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Question 564
Biochemistry → General
Classification
Question
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A cytoskeletal element is 4–12 nm in diameter, non-tubular and composed of contractile proteins. Which additional finding is expected?
Question Stem
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Options
A
Tubulin is its predominant protein
B
It forms mitochondrial cristae
C
Actin is more abundant than myosin
D
It is restricted to the region around the nucleus
E
It contains rRNA as its major component
Explanation
Microfilaments are long, fine, thread-like, non-tubular cytoskeletal structures measuring approximately 4–12 nm in diameter. They contain the contractile proteins actin and myosin, with actin being more abundant, and are distributed throughout the cytoplasm.
Option Validity
A) Tubulin forms microtubules.
B) Cristae are folds of the inner mitochondrial membrane.
D) Microfilaments are described throughout the cytoplasm rather than being restricted to the perinuclear region.
E) rRNA is a component of ribosomes rather than microfilaments.
Further Reading
Saxena R. Textbook for MRCOG-1: Basic Sciences in Obstetrics & Gynaecology. Chapter 4 — Cytoskeleton: Microfilaments. Printed page 128.