Antibodies and Natural/ Passive Immunity

Question 1

What are antibodies?

Answer 1

Proteins made up of 4 polypeptide chains, 2 heavy and 2 light. Each chain has a variable region and a constant region. The chains are connected by disulphide bridges

Question 2

What is Agglutination?

Answer 2

Antibodies bind to antigens on pathogens and cause them to clump together, these clumps are then destroyed by phagocytosis. This makes it easier for phagocytes to engulf more pathogens at a time.

Question 3

What is Neutralizing toxins?

Answer 3

some antibodies work by neutralizing toxins released by pathogens

Question 4

How do antibodies prevent viruses from entering host cells?

Answer 4

Viruses have spike proteins on their surface which recognize and bind to receptors on the surface of the host cell which allow them entry into the cell. Antibodies can bind to these on viruses and stop them attaching to their host cells

Question 5

What is antigenic variability?

Answer 5

Pathogen may mutate frequently so that its antigens change suddenly rather than gradually which means vaccines become ineffective because the new antigens on the pathogen are no longer recognized by the immune system