Cell Biology Questions and Answers – Cytoskeleton – Intermediate Filaments

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This set of Cell Biology Multiple Choice Questions & Answers (MCQs) focuses on “Cytoskeleton – Intermediate Filaments”.

1. Intermediate filaments are branched structures.
a) True
b) False
View Answer

Answer: b
Explanation: Intermediate filaments are strong, flexible, unbranched structures, found only in animal cells. These provide mechanical strength to the cells.
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2. Intermediate filaments are _________________
a) heterogenous
b) homogenous
c) labile
d) weak
View Answer

Answer: a
Explanation: Unlike microfilaments and microtubules, intermediate filaments are chemically heterogenous, encoded by 70 different types of genes.

3. How many types of polypeptides are found in intermediate filaments?
a) 2
b) 5
c) 10
d) 12
View Answer

Answer: b
Explanation: Depending upon the cell type, intermediate filaments are composed of different polypeptide subunits. The polypeptide subunits found in intermediate filaments are divided into 5 major subclasses.

4. The type V intermediate filaments are called ___________
a) lamins
b) collagen
c) lignin
d) fibrin
View Answer

Answer: a
Explanation: Classes I, II, III and IV of polypeptide subunits of intermediate filaments are involved in the construction of cytoplasmic filaments. Class V, called lamins, are present as a part of inner lining of the nucleus.

5. Plectins are _____________
a) filaments
b) proteins
c) peripheral organelles
d) fibres
View Answer

Answer: b
Explanation: Intermediate filaments radiate through the cytoplasm of a cell and are interconnected to other cytoskeletal elements through cross-bridges. In most cells, these cross-bridges are made up of plectins.
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6. Unlike other cytoskeletal elements, in the assembly of intermediate filaments there is no requirement of ______________
a) ATP/ GDP
b) Nucleation
c) Reduction
d) Hydrolysis
View Answer

Answer: a
Explanation: Unlike microtubules and microfilaments, in the assembly steps of intermediate filaments there is no direct involvement of ATP or GDP.

7. Intermediate filaments lack polarity.
a) True
b) False
View Answer

Answer: a
Explanation: Unlike microtubules and microfilaments, intermediate filaments lack polarity and bothe the ends of the filaments are same in nature.

8. Intermediate filaments tend to be less sensitive to __________________
a) chemicals
b) plectins
c) acidification
d) condensation
View Answer

Answer: a
Explanation: Intermediate filaments are less sensitive to chemical agents and difficult to solubilize them, although they behave dynamically in vivo.

9. Which is a type of intermediate filament found in epithelial cells?
a) keratin
b) dynein
c) myosin
d) kinesin
View Answer

Answer: a
Explanation: Keratin filaments are found primary in epithelial cells including epidermal cells, liver hepatocytes and pancreatic acinar cells.
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10. Neurofilaments are the type _____ intermediate filaments.
a) I
b) II
c) III
d) IV
View Answer

Answer: d
Explanation: Neurofilaments consist of type IV polypeptide subunits of intermediate filaments. Neurofilaments are present in mature nerve cells.

11. Absence of the intermediate filament desmin, has a negative impact on _______________
a) hepatocytes
b) nerve cells
c) epithelial cells
d) muscle cells
View Answer

Answer: d
Explanation: Absence of intermediate filaments desmins makes the muscle cells extremely fragile. Desmin polypeptide plays a key role in maintaining the alignment of myofibrils of the muscle cells.

12. Vimentin is a ___________
a) intermediate filament
b) inherited disorder
c) neurodegenerative disease
d) microfilament
View Answer

Answer: a
Explanation: Vimentin is a type III intermediate filament, found in macrophages, fibroblasts, white blood cells. Deficiency of gene expressing vimentin leads to minor abnormalities.

13. ‘Epidermolysis bullosa simplex’ is caused by the deficiency of ____________ polypeptide.
a) myosin
b) keratin
c) kinesin
d) niacin
View Answer

Answer: b
Explanation: ‘Epidermolysis bullosa simplex’ is a genetic disorder that associated with extremely fragile skin that blisters easily. The disease is caused by mutations in the gene encoding K14, a type I keratin polypeptide.
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14. Aggregation of neurofilaments leads to ____________
a) vision disorders
b) skin disorders
c) lung disorders
d) neurodegenerative disorders
View Answer

Answer: d
Explanation: Neurofilaments are the intermediate filaments that constitute mature neuronal cells. Aggregation of these neurofilaments blocks axonal transport, associated with neurodegenerative disorders like Alzheimer’s and Parkinson’s disease.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn