Cells are the building blocks of all living organisms. It is the structural and functional working unit of life. Therefore it is also be described as a fundamental unit of life. The term cell was first identified in the year 1665 by an English philosopher Robert Hook and later in the year 1839 German scientists – Schwann and Schleiden presented basic principles and theories of the cell.
Cell Structure and its Functions
The cell structure varies in their shape, and size, it is mainly depended on their functions. There are several cells involved in performing different functions throughout the life. Prokaryotic and eukaryotic are two types of cell which are classified based on the presence or absence of a true nucleus. The shape and size of the cells vary based on the type of function it performs.In general, the cells are curved, spherical, rod, concave, flat, rectangular, oval and it can be clearly examined only under the electric microscope.
Eukaryotic cells are those cells which contain a true nucleus and are found only in all multicellular organisms. Both plant an animal cell are examples of Eukaryotic cells.
Prokaryotic cells are the cells without the nucleus. Bacteria and other unicellular organisms are examples of Prokaryotic cells.
Every cell structure has some specific functions. Here we would discuss the functions of the main cell components: plasma membrane, cytoplasm, and nucleus.
Cytoplasm is a primary component of the cell where all the cell structures are embedded within it. It is a jelly-like liquid component that combines the cell membrane and the nucleus. Most of the chemical reactions within a cell take place in this cytoplasm. Other cell organelles including endoplasmic reticulum, vacuoles, mitochondria, ribosomes, are all suspended in this cytoplasm.
Every cell has three basic components namely plasma membrane, nucleus, and cytoplasm. Among these, the plasma membrane is the outer covering of a cell within which all other organelles including cytoplasm and nucleus are enclosed. It is also referred as the cell membrane. By structure, it is a porous membrane (with pores) which permit the movement of selective substances in and out of the cell. Besides this, cell membrane also protects the cellular component from damage and leakage. It forms the wall like structure between two cells as well as between the cell and its surroundings.
Plants are special, so are their cell structures. Since plants are immobile and cannot hide or run away like animals do during the atmospheric changes. Plants have an advanced cell structure that protects them and makes them rigid and is called cell wall. The cell wall is a thick outer layer and is present only in plants cell which protects the plasma membrane and other cellular components. The cell wall is the outermost layer of plant cells.
The nucleus is the most prominent and largest organelle of the cell. It is present in all eukaryotic cells except in few cells of mammalian RBCs. The word nucleus is derived from a Latin word meaning ‘kernel’. It is a double-membrane bound cell organelle comprising most of the genetic material of the cell – the DNA.The shape of the nucleus is mostly round, oval, or disc-shaped depending on the type of cell. It occupies about 10% of the total cell volume.
The primary function of the nucleus is to create an identical copy of the DNA by replication. It is responsible for cell division, protein synthesis, controlling the heredity characteristics, growth and differentiation of an organism.It is known as the control center of the cell as it is responsible for regulating gene expression, cell’s growth, reproduction and other activities of the cell.
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