BB 314 - Unit 6 Cytoskeleton Quiz

Questions and Answers

Which of the following statements about the cytoskeleton is true? Choose all that apply.

The cytoskeleton is made up of three types of protein filaments. (correct)

Intermediate filaments are so named because their size is 'intermediate', compared to the other two. (correct)

Actin is the smallest filament. (correct)

The cytoskeleton of a cell can change in response to the environment. (correct)

The cytoskeleton controls the location of organelles in eukaryotic cells. (correct)

Match the images with the types of skeletal filament they represent:

Image A = Microtubules Image B = Intermediate Filaments Image C = Actin Filaments

Select the correct cytoskeletal filament that corresponds to each statement:

Monomer that binds ATP = Actin Filaments Includes keratin and neurofilaments = Intermediate Filaments Used in the eukaryotic flagellum = Microtubules Their stability involves a GTP cap = Microtubules Directly involved in muscle contraction = Actin Filaments Supports and strengthens the nuclear envelope = Intermediate Filaments A component of the mitotic spindle = Microtubules Important for formation of the contractile ring during cytokinesis = Actin Filaments

In the polymerization in vitro of actin filaments and microtubules from their subunits, what does the 'lag phase' correspond to?

Nucleation Signup and view all the answers

For both actin and microtubule polymerization, nucleotide hydrolysis is important for what?

Decreasing the binding strength between subunits on filaments Signup and view all the answers

In a centrosome (i.e. an MTOC), which structures serve as nucleation sites for the formation of microtubules?

Gamma-tubulin rings Signup and view all the answers

Kinesin and dynein motor proteins each use the energy of _ to power their movements along __.

ATP hydrolysis; microtubules Signup and view all the answers

_______ are the motor protein that move directionally along actin filaments.

Myosins Signup and view all the answers

If a cell is treated with the drug Vinblastine, which cellular property/process would NOT be affected?

Reformation of the nuclear envelope Signup and view all the answers

Study Notes

Cytoskeleton Basics

Intermediate filaments are termed 'intermediate' due to their size relative to actin filaments and microtubules.
The cytoskeleton adapts and changes in response to environmental cues.
It plays a crucial role in determining the positioning of organelles within eukaryotic cells.
Comprises three main types of protein filaments: microtubules, intermediate filaments, and actin filaments.
Actin filaments are the smallest among these filament types.

Types of Cytoskeletal Filaments

Microtubules: Represented by black lines in images; play roles in cellular structure and function.
Intermediate Filaments: Include proteins like keratin and neurofilaments; provide support and strength.
Actin Filaments: The thinnest filaments, crucial for muscle contraction.

Filament Characteristics

Actin filaments bind ATP; essential for their dynamics and function.
Intermediate filaments are responsible for structural integrity and include keratin.
Microtubules are involved in flagellar motion and support the mitotic spindle.
A GTP cap stabilizes microtubules and is vital for their assembly and function.

Polymerization Dynamics

"Lag phase" in actin and microtubule polymerization refers to the initial phase of nucleation, where monomers aggregate to form stable nuclei before elongation occurs.
Nucleotide hydrolysis (ATP or GTP) reduces binding strength between filament subunits, facilitating dynamic rearrangements.

Microtubule Organizing Centers

In centrosomes (microtubule organizing centers), gamma-tubulin rings act as nucleation sites, crucial for microtubule growth.

Motor Proteins

Kinesin and dynein use ATP hydrolysis for their movement along microtubules, enabling intracellular transport.
Myosins are the motor proteins that translocate along actin filaments, essential for various cellular processes.

Drug Effects

Vinblastine disrupts microtubule dynamics but does not impact the reformation of the nuclear envelope, illustrating differential effects of drugs on cellular functions.

Description

Test your knowledge on the cytoskeleton with this quiz from BB 314, Unit 6. Explore the structure and functions of the cytoskeleton, including its role in cell organelle positioning and the types of protein filaments involved. Answer multiple-choice questions to assess your understanding.