Exam 9: The Cytoskeleton and Cell Motility

Nucleation of microtubules takes place rapidly inside a cell,where it occurs in association with a variety of specialized structures called _____________.

What motor is associated with microfilaments?

Which of the following is a function performed by the cytoskeleton?

_________ proteins are able to alter the three-dimensional organization of an actin filament population.

What end of a microtubule is associated with the centrosome?

The focal complexes that form near the leading edge of a motile cell exert traction force through their associated __________ and then typically disassemble as the cell moves forward or mature into larger,more contractile focal adhesions.

The protein Crescentin (CreS)has been implicated in regulating the shape of some bacterial cells and forms bundled filaments that give bacteria containing it a highly curved shape; it resembles __________.

An abnormally high level of _______ of the MAP protein tau is implicated in the development of strange,tangled filaments called _________ that have been seen in the brains of patients suffering from several fatal neurodegenerative diseases like Alzheimer's disease.

Why does an actin thin filament manage to move continuously during a contraction cycle?

Using a macrophage‐like cell line,researchers infected one set of petri dishes with wild‐type Listeria,and,as a negative control,infected another set with a Listeria mutant that was unable to enter cells.At specific time points,the cells were fixed and prepared for electron microscopy.Four hours after infection,they observed that many of the wild‐type Listeria in the cytoplasm ______________.

The sperm basal body becomes ______________.

What kind of cells seems to rely mostly on microfilaments for long-distance transport of cytoplasmic vesicles and organelles,probably due to the restricted microtubule distribution in these cells?

Fluorescence microscopy allows investigators to view things _________ of regular light microscopes.

Which of the following nonmuscle cell activities do not involve actin filaments often working in concert with myosin motors?

What seems to control the assembly and disassembly of intermediate filaments?

What is the name of the lightly staining areas at the outer edges of a sarcomere?

The microtubule wall is composed of globular proteins arranged in longitudinal rows called _________.

What protein is thought to act like a "molecular ruler" by regulating the number of actin monomers that are allowed to assemble into a thin filament?

An investigator couples a photoactivatable fluorescent compound to actin monomers and injects the labeled actin into live cells.She then allows the labeled actin to be incorporated into actin polymers in the cell.By shining light of a specific wavelength in a small rectangular‐shaped region of the lamellipod,she could turn on the fluorescence of the labeled actin and observe how the labeled filamentous actin behaved in motile cells.If she activates a region at the front of the lamellipod,what will she observe?

Which of the following does not describe the types of microfilament organization normally seen in cells?