Question

The eukaryotic cytoskeleton

	A.	Anchors organelles
	B.	Provides structure and shape to the cell
	C.	Aids in cell movement
	D.	All of the above

Answer 1

all are correct

Answer 2

D. All the above

So there are primarily three different types of fibers in the cytoskeleton; microtubules, intermediate filaments and microfilaments.

Microtubules are constructed of the monomer tubulin and are anchored at their negative ends by the centriole (or basal body in the case of cilia and flagella). They are the largest and thickest of the cytoskeleton structures. They are, however, short lived structures that change constantly in an active cell. Microtubules function to move vesicles and organelles around in the cell (dynien and kinesin are needed). Vesicles destined for secretion from the cell utilize microtubules to travel to the plasma membrane.

Intermediate filaments don't serve a function in cell movement (unlike the other two). They are primarily the backbone of the cell. Intermediate filaments are constructed from keratin (there are many different types of keratin). They also provide structure for the nuclear lamina. They are called intermediate filaments because of their size (smaller than microtubules and bigger than microfilaments).

Microfilaments are thin and flexible fibers. They are the smallest and are made of actin. They are involved in cell movement (as in muscle cells; rich in actin) and phagocytosis (cellular eating). Depending on their construction they serve different functions. For example, if they are in a parallel formation they function in maintaining cellular structure, if they are in bundles, they contract the cell.

So, in short, two of the cytoskeletal fibers function in cellular motion (microtubules and microfilaments), whereas intermediate filaments function to maintain the integrity of the cell shape

Answer 3

D. all

Answer 4

Provides structure and shape to the cell

Answer 5

Provides structure and shape to the cell