cell introduction
what is cell?
'cell is the functional unit of life'.
A cell is capable of carrying out all the life function; such as nutrition, excretion, respiration, etc. Additionally, the cell is the smallest unit of life and all the living beings are made up of cells.
what is a cell? Cells are the basic 'building blocks of all living things'. The human body is composed of trillions of cells. they provide structure for the body, take in nutrients into energy, and carry out specialized functions.
organelle which are made up of single cell are called unicellular(uni = single). whereas organelle are made up of more then one cell or many cells are called multicellular(multi = many).
discovery of cells
Cells were first discovered by Robert Hooke in 1665. He observed the cell in a cork slice with the help of a primitive microscope,but the cell was dead.
Living cells were first discovered by Leeuwenhoek (1674),in pond water, with the help of improved microscope.
Robert brown discovered the nucleus in the cell.
Cell theory was first presented by two biologists, Schleiden (1838) and Schwann (1839),was further expanded by Virchow (1855) by suggesting that all cells arise from pre-existing cells.
In 1940, it was possible to observe and understand the complex structure of the cell and its various organelles,after the discovery of the electron microscope.
There is many living organism such as Amoeba, Chlamydomonas, Paramoecium and bacteria are only have single cell that constitute whole organism, These organism are called unicellular.
Cells are different kind which perform various functions are as following picture
The shape and size of cells are related to the specific function they perform. Some cells like Amoeba have changing shapes. In some cases the cell shape could be more or less fixed and peculiar for a particular type of cell:fro example, nerve cells have typical shape.
In 1940, it was possible to observe and understand the complex structure of the cell and its various organelles,after the discovery of the electron microscope.
There is many living organism such as Amoeba, Chlamydomonas, Paramoecium and bacteria are only have single cell that constitute whole organism, These organism are called unicellular.
Cells are different kind which perform various functions are as following picture
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| Nerve cell |
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| Ovum |
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| smooth muscle cell |
The shape and size of cells are related to the specific function they perform. Some cells like Amoeba have changing shapes. In some cases the cell shape could be more or less fixed and peculiar for a particular type of cell:fro example, nerve cells have typical shape.
Each cell has got certain specific components within it known as cell organelles.
Each kind of cell organelle performs a specific function, such as making new material in the cell, clearing up the waste material from the cell and so on.
A cell is able to live and perform all its functions because of these organelle. These organelles together constitute the basic unit called the cell.
All cell are made up of same organelles, no matter what their function is or what organism they are found in.
What is a cell made up of? what is the structural organisation of cell?
we study a cell under a microscope, we would come across three features in almost every cell; plasma membrane, nucleus and cytoplasm.
Very informative
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