Exam 14: The Cytoskeleton and Cell Movement

When a striated muscle is stimulated to contract, calcium is released primarily from the _______ and interacts with a group of three thin-filament proteins called _______, which in turn cause the long, thin protein _______ to move away from the cross-bridge binding sites on the _______ molecules. This allows the cross-bridge cycle to occur.

What is one way in which the more rapid growth of actin filaments at one end of the cell (the plus end) compared to the other end (the minus end) is advantageous to the cell?

Dynein and kinesin are similar in that they consist of heavy chains with globular heads that bind both _______ and _______.

What is the polarity of microtubule assembly in an axon of a nerve?

Why might colchicine, a tubulin-binding drug, be used to treat cancer?

A centrosome is

What is a sarcomere? (Include the structures that bound it in your definition.)

Which of the following is not one of the functions of the cytoskeleton?

Describe the genetic defect that causes Duchenne's and Becker's muscular dystrophy and the molecular processes that characterize the diseases.

In cells, actin filaments form a network that provides mechanical support, determines cell shape, and allows for movement of the cell surface.

Like myosins, kinesins and dyneins are both families of proteins. Which statement is true of all kinesins and dyneins?

Each monomer of actin binds one molecule of the nucleotide triphosphate

The basis for muscle contraction is the

Kinesin I is a motor protein molecule consisting of

Which movement is not based on actin-myosin interactions?

One approach to testing whether keratin intermediate filaments are dynamic is to inject biotin-labeled keratin into living fibroblasts and then to compare, at different times, the distribution of biotin-labeled keratin with that of endogenous keratin intermediate filaments. Assuming that keratin intermediate filaments turn over dynamically with a half-time of one hour, predict the comparative distribution of biotin-labeled keratin and keratin intermediate filaments 10 minutes and four hours after microinjection.

The intermediate filament protein _______ is the major protein of the human skin, hair, and fingernails. The most prominent secondary structure in this protein is the _______. The monomers of this protein associate first to form dimers and then are assembled into protofilaments, _______ (number) of which associate laterally to form an intermediate filament.

The desmin filaments in muscle cells connect

The discovery that the intermediate filament protein keratin is essential for mechanical strength of epithelial cell layers was made in

Intermediate filament proteins vary in size but share structural features. Describe these shared features.