Antibodies

Question 1

Antibodies

Answer 1

Y shaped glycoproteins called immunoglobulins

Question 2

What are antibodies made of ?

Answer 2

Two identical polypeptide chains called heavy chains and light chains

Question 3

What are the chains held together by ?

Answer 3

Disulfide bridges within the chains and within the polypeptide chains holding them together

Question 4

What are antibodies produced by ?

Answer 4

B-lymphocytes

Question 5

Structure of antibodies

Answer 5

Quaternary

Question 6

What 2 regions do each polypeptide chain have ?

Answer 6

• constant region
• variable region

Question 7

Hinge region

Answer 7

Provides the molecule with flexibility allowing it to bind two separate antigens one at each of its antigen- binding site

Question 8

Antibody binds to an antigen

Answer 8

Antigen-antibody complex

Question 9

Is the amino acid sequence in the variable regions of the antibodies the same or different ?

Answer 9

Different

Question 10

Variable region

Answer 10

Where the antibody attaches to the antigen to form an antigen-antibody complex

Question 11

What is at the end of a variable region ?

Answer 11

Antigen-binding site

Question 12

How many amino acids Is each antigen-binding site composed of ?

Answer 12

110-130 amino acids

Question 13

Epitope

Answer 13

The part of the antigen that bids to the antibody

Question 14

What can antibodies act as ?

Answer 14

Anti-toxins

Opsonins

Agglutinins

Question 15

How do antibodies defend the body ?

Answer 15

1. Antibody of the antigen-antibody complex acts as an opsonin thus complex is easily engulfed and digested by phagocytes
2. Most pathogens can no longer effectively invade the host cells once they are part of an antigen-antibody complex
3. 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
4. Antibodies act as anti-toxins binding to the toxins produced by pathogens and making them harmless

Question 16

Opsonins

Answer 16

Bind to the pathogen and then act as binding sites for phagocytic cells ( facilitating phagocytosis )

Question 17

Agglutinins

Answer 17

Clump pathogens together by binding antigens to both binding sites and then cross linking them

Question 18

Anti-toxins

Answer 18

Bind to molecules released by pathogens and make them harmless to the organism

Question 19

Neutralisation

Answer 19

When an opsonin binds to pathogen but prevents attachment of the pathogen to the host cell