Cellular Transport and Microtubule Structure Quiz

What is the main component of the cell cortex in erythrocytes?

Actin
Ankyrin
Glycophorin
Spectrin (correct)

Which protein links the two-dimensional web of spectrin to the plasma membrane?

Ankyrin (correct)
Glycophorin
Actin
Band 3

What is the function of spectrin in erythrocytes?

Synthesizing proteins
Acting as enzymes
Determining cell flexibility and shape (correct)
Carrying oxygen

Mutations in genes coding for proteins in the erythrocyte cell cortex have been linked to which condition?

Hemolytic anemia (A) Signup and view all the answers

Which transmembrane proteins are bound to peripheral membrane proteins in the erythrocyte cell cortex?

Glycophorin and Band 3 (D) Signup and view all the answers

What is the primary function of microvilli?

To increase the surface area available for absorption (D) Signup and view all the answers

Which of the following statements about microvilli is incorrect?

They possess intrinsic movement capacity (C) Signup and view all the answers

What is the primary function of stereocilia?

To detect and sense fluid motion (B) Signup and view all the answers

Which of the following statements about intermediate filaments is correct?

They are highly stable polymers of fibrous proteins (A) Signup and view all the answers

What would happen if myosin II is inhibited during mitosis?

The cell would become multinucleated (C) Signup and view all the answers

Which of the following statements about the functions of actin filaments, myosin I, villin, and fimbrin is correct?

They are involved in the formation of microvilli (C) Signup and view all the answers

Which statement about microtubule structure is correct?

Microtubules are composed of 13 protofilaments, each formed by alternating α-tubulin and β-tubulin subunits. (B) Signup and view all the answers

Which statement correctly describes the dynamic instability of microtubules?

Dynamic instability refers to the continuous assembly and disassembly of microtubules, resulting in their growth and shrinkage. (D) Signup and view all the answers

Which of the following statements about tubulin is true?

Tubulin, along with histones, are among the most evolutionary conserved proteins across animal species. (B) Signup and view all the answers

Which of the following cellular structures are composed of stable microtubules?

Cilia, flagella, and centrioles (C) Signup and view all the answers

What is the primary function of unstable microtubules in cells?

Mediating changes in cell shape and organelle movements (A) Signup and view all the answers

Which of the following statements accurately describes the polarity of microtubules?

The polarity of microtubules arises from the alternating arrangement of α-tubulin and β-tubulin subunits within each protofilament. (D) Signup and view all the answers

Which statement best describes the behavior of microtubules (MTs) with bound GDP-tubulin?

They depolymerize rapidly and can disappear within 1 minute. (D) Signup and view all the answers

At high concentrations of non-polymerized GTP-tubulin, what is the relationship between the rate of tubulin assembly and the rate of GTP hydrolysis?

The rate of tubulin assembly is faster than the rate of GTP hydrolysis. (D) Signup and view all the answers

What happens when the rate of tubulin assembly decreases and the GTP hydrolysis rate is higher at low concentrations of non-polymerized GTP-tubulin?

An unstable GDP cap is formed, the protofilaments spring apart, and the MT shortens. (A) Signup and view all the answers

Which statement accurately describes the polymerization rates at the different ends of a microtubule?

The polymerization rate at the (+) end is 2-3 times higher than at the (-) end. (C) Signup and view all the answers

What is the Critical Tubulin Concentration (Cc) and how does it affect microtubule growth or shrinkage?

Cc is the concentration at which microtubule length is constant. If the tubulin dimer concentration is higher than Cc, the microtubule will grow. If it is lower than Cc, the microtubule will shrink. (A) Signup and view all the answers

What factors influence the concentration of tubulin in the cytoplasm?

The rate of tubulin synthesis and degradation, as well as polymerization and depolymerization events. (D) Signup and view all the answers

Which of the following best describes the role of the nuclear lamina?

It provides structural support and strengthens the nuclear envelope. (D) Signup and view all the answers

What happens to the nuclear lamina intermediate filaments during mitosis?

They disassemble in a tightly regulated process during the initial stages. (D) Signup and view all the answers

Which of the following best describes the role of plectin in relation to intermediate filaments?

It cross-links intermediate filaments to increase resistance and binds them to other cytoskeletal structures. (B) Signup and view all the answers

Which of the following human disorders is associated with mutations in keratin genes, leading to fragile cells in the epidermis?

Epidermolysis Bullosa Simplex (A) Signup and view all the answers

What is the primary function of intermediate filaments in the context of the nuclear lamina?

To provide structural support and resistance to the nuclear envelope. (D) Signup and view all the answers

During which stage of the cell cycle does the nuclear lamina re-assemble?

At the end of mitosis (C) Signup and view all the answers