Centrosome and Centrioles– Class 11 | Chapter – 8 | Short Notes Series PDF

Centrosome and Centrioles: Centriole in the centrosome is involved in the formation of spindle apparatus during the cell division. The centriole is made up of tubulin proteins assembled in a cylinder like a cartwheel structure. The mother and the daughter centrioles come together to form the centrosome. The centrosome is responsible for the formation of the spindle apparatus during the cell division. The main difference between centriole and centrosome is that centriole is the microtubule unit which forms the centrosome whereas centrosome is an organelle in the cytoplasm which is made up of two centrioles.

Centrosome and Centrioles

Centrioles

A centriole is a cylindrical structure, assembled of two centrioles – mother and daughter centrioles – in an orthogonal manner to form the centrosome. A centriole is made up of nine triplet microtubules assembled in a cylinder-like structure. Centrin, cenexin and tektin are the types of microtubules which are arranged in this cylindrical structure to form the centrioles. Centrioles form aster during the interphase and spindle apparatus during cell division.

Structure
1. A centriole is a small set of microtubules arranged in a specific way.
2. There are nine groups of microtubules.
3. When two centrioles are found next to each other, they are usually at right angles.
4. The centrioles are found in pairs and move towards the poles (opposite ends) of the nucleus when it is time for cell division.

Functions
1. They help in cell division by forming microtubule-organising centres.
2. Centrioles can be transformed into basal bodies.
3. Basal bodies from the centrioles gives rise to cilia and flagella.

Centrosome

A centrosome is an organelle which serves as the organizing center of all microtubules in the animal cell. It is composed of two centrioles arranged in an orthogonal manner. The two centrioles are surrounded by pericentriolar material (PCM). The PCM is an amorphous mass, anchoring microtubules by microtubule nucleation. The anchoring microtubule types are γ-tubulina, ninein, and pericentrin. Centrosomes are only involved in the metazoan lineage of eukaryotes. Thus, plant and fungal cells lack centrosomes. Plant cell spindle is formed independently, without the control of centrosomes.

Characteristics
1. A region surrounding centrioles, located near nucleus
2. Contains one or two centrioles
3. Centrioles are surrounded by microtubules

Functions
1. Initiates and regulates cell division
2. Forms spindle fibres, with the help of asters

 


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By Team Learning Mantras