Question

What is a cyclosis?
A) The circular movement of cytoplasm inside the cell
B) Up and down movement of protoplasm
C) To and fro movement of nucleoplasm
D) None of the above

Answer 1

Hint: The process is related to the flow of cytoplasm within a cell to maintain a steady stream due to the presence of the motor proteins.

Complete Answer:
Cyclosis also is known as cytoplasmic streaming or protoplasmic streaming is the flow inside the cytoplasm. It is observed generally in large plant and animal cells. Here, the cytoplasm is not at rest, it is continuously moving inside the cell in a circular direction.

Additional information:
-The cytoplasm flow occurs to speed up the transport of molecules and organelles around the cell.
-The force applied in the flowing of the cytoplasm is from the cytoskeleton.
-The cytoskeleton is the small network of protein filaments and tubules present in the cytoplasm of the cells.
-The cytoskeleton gives shape to the cell and attaches various cell organelles.
-In smaller cells, the molecules will be able to diffuse rapidly, this does not require cytoplasmic streaming but in the case of larger cells, the rate of diffusion becomes lower which requires cytoplasmic streaming for the movement of the nutrients.
-The cytoplasmic streaming has been studied in the genus Chara of the green algae having very large cells up to 10 cm in length.

So, the correct answer is ‘Circular movement of cytoplasm inside the cell'.

Note: Cyclosis was first discovered in 1830. It depends upon the pH and temperature in the cell. The chloroplast of the plant cell also moves around the cells in a circular stream to get a position of optimum light absorption for photosynthesis. The cytoplasmic streaming is highest at the neutral pH but it decreases at both high and low pH.