Antigens and Antibodies.

https://www.youtube.com/watch?v=cYRe5ftY8pI

What are antigens

Molecules that are recognised as foreign by the immune system, they are often found on the surface of pathogens, often leads to immune response.

What happens during an immune reponse

Antibodies are produced which specifically bind to the antigen.

Why do antigens on the surface of ur cells not trigger immune response

The immune system identified these antigens as self.

What are antibodies

Glycoproteins consisting of four polypeptide chains, 2 long heavy chains which are identical to each other, and 2 shorter light chains which are identical to each other

The chains are held to each other by disulfide bridges

Heavy chain contains site at which the antibody can bind to a cell.

How many antigen binding sites are on an antibody

Two antigen binding sites. This means one antibody molecule binds to two antigen molecules like this

When antigens bind, it is called an antigen-antibody complex.

What is the hinge region

It is flexible, allows the distance between two antigen binding sites to vary

What is the constant region

Has the same structure for every antibody, no matter which B lymphocyte produced it.

What the variable region

The ends of the antibodies are different, and it is called the variable regions . Different on different antibodies so that its complementary to antigen.

What are the 3 types of antibody

Opsonins, Agglutinins and anti toxins.

What are agglutinins

Bind to antigens, and cause clumping which prevents them from entering the body cells so they can be engulfed by phagocytes.

What are anti toxins

They bind to toxins to prevent harm to human cells. Phagocytes then engulf the ‘toxin antibody’ complexes.