Cell Biology

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Questions and Answers

What is the main function of the cytoskeleton?

To synthesize proteins for cell growth

To store genetic information

To provide a structural framework for the cell and support the large volume of cytoplasm (correct)

To regulate cellular respiration

What are the components of the cytoskeleton in a eukaryotic cell?

Nucleus, nucleolus, nuclear envelope

Microtubules, intermediate filaments, actin filaments (correct)

Ribosomes, endoplasmic reticulum, Golgi apparatus

Lysosomes, peroxisomes, vacuoles

What is the structure of intermediate filaments?

Two-stranded helical polymers of Actin

Spherical structures made of Microtubulin

Hollow cylinders made of Tubulin

Rope-like structure composed of fibrous proteins (correct)

How do the three cytoskeleton components distribute in the cell?

Each shows a different distribution in the cell Signup and view all the answers

Which structure is formed by the association of protofilaments?

Protofibrils Signup and view all the answers

What is the composition of the nuclear lamina?

Intermediate filaments and associated proteins Signup and view all the answers

Which disorder is caused by mutations in Keratin genes?

Epidermolisis Bullosa Simplex Signup and view all the answers

What is linked to alterations in Neuron Intermediate Filaments and abnormal assembly of neurofilaments?

Amyotrophic Lateral Sclerosis Signup and view all the answers

What is the structure of microtubules?

Hollow cylindrical tube with 13 protofilaments Signup and view all the answers

What determines whether a microtubule will grow or shrink?

Concentration of free tubulin dimers Signup and view all the answers

How do microtubules display growth polarity?

Preferential addition of tubulin dimers at the (+) end and loss at the (-) end Signup and view all the answers

What inhibits the binding of MAPs to microtubules, favoring microtubule disassembly?

Phosphorylation Signup and view all the answers

Which protein promotes actin polymerization by forming a complex with G-actin-ATP?

Profilin Signup and view all the answers

What is the function of capping proteins like CapZ and tropomodulin in relation to actin filaments?

Stabilize actin filament ends Signup and view all the answers

What is the role of intermediate filaments in cells?

Provide mechanical strength to the cell Signup and view all the answers

Which proteins determine filament patterns in actin cross-linking?

Fimbrin and α-actinin Signup and view all the answers

What is the function of kinesins in vesicle transport?

Mediate anterograde transport Signup and view all the answers

What is the structure of the axoneme in cilia and flagella?

9 doublet microtubules surrounding a central pair of singlet microtubules Signup and view all the answers

What is the function of basal bodies in cilia and flagella?

Serve as the growing point of cilia and flagella Signup and view all the answers

What is the dynamic behavior illustrated by the actin filament treadmill?

Rapid addition of ATP-actin monomers to the (+) end and ATP hydrolysis to ADP after polymerization Signup and view all the answers

What is the structure formed by the association of protofilaments?

Protofibrils Signup and view all the answers

What is the main component of the nuclear lamina?

Intermediate filaments Signup and view all the answers

What disorder is caused by mutations in several Keratin genes?

Epidermolysis bullosa simplex Signup and view all the answers

What is the tightly regulated process involving nuclear lamina intermediate filaments during the initial stages of mitosis?

Disassembly Signup and view all the answers

Which disorder has been linked to alterations in Neuron Intermediate Filaments and abnormal assembly of neurofilaments?

Amyotrophic lateral sclerosis Signup and view all the answers

Study Notes

Microtubules, Centrioles, and Microfilaments in Cell Biology

Kinesins mediate anterograde transport while dyneins mediate retrograde transport, with the type of receptors on the vesicle surface determining transport direction
Vesicle transport is vital in neurons for delivering molecules synthesized in the cell body or mitochondria to the axon terminal
Axonal transport occurs in both directions at a speed of up to 400 mm/day, relying on kinesin, dynein, and microtubules
Unstable microtubules maintain cell shape, facilitate cellular transport, and aid in mitotic spindle formation for chromosome distribution during mitosis
Cilia and flagella have similar structures but differ in length, number, and function, with cilia being short and abundant, and flagella being long and scarce, used for locomotion or movement of fluids along the cell surface
The axoneme, formed by 9 doublet microtubules surrounding a central pair of singlet microtubules, serves as the central bundle of microtubules in cilia and flagella
Basal bodies, with the same structure as centrioles, are the growing point of cilia and flagella and have 9 triplets of microtubules tilted towards the central axis
Centrioles, exclusive to animal cells, are involved in the formation of the mitotic spindle and are duplicated before mitosis
The centrosome, functioning as a Microtubule Organizing Center (MTOC), is made up of pericentriolar material (PCM) and sometimes contains 2 centrioles oriented perpendicular to each other
Microfilaments, the thinnest filaments in the cytoskeleton, are two-stranded helical polymers of actin, with structural and growing polarity, and high rates of polymerization and depolymerization
Actin exists as free globular monomers (G-actin) or forms fibrous polymers (F-actin), with ATP hydrolysis reducing the binding strength between actin monomers and leading to depolymerization
Actin filament treadmill illustrates the dynamic behavior of actin filaments, with ATP-actin monomers rapidly added to the (+) end and ATP hydrolyzed to ADP after polymerization, creating a flow of actin monomers from the (+) end to the (-) end of the filament

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Description

Explore the crucial role of microtubules, centrioles, and microfilaments in cell biology with this quiz. Test your knowledge on axonal transport, cilia and flagella structures, centriole function, and the dynamic behavior of actin filaments. Delve into the intricate world of cellular transport, mitotic spindle formation, and cytoskeletal dynamics.