Which of the following statements about the cytoskeleton is true

Question 1

Which of the following statements about the cytoskeleton is true?

1. Transport vesicles among the membranes of the endomembrane system produce the cytoskeleton.

2. Microfilaments are structurally rigid and resist compression, while microtubules resist tension (stretching).

3. Chemicals that block the assembly of the cytoskeleton would cause little effect on the cell’s metabolism.

4. The dynamic aspect of cytoskeletal function is made possible by the assembly and disassembly of a large number of complex proteins into larger aggregates.

5. Movement of cilia and flagella is the result of motor proteins causing microtubules to move relative to each other.

Question 2

Which of the following statements about the cytoskeleton is false?

(a) The cytoskeleton is made up of three types of protein filament.
(b) The bacterial cytoskeleton is important for cell division and DNA segregation.
(c) Protein monomers that are held together with covalent bonds form cytoskeletal filaments.
(d) The cytoskeleton of a cell can change in response to the environment.

Question 3

Which of the following statements about the cytoskeleton is correct? Choose all that apply.

a) Cytoskeletal elements are rigid, and once established are not easily changed.

b) The cytoskeleton is made of a mixture of protein and lipid.

c) The cytoskeleton is made of a mixture of protein and carbohydrates.

d) The cytoskeleton provides shape and support to eukaryotic cells, particularly animal cells.

e) The cytoskeleton forms the cell wall of plant cells.

f) Cytoskeletal elements can be found in the cytoplasm and in at least one organelle.

Answer to question 1

The answer is option (4) The dynamic aspect of cytoskeletal function is made possible by the assembly and disassembly of a large number of complex proteins into larger aggregates.

There are three types of the cytoskeleton: actin filaments (microfilament), microtubules, and intermediate filaments. Microfilaments are composed of actin protein subunits, microtubules are composed of tubulin proteins, and intermediate filaments are composed of fibrous polypeptides. For example, actin is the subunit protein to build up the microfilaments and the length of microfilaments is determined by the assembly and disassembly of these actin proteins.

  • Option (1) is incorrect because the transport vesicle does not produce a cytoskeleton. The cytoskeleton is made up of various proteins, such as actin, tubulin and fibrous polypeptide.
  • Option (2) is incorrect because the functions of the microfilament and microtubule are to help cell movement, maintain the cell shape and assist in moving stuff around within the cell. The resistance of compression and tension are the major functions of the extracellular matrix (ECM).
  • Option (3) is incorrect because the assembly blockage of the cytoskeleton leads to the cells being unable to move and divide.
  • Option (5) is incorrect because the movement of the cilia and flagella is the result of the motor proteins (dynein) reaching out to the neighboring one (another dynein) when ATP is present, thus resulting in the bending of the microtubules. So the microtubules don’t move by themselves. The movement of the cilia and flagella is caused by the movement of the motor proteins.

Answer to question 2

The FALSE statement is (c) protein monomers that are held together with covalent bonds form cytoskeletal filaments

The cytoskeleton filaments are composed of proteins as their monomeric units. These monomers interact through hydrophobic interactions between them. They also form other bonds that are weak. These monomers do not interact through covalent bonds.

  • Option (a) The cytoskeleton is made up of three types of protein filament is incorrect because there are three filaments in this structure the microfilament, microtubule, and intermediate filaments.
  • Option (b) The bacterial cytoskeleton is important for cell division and DNA segregation is incorrect because bacteria contain a cytoskeleton that helps cells divide and separate DNA molecules.
  • Option (d) The cytoskeleton of a cell that can change in response to the environment is incorrect because the filaments of the cytoskeleton have dynamic nature that changes based on the environment.

Answer to question 3

The following statements about the cytoskeleton are correct. (D) and (F)

The cytoskeleton does provide shape and support to different cells. The cytoskeleton is made up of various proteins but not other macromolecules. The cytoskeleton is very dynamics and changes pretty easily which is necessary as the cell navigates various environments. The cytoskeleton does not form the cell wall, but the cytoskeleton does act as a template for some cell walls. Finally the cytoskeleton is found in the cytoplasm and does make up a few organelles such as the flagella and cilia.

Leave a Comment