Question

All of the following statements are true EXCEPT:

a. Intermediate filaments are a heterogeneous group of proteins with a central helix flanked by globular domains
b. Intermediate filaments assemble by several mechanisms that do not include nucleotide hydrolysis
c. Intermediate filaments resist tensile forces
d. Intermediate filaments are not found in neurons (due to their requirement for rapid axonal signaling)
e. Assembly and disassembly of intermediate filaments are controlled by phosphorylation and dephosphorylation

Answer 1

The statement that d)intermediate filaments are not found in neurons is incorrect; they exist as neurofilaments that support neuronal structure without impeding rapid signaling.

Step-by-step explanation:

The question is centered on intermediate filaments, an essential component of the cytoskeleton responsible for maintaining cell structure and bearing tension. These filaments are comprised of fibrous proteins like keratin and provide mechanical support by resisting tensile forces and anchoring cellular structures such as organelles and the nucleus. They differ from microfilaments and microtubules in that their assembly and disassembly involve processes such as phosphorylation but do not require nucleotide hydrolysis.

Upon evaluating the statements provided, it is statement d that is incorrect. Intermediate filaments are indeed found in neurons; in particular, the type known as neurofilaments are present in the axons of neurons, where they help maintain axonal caliber and facilitate electrical conduction. Their presence does not hinder the requirement for rapid axonal signaling but rather supports the neuron's structure.