Long, cylindrical, hollow and unbranched organelles present in the cytoplasm of cells are called microtubules. In 1953, Robert and Franchi discovered it from animal nerve cells. In 1953, scientists Ledbetter and Porter first observed their location in plant cells.
Microtubules are the sub-structural components of flagella and cilia. It is attached to the centromere of the chromosome. Spindle fibers contain microtubules. It is present in centriole and basal body.
Microtubules are long, cylindrical and hollow organelles. Its diameter is 10-20 mm and length is few microns. One end of them is marked as ‘+’ and the other end as ‘-‘. Each microtubule contains 13 prototubules. Each prototubule is composed of dimeric proteins. Each dimeric protein molecule consists of α and β ubulin.
Functions/importance of microtubules
- Microtubules provide cell shape and mechanical strength.
- It plays the role of cytoskeleton.
- It forms the circulatory system or transport system of the cytoplasm.
- Assists in cellular movement.
- It acts as spindle fibers during cell division.
- Helps in opposite pole movement of chromosomes.
- Helps in cell wall formation.
- Helps in the formation and movement of cilia and flagella.
- Centrioles form in animal cells.
- It binds to the cell membrane and nuclear membrane to maintain biological connections.
- It helps in the secretion of essential substances.
- It helps in the transmission of nerve impulses between nerve cells.
- It indicates the arrangement of microfibrils.
- It helps in communication and transportation.