Question

How many statements are incorrect amongst the following?

a. Microfilaments help in the formation of a cleavage furrow during cell division.
b. Microtubules present in the cytoplasm are highly liable.
c. The nuclear lamina is a network of acidic proteins and intermediate filaments.
d. Microtubules control the orientation of microfibrils in a cell wall.

• A. One
• B. Three
• C. Four
• D. Two
• E. None

Answer 1

Answer: (E)

None

• Animal cell cleavage furrow formation is caused by a ring of actin microfilaments called the contractile ring, which forms during early anaphase. During cellular cleavage, the contractile ring tightens around the cytoplasm of the cell until the cytoplasm is pinched into two daughter cells.
• Microtubules, the third principal component of the cytoskeleton, are rigid hollow rods approximately 25 nm in diameter. Like actin filaments, microtubules are dynamic structures that undergo continual assembly and disassembly within the cell. They function both to determine cell shape and in a variety of cell movements, including some forms of cell locomotion, the intracellular transport of organelles, and the separation of chromosomes during mitosis.
  
• The nuclear lamina is a dense (~30 to 100 nm thick) fibrillar network inside the nucleus of most cells. It is composed of intermediate filaments and membrane-associated proteins. Besides providing mechanical support, the nuclear lamina regulates important cellular events such as DNA replication and cell division.

So, the correct answer is 'None'.