RIMS Nursing Officer - 2022
Applied Physiology
Easy
Which of the following is called the main microtubule organizing centre (MTOC) in animal cells?
Appeared in: RIMS Nursing Officer - 2022
Explanation
- The centrosome is the primary microtubule-organizing center (MTOC) in animal cells, responsible for nucleating and anchoring the microtubule network.
- It is composed of two barrel-shaped centrioles arranged perpendicularly, surrounded by a protein matrix called the pericentriolar material (PCM).
- The PCM contains γ-tubulin ring complexes, which serve as the templates for the initiation (nucleation) of new microtubules.
- During cell division (mitosis), the centrosome duplicates, and the two resulting centrosomes migrate to opposite poles of the cell to form the mitotic spindle, which is essential for chromosome segregation.
Why Other Options Were Wrong
- Option A: Mitochondria are the 'powerhouses' of the cell, primarily responsible for generating ATP through cellular respiration. They do not organize microtubules.
- Option C: Ribosomes are cellular machines responsible for protein synthesis (translation). They are not involved in organizing the cytoskeleton.
- Option D: The Golgi apparatus (or Golgi bodies) modifies, sorts, and packages proteins and lipids for transport. While its location is influenced by the microtubule network, it does not organize it.
Related Visual
Clinical Relevance
- Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Function of cellular organelles, specifically the Microtubule Organizing Centre (MTOC) as background academic context rather than a clinical decision trigger.
- The central role of the centrosome and microtubules in cell division makes them a critical target for cancer chemotherapy.
- Drugs that interfere with microtubule dynamics, such as taxanes (e.g., Paclitaxel) and vinca alkaloids (e.g., Vincristine), disrupt the formation of the mitotic spindle, leading to cell cycle arrest and apoptosis in rapidly dividing cancer cells.
- What if? If the question asked about the MTOC for cilia or flagella, the correct answer would be the basal body. The basal body is structurally similar to a centriole and anchors the microtubule-based axoneme of these motile structures.
How to Approach the Question
- First, identify the key phrase in the question: 'main microtubule organizing centre (MTOC)'.
- Recall the definition of an MTOC as the structure from which microtubules emerge and are organized.
- Systematically review the primary function of each organelle listed in the options.
- Eliminate Mitochondria (energy production), Ribosomes (protein synthesis), and Golgi bodies (protein modification and packaging) as their main roles do not involve organizing microtubules.
- Identify the Centrosome as the organelle whose primary function includes organizing the cytoskeleton and forming the mitotic spindle, which directly aligns with the definition of an MTOC.
- Therefore, the Centrosome is the correct answer.
Concept Tested & Keywords
- Concept Tested: Function of cellular organelles, specifically the Microtubule Organizing Centre (MTOC).
- Stem keywords: microtubule organizing centre, MTOC, animal cells
- Lead-in keywords: Which of the following
- Negative lead-in flag: false
Question ID
Qgf34ZB4lcwUSNRHJ9PeAy
Reference Book
E6 Anatomy Grays 43e Vol 1 Part 1 pp. 41-43, 42-44
E6 Pathology-Textbook of PATHOLOGYHarsh Mohan Part 1 (1-214) p. 48-50
Practise the full RIMS Nursing Officer - 2022
Attempt every question from this paper in a timed mock, then review the full solution for each one.
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