What is a Cell?
The cell is defined as the smallest structural and functional unit of life. It is a complex unit that performs a variety of functions.
The credit for the discovery of cells goes to Robert Hooke in 1665. He with the help of a microscope was able to locate honeycomb-like structures in a slice of cork. These structures were compartmentalized and separated from each other.
The Discovery of a cell date back to 1665What is and is supposed to be one of the major discovery after an improvement in resolution as well as magnification of microscopes? Cell shows a variety of shapes, sizes, and counting and they differ for different organisms depending upon the function it requires to perform.
Today millions of cells are known in a variety of shapes and sizes. These variations are a result of a variety of functions performed by cells. Cells are generally divided into two groups based on the number of cells present namely unicellular and multicellular.
Unicellular: (uni: one; cellular: cell) Organisms made up of single cells are known as unicellular eg: ameba, paramecium, etc. All the necessary functions are performed by this single cell.
Multicellular: ( multi: many; cellular: cell) Organisms made up of more than one kind of cell are known as multicellular. In this type group of specialized cells are made to carry out specific functions.
What is the Shape of cells?
Cells are known to occur in many shapes viz. spherical (Red Blood Cells), elongated, spindle-shaped (muscle cells), branched (nerve cells), etc. There are certain cells that have no definite shape i.e. the shape keeps on changing e.g. ameba which is a unicellular organism with projections protruding out of the main body. These projections are known as Pseudopodia (pseudo: false; podia: feet).
What is the size of cells?
Different-sized cells are known to exist with sizes ranging from a few micrometers to as large as a few centimeters. Cells are not visible by the naked eye and can only be seen using a microscope. The smallest sized cell known is around 0.1-0.5 micrometer in a few bacteria with the largest cell being that of an ostrich egg measuring 170mm × 130mm.