Question

What is the streaming movement? Explain it with the help of a diagram by giving an example.

Answer 1

Hint: The peripheral parts of the cytoplasm sometimes undergo movement in response to light. The movement of peripheral cytoplasm occurs to transport various materials from one part of the cell to another. The movements occur without causing any deformation of the cell wall structure.

Complete answer:
Streaming movement is referred to the cytoplasmic movement under the force of cytoskeleton. It is believed to take place in larger cells and help in efficient transport of molecules from one part of the cell to another.
Cytoplasmic streaming is primarily of two types – Rotation and Circulation. In rotation, the peripheral cytoplasm moves around a vacuole. The movement can be anticlockwise or clockwise. Circulation, on the other hand, is the movement of cytoplasm around two or more vacuoles.
Cytoplasmic streaming is known to be affected by pH, temperature and exposure to light. The streaming movement is highest at neutral pH.
Cytoplasmic streaming in plant cells is best observed under electron microscope. The movement takes place around a central vacuole. The movement is depicted by the movement of chloroplasts along with the cytoplasm. The streaming movement is believed to be carried out with the help of movable proteins or motor proteins composed of actin filaments. The cellular organelles are attached to myosin molecules. These molecules move along the actin filaments dragging the organelles along with it. This kind of streaming is known as Rotation streaming and it takes place in Chara corallina.

Note: Cytoplasmic Streaming refers to the movement of the peripheral cytoplasm. It occurs in plants like Chara corallina in response to light and is known to increase the efficiency of photosynthesis in the plants. Streaming is also associated with enhanced transport of nutrients which results in better overall growth of the plant. The process also occurs in animal cells during cell division in order to keep the nucleus in the centre position of the cell.