ch.4 the cytoskeleton

Question 1

the cytoplasm of all eukaryotic cells is crisscrossed by a network of protein fibers that supports the shape of the cell and anchors organelles to fixed locations. This network is called the _________.

Answer 1

cytoskeleton

Question 2

eukaryotic cells may contain the following three types of cytoskeleton fibers:

Answer 2

1. actin filaments (sometimes called microfilaments
2. microtubules
3. intermediate filaments

Question 3

actin filaments

Answer 3

-each filament is composed of 2 protein chains loosely twined together like two strands of pearls (each pearl is the actin).
-7nm

Question 4

microtubules

Answer 4

-largest of the cytoskeleton elements (25nm)
-each composed of a ring of 13 protein protofilaments

Question 5

intermediate filaments

Answer 5

-most durable element of the cytoskeleton in animal cells is a system of tough, fibrous protein molecules twined together in an overlapping arrangement.
-8-10 nm

Question 6

centrioles

Answer 6

barrel-shaped organelles found in the cells of animals and most protists.
-they occur in pairs, usually located at right angles to each other near the nuclear membranes.

Question 7

four components are required to move material along microtubules:

Answer 7

1. a vesicle or organelle that is to be transported
2. a motor protein that provides the energy-driven motion
3. a connector molecule that connects the vesicle to the motor molecule
4. microtubules on which the vesicle will ride like a train on a rail.