Cytoskeleton

Question 1

What are microtubules?

Answer 1

Made up of alpha- and beta-tubulin monomers linked up together forming a heterodimer subunit. Heterodimers come together to form a protofilament. 13 protofilaments will then form a microtubule

Function: cell division, cellular movement, intracellular transportation and structural support

Are dynamic as they are able to polymerize and depolymerize

Grow rapidly at the plus end

Question 2

What are microfilaments?

Answer 2

Made up of actin monomer subunits arranged in a long spiral chain

Function: cell division, cellular movement, intracellular transportation and structural support

More growth of actin filaments at the plus end

Question 3

What are intermediate filaments?

Answer 3

Made up of smaller strands in rods, 8 rods are aligned in a staggered array with another 8 rods, that twist together to form an intermediate filament

Less dynamic than actin filaments and microtubules

Function: mechanical support

Question 4

What are the functions of cytoskeleton? (Structural support)

Answer 4

Dynamic scaffold provide structural support that can determine the shape of the cell and resist forces that tends to it

Shape of many cells depends on the radial array of microtubules in the cytoplasm due to its rigidity

Shape of microvilli is supported by actin filaments

Question 5

What are the functions of cytoskeleton? (Intracellular transportation)

Answer 5

Microtubulues and actin filaments serve as a network of highways for the transportation of organelles and vesicles within/out of the cell

Motor proteins (kinesin and dynein) require ATP to transport organelles and vesicles along microtubules

Motor proteins (Myosin Va and Myosin VI) require ATP to transport organelles and vesicles along actin filaments

Question 6

What are the functions of cytoskeleton? (Cellular movement)

Answer 6

By cillia or flagella –> both are composed of microtubules

Cell moves by the formation of lamellipodia and filopodia that extend beyond the leading edge of lamellipodia

Involves the polymerization and depolymerization of actin filaments at the plasma membrane

Question 7

What are the functions of cytoskeleton? (Cell division)

Answer 7

Mitotic spindle is formed by microtubules (prophase)

Contractile ring is formed by actin filaments (cytokinesis)

Question 8

What are the functions of cytoskeleton? (mechanical stability)

Answer 8

Intermediate filaments are able to stretch to help resist tension, providing mechanical support to cells