Cell Biology: Microtubule Functions

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Questions and Answers

What is a primary function of microtubules in cells?

Synthesis of proteins

Production of ATP

Maintenance of cell shape (correct)

Transport of lipids

What happens when GTP is hydrolyzed faster than new tubulin subunits are added?

Microtubules elongate significantly

Microtubules stabilize and resist disassembly

Disassembly and shrinkage of microtubules occur (correct)

New organelles are formed

Which of the following moves along microtubules using globular heads?

Actin filaments

Myosin molecules

Intermediate filaments

Kinesins and dyneins (correct)

What role does taxol play in cancer treatment?

It inhibits microtubule disassembly Signup and view all the answers

Which process marks the initial stage of actin filament polymerization?

Nucleation Signup and view all the answers

What structural role do the actin filaments serve in a cell?

Supports and modifies cell morphology Signup and view all the answers

How do kinesins and dyneins differ in their function within the cell?

Kinesins move towards the plus end of microtubules, dyneins move towards the minus end Signup and view all the answers

What are the building blocks of microtubules?

Alpha and beta tubulin dimers Signup and view all the answers

What is a characteristic feature of intermediate filaments?

They maintain cell integrity and shape Signup and view all the answers

What structural feature do microtubules possess that influences their direction of movement?

Polarity (plus and minus ends) Signup and view all the answers

Which type of filament is responsible for muscle contraction and also plays a role in cell motility?

Actin filaments Signup and view all the answers

Which key protein assists in initiating microtubule assembly in the centrosome?

Gamma-tubulin Signup and view all the answers

What is the main function of enterocytes in the small intestine?

Absorbing nutrients Signup and view all the answers

How do myosin filaments interact with actin filaments?

By using ATP to produce movement Signup and view all the answers

Which characteristic of microtubules is critical for their function in cell motility?

Their dynamic instability Signup and view all the answers

What is an effect of drugs that target microtubules?

Stabilize the microtubule structure Signup and view all the answers

What triggers the contraction of actin and myosin filaments?

Calcium Signup and view all the answers

How do intermediate filaments contribute to cellular integrity?

By integrating into a mechanical network Signup and view all the answers

What is the mechanical response of intermediate filaments to low forces?

They stretch Signup and view all the answers

Which of the following describes the mechanical properties of microtubules?

They easily deform and are prone to rupture Signup and view all the answers

What is the role of proteins at the cell membrane concerning intermediate filaments?

They bind the filaments of neighboring cells Signup and view all the answers

Which cell type would most likely rely heavily on intermediate filaments for mechanical support?

Epithelial cells of the skin Signup and view all the answers

What interaction leads to the assembly of intermediate filaments?

Coiled coil interactions Signup and view all the answers

How do actin filaments compare to intermediate filaments in terms of mechanical robustness?

Actin filaments are less robust than intermediate filaments Signup and view all the answers

Study Notes

Microtubules

Microtubules maintain cell shape, facilitate cell motility via cilia or flagella, and assist in chromosome movement during cell division.
Organelles are also moved along microtubules, indicating their dynamic role in cellular organization.
Hydrolysis of GTP at the plus end of microtubules can lead to disassembly if new subunits are not added quickly enough, forming GDP-bound tubulin.
Microtubules grow from organizing centers like centrosomes and mitotic spindles, essential for proper cell functionality during division.
Antimitotic drugs like Taxol (Paclitaxel), derived from the Pacific yew tree, are employed in human cancer treatment by stabilizing microtubules.
Kinesins and dyneins are motor proteins that use their globular heads to transport cargo along microtubules.

Actin Filaments

Actin filaments support cell morphology and provide structural support to the plasma membrane, allowing cells to change shape and move.
Actin polymerization starts with nucleation, involving the formation of dimers and trimers before adding monomers to either end of the filament.

Intermediate Filaments

Intermediate filaments create a mechanical network throughout cells, extending from the nucleus to the cell membrane, connecting neighboring cells and enhancing tissue strength.
They play a crucial role in cells subjected to significant mechanical stress, such as skin cells.
Unlike microtubules and actin filaments, intermediate filaments exhibit unique mechanical properties; they stretch under low forces and resist at high forces, making them more robust.
Intermediate filaments are formed through coiled coil interactions, ensuring their durability and ability to maintain cell integrity under stress.

General Cell Structure and Function

Over 200 cell types exist in the human body, each with a specialized shape and structure to perform specific biological functions.
Neurons extend axons and dendrites to relay signals over long distances, requiring structural support and transport mechanisms for biochemical components.
Enterocytes form microvilli to enhance nutrient absorption, demonstrating the relationship between cell structure and efficiency in function.

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Description

Explore the critical roles of microtubules in maintaining cell shape, facilitating cell motility, and assisting in chromosome and organelle movements during cell division. This quiz will test your understanding of microtubule dynamics and their function in cellular activities.