Vacuole Structure Functions and Types

Vacuole:-

Vacuole is discovered by Dujardin.  It is unit membrane-bound structure which is selectively permeable. Approx.90% of the volume of many plant cells is occupied by it.
It Is surrounding membrane is known as Tonoplast (Greek- ton meaning ‘stretching’, ‘tension’, ‘tone’ Plastos ‘formed, molded’ ) and fluid is cell sap, cell sap contains water, sugar, mineral salts, vitamin, and metabolic waste that are called as Ergastic Substance.
They have V-type H+ ATPase on their membrane.
Sometimes pigments like anthocyanin also present in the cell which provides color Red, Blue, Yellow Purple to flower and fruits.

Picture

Source- Wikimedia

Picture

Types:-

(1) Sap vacuoles (central vacuoles): – Fluid filled vacuoles. Solute presents is sap maintain a proper osmotic pressure in the cell for its turgidity and water absorption. They play role in cell enlargement.  They store and concentrate waste products. A water-soluble pigment such as anthocyanin provides color to the cell. The color of beet is also due to anthocyanin.

(2) Contractive vacuole: Found in some protozoans and algal cells found cells mostly in fresh water. It possesses a highly extensible and collapsible membrane.  They help in osmoregulation. They contain a large number of mitochondria which provide energy for their contraction.

(3) Food Vacuoles: – found in cells of protozoan, protest. They are formed at the time of ingestion and eliminated at the time of egestion. It contains digestive enzymes which cause digestion of ingested food.

(4)Air vacuoles ( Pseudovacuoles, or  Gas Vacuoles): found in prokaryotes and helps in floating

Function:-

  1. It stores waste products.
  2. It helps to maintain osmotic pressure and turgidity into cells.
  3. flower’s color due to anthocyanin attract insect that helps in pollination.
  4. It helps in floating of bacterial cells.

For other information


References and source:-
Wikimedia
RSER books
NCERT books
Molecular Biology of the Cell-Alberts
Cell and Molecular Biology Concepts and Experiments.Gerald Karp
Cell Biology, Genetics, Molecular Biology, Evolution and Ecology by Verma, Agarwal

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