Antibodies and B-Cell Activation

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Questions and Answers

What initiates B cell activation?

Direct interaction with pathogens

Recombination of DNA

Release of cytokines

Binding to a specific antigen (correct)

Which process contributes to antibody diversity through DNA rearrangements?

Apoptosis

Alternative splicing

Recombination (correct)

Somatic hypermutation

What role does Activation-induced cytidine deaminase (AID) play in B cells?

Induces somatic hypermutation (correct)

Facilitates antigen binding

Enhances polyclonal expansion

Triggers apoptosis

Where does the diversification of activated B cells primarily occur?

Spleen Signup and view all the answers

What characterizes monoclonal antibodies?

Result from B cell isolation Signup and view all the answers

How do antibodies primarily aid in pathogen elimination?

By precipitating antigens Signup and view all the answers

What is the main advantage of using phage display in antibody engineering?

It allows screening of a large number of protein sequences Signup and view all the answers

What is a characteristic feature of polyclonal antibodies?

Collection of antibodies from various B cells Signup and view all the answers

What are the two types of light chains found in antibodies?

Alpha and kappa Signup and view all the answers

What structural feature confers specificity in the binding of antibodies to antigens?

Hypervariable loops Signup and view all the answers

Which part of the antibody is designated as the 'Fc' region?

Constant heavy chain Signup and view all the answers

How do antibodies differ in terms of their heavy chains?

The type of antibody depends on the heavy chain. Signup and view all the answers

What is a key feature of the antibody structure known as 'Fab'?

It is involved in antigen binding. Signup and view all the answers

Why are antibodies considered 'big business'?

They can be engineered for various therapeutic uses. Signup and view all the answers

Which statement about the immunoglobulin fold is true?

It consists of a conserved structure enabling stability. Signup and view all the answers

What can antibodies bind to apart from large antigens?

Small molecules. Signup and view all the answers

What is the primary function of ATP hydrolysis in muscle contraction?

Causes a conformational change in myosin Signup and view all the answers

Which of the following best describes the structure of G-actin?

It is a globular protein that binds adenosine nucleotide Signup and view all the answers

What initiates the contraction of a muscle cell?

Influx of Ca2+ Signup and view all the answers

How do thick and thin filaments differ in muscle fibers?

Thick filaments are composed primarily of myosin, while thin filaments consist of G-actin Signup and view all the answers

Which component is essential for the binding of myosin to actin?

Calcium ions (Ca2+) Signup and view all the answers

What structural feature allows the myosin tail to form aggregates?

The presence of 7 residue, non-polar pseudo-repeats Signup and view all the answers

What is the role of the troponin complex in muscle contraction?

It binds to tropomyosin and regulates myosin binding sites Signup and view all the answers

What does the Walk-Along mechanism describe in muscle contraction?

The sequential interaction of myosin heads with actin filaments Signup and view all the answers

Study Notes

Antibodies

Antibodies are Y-shaped proteins that bind to specific antigens.
The Y shape has two arms called Fab regions, which bind to antigen.
The base of the Y is called the Fc region, which binds to immune cells.
The variable regions (VH and VL) of the Fab region determine the antibody's specificity for its antigen.
Antibodies can bind many different kinds of antigens, including proteins, small molecules, and cells.
Antibodies are used in many medical applications, such as diagnosing diseases, treating tumors, and preventing infections.

Antibody Diversity

Antibody diversity is achieved through two steps:
- Recombination: DNA segments for variable regions are randomly rearranged.
- Somatic hypermutation: Point mutations are introduced into the variable regions, fine-tuning antibody affinity.

B-Cell Activation

B-Cells are responsible for producing antibodies.
B-cells are activated by binding antigen and interacting with T-cells.
Activated B-cells undergo differentiation into plasma B cells, which produce antibodies.
Activated B-cells diversify in the spleen.

How Antibodies Help

Antibodies help fight infection by:
- Neutralizing pathogens: Directly blocking the pathogen from entering cells.
- Precipitating antigens: Forming complexes that can be phagocytosed by immune cells.
- Activating complement: A cascade of proteins that leads to the lysis of the pathogen.
- Promoting phagocytosis: Making it easier for immune cells to eat the pathogen.

Monoclonal Antibodies

Monoclonal antibodies are produced by a single B-cell clone.
Monoclonal antibodies are highly specific for a particular antigen.
Monoclonal antibodies are used in a wide range of applications, including treating cancer, diagnosing diseases, and researching new antibodies.

Myosin

Myosin is a motor protein that enables muscle contraction.
Myosin consists of a long filamentous tail and a globular head.
The head of myosin binds to actin and hydrolyzes ATP, generating a force that moves the actin filament.
The muscle contraction process requires ATP hydrolysis, which provides energy for the movement.

Muscle Contraction

The myosin head binds to actin, forming a crossbridge.
ATP is hydrolyzed, causing the myosin head to swivel and move the actin filament.
This process of "walking" on the actin filament is called the "walk-along mechanism."
Contraction is triggered by calcium influx into muscle cells.

Other Components of Myofibrils

Troponin Complex & Tropomyosin:
- Tropomyosin binds to actin, blocking myosin binding sites.
- Troponin complex binds to both tropomyosin and calcium -- Calcium binding to troponin moves tropomyosin, exposing myosin binding sites on actin.

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Description

This quiz covers the fundamentals of antibodies, including their structure, function, and the mechanisms of diversity. It also explores the process of B-cell activation, crucial for antibody production. Test your knowledge on immunology concepts today!