Keratins, neurofilaments, and vimentins are all categories of intermediate filaments. Which of the following properties is not true of these types of intermediate filaments?
(a) They strengthen cells against mechanical stress.
(b) Dimers associate by noncovalent bonding to form a tetramer.
(c) They are found in the cytoplasm.
(d) Phosphorylation causes disassembly during every mitotic cycle.
Choice (d) is untrue. Keratins, neurofilaments, and vimentins are cytoplasmic intermediate filaments [choice (c)], which tend to be very stable once formed. The nuclear intermediate filaments are disassembled and reformed during mitosis; this process is regulated by phosphorylation.
You might also like to view...
A calorie is the commonly used unit of chemical energy. It is also the unit of
A. light. B. magnetism. C. sound. D. heat. E. radioactivity.
A researcher isolates a species of fungus that only reproduces sexually. He introduces individual fungi—all of the same mating type (e.g., with the same mating type alleles)—into a petri dish. What do you expect will happen with the fungi in this dish?
A. Fungi in the dish will mate, forming spores via sexual reproduction. B. Fungi in the dish will not mate, but will from spores via asexual reproduction. C. No spores will be formed by fungi in the petri dish.
Surgical removal of the pancreas would
A. increase the acidity of the small intestine. B. prevent the production of chyme in the stomach. C. eliminate the ability to store bile in the gallbladder. D. block the secretion of bile. E. All of these changes would be a result of pancreas removal.
Intervertebral discs are absent between these vertebrae.
What will be an ideal response?