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Practical: Study of Nostoc

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 Practical: Study of Nostoc Nostoc is a filamentous, photosynthetic cyanobacterium. It commonly occurs in freshwater, moist soil, wet rocks and other damp habitats. Colonies are usually gelatinous because numerous filaments remain embedded in a mucilaginous matrix. Materials Required Fresh or preserved Nostoc material, clean glass slide, cover slip, dropper, dissecting needle, water, blotting paper and compound microscope. Procedure Take a small quantity of Nostoc colony with the help of a dissecting needle and place it on a clean glass slide. Add one or two drops of water and gently tease the material so that the filaments become separated. Place a cover slip carefully over the material without trapping air bubbles. Remove excess water with blotting paper. First observe the preparation under low power and then under high power of the compound microscope. Observations The plant body of Nostoc is thalloid and usually forms a soft, jelly-like colony. A colony contains numerous ...

Nucleus: Chemical constituents

  Chemical constituents of Nucleus Nucleus is called apparatus of heredity. It is the largest extractoplasmic component of cell which contains all the genetic information to control morphology, function and heredity. It is called control room / director/heart of cell. A nucleus in metabolic phase (nondividing phase) I phase is called interphase nucleus. It is not an organelle of cell but component of protoplasm or called extractoplasmic organelle . Nucleus has DNA 9-12 % , RNA 5 % , Lipids 3 % and Ca , Mg , Mn , Na , P , Fe and K , 80 % proteins (65 % acidic non-histone which have height mol. wt., rich in tyrosine and tryptophan, forms enzymes, and helps in transciption of dNA to form RNA ; 15 % proteins are basic like, histone proteins of low mol. wt ., rich in lysine and arginine), DNA : histone ratio is roughly 1 : 1 . Histones neutralize acidity of nucleic acid and prevent transcription of dNA . Histones are structural proteins and suppress genes . Non- histones are functional ...

Wild Mushroom collected from Gorubathan

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