Cell Organelles: Cytoskeleton Structure and Function

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What is the primary function of microtubules in the cytoskeleton?

Intracellular transportation (correct)
Muscle contraction
Providing structural support to the nucleus
Maintaining the shape of the cell

What is the diameter of intermediate filaments?

10 nm (correct)
50 nm
25 nm
5-9 nm

What type of protein subunits make up microfilaments?

Lamins
Keratins
Actin (correct)
Tubulin

What is the structural role of intermediate filaments in the cell?

Providing structural support to specific tissues (C) Signup and view all the answers

What is the composition of microtubules?

Heterodimers of alpha and beta tubulin (D) Signup and view all the answers

What is the function of motor proteins in the cytoskeleton?

Transporting materials and organelles (B) Signup and view all the answers

What is the primary function of microfilaments in skeletal muscles?

To integrate with thick myosin filaments for contraction (B) Signup and view all the answers

What is the characteristic feature of intermediate filaments in epithelial tissues?

They are composed of cytokeratins (B) Signup and view all the answers

Which type of filament is involved in the movement of vesicles and granules in the cytoplasm?

Microfilaments (C) Signup and view all the answers

What is the role of microfilaments in the process of cytokinesis?

To form a 'purse-string' ring of filaments (B) Signup and view all the answers

Which type of intermediate filament is characteristic of glial cells?

Glial Fibrillary Acidic Proteins (GFAP) (D) Signup and view all the answers

What is the clinical significance of finding intermediate filaments from cell A in cell B?

It indicates the presence of a tumor (B) Signup and view all the answers

What is the primary function of kinesins and dyneins in cells?

To facilitate the transport of organelles and vesicles (A) Signup and view all the answers

What is the composition of the central sheath in cilia and flagella?

2 microtubules bound to peripheral microtubules by radial spoke proteins (C) Signup and view all the answers

What is the function of centrioles in non-dividing cells?

To serve as a site for microtubule nucleation and organization (A) Signup and view all the answers

What is the primary function of microtubules in the mitotic spindle?

To align and separate chromosomes during cell division (A) Signup and view all the answers

What is the characteristic feature of microtubules in cilia and flagella?

9-double microtubules with dynein (B) Signup and view all the answers

What is the function of radial spoke proteins in cilia and flagella?

To bind peripheral microtubules to the central sheath (A) Signup and view all the answers

What is the characteristic of microfilaments?

They are composed of actin filaments and have structural roles (D) Signup and view all the answers

What is the primary function of intermediate filaments?

To provide mechanical support and stability to the cell (D) Signup and view all the answers

What is the characteristic of inclusions?

They are not considered organelles and are not enclosed by a membrane (A) Signup and view all the answers

What are glycogen granules?

Aggregates of a carbohydrate polymer (A) Signup and view all the answers

What is the characteristic of pigmented granules?

They are stable in non-dividing cells (A) Signup and view all the answers

What are fat droplets?

Accumulations of lipid molecules (B) Signup and view all the answers

What is the primary function of proteasomes in the cell?

To degrade non-functional polypeptides and denatured proteins (A) Signup and view all the answers

What is required for the proteasome degradation function to occur?

Ubiquitin (B) Signup and view all the answers

What is the outcome of proteasome degradation?

Release of resulting peptides that can be reused by the cell (C) Signup and view all the answers

What is the primary function of peroxisomes?

Fatty acid oxidation (C) Signup and view all the answers

How do proteins get internalized by peroxisomes?

Through a signal sequence (C) Signup and view all the answers

What is a byproduct of peroxisomal oxidation reactions?

H2O2 (A) Signup and view all the answers

What is the role of catalase in peroxisomes?

To break down H2O2 (B) Signup and view all the answers

What is the role of peroxisomes in lipid metabolism?

To break down fatty acids (A) Signup and view all the answers

What is the diameter of peroxisomes?

0.5 µm (B) Signup and view all the answers

Where are peroxisomal enzymes synthesized?

In free cytosolic polyribosomes (D) Signup and view all the answers

What is the main function of lysosomes in cellular processes?

To recycle old or damaged organelles and digest food particles (C) Signup and view all the answers

What is the characteristic of proteasomes that distinguishes them from lysosomes?

Their non-membranous structure (A) Signup and view all the answers

What is the fate of residual bodies in certain cell types?

They are converted into lipofuscin granules (B) Signup and view all the answers

What is the function of hydrolytic enzymes in lysosomes?

To break down and digest bulk materials (A) Signup and view all the answers

What is the characteristic of lysosomes in macrophages and neutrophils?

They are larger in diameter (D) Signup and view all the answers

What is the result of the fusion of phagosomes and lysosomes?

The formation of secondary lysosomes (C) Signup and view all the answers