Exam 9: The Cytoskeleton and Cell Motility

A new field of mechanical engineering that involves the development of tiny machines capable of performing specific activities in a submicroscopic world is called ________.

In what form are proteins and neurotransmitters usually transported down the axon of a nerve cell?

The current model for the nucleation of microtubules is that a helical array of gamma-tubulin subunit forms an open,ring-shaped template on which the first row of alphabeta-tubulin dimers assembles.How does this model account for the polarity of microtubules?

The peripheral doublets of the axoneme are connected to one another by a(n)________ composed of an elastic protein _______.

How do muscle cells become multinucleate?

If you were to fix a fish keratocyte and stain it with fluorescent antibodies for myosin II,where would you see the myosin II?

What is the minimum number of kinesin heads in contact with a microtubule at all times?

Which type of actin-binding protein is known to decrease cytoplasmic viscosity by breaking existing actin filaments into two or more pieces?

What part of the molecular motor kinesin is responsible for binding to the cargo to be hauled?

You inject radioactively labeled keratin subunits into cultured skin cells.What happens a few minutes later?

In a growing plant cell,cellulose microfibrils are oriented _______ the direction of cell growth.

A(n)________ motor,like muscle myosin (myosin II)and unlike myosin V,remains in contact with its track,in this case the thin filament,for only a small portion,less than 5 percent,of the overall cycle.

A shift in the concentration or activity of which type of proteins can cause a shift in the equilibrium between actin monomers and polymers?

What happens to the Z lines after contraction of the sarcomere?

Structures that move from the cell body of a neuron down the axon toward the neuron terminals are said to move in a(n)_________ direction.

Which of the following appears to be the most extensible?

What blocks the myosin-binding sites on actin thin filaments in a stimulated sarcomere?

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

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

Which of the following words best describes the structure of an actin filament?