Which of the following statements about actin is false?
(a) ATP hydrolysis decreases actin filament stability.
(b) Actin at the cell cortex helps govern the shape of the plasma membrane.
(c) Actin filaments are nucleated at the side of existing actin filaments in lamellipodia.
(d) The dynamic instability of actin filaments is important for cell movement.
(d) Dynamic instability is a phenomenon associated with microtubules and not actin. Actin disassembly and assembly are both important for cell movement. However, this differs from dynamic instability in that the growth of actin filaments occurs at the leading edge; this growth occurs in a directed fashion because of actin-binding proteins that promote the formation of new filaments at the leading edge. Actin-binding proteins that destabilize actin filaments promote actin disassembly away from the leading edge. The actin assembly and disassembly in moving cells differs from the stochastic growth and disassembly of the microtubules.
You might also like to view...
In most animals with digestive tract, digestion occurs in four successive steps and the material being
digested moves passively through the digestive tube.
Indicate whether the statement is true or false.________ is an evolutionary mechanism that favors the reproductive success of certain members of a population over others as a result of differences in anatomical, physiological, or behavioral traits they possess
Fill in the blank(s) with correct word
Which of the following describes a red pigment?
a. It can absorb the green wavelength. b. It cannot absorb the red wavelength. c. It cannot absorb the green wavelength. d. It can absorb the red wavelength.
During a fever, the __________ readjusts the set point of the body to a __________ temperature.
a. thyroid; lower b. hypothalamus; lower c. hypothalamus; higher d. pineal gland; higher e. adrenal glands; lower