responsible for metabolism which includes all the chemical reactions that occur within an organism to keep it alive.

Conductivity and Contraction:

It is the transmission of the excitation waves from the point of stimulation throughout the cell. This property is highly developed in nerve cells & in the muscle cells to a smaller extent. Contraction is a size change phenomenon, generally in the form of a shortening. It is highly muscular.

Growth

Growth means an increase in cell size which results in an increase in cytoplasm. Growth occurs on cell division; the protoplasm is consumed and the scale expanded. A cell's maximum size is largely limited by its surface area. Beyond the maximum size, the increase in a number of cells occurs when further growth of tissue is essential. This is done by cell division. 

Conclusion

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