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Eukaryotic-Vacuole-Centrioles | Notes-by-UK-Sir | Cell-Bio-13

CELL    (Vacuole-Centrioles)

Centrosome



Want to Know about Ribosome, Peroxisome, Glyoxysome :

https://uksirnotes.blogspot.com/2021/07/Ribosome-Peroxisosomes-Glyoxysome-uksirnotes.html

Want to Know about Cytoplasm, RER, SER:



Centrosome   Or Central apparatus /diplosome.

       Consists of = 2 Centrioles + centrosphere/ kinoplasm

       Name was given By Boveri 1888.

       This is Main - Micro Tubule Organizing Centre (MTOC).

       Present in – all animal cells, protozoan protists, some fungi and that plant cells where flagellated structure exsist.

       Absent in higher plants and in some algae.

Structure

centriole


Centrioles -

       2 Minute sub microscopic sub cylindrical centrioles present right angle to each other.

       No membranous covering found.

       Size -  Length-  up to- 0.5 μm , diameter- 0.15 μm.

       As pair of centrioles present, so called as  – diplosome.

       Ultra structure gives a – Cart wheel appearance.



Centriole structure

       At center- fibrils absent, a central rod (hub) present (diameter-2.5 nm).

       9 spoke arise from center.

       A whorl of 9 peripheral fibrils present.

       The fibrils made up of 3 sub fibrils called as triplet fibrils.(A, B, C)

       Sub fibrils- diameter – 25 nm.

       Connected by C to A proteinaceous linker.

       Spoke contain thickenings - X and Y.

       X attached with A sub fibril , Y attached to Linker.

       The Micro Tubule Organizing Centre (MTOC)  or Massules –is dense amorphous protoplasmic  structure  (form by Gamma Tubulins).

       Arrangement consider as – 9+0.


Centrosphere:

       These centrioles cover up specific cytoplasm- centrosphere or kinoplasm or cytocentrum.

       This Contain a fibrous material complex.

       Centrioles can self-replicate.

       Before nuclear division- both move to opposite poles. (in S- G2 phage)

       Also replicate – during formation of basal body.

 

Function

       Help in cell division.

       Formation of axial filament or tail in spermatozoa.

       Can form basal body.

       Basal body give rise to cilia and flagella.



Vacuoles

       These are - Membranous Fluid filled sacs present with in cytoplasm.

Types-

       Sap Vacuoles : most common type, present in higher plant cells.

       Protein Bodies- protein storage vacuoles in seeds.

       Contractile vacuoles- special vacuoles related to osmoregulation, in fresh water protozoans.

       Food vacuoles- indigested food present, also called digestive vacuoles or gastriole.

       Gas Vacuoles- metabolic gases storage, also called pseudo vacuoles. Present In some prokaryotes.


Structure

Vacuole


       Sap vacuoles are  – commonly large central vacuoles.

       Develop from ER or Golgi complex.

       Occupy – 80-90% of cell volume.

       Covered by a membrane called as tonoplast.

       Filled with a liquid – cell sap.

       Cell sap is slightly Acidic and contain some enzymes.

       In citrus fruits-very much acidic- sour.

 

Function

       Help in Growth of cell by enlargement of vacuoles.

       Storage of primary metabolites like- sugars , organic acids, proteins etc.

       Toxic secondary materials stored – nicotine, tannins etc.- later help in plant defense.

       Site of Pigment deposition –pigments like anthocyanin (slightly soluble in water)- which gives blue , violet, purple, dark red, scarlet (blood red) color.

       Help in break down of macromolecules for recycling.


Want to Know about Ribosome, Peroxisome, Glyoxysome :

https://uksirnotes.blogspot.com/2021/07/Ribosome-Peroxisosomes-Glyoxysome-uksirnotes.html

Want to Know about Cytoplasm, RER, SER:

Want to Know about Flagella and cilia:



That's all about Eukaryotic-Flagella-Cilia-Movement . Feel free to ask doubts in comment section.. UKsir


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