40 Questions
What is the primary function of microtubules in the cytoskeleton?
Intracellular transportation
What is the diameter of intermediate filaments?
10 nm
What type of protein subunits make up microfilaments?
Actin
What is the structural role of intermediate filaments in the cell?
Providing structural support to specific tissues
What is the composition of microtubules?
Heterodimers of alpha and beta tubulin
What is the function of motor proteins in the cytoskeleton?
Transporting materials and organelles
What is the primary function of microfilaments in skeletal muscles?
To integrate with thick myosin filaments for contraction
What is the characteristic feature of intermediate filaments in epithelial tissues?
They are composed of cytokeratins
Which type of filament is involved in the movement of vesicles and granules in the cytoplasm?
Microfilaments
What is the role of microfilaments in the process of cytokinesis?
To form a 'purse-string' ring of filaments
Which type of intermediate filament is characteristic of glial cells?
Glial Fibrillary Acidic Proteins (GFAP)
What is the clinical significance of finding intermediate filaments from cell A in cell B?
It indicates the presence of a tumor
What is the primary function of kinesins and dyneins in cells?
To facilitate the transport of organelles and vesicles
What is the composition of the central sheath in cilia and flagella?
2 microtubules bound to peripheral microtubules by radial spoke proteins
What is the function of centrioles in non-dividing cells?
To serve as a site for microtubule nucleation and organization
What is the primary function of microtubules in the mitotic spindle?
To align and separate chromosomes during cell division
What is the characteristic feature of microtubules in cilia and flagella?
9-double microtubules with dynein
What is the function of radial spoke proteins in cilia and flagella?
To bind peripheral microtubules to the central sheath
What is the characteristic of microfilaments?
They are composed of actin filaments and have structural roles
What is the primary function of intermediate filaments?
To provide mechanical support and stability to the cell
What is the characteristic of inclusions?
They are not considered organelles and are not enclosed by a membrane
What are glycogen granules?
Aggregates of a carbohydrate polymer
What is the characteristic of pigmented granules?
They are stable in non-dividing cells
What are fat droplets?
Accumulations of lipid molecules
What is the primary function of proteasomes in the cell?
To degrade non-functional polypeptides and denatured proteins
What is required for the proteasome degradation function to occur?
Ubiquitin
What is the outcome of proteasome degradation?
Release of resulting peptides that can be reused by the cell
What is the primary function of peroxisomes?
Fatty acid oxidation
How do proteins get internalized by peroxisomes?
Through a signal sequence
What is a byproduct of peroxisomal oxidation reactions?
H2O2
What is the role of catalase in peroxisomes?
To break down H2O2
What is the role of peroxisomes in lipid metabolism?
To break down fatty acids
What is the diameter of peroxisomes?
0.5 µm
Where are peroxisomal enzymes synthesized?
In free cytosolic polyribosomes
What is the main function of lysosomes in cellular processes?
To recycle old or damaged organelles and digest food particles
What is the characteristic of proteasomes that distinguishes them from lysosomes?
Their non-membranous structure
What is the fate of residual bodies in certain cell types?
They are converted into lipofuscin granules
What is the function of hydrolytic enzymes in lysosomes?
To break down and digest bulk materials
What is the characteristic of lysosomes in macrophages and neutrophils?
They are larger in diameter
What is the result of the fusion of phagosomes and lysosomes?
The formation of secondary lysosomes
Learn about the cytоскelеton, a non-membranous organelle that plays a crucial role in cell movement, shape, and organization of organelles and cytoplasmic vesicles. Discover its three types and functions.
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