Eukaryotic-Vacuole-Centrioles | Notes-by-UK-Sir | Cell-Bio-13
CELL (Vacuole-Centrioles)
Centrosome
Want to Know about Ribosome, Peroxisome, Glyoxysome :
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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
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