04 Apr


  • Living thing (Plants,Animals and Microbes).
  • Derived from cellula (small room).
  • Microscopic Structure.

==> It was discovered by Robert Hooke in 1665.

==> Later on it was discovered by Robert Brown in 1831 along with the nucleus.

  • Cytology (cell biology)
  • Schleiden and schwann theory

Living organisms are made up of cell.

Cell is surrounded by a membrane.

Present of nucleus with in cell.

Cell is the basic unit of life.

Cell is the basic structural and functional unit of life.

Cell form ==> Tissue ==> Organs ==> Organ system ==> Living organisms

There are two types of cells.

a) Unicellular     b) multicellular

Every cell perform it's own function.

Generalized Structure and function of cell:

CEll organelles:

a) Cell wall

b) cell membrane/ Plasma membrane.

1. Cell Wall:

  • It provides protection to the cell.
  • It provides mechanical support to the cell.
  • It has a definite shape.
  • It provide passage for the exchange of material.
  • It has porous pores (pits) which helps in exchange of material.

a) Primary Cell Wall:

  • It is the inner most cell wall.
  • It is delicate/softer in nature.
  • It is flexible and plastically stretchable.
  • It is extremely thin.
  • It is made up of cellulose.
  • It develops in a newly growing cell.

b) Secondary cell wall:

  • It is the outer most wall.
  • It is thick and stronger.
  • It is made up of cellulose and Hemi-cellular Lignin.
  • It develops when the cell has attain it's maximum size.
  • Once it develops it does not allow any further expansion or enlargement of cell.

c) Middle Lamella:

  • It consists of sticky gel like material.
  • It consists of water , calcium, potassium, magnesium and waxes.
  • It is responsible to hold the cell wall.

2. Cell membrane:

  • Cell membrane is present after cell wall.
  • It is responsible to provide protection.
  • It provides mechanical support.
  • It has a definite shape.
  • It provides passage for exchange of material.

      ==>Selectively permeable (allows only necessary for cell)

  • It is made up of Proteins, lipids and fats.
  • Carbohydrates are present in Conjugated form i.e minute concentration.

Fluid Mosaic Model:

  • According to Fluid Mosaic Model the plasma membrane is Lipid bi-layer.
  • Irregular Protein molecules are scattered across the cell membrane.
  • Protein molecules are embedded.
  • Protein molecules are present like ice berg.


It is a fluid filled region which is present in between the plasma membrane and nuclear membrane is termed as Cytoplasm

  • It is a store house of multiple nutrients (vitamins, Sugar, Acid).
  • It is that region where the maximum cellular activities takes place.
  • Cytoplasm provides a site and protection to other sub-cellular organelles.
  • It is also responsible to provide a medium to pass the genetic material.
  • It is that region from where the cell expands.
  • Cyclosis is a movement of fluid into the cytoplasm.

4. Endo-plasmic Reticulum:

It is a network of cisternae (elongated sacs extending out from the nuclear membrane).

  • There are two types.

a) Rough endo-plasmic reticulum:

  • Rough appearance.
  • Ribosomes are attached with rough endo-plasmic reticulum.

b) Smooth endo-plasmic reticulum:

  • It has smooth appearance.
  • Ribosomes are not attached with Smooth endo-plasmic reticulum.
  • It is involved in synthesis of fats (steroids).

5. Ribosomes:

  • There are non-membranous.
  • Roughly, Spherical shaped granules. (formed in nucleus)
  • They are made up of equal amounts of RNA and Proteins.
  • Ribosomes are involved in protein synthesis.

5. Golgi apparatus:

Camillo golgi discover it. 

  • It is a network of vesicles.
  • Synthesized proteins at the Rough Endo plasmic Reticulum transfers to golgi-complex and golgi-complex is responsible to convert those protein into the further finishing products.

6. Lysosomes /spliting bodies:

  • They are released by golgi- complex.
  • They are involved in the removal of death cell from the body.

7. Mitochondria:

  • It is a double membrane of cell organelles.
  • Selfly replicate.
  • Number of mitochondria may vary from cell to cell.
  • Process of cellular respiration takes place as a result of which the synthesis of ATP( Adenocine tri phosphate). It is the energy currency of cell.

8. Centriole:

  • It is only present in animals.
  • It is involved in the process of cell division.

9. Vacule:

  • Present in both Plant and Animal cells.
  • In case of Plant cell large in size present in the center of the cell.
  • In case of Animal cell smaller in size and present away from the nucleus.
  • Store house of water.


It is present only in Plants.

It has three types.

       Chloroplast : 

  • It is present in leave cells.
  • It is present in the process of photosynthesis.
  • It is present in petals.
  • It is responsible for colour production other than green.
  • It is responsible for food storage.

11. Nucleus:

  • With the formation of genetic material takes place in nucleus.
  • It also involved in the regulation of cellular activities.
  • It contains the genetic information.
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