Cytoskeleton Quiz

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Questions and Answers

What is the main function of intermediate filaments?

Provide strength and bear tension (correct)

Facilitate cell movement

Regulate gene expression

Act as enzymes in cellular reactions

Which type of intermediate filament makes up the epithelium?

Neurofilament

Nestin

Acidic and basic/neutral keratins (correct)

Vimentin and desmin

What is the subunit of intermediate filaments?

Dimers (correct)

Monomers

Oligomers

Polymers

What are microtubules made of?

Tubulin subunits Signup and view all the answers

Where are cytoplasmic microtubules found?

In the cytosol Signup and view all the answers

What are the main functions of cytoplasmic microtubules?

Maintaining axons, altering cell shape, and moving vesicles Signup and view all the answers

Which type of intermediate filament is found in muscle and connective tissue?

Vimentin and desmin Signup and view all the answers

What is the size of microtubules?

25 nm Signup and view all the answers

Which part of the cell do cilia and flagella belong to?

Cytoskeleton Signup and view all the answers

What is the main function of microtubules in the cell?

Facilitate intracellular movement Signup and view all the answers

Which type of intermediate filament makes up the neural part of the embryo?

Nestin Signup and view all the answers

What are microtubules made up of?

Protofilaments made of a-tubulin and b-tubulin Signup and view all the answers

What is the main difference between intermediate filaments and microtubules?

Intermediate filaments provide strength, while microtubules facilitate movement Signup and view all the answers

What determines the growth of the positive end of a microtubule?

Free tubulin Signup and view all the answers

What is the function of thymosin b4 in relation to actin?

Binds g-actin and competes with profilin Signup and view all the answers

Which protein is responsible for making new branches on actin filaments?

ARP 2/3 complex Signup and view all the answers

What is the function of kinesins and dyneins?

They are motor proteins involved in cellular movement Signup and view all the answers

What is the function of histones in chromatin?

They bind to DNA and condense it into chromosomes Signup and view all the answers

Which myosin class is involved in muscle contraction?

Myosin 2 Signup and view all the answers

What is the main bacterial genome structure?

Single circular chromosome Signup and view all the answers

What is the function of topoisomerases in DNA?

They induce and relax supercoils Signup and view all the answers

What happens to DNA at increased temperature and pH?

Denaturation Signup and view all the answers

Which bases form complimentary pairs in DNA?

A-T, G-C Signup and view all the answers

What is the structure of the DNA double helix?

Right-handed B-DNA and left-handed Z-DNA Signup and view all the answers

What is the size of intermediate filaments?

8-12 nm Signup and view all the answers

Which type of intermediate filament is found in muscle and connective tissue?

Vimentin and desmin Signup and view all the answers

What is the subunit of microtubules?

Tubulin Signup and view all the answers

Where are cytoplasmic microtubules found?

Cytosol Signup and view all the answers

What is the function of neurofilaments?

Found in nerve cells Signup and view all the answers

What is the main function of microtubules in the cell?

Cellular movement Signup and view all the answers

What is the main difference between microtubules and intermediate filaments?

Size and composition Signup and view all the answers

What are the main functions of cytoplasmic microtubules?

Maintaining axons, altering cell shape, and moving vesicles Signup and view all the answers

What is the composition of IF dimers?

Fibrous proteins Signup and view all the answers

What is the main function of microtubules in the cell?

Providing a scaffold for motor proteins Signup and view all the answers

Which protein is responsible for making new branches on actin filaments?

ARP 2/3 complex Signup and view all the answers

What determines the growth of the positive end of a microtubule?

GTP concentration Signup and view all the answers

Which type of intermediate filament makes up the neural part of the embryo?

Nestin Signup and view all the answers

What is the main function of acidic and basic/neutral keratins?

Make up the epithelium Signup and view all the answers

What is the function of kinesins and dyneins?

Facilitating intracellular transport along microtubules Signup and view all the answers

What is the main difference between intermediate filaments and microtubules?

Polar plus and minus ends Signup and view all the answers

What are the main functions of cytoplasmic microtubules?

Scaffold for motor proteins and intracellular transport Signup and view all the answers

What is the main function of intermediate filaments?

Resisting bending Signup and view all the answers

What is the main function of vimentin and desmin in the cell?

Provide structural support in muscle and connective tissue Signup and view all the answers

What is the main bacterial genome structure?

Single circular chromosome Signup and view all the answers

What happens to DNA at increased temperature and pH?

Denaturation Signup and view all the answers

What is the size of microtubules?

30nm Signup and view all the answers

What is the function of histones in chromatin?

Structural support Signup and view all the answers

What are microfilaments composed of?

Actin subunits Signup and view all the answers

Which bacterial cytoskeletal element is involved in DNA segregation and cell shape?

MreB Signup and view all the answers

What are the major structural elements of the cytoskeleton?

Microfilaments, microtubules, intermediate filaments Signup and view all the answers

What is the composition of microtubules?

Tubulin subunits Signup and view all the answers

What is the function of intermediate filaments in eukaryotic cells?

Structural support Signup and view all the answers

What are the bacterial cytoskeletal elements structurally similar to those in eukaryotes?

MreB and FtsZ Signup and view all the answers

What are microtubules essential components of?

Cilia and flagella Signup and view all the answers

What is the dynamic nature of the cytoskeleton?

Dynamic and changeable Signup and view all the answers

Which type of cytoskeletal element is composed of tubulin subunits?

Microtubules Signup and view all the answers

What roles does the cytoskeleton play in the cell?

Cell movement and division Signup and view all the answers

Which type of proteins promote depolarization of microtubules?

Stathmin/Op18 Signup and view all the answers

What do some microtubule-binding proteins use ATP for?

Both a and b Signup and view all the answers

What do microtubule-associated proteins (MAPs) do?

Bind at regular intervals along a microtubule wall Signup and view all the answers

Which proteins act at the ends of microtubules and promote the peeling of subunits from the ends?

Catastrophins Signup and view all the answers

What is the function of microtubule-stabilizing/bundling proteins like MAPs?

Allow interaction with other cellular structures and filaments Signup and view all the answers

Which proteins bind to tubulin heterodimers and prevent their polymerization?

Stathmin/Op18 Signup and view all the answers

What do some microtubule-binding proteins use ATP for?

Both a and b Signup and view all the answers

What is the function of microtubule-destabilizing/severing protein katanin?

Sever microtubules Signup and view all the answers

What do microtubule-binding proteins use ATP for?

Both a and b Signup and view all the answers

What is the function of microtubule-destabilizing/severing protein stathmin/Op18?

Promote depolarization of microtubules Signup and view all the answers

What are the protein building blocks of microtubules?

Tubulin heterodimers Signup and view all the answers

What contributes to the dynamic instability of microtubules?

GTP hydrolysis Signup and view all the answers

What is the function of microtubule-associated proteins (MAPs)?

Regulate microtubule dynamics and stability Signup and view all the answers

Where do microtubules originate from?

Centrosomes Signup and view all the answers

What is the inherent polarity of protofilaments in microtubules?

Bipolar Signup and view all the answers

What type of drugs target microtubule dynamics for cancer treatment?

Taxanes and vinca alkaloids Signup and view all the answers

What occurs more quickly at the plus ends of microtubules?

Tubulin polymerization Signup and view all the answers

What is the process of microtubule assembly involving nucleation, elongation, and critical concentration of tubulin dimers known as?

Tubulin polymerization Signup and view all the answers

What do microtubule-organizing centers (MTOCs) do within cells?

Nucleate and anchor microtubules with fixed polarity Signup and view all the answers

What type of ends do protofilaments in microtubules have?

Positive and negative ends Signup and view all the answers

Study Notes

Microtubules: Structure, Assembly, and Function

Microtubules (MTs) are the largest structural elements of the cytoskeleton, involved in various cell functions.
Two types of microtubules exist: cytoplasmic microtubules and their functions in maintaining axons, formation of spindles, and cell shape.
Tubulin heterodimers are the protein building blocks of microtubules, consisting of protofilaments with α and β-tubulin.
Protofilaments have inherent polarity with plus and minus ends, and microtubules form through reversible polymerization of tubulin dimers.
Microtubule assembly involves nucleation, elongation, and critical concentration of tubulin dimers.
Addition of tubulin dimers occurs more quickly at the plus ends of microtubules, leading to treadmilling.
GTP hydrolysis contributes to the dynamic instability of microtubules, involving GTP-tubulin and dynamic instability with catastrophe and rescue phases.
Microtubules originate from microtubule-organizing centers (MTOCs) and centrosomes containing γ-tubulin ring complexes (γ-TuRCs).
MTOCs organize and polarize microtubules within cells, nucleating and anchoring MTs with fixed polarity.
Microtubules facilitate various cellular functions, including maintaining cell shape and facilitating intracellular transport.
Microtubule-based drugs such as taxanes and vinca alkaloids target microtubule dynamics for cancer treatment.
Microtubule-associated proteins (MAPs) regulate microtubule dynamics and stability, influencing their functions in the cell.

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Description

Test your knowledge of the cytoskeleton with this quiz. Explore the different types of intermediate filaments and their roles in animal cells. Learn about the composition, stability, and functions of various classes of intermediate filaments, including keratins, vimentin, desmin, and neurofilament.