Retta - L4 part 1

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Questions and Answers

What primary role does the cytoskeleton serve in cells?

To store genetic information

To produce proteins for cellular functions

To provide energy for cellular activity

To give cells shape and enable movement (correct)

Which protein is primarily associated with actin filaments?

Collagen

Tubulin

Actin (correct)

Keratin

Microtubules are composed of which type of protein?

Actin

Keratin

Elastin

Tubulin (correct)

What is a function of intermediate filaments within the cytoskeleton?

Providing structural support and stability Signup and view all the answers

How do cells change their shape?

By remodeling the cytoskeleton Signup and view all the answers

What staining method can be used to detect cytoskeletal proteins?

Coomassie blue dye Signup and view all the answers

Which of the following is NOT a component of the cytoskeleton?

Plasma membrane Signup and view all the answers

What cellular functions are regulated by the cytoskeleton?

Migration, proliferation, and cell shape Signup and view all the answers

What is the primary purpose of using secondary antibodies in immunofluorescence?

To allow for the use of a single dye for multiple primary antibodies Signup and view all the answers

What color would you expect to see in a microscope when visualizing microtubules labeled with a green fluorescent dye?

Green Signup and view all the answers

Which of the following is NOT true about primary antibodies used in immunofluorescence?

They can bind to DNA directly. Signup and view all the answers

What does the term 'immunofluorescence' specifically refer to?

Fluorescence microscopy utilizing antibodies Signup and view all the answers

If an antibody against tubulin is labeled with red fluorescent dye, what would the red color indicate in a microscopic view?

Microtubules composed of tubulin Signup and view all the answers

Which of the following denotes the role of fluorescent dyes in immunofluorescence?

They indicate the presence of specific proteins. Signup and view all the answers

When using fluorescent microscopy, which of the following representations is correct for detecting DNA?

It emits blue light when labeled with a specific dye. Signup and view all the answers

What is one disadvantage of directly labeling primary antibodies in immunofluorescence?

It does not allow the detection of multiple proteins simultaneously. Signup and view all the answers

How can actin filaments be distinguished from microtubules in a microscopy setup?

By the type of primary antibody used Signup and view all the answers

What is the function of cytoskeletal filaments?

To undergo continuous remodelling while maintaining functions Signup and view all the answers

What happens if cytoskeleton dynamics are blocked?

Cells will likely die due to disrupted functions Signup and view all the answers

What is the role of nucleation in filament formation?

It initiates the formation of protein subunit chains Signup and view all the answers

What are the building blocks of actin filaments?

Globular actin subunits Signup and view all the answers

Which characteristic distinguishes the three types of cytoskeletal components?

Their unique mechanical properties and dynamics Signup and view all the answers

What primary role do microtubules play during cell division?

They form the mitotic spindle. Signup and view all the answers

Which component of the cytoskeleton is primarily responsible for providing mechanical strength against shear stress?

Intermediate filaments Signup and view all the answers

Which cytoskeletal structure is involved in the movement of organelles like mitochondria within the cell?

Microtubules Signup and view all the answers

During which process does the actin cytoskeleton play a major role?

Cytokinesis Signup and view all the answers

How does the cytoskeleton contribute to muscle contraction?

Through the interaction of actin and myosin. Signup and view all the answers

What role do actin filaments play in the structure of microvilli?

They support the shape and position of microvilli. Signup and view all the answers

What feature of the cytoskeleton allows it to respond to stretching in epithelial tissues?

Dynamic structure and self-assembly Signup and view all the answers

Which property of white blood cells is directly influenced by the cytoskeleton?

Cell migration Signup and view all the answers

What is the relationship between mitosis and cytokinesis?

Cytokinesis follows the completion of mitosis. Signup and view all the answers

Which cytoskeletal component is NOT involved in shaping the cell surface?

Intermediate filaments Signup and view all the answers

What is the primary purpose of using GFP in the context of fluorescent microscopy?

To directly label proteins for visualization Signup and view all the answers

How can researchers track actin dynamics using fluorescent microscopy?

By tagging actin with fluorescent dye or proteins Signup and view all the answers

What does the term 'recombinant protein' refer to in the context of fluorescent microscopy?

A protein formed by the fusion of two or more proteins Signup and view all the answers

What is the function of phalloidin in the study of actin?

To selectively bind to actin and enable its visualization Signup and view all the answers

Which of the following is a characteristic of indirect fluorescent microscopy?

It requires antibodies to label the proteins of interest Signup and view all the answers

Which type of fluorescent protein can be used as a tag alongside actin in microscopy?

Blue, yellow, or red fluorescent proteins Signup and view all the answers

What occurs during the process of creating a fusion protein with a fluorescent tag?

A single DNA sequence encodes for both proteins Signup and view all the answers

What is a potential drawback of using direct fluorescent microscopy?

It can lead to nonspecific binding of tags Signup and view all the answers

Which dye would emit green light when bound to actin?

Fluorescein Signup and view all the answers

What is the arrangement of components in a bipolar mitotic spindle observed via fluorescent microscopy?

Microtubules and chromosomes are associated together Signup and view all the answers

Study Notes

Cytoskeleton Overview

The cytoskeleton consists of actin filaments, microtubules, and intermediate filaments, playing a crucial role in cell shape, movement, and division.
It regulates diverse cellular functions such as polarization, migration, and proliferation.
Cytoskeletal proteins can be visualized using Coomassie blue dye, demonstrating their filamentous structures.

Types of Cytoskeletal Filaments

Actin filaments (microfilaments) are composed of the protein actin, essential for cell shape and movement.
Microtubules consist of tubulin and are vital for maintaining cell structure and chromosome separation during mitosis.
Intermediate filaments are formed from various proteins and provide mechanical strength.

Visualization Techniques

Immunofluorescence microscopy can detect actin and tubulin using antibodies specific to each protein.
Primary antibodies recognize target proteins while secondary antibodies, often labeled with fluorescent dyes, amplify detection.
Direct fluorescence microscopy involves tagging proteins with fluorescent proteins (e.g., GFP) for real-time observation of cytoskeleton dynamics.

Mitosis and Cytoskeleton

The mitotic spindle, composed of microtubules, is crucial for chromosome separation during mitosis.
Cytokinesis, the division of the cytoplasm, relies on the actin cytoskeleton to form the contractile ring.

Cytoskeletal Functions

Supports intracellular traffic of organelles like the Golgi apparatus and endoplasmic reticulum (ER) via actin.
Maintains the stability and shape of the plasma membrane, enabling functions such as endocytosis.
Provides mechanical linkage to withstand stress, allowing cells to respond to physical stretching and shear stress, particularly in endothelial cells.
Plays a vital role in cell migration, essential for immune response, and in muscle contraction via interactions between actin and myosin.

Cell Protrusions and Stability

Microvilli, supported by actin filaments, are crucial for increasing surface area in epithelial cells of the digestive system.
The positioning of organelles like mitochondria is determined by microtubules, which facilitate their movement within the cell.

Coloring and Labeling

Fluorescent dyes (e.g., Rhodamine, fluorescein) can be conjugated to phalloidin, allowing specific visualization of actin filaments.
Different dyes emit distinct colors, allowing simultaneous detection of multiple components within the cell.

Summary of Cytoskeletal Components

Intermediate filaments provide mechanical strength against stretching and shear stress.
Microtubules position organelles and enable intracellular transport.
Actin filaments define cell shape and are critical for motility and the formation of structures like microvilli.### Role of Intermediate Filaments
Intermediate filaments provide mechanical resistance to cells.
They are interconnected through specific connecting proteins at cell interfaces.
These connecting proteins, described as "protein buttons," anchor cells together, creating a mechanical structure.

Dynamics of Cytoskeletal Filaments

Cytoskeletal filaments offer structural integrity but are inherently dynamic and not stable.
They continually undergo remodeling, forming and disassembling while fulfilling their cell functions.
Disruption of cytoskeleton dynamics, such as through drug intervention, can lead to cell death.

Actin Filaments and Cytoskeleton Dynamics

Actin filaments are critical for maintaining cell structure; blockage by agents like phalloidin disrupts dynamic processes.
All cytoskeletal filaments feature a stable structure, but this structure changes over time due to continuous remodeling.

Composition of Cytoskeletal Filaments

Each filament type consists of specific smaller protein subunits:
- Actin filaments are made of actin proteins.
- Microtubules are composed of tubulin.
- Intermediate filaments consist of various proteins.
Filaments are elongated structures made up of chains of globular protein subunits.

Nucleation Process

Nucleation is the essential first step in filament formation, involving the interaction of initial subunits.
Formation of a nucleus, where a few subunits (typically three) come together, is crucial for retaining structure.
Following nucleation, additional subunits attach to elongate the filament.

Mechanical Properties of Filaments

Each cytoskeletal filament type displays distinct mechanical properties and dynamics.
While all filament types are dynamic, they exhibit different behaviors and response patterns in the cell.

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Description

Explore the structure, origin, and function of the cytoskeleton. This quiz covers key components like actin filaments, microtubules, and intermediate filaments, as well as their role in cellular processes such as polarization, migration, and proliferation.