Plant Cellular Structures
Anton Leeuwenhoek and Robert Hooker (1665) with the help of a simple microscope studied thin sections of cork. Surprisingly they found honeycomb like structures in it. Marveled by the findings they studied other biological materials and found similar structures in all of them. Such honeycomb like structures was found and they made some details studies, based on which they proposed that cells are the basic units of an organism. They are derived from pre-existing cells by cell division. They called this as cell theory or cell lineage theory. Since then remarkable progress has been made with respect to architectural aspects of the cells. New tools like electron microscope and X-ray diffraction methods have revealed the ultra structures of many submicroscopic organelles. Today we know that cells are the basic structural and functional units of an organism endowed with a unique capacity for auto regulation and self perpetuation. The cell innumerable with its many components and structures performing functions as a unit.
Number and Shape of Cells:
The number of cells varies from organism to organism. Quite a number of low plants are just made up of only one cell. Its entire life cycle is completed with only one cell. Many multicellular filamentous or thalloid algae are made up of a few hundred to millions of cells. Higher plants, however, contain billions of cells of various shapes, structures endowed with different functions. Nonetheless different kinds of cells retain their own characteristic features.
The size of cells vary from 1nm to as large as 2" as in Valonia. In some of the Siphonales members the cells may reach a length of few meters. In higher plants the cells may be 5-10mm in size but some fibrous cells may grow to the length of 3.5 mm.
Chemical composition of the cell:
Most of the living cells contain water as the major component. Lipids, proteins, Carbohydrates and Nucleic acids from major organic components. However, a large number of inorganic solutes are also found.
The marvel of the living cell is the organization and interaction of myriads of chemical components into autocatalytic and autoregulatory units.
Structural composition: Protoplasm is the structural and physiological basis of life. It exhibits semi viscous and sol gel properties. It is surrounded by a membrane called plasma lemma which in turn is protected by a rigid non living cell wall. Within the protoplasmic fluid quite a number of highly organized cell organelles are found. Viz. Endoplasmic reticulum, Golgi bodies, vacuoles, plastids, micro bodies, cytoskeleton etc. Besides, protoplasm also contains many non living cell inclusions like starch grains, fat globules, oxalate crystals, needle shaped raphides, etc.
All the above said cell organelles present in the protoplasmic fluid from a kind of cellular community, where each performs set of functions required from the wholesome growth and sustenance of the cell.