Body Structure of Amoeba - QS Study
QS Study

Amoeba appears as a colourless and transparent drop of jelly when viewed under a microscope. It lacks a definite body shape because it changes its shape by producing the pseudopodia every moment. So, it is not possible to describe its definite shape, anterior or posterior ends, dorsal and ventral surfaces. Moreover, as Amoeba’s shape is changeable, its body cannot be divided into two similar parts. This condition is called ,asymmetry. In size, a full grown Amoeba generally may be from 1/20 mm to. 1 mm. The body of Amoeba can be divided into two main parts, Plasmalema and Protoplasm.

A. Plasmalema or Plasma membrane: The body of Amoeba is covered with plasmalema formed by the combination of protein and lipid. This membrane is extremely thin, living, semi-permeable and elastic.

Functions:

  • Plasmalema of Amoeba gives its shape.
  • It holds the various organelles inside the protoplasm.
  • The membrane being elastic it can produce pseudopodia easily.
  • By the process of diffusion, through the plasmalema it takes oxygen and water. It also discharges carbon dioxide and excretory materials through the membrane.
  • It helps the Amoeba to become attached to any solid surface.

B. Protoplasm: The thick jelly like substance surrounded by the plasmalema is the protoplasm. It can be divided into two parts, Cytoplasm and Nucleus.

i. Cytoplasm: Without the nucleus, the rest of the protoplasm is cytoplasm. It is divisible into two parts, such as Ectoplasm and Endoplasm.

Ectoplasm: The part of cytoplasm immediately behind the plasma membrane is known as ectoplasm. This part is thick, transparent, non-granular and contractile.

Functions:

  1. Ectoplasm protects the organelles inside the body.
  2. It helps to maintain the shape of the body.
  3. It assists the Amoeba in producing pseudopodia

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ii. Endoplasm: The granular portion of cytoplasm which is surrounded by the ectoplasm is known as the endoplasm. This part is semi transparent and less viscous. The relatively thick outer part of endoplasm is called plasmagel and inner liquid part plasmasol. The granules of plasmagel generally always remain stable. But the granules present in plasmasol show active movement. The difference between plasmagel and plasmasol is .not consistent because one can be transformed to other.

Functions:

  1. Endoplasm contains the organelles of the cell,
  2. It assists in various physiological functions.
  3. Frequent change in the density of the plasmagel and plasmasol helps in producing pseudopodia.