Antibodies and monoclonal antibodies
Antibodies
- An antibody is a Y-shaped protein made by plasma cells.
- Each one fits one antigen exactly — like a lock and key.
- We can even mass-produce a single type for medicine.
Antibody structure and action
- The two tips of the Y are the antigen-binding sites.
- Each site has a variable region — a special shape that fits one antigen only.
- Antibodies help by: sticking to antigens, clumping pathogens together, marking them for phagocytes, and blocking toxins.
Practice
The variable region of an antibody:
The two tips of the Y are variable regions — each shaped to bind one specific antigen.
Practice
One way antibodies help destroy pathogens is by:
Antibodies clump pathogens, mark them for phagocytes, and block toxins.
Monoclonal antibodies
- A monoclonal antibody is a single, identical type of antibody, made by the hybridoma method:
- an animal is given an antigen, so it makes B-lymphocytes that produce the wanted antibody.
- those B-lymphocytes are fused with tumour cells (which divide endlessly).
- the fused hybridoma both makes the antibody and divides without stopping.
Practice
A hybridoma is made by:
The B-lymphocyte supplies the wanted antibody; the tumour cell makes it divide endlessly — together a hybridoma.
What they're used for
- diagnosis — detecting a specific molecule (e.g. a pregnancy test).
- treatment — carrying drugs to specific target cells, such as cancer cells.
Practice
Monoclonal antibodies are used in:
They detect specific molecules for diagnosis, and can carry drugs to specific target cells for treatment.
You've got it
Key idea
- an antibody is Y-shaped; the tips are variable regions that bind one antigen
- antibodies clump, mark, and block toxins so pathogens are dealt with
- monoclonal = one identical antibody, made by a hybridoma (B-lymphocyte + tumour cell)
- used in diagnosis (pregnancy test) and treatment (target drugs to cancer cells)