Antigens Antibodies and Interactions | Immunity | Don't Memorise

Summary

This video explores the concept of antigen-antibody interaction, explaining how antibodies, or immunoglobulins, are Y-shaped protein molecules with constant and variable regions. The variable region adapts to the structure of antigens, triggering an immune response. The ELISA test, based on antigen-antibody interaction, is introduced as a method to detect substances in samples. Additionally, the video touches on the two types of immunity: innate immunity, which is non-specific and present from birth, and acquired immunity, which develops over time through exposure to pathogens.

Takeaways

• 🧬 Antibodies, also known as immunoglobulins (IG), are Y-shaped protein molecules made up of peptide chains.
• 🧩 The structure of an antibody is divided into two parts: the constant region and the variable region.
• 🔄 The constant region remains the same across all antibodies, while the variable region changes based on the antigen it needs to bind with.
• 🧪 Antibodies have antigen-binding sites in the variable region, designed to interact with specific antigens.
• 🦠 Antigens are molecules that trigger an immune response upon entering the body, leading to the production of matching antibodies.
• 🤝 The antigen-antibody interaction is crucial for triggering a cascade of immune responses to fight infections.
• 💉 The ELISA (Enzyme-Linked Immunosorbent Assay) test is a lab test that uses antigen-antibody interactions to detect and measure specific components in a liquid sample.
• 🎨 In the direct ELISA test, enzymes linked to antibodies bind to antigens, leading to a color change that indicates the amount of analyte present.
• 🛡️ Immunity is divided into two categories: innate immunity, present from birth, and acquired immunity, which develops over time through exposure to pathogens.
• 📚 Acquired immunity is highly specific and is developed as the body encounters various pathogens throughout an individual's lifetime.

Q & A

What are antibodies, and how are they structured?

Antibodies, also known as immunoglobulins (Ig), are Y-shaped protein molecules made up of different peptide chains. They consist of two main regions: a constant region, which remains the same in all antibodies, and a variable region, where peptide chains can alter depending on the structure of the antigen.

What is the difference between the constant region and the variable region of an antibody?

The constant region of an antibody has peptide chains that remain the same across all antibodies, while the variable region contains peptide chains that can change depending on the structure of the antigen. The antigen-binding site is located within the variable region.

What is the main function of antibodies in the immune system?

Antibodies bind to specific antigens, triggering a cascade of immune reactions that activate the immune system. This process is crucial in helping the body fight off infections.

How do antibodies recognize and bind to antigens?

Antibodies have a specific antigen-binding site in their variable region, which matches the structure of the antigen. When the antigen enters the body, immune cells secrete antibodies that are specific to that antigen, allowing them to bind to it.

What are some common types of antibodies found in humans?

Humans have different types of antibodies, including IgM, IgG, IgA, and IgE. These antibodies play various roles in the immune system, though the script only mentions their names without going into detail.

What is the principle behind the ELISA test?

The ELISA (enzyme-linked immunosorbent assay) test is based on the interaction between antigens and antibodies. In this test, a sample containing antibodies is added to a 96-well plate, where the antibodies bind to a known antigen coated on the bottom. An enzyme linked to the antibodies interacts with a substrate, causing a color change that helps detect the presence of specific analytes.

How does the color change in the ELISA test help detect the analyte?

The intensity of the color change in the ELISA test indicates the amount of the analyte being measured. The enzymes linked to the antibodies bind to the antigen, and when a substrate is added, it reacts with the enzyme to produce a visible color change.

What is the difference between innate and acquired immunity?

Innate immunity is a nonspecific defense mechanism present from birth, while acquired immunity develops over a person's lifetime as they encounter pathogens. Acquired immunity is highly specific and adapts to target particular pathogens.

How do antigen-antibody interactions trigger an immune response?

When an antibody binds to a specific antigen, it triggers a cascade of immune reactions that activate various immune cells. This response is essential for the body to fight infections and eliminate pathogens.

What type of test is direct ELISA, and how does it differ from other ELISA tests?

Direct ELISA is a type of ELISA test where the antibody directly binds to the antigen coated on the plate. There are other types of ELISA, such as indirect and sandwich ELISA, but the script focuses only on direct ELISA.