Antibodies Flashcards
Antibodies
Y shaped glycoproteins called immunoglobulins
What are antibodies made of ?
Two identical polypeptide chains called heavy chains and light chains
What are the chains held together by ?
Disulfide bridges within the chains and within the polypeptide chains holding them together
What are antibodies produced by ?
B-lymphocytes
Structure of antibodies
Quaternary
What 2 regions do each polypeptide chain have ?
- constant region
- variable region
Hinge region
Provides the molecule with flexibility allowing it to bind two separate antigens one at each of its antigen- binding site
Antibody binds to an antigen
Antigen-antibody complex
Is the amino acid sequence in the variable regions of the antibodies the same or different ?
Different
Variable region
Where the antibody attaches to the antigen to form an antigen-antibody complex
What is at the end of a variable region ?
Antigen-binding site
How many amino acids Is each antigen-binding site composed of ?
110-130 amino acids
Epitope
The part of the antigen that bids to the antibody
What can antibodies act as ?
Anti-toxins
Opsonins
Agglutinins
How do antibodies defend the body ?
- Antibody of the antigen-antibody complex acts as an opsonin thus complex is easily engulfed and digested by phagocytes
- Most pathogens can no longer effectively invade the host cells once they are part of an antigen-antibody complex
- Antibodies act as agglutinins causing pathogens carrying antigen-antibody complexes to dump together —> helps prevent them spreading through the body and makes it easier for phagocytes to engulf a number of pathogens at the same time
- Antibodies act as anti-toxins binding to the toxins produced by pathogens and making them harmless
