NEET Notes: Centrosome, Centrioles & Microbodies

NEET Notes: Centrosome, Centrioles & Microbodies

Centrosome and centrioles are important cell organelles found mainly in animal cells. They play a key role in cell division and help in the formation of spindle fibers. These Class 11 Biology notes are based on NCERT and are useful for NEET preparation.

Centrosomes are organelles typically found in animal cells that help in cell division.

The Architecture of Centrioles: This diagram shows the perpendicular arrangement of centrioles and the characteristic "9+0" cartwheel pattern of microtubule triplets.

• Structure:

  • A centrosome contains two cylindrical structures called Centrioles.

  • They are surrounded by amorphous pericentriolar materials.

  • The two centrioles lie perpendicular (at 90°) to each other.

• The "9+0" Arrangement:

  • Unlike cilia/flagella, centrioles have no central microtubules.

  • They consist of 9 evenly spaced peripheral triplets of tubulin protein.

• Cartwheel Appearance: The central part of the centriole is proteinaceous and called the hub, which is connected to the peripheral triplets by radial spokes.

Functions of Centrosome (Important for NEET)

- Helps in formation of spindle fibres during cell division  

- Organizes microtubules in the cell  

- Forms basal body of cilia and flagella  

• Function:

1. Forms the basal body of cilia and flagella.

2. Forms spindle fibers that give rise to the spindle apparatus during cell division in animal cells.

Practice Quiz: Centrosome & Centrioles

Q1. The arrangement of microtubules in a centriole is described as: 

A) 9 + 2 arrangement 

B) 9 + 0 arrangement 

C) 4 + 4 arrangement 

D) 2 + 9 arrangement

Q2. In a centrosome, the two centrioles are typically oriented: 

A) Parallel to each other 

B) Perpendicular to each other 

C) At a 45-degree angle 

D) Randomly scattered

Q3. The central proteinaceous part of the centriole is called the: 

A) Spoke 

B) Hub 

C) Doublet 

D) Satellite

Q4. Which of the following organelles forms the basal body of cilia and flagella? 

A) Centriole 

B) Ribosome 

C) Golgi body 

D) Lysosome

Answer Key:

1-B, 2-B, 3-B, 4-A, 

Conclusion:

Centrosome and centrioles are essential for cell division and microtubule organization. Their unique 9+0 arrangement and role in spindle formation make them important topics for NEET and board exams.

⬅️ Previous 🏠 Index Next ➡️