What is Cell?
CELL is the structural and functional unit of all living organisms.
Each and every organism on Earth is divided into cells. It is the smallest and basic structural unit of all organism.
You can think a cell of a small compartment that keep holds all the biological equipments necessary to keep an organism alive and successful. Living things may be either single celled or they can be very much complex, for instance human being – the most complex living creature, yet made of that basic unit of life, a cell.
There are smaller pieces that constitutes to make up cells, such as organelles and macromolecules. A mitochondria is a perfect example of an organelle while a protein is an example of macromolecule.
Cells can connect together to build up larger structures. They might group to form the tissues of organs like stomach and eventually the entire digestive system. Just as in the same way atoms are the basic unit of matter, here cells are the basic unit of organisms.
In larger organisms, the primary purpose of a cell is to organize. Cells holds different varieties of pieces and there different types of cells. Each type has separate purpose. It eases the task of cells, as by dividing responsibilities among different groups of cells eases for an organism to grow and survive.
No matter what organism the cell comes from, it has almost the same basic functions. Cells must be able to get nutrients from the surrounding environment, make new cells (or reproduce) and the use the absorbed nutrients to make energy for the corresponding organism they are part of. Though there are many other things well, a cell can do in addition to these mentioned three things, for example, they get rid of wastes in the body, sends electrical signals to the brain, carry oxygen through the body, fights off diseases and in the case of plants they synthesis energy from the natural sunlight.
Broadly classifying, cells are of two type plant cell and animal cell. Although, overall functions are same, there are some very important differences between plant and animal cells.
The very first difference is that plant cells contains an organelle known as chloroplast. Chloroplast contain a special pigment named chlorophyll (which is solely responsible for plant’s green color). Chlorophyll is very much able to capture the energy from sun and eventually converts this captured energy in the form of sunlight into ATP (energy for the plant).
The second big difference lies in the structure of cell itself. Animal cells are smaller than those of plant’s cells and surrounded by a membrane around them which is very flexible and allows molecules, nutrients and gases to pass into the cell. While plant cells are larger and is addition to the membrane they have a very rigid cell wall. This rigid cell wall provides protection to the plants as the animal cell membrane does.
Its the basic building block of all organisms. Virus is the exception, it contains RNA/DNA surrounded by proteins and lipids. It may be divided into two categories
->Unicellular(Best example is Bacteria,a single cell organism)
->Multicellular(Consists of huge number of cells. Eg. Human about 10 trillion cells)
Some basic characteristics of cell are.,
- Size of the cells of all plants and animals ranges between 1 to 100 micron
- These are visible under microscope.
Robert hooke discovered the cell in the year of 1655.Cell theory proposed by Schleiden and Schwann in 1839 states that all living organism are made of cells,as a basic unit and it is responsible for regulating cell function and transmitting information to the next generation through Hereditary information present inside the cell.
There are two types of cells
Above types can be explained through the next post.