Question

In Which of the following you would be able to see centrioles
(a) Motile algae
(b) All plant cells
(c) Animal cells
(d) Both (a) & (c)

Answer 1

Centrioles are paired barrel-shaped organelles located in the cytoplasm of certain Multicellular organisms near the nuclear envelope. Centrioles play a role in organizing microtubules that serve as the cell's skeletal system. They help determine the locations of the nucleus and other organelles within the cell.

Complete answer:
Centrioles are self-duplicating cylindrical cell organelles, found in all animal cells and in the cells of dinoflagellates, euglenoid flagellates, fungi, thallophytes, bryophytes, pteridophytes, and angiosperms. They are absent in prokaryotes, diatoms, yeasts, and gymnosperms. Plants do not have centrioles in them, but exceptions are there like algae. A cell may contain one or two of them. If two Centrioles are present in a cell, they are collectively called diplosome. In that case, they may be oriented at right angles to each other. In animal cells, Centrioles are actively associated with cell division and they participate in the formation of mitotic spindles. In flagellated and ciliated cells, they give rise to the kinetosome or basal body of cilia or flagella. Centrosome and centrosphere are visible only in non- dividing cells.

Additional Information:
- The position of Centrioles is different in different kind of cells, but constant for each type
- They may occupy a central, apical, or axial position within the cell. Centrioles are surrounded by a clear cytoplasmic area, called centrosome or microcentrum.
- It in turn is surrounded by a dense zone, called centrosphere, which contains fine fibrous materials. Centrioles are hollow cylinders open at both ends.
So, the correct answer is ‘Both (a) & (c) ’.

Note:
- Centrioles, centrosomes, and centrosphere collectively constitute the cell center or central body.
- Ribosomes, mitochondria, and plastids are absent in the cell center. Often Golgi bodies and mitochondria remain crowded around the centrosphere in the form of a ring.
- Centrosome and centrosphere are visible only in non- dividing cells. During cell division, they transform into the mitotic apparatus.