Cell Biology Quiz

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Questions and Answers

What is the thickness of microtubules?

25 nm (correct)

100 nm

10 nm

50 nm

What are microtubules composed of?

Subunits of actin

Subunits of keratin

Subunits of globular protein tubulin (correct)

Subunits of collagen

How many protofilaments does a microtubule usually have?

13 (correct)

Which end of the microtubule is exposed to a-tubulin?

Minus end Signup and view all the answers

What does each tubulin monomer bind?

One molecule of GTP Signup and view all the answers

What drives the polymerization and depolymerization of microtubules?

Hydrolysis of GTP on B-tubulin monomer Signup and view all the answers

What is the role of y-tubulin in microtubules?

Involved in polymerization and organization Signup and view all the answers

What type of subunits are a-tubulin and B-tubulin?

Closely related units called a-tubulin and B-tubulin Signup and view all the answers

How does the length of microtubules change?

By adding or removing heterodimers Signup and view all the answers

What gives the microtubule structure polarity?

Organization of subunits pointing the same direction Signup and view all the answers

What is the result of myosin head hydrolyzing ATP to ADP and inorganic phosphate?

Release of energy Signup and view all the answers

What happens when the myosin head binds to actin?

Formation of a cross-bridge Signup and view all the answers

What are kinesins and dyneins involved in during interphase?

Transport and positioning of organelles and vesicles Signup and view all the answers

What is responsible for the movement of cilia and flagella?

Dynein Signup and view all the answers

What is the function of molecular motors in muscle contraction?

Formation of cross-bridges Signup and view all the answers

What occurs when the myosin head is in a low-energy configuration?

Release of energy Signup and view all the answers

What leads to the movement of the thin filament toward the center of the sarcomere?

Binding of myosin head to actin Signup and view all the answers

What is the primary result of the hydrolysis of ATP to ADP and inorganic phosphate?

Release of energy Signup and view all the answers

What is the role of kinesins and dyneins during cell division?

Movement of centrosomes and chromosomes Signup and view all the answers

What is the function of dynein in cellular processes?

Movement of cilia and flagella Signup and view all the answers

What is the role of GTP binding to α-tubulins in stabilizing microtubules?

It protects microtubules from fast disassembly Signup and view all the answers

What is the function of centrosomes in cell biology?

Anchoring the minus ends of microtubules in interphase Signup and view all the answers

What is the main difference between cilia and flagella?

Cilia are more numerous and shorter, while flagella are responsible for cell movement Signup and view all the answers

What is the primary function of molecular motors, such as kinesins and dyneins?

Transport cell structures within the cell Signup and view all the answers

What are the steps involved in motor movement associated with microtubules?

Filament binding, conformational change, filament release, and conformational relaxation Signup and view all the answers

What is the role of basal bodies in cell biology?

Involved in the formation of flagella and cilia, anchoring in the plasma membrane Signup and view all the answers

What determines the rate of microtubule polymerization?

The critical concentration of α-tubulin Signup and view all the answers

What is the function of microtubule-organizing centers (MTOCs) in cell biology?

Play a central role in microtubule nucleation and organization Signup and view all the answers

What is the primary function of centrosomes in cell division?

Play a role in spindle formation during cell division Signup and view all the answers

What is the consequence of concentrations of α-tubulin being below the critical concentration?

Depolymerization of microtubules Signup and view all the answers

Study Notes

Microtubules, Centrosomes, and Molecular Motors in Cell Biology

Microtubules exhibit dynamic instability with faster growth and shortening at the plus end, and slower growth and shortening at the minus end.
GTP binding to α-tubulins stabilizes microtubules, protecting them from fast disassembly, while GDP-tubulin at the minus end is more prone to depolymerization.
Microtubules can undergo rapid cycles of assembly and disassembly and treadmilling, where one end polymerizes while the other end disassembles.
The rate of microtubule polymerization depends on the critical concentration of α-tubulin, with concentrations above leading to polymerization and below leading to depolymerization.
Microtubule-organizing centers (MTOCs) play a central role in microtubule nucleation and organization, with centrosomes and basal bodies being key MTOCs.
Centrosomes, containing centrioles and pericentriolar material, anchor the minus ends of microtubules in interphase and play a role in spindle formation during cell division.
Basal bodies, formed from centrioles, are involved in the formation of flagella and cilia, containing nine triplets of microtubules and anchoring in the plasma membrane.
Cilia and flagella, hair-like cell appendages, are formed by microtubules and surrounded by a membrane, with cilia being more numerous and shorter, while flagella are responsible for cell movement.
Molecular motors, such as kinesins and dyneins, can change ATP energy into mechanical energy, bind to microtubules, and transport cell structures within the cell.
There are different types of molecular motors associated with microtubules and microfilaments, such as kinesins and dyneins for microtubules and myosins for microfilaments, each moving in different directions and carrying different cargo.
The motor movement consists of four steps: filament binding, conformational change, filament release, and conformational relaxation, allowing for the transport of cellular structures.
Molecular motors associated with microtubules, such as kinesins and dyneins, move in different directions and carry different cargo, while myosins associated with microfilaments also transport cargo within the cell.

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Description

Test your knowledge of microtubules, centrosomes, and molecular motors in cell biology with this quiz. Explore dynamic instability, microtubule nucleation, MTOCs, and the functions of centrosomes and basal bodies. Learn about the role of molecular motors like kinesins and dyneins in cell structure transport.