All the living organisms that exist in this universe – like mushrooms, plants, humans, elephants etc. are made up of a basic unit called cell. Let’s see what is cell and cell structure. A cell is the smallest biological and functional unit of all living organisms. Hence it is also referred to as the fundamental unit of life. In 1665 English physicist, Robert Hook first observed the cell as the smallest unit.
A typical cell contains cytoplasm which is bounded by a thin layer membrane known as cell membrane. The main function of cell membrane is to protect the contents of the cell from the outside substances. Selective substances are only allowed to enter the cell through cell membrane. It consists of other cell organelles like mitochondria, nucleus etc. Cells are combined together to form tissues and eventually tissues form organs and then organs form larger systems such as digestive system. They aggregate together to form different forms of life in different shapes and sizes. Some of the organisms are multi-cellular like humans whereas others are unicellular like bacteria and protozoa. There is a special function of cell in which they can replicate themselves.
There are some interesting facts about the cells. It is said that there are more nerve cells present in the brain than the stars in the milky way. Joining together, the blood cells of the blood vessels can form a path that will be about hundred thousand kilometers long and can circle the earth twice. Moving towards DNA, the heredity part of our body, if we join the DNA present in the nucleus of all the cells of a human body then we can measure the distance between earth and the sun around 600 times. These cells are very small and cannot be seen by our naked eyes. They can be seen only through some special equipments such as microscope. Microscope was discovered in 17th century.
There are many types of cells: Plant cell and animal cell are two broad classifications of cells. About seventy five to hundred trillion cells are present in a human body. All these cells are made up of atoms.
This article gives us a quick view on cells and introduces us to some of the interesting facts about cells. But for more extensive understanding of cell structure and it’s function, you can refer to NCERT solutions based on cell structure. Click here – Cell structure and functions