Cells can be defined as the basic unit of life responsible for all life’s processes. A cell has the quality to replicate itself and thus known as the building block of life. Inside each cell, a fluid which is known as cytoplasm is present which is enclosed by a membrane.
In the cytoplasm, there are several biomolecules present like lipids, nucleic acids and proteins. The cellular structures present are called the cell organelles that are suspended in the cytoplasm. Cells are of different shapes and sizes, essentially like building blocks of structures.
Characteristics of Cells
Important characteristics of cells are -
Cells assist in giving design and structural support to the body of a life form.
The cell interior consists of a number of different individual organelles surrounded by a separate membrane.
The nucleus holds hereditary data essential for multiplication and cell development.
Mitochondria is a double membrane-bound organelle that's mainly liable for the energy transactions that's vital for the survival of the cell.
Lysosomes digest undesirable materials present in the cell.
The endoplasmic reticulum assumes a significant part inside the inner association of the cell by incorporating specific particles and handling, guiding and putting them to their fitting areas.
Robert Hooke is the first researcher to watch a cell employing a magnifying device. Yes, cells are too tiny to ascertain with our naked eyes. But not every cell is microscopic. Within our body, we will observe the spread of cells of various shapes and sizes.
Number of Cells
Cells are the most minimal degree of association in each living thing. The count of the cells may vary from organism to organism. Humans have more cells than bacteria. If an organism is formed from one cell, it's called a unicellular organism (uni: one; cellular: cell). Whereas, the organisms which are made from more than one cell are called multicellular organisms (multi: many; cellular: cell). Among the multicellular organisms, the count of the cell varies. Some may have billions of cells while other organisms may have trillions (like humans). But every organism starts its life from one cell which further divides into thousands and millions.
Unicellular v/s Multicellular
As the size of the living being gradually increases, so does the quantity of cells that they have. Notwithstanding, this check won't decide the proficiency of a creature i.e., capacity and effectiveness of a cell in a unicellular life form and multicellular organic entity will be something similar.
Living organisms are made from differing types of cells, of different shapes and sizes. A unicellular organic entity varies fit as a fiddle from another unicellular creature. Within a multicellular organism, there is a spread of cells. Some are short while others are long and slender; some are roundabout while some are oval.
Size and Shape of Cell
The shape and size vary from cell to cell consistent with their functions and composition. For example, a neuron is long and branched, meant for the transmission of signals throughout our body while a muscle fibre is little and spindle-shaped which helps in movement.
Considering an animal cell, we can generalize the form of a cell as round (spherical) or irregular. Plant cells are far more rigid and rectangular in shape. The size of a cell is often as small as 0.0001 mm (Mycoplasma) and as large as six to 12 inches (Caulerpa taxifolia). For the most part, the unicellular creatures are minuscule, similar to bacteria. But one cell like an egg is large enough to the touch. Regardless of their shape, they all comprise similar organelles and assist us with playing out the everyday exercises proficiently.