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STRUCTURE OF A GENERALIZED CELL

STRUCTURE OF A GENERALIZED CELL
The modern technology by which we can isolate various components of cell including its organelles is called cell fractionation.
CELL FRACTIONATION
Following steps are involved in cell fractionation.
1. Disruption
The tissues are homogenized or disrupted with special instruments.
2. Spinning
The homogenized or disrupted cells are made to spin in a special medium in a centrifuge at high speed.
3. Density Gradient Centrifugation
The various cellular parts separate out in different layers depending upon their size, weight and density of the medium. After this we can study their structure and function in detail under electron microscope. A cell consists of the following basic components:
  1. Plasma membrane, also a cell wall in plant cells.
  2. Cytoplasm, containing cell organelles.
  3. Nucleus, with nuclear or chromatin material.
Types of cells
There are two main types of cells i.e. prokaryotic and eukaryotic cells.
(i) Prokaryotic Cell
  • A prokaryotic cell lacks a definite nucleus and their nuclear material is directly submerged in the cytoplasm and is not separated from it by membrane.
  • Example is bacteria.
(ii) Eukaryotic Cell
  • A eukaryotic cell has a distinct nucleus (chromatin material is bounded by a membrane).
  • For example plants and animals.
  • These cells are complex and vary greatly in size.
  • They could be as big as an Ostrich’s egg.
  • Most of the cells are microscopic and are not visible to the naked eye. Their size is measured in micrometer (ΞΌm).
  • 1 ΞΌm = 0.000,001 m = 1 x 10-6 m.


Electron microscopic structure of an animal cell        Electron microscopic structure of a plant cell.

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