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
Define Principle for Iodine Number Estimation - Lipids? Iodine number is defined as the number of grams of iodine absorbed by 100 grams of fat, it gives an idea of the relative

Define measuring body composition- Multiple isotope Dilution? Multiple isotope dilution (Total and extracellular body water): It is based on the principle that certain substanc

Q. What are the endocrine glands that regulate sexual activity in males? How does this regulation work and what are the involved hormones? In males the sexual activity is regul

State the purpose of a neuropsychological screening The purpose of a neuropsychological screening examination is to determine if there is reasonable evidence, beyond initial cl

Regeneration - Development Biology Regeneration has, intrigued scientists for several generations and has resulting in voluminous literature on the subject beginning from the

Conventions for using binomial nomenclature The names of higher categories are often synthesized from Latin words in the same manner as generic or specific names, and always s

Two atoms always represent the same element if they have. A) the same number of particles in the nucleus. B) The same number of electrons. C) The same number of shells. D) The same

Explain Diet history and nutrient intake Diet history  and  nutrient intake : This  is used  to evaluate diet for nutrient or food intake. Common methods used include the 24-h

Q. Concerning their biological function what is the difference between meiosis and mitosis? The main biological function of mitosis is cellular multiplication a fundamental pro

Explain the Uses of ISO in Cereal products  Cereal products  ISP is sometimes used instead of, or in mixture with isolates and soy flour, in the formulation of milk replac