Economical importance of bryophytes

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ECOLOGICAL IMPORTANCE OF BRYOPHYTES Mosses and Bryophytes are the first organiasms to colonise rocks. They colonise rock by acidic secretion. This acidic secretion is due to the death of mosses. When the rock is decomposed it helps in soil formation. Therefore New soils are formed. The soil act as binders.  It prevent soil erosion. The water retention capacity of the soil is high ie, water holding capacity of the soil is high.  This reduces surface water run-off which prevent soil erosion. Bryophyte helps in the recycling of nutrients. ECONOMICAL IMPORTANCE OF BRYOPHYTES. 1) SPHAGNUM Sphagnum has high absorptive power with antiseptic property. This can be used to replace cotton in bandages. 2) MERCHANTIA   Mercahntia cures pulmonary tuberculosisand affliction (pain) in liver. Antibiotic substances are also extracted from bryophytes. it also acts as antiseptic, and as preservative POLYTRICHUM Polytrichum dissolove stone in kidney and in gall bladder. 3) IN RESEARCH It is used in the fie
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what is endosymbiosis theory of eukaryotic cell origin , notes

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Origin of eukaryotic cell
    We know that the eukaryotic cell has  a well developed nucleus and cell organelles. Therefore, a natural question is how the eukaryotic cell originated from a prokaryotic cell, or independently. A number of theories are available to explain the origin of eukaryotic cell. However, the most important of among these theories is endosymbiosis theory. Other theories like micromutation theory and hydrogen hypothesis are also important. 

Endosymbiosis theory 
     A popular hypothesis for the origin of eukaryotic cell ( including cell organelles ie., mitochondria a and chloroplast) is endosymbiosis theory, according to which the origin of eukaryotic cell and it's organelles describe in following stetments ie., 

1 large prokaryotic cell ( capable of engulfing other small prokaryotic cell) engulfed an aerobic bacteria or photosynthetic bacteria( cyanobacteria) 
2.the engulfed bacteria, instead of digested remain as a symbiont, benefiting the host cell by removing the harmful oxygen and helping in the production of ATP and also some provide food. 
3.the host cell grew, as partly dependent on the bacterium. 
4. The aerobic bacteria eventually become morochondrion and some of those cells also engulfed the blue- green algal cells which later become chloroplast. 

     However, the basic concepts of endosymbiosis theory, was first articulated in 1910 by the botanist Konstantin Mereschkowsky. 

  Later in 1967 , Lynn Margulis provided substantial evidence in favour of endosymbiosis theory, and modified this theory. She believed that a prokaryotic cell First develop a membrane around it's DNA to from a proto-eukaryote with out other membrane bound organelles. This proto-eukaryote served as the host for the bacteria, which eventually become mitochondria, chloroplast and flagella she also believed that the eukaryotic flagellum arose from ectosymbiontic  bactetium spirochete. 
  

      The endosymbiotic origin of mitochondria and Chloroplast is widely believed because of the many similarities between Prokaryotes and and those organelles. These similarities include the following

1.both have similar shape and size. 
2.both have their own circular DNA  that lacks histone proteins, and attached to the inner membrane. 
3.both have the ribosomes of same size ie., 70S type. 
4.both have similar type of cell division, using similar machinery. 
5.both have similar outer membrane. 
6.both originated from the preexisting entities. 
7.in both the first amino acid in protein synthesis is formyl methionine. 

      Molecular and biochemical evidences also suggest that mitochondria originated from the protobacteria and Chlo originated from cyanobacteria. 

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