Amoeba proteus-class Sarcodina
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The amoeba proteus is in the class sarcodina and is a fresh water organism living in slow streams on the underside of leafy vegetation
What is the structure of the amoeba?
The amoeba is an eukaryotic cell havin an outer ectoplasm and an inner endoplasm which together make up cytoplasm. The amoeba has no definite shape.
Describe the mode of nutrition of the Amoeba proteus
First food is ingested by endocytosis and the digestive enzymes are poured into the food vacuole from the cytoplasm. The digestion of food WITHIN the food vacuole, INSIDE the cell cytoplasm is called INTRA-CELLULAR DIGESTION. Undigested food is egested from the cell by exocytosis. INGESTION/EGESTION is able to take place at any point on the plasmalemma/cell membrane of the cell.
Describe the mode of Respiration of the Amoeba proteus
It takes place by the process of simple diffusion. Oxygen moves from the outside of the cell to the inside of the cell, while Carbon dioxide moves from the inside of the cell to the outside. Both of gases move down a concentration gradient to high concentration to low concentration.
There is so special respitory structure for the uptake of oxygen and release of carbon dioxide.
Describe the process of excretion for the Amoeba proteus.
There is no special structure for excretion which also takes place by the process of diffusion. But note the presence of the contractile vacuole which function is osmo-regulation controlling the flow of water into the cell. During this process of osmo-regulation waste substances dissolved in the water are excreted at the same time that water is pumped out of the cell. This means the function of the contractile vacuole is secondary excretory.
N.B They live in water which is a hypo-osmotic medium. Water is moving from the inside of the cell to the outside.
Describe how the Amoeba proteus moves.
First it begins with the formation of a clear hyaline cap. Into the hyaline cap flows fluid endoplasm (plasmasol) or Cytoplasmic streaming. As the plasmsol flows forward, it is converted into plasmagel. Pseudopodium is then extended further in a definite direction by chemical processes.
Describe how the Amoeba proteus reproduce.
There is no sexual reproduction by the Amoeba proteus. A-sexual reproduction takes the form of binary fission. First is the division of the nucleus(caryokinesis) because it is the control centre of the cell. Nuclear division is then followed by cytoplasmic division(cytokinesis). After this process one amoeba divides into two seperate Amoebi.
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