Dunaliella salina - Overview

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                 Dunaliella salina Dunaliella salina is a unicellular microalgae belong to division Chlorophyta . It is found in salinity environments such as salted brines, salt evaporation ponds, and hypersaline lakes  .It is able to tolerate varying NaCl concentrations, ranging from 0.2% to approximately 35% . Thus, Dunaliella salina is a hyper-halotolerant organism found in high densities in saline lakes.  The ability to tolerate high salt concentrations is advantageous, since competition is minimal in high salt concentration areas.  How D.salina   tolerate high salt concentration? D. salina has adapted to survive in high salinity environments by accumulating glycerol to balance osmotic pressure. Note :  D. salina is also adapted to solar radiation using β-carotene to protect against ionizing energy.                 Red Colour of Salt Brines  Dunaliella salina...
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Phagocytosis: Definition, Process,Examples

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                        Phagocytosis

Performed by  Neutrophils, Monocytes  in blood and macrophages in tissues.

Neutrophils- Polymorpho nuclear leucocytes(PMNL)

Monocyte -Mononuclear leucocytes

Macrophages: Macrophages are large irregular shaped cells that engulf microbes,virus,cellular debris etc.in response to infection.
   

             Steps of Phagocytosis   

1) Vasodilation: At site of entry of bacteria 🦠, diameter of blood vessels increased due to histamine.


2)Adhesion: Accumulation of leucocytes at periphery of blood vessels due to decreased blood flow (blood stasis).


3) Diapedesis : Now the leucocytes (neutrophils and monocytes) migrate from the blood vessel by active movement (amoeboid movement) into the E.C.F.This kind of active movement of cell is called Diapedesis.


4)Chemotaxis :Now this leucocyte cells move towards the pathogen by chemotactic movement (active).



5) Phagocytosis:
a) Attachment- The infective agent gets attracted to the membrane of the phagocyte.

b) Ingestion- Phagocyte engulfs the particular material into a vacuole (phagosome) .The membrane of which fuses with a lysosome forming a phagolysosome
Lysosome contains hydrolytic enzymes and other bactericidal 🦠 substances.

c) Intracellular killing of bacterium - 
Most bacteria ar FC

e slaughtered in the phagolysosome by the hydrolytic enzymes within a few minutes of Phagocytosis.

*In response to pathogenic infection, phagocytosis is exhibited by phagocytes.


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