Contractile vacuoles of amoeba, Biology

Contractile Vacuoles of Amoeba

Microscopic observations revealed that in protozoans contractile vacuole exhibits a cyclic functioning. It gradually gets filled with fluid and increases in volume (diastole) till it reaches a critical size. Then it moves towards the cell boundary, suddenly expels its contents to the outside and decreases in size (systole). The mechanisms of filling and discharge of the vacuole are not yet clearly understood. Electron microscopic studies show that the contractile vacuole contains a single membrane enclosing the lumen.

556_Contractile Vacuoles of Amoeba.png

Figure: Contractile Vacuoles of Amoeba

This membrane is surrounded by a layer of densely packed vesicles around which there is a layer of mitochondria which presumably supply energy for the osmotic work done by the vacuole. The vesicles empty their contents into the contractile vacuole by fusion of their membranes. According to current theories, the small vesicles initially contain a fluid isosmotic to the cytoplasm. The fluid later becomes hypoosmotic due to the removal of salts, particularly potassium, by active transport. The hypoosmotic vesicles now fuse and open into the contractile vacuole leading to diastole. It is also believed that contractian of myofibrils present in the vacuolar membrane is probably responsible for the expulsion of the fluid during systole.

Posted Date: 1/16/2013 1:22:15 AM | Location : United States







Related Discussions:- Contractile vacuoles of amoeba, Assignment Help, Ask Question on Contractile vacuoles of amoeba, Get Answer, Expert's Help, Contractile vacuoles of amoeba Discussions

Write discussion on Contractile vacuoles of amoeba
Your posts are moderated
Related Questions
Hormone s . The thyroid gland secretes following hormones. Thyroxine (tetraiodothyronine or T 4 )' and tri-iodothyronine or T 3 are secreted by the thyroid follicular cells.

how connective tissues are like an estuary

It is the preparatory phase. Cell organelle replicate and size of the cell increases. DNA molecule undergoes replication. Each chromosome exists as a pair of chromatids joined toge

What is Microbodies ? Microbodies : Microbodies are formed by pinching off of vesicles from rough endoplasmic reticulum. They are not found in every cell, but are present a

A number of protein-coding genes are active in all cells and are required for so- called house-keeping functions such as the enzymes of glycolysis, the citric acid cycle and the pr

Q. What are alkalosis and acidosis? Acidosis is the condition in which the blood pH is abnormally low Alkalosis is the condition in which the blood pH is abnormally high Normal

Explain the Failure to Management of Ledge Apical transportation or perforation: movement of the physiological foramen to a new iatrogenic location. Three types of apical tr

Closed Heart Surgery Blind operations and access is obtained into the heart through incision on the ventricular or atrial wall. Commonest closed heart surgery done is m

Q Are there living beings without cells? Viruses are considered the only living beings that do not have cells. Viruses are constituted by genetic material RNA or DNA enwrapped

Illustrate the aqueous phase in sol processing In a sol possessing a continuous aqueous phase, the colloidal particles have an electrically charged surface.  The ionized groups