Question

The number of membranes that surround centriole structure is
A. 3
B. 0
C. 1
D. 2

Answer 1

Centrosomes are organelles of a cell. They are present in the cytoplasm of the cell. Centrosome comprises two centrioles that help the cell to divide. They are present in all eukaryotic cells, and absent in prokaryotes. The centrioles are cylindrical structures present freely in the cytoplasm.

Complete answer:
Centrioles are present in the cytoplasm of certain eukaryotes, but absent in prokaryotes. The centrioles are present in a region of the cytoplasm close to the cell nucleus. The region is called the centrosome. There are two centrioles present in the centrosome located at right angles to each other. Centrioles are composed of microtubules triplets arranged in a cylindrical form.
Centrosomes lack a limiting membrane or the genetic materials like DNA and RNA.

Hence, option (B) is correct.

Additional Information: Centrosomes were named by a German Zoologist Theodor Boveri. These organelles replicate during the process of cell division. Centrioles help the cells to divide. The specific role the centrioles is to form the spindle fibres during cell division.
Centrioles also play an important role in locomotive organs like cilia and flagella. Centrioles are known to play an important role in the formation of cilia and flagella. Apart from the formation, centrioles regulate the movement of these structures. As a result, centrioles help the animals to move efficiently.
In humans, centrioles of the sperm cells help to form the sperm flagella and aid movement of sperms. It is the sperm cells that contribute to the formation of the centrosome in the zygote.

Note: Centrosomes comprise centrioles and aster rays. They are located close to the nucleus of the cell. Centrioles are cylindrical structures composed of a protein called tubulin. Centrioles help in spindle fibre organization during mitosis and meiosis. They also help in formation of cilia and flagella.