Cytoskeleton Functions and Structure

Questions and Answers

What structure do both cilia and flagella have in common?

They are covered by a rigid cell wall.

They are both composed of RNA.

They are made up of a lipid bilayer.

They both consist of microtubules. (correct)

How do motile cilia typically move?

By rotating in a circular motion.

By undergoing power and recovery strokes. (correct)

By waving back and forth.

By pulsating like a heart.

What is a primary function of cilia that are non-motile?

To act as signal-receiving antennas. (correct)

To propel the cell through water.

To provide structural support to the cell.

To generate ATP for cellular energy.

What is one significant difference between cilia and flagella?

Cilia usually occur in larger numbers per cell. Signup and view all the answers

Which cell type specifically uses cilia to sweep mucus out of the lungs?

Epithelial cells. Signup and view all the answers

In which scenario would a flagellum be used?

For enabling sperm movement in reproduction. Signup and view all the answers

What movement pattern does a flagellum typically exhibit?

A propeller-like motion. Signup and view all the answers

Which of the following is NOT a role of cilia or flagella?

Creating cellular energy through ATP synthesis. Signup and view all the answers

What is a unique characteristic of primary cilia in vertebrate animals?

They are present on almost all cell types. Signup and view all the answers

How do cilia assist in the movement of an egg toward the uterus?

By sweeping fluid along the reproductive tract. Signup and view all the answers

Study Notes

The Cytoskeleton

A complex network of protein tracks and tubules found in the cytosol of eukaryotic cells.
Provides mechanical support, maintains three-dimensional shape, and is crucial for animal cells that lack rigid walls.

Functions of the Cytoskeleton

Offers mechanical support and helps maintain cell shape.
Serves as a transport system for organelles and cellular components.
Aids in cell division and movement of cells or parts of cells.
Connects cells to one another to form tissues.

Structure of the Cytoskeleton

Composed of three major components: microfilaments, intermediate filaments, and microtubules.
Each component differs in protein type, diameter, and assembly into larger structures.

Motor Proteins

Molecular machines that use ATP for movement along cytoskeletal components.
Three classes include myosin, kinesin, and dynein, all aiding in organelle transportation.

Microfilaments (Actin Filaments)

Thin solid rods with a diameter of approximately 7 nanometers, constructed from actin proteins.
Have a plus and minus end and are twisted double chains of actin subunits.
Functions include:
- Providing strength against stretching and compression.
- Anchoring cells to one another and forming a network just inside the plasma membrane.
- Contributing to the structure of microvilli in nutrient-absorbing cells.
- Facilitating cell motility through interactions with myosin in muscle contraction and amoeboid movement.

Intermediate Filaments

Named for a diameter of 10 nanometers, larger than microfilaments.
Constructed from various protein subunits, including keratins; found in some animal cells.
Functions include:
- Supporting cell shape and anchoring organelles.
- Providing structural integrity to cells, especially in hair and nails.
- Binding some cells together through desmosomes.

Microtubules

Hollow rods with a diameter of 23 nanometers, made of tubulin dimers (α-tubulin and β-tubulin).
Functions include:
- Providing shape and support for the cell.
- Serving as tracks for motor proteins (kinesin and dynein) to move organelles.
- Guiding vesicle transport from the ER to Golgi apparatus and vice versa.
- Involved in chromosome separation during cell division and movement of cilia and flagella.

Cilia and Flagella

Extensions containing microtubules, differing in length, number, and beating patterns.
Both structures aid in locomotion for unicellular organisms and sperm.
Cilia can move fluids across cell surfaces, like in the trachea and oviduct.
Primary cilia serve as signal-receiving antennas for cells, transmitting environmental signals to trigger internal cellular responses.

Description

Explore the fascinating world of the cytoskeleton, a complex protein network vital for maintaining the shape and integrity of eukaryotic cells. This quiz covers its mechanical support, transport functions, and role in cell division and movement.