Antibodies

Question 1

What are antibodies?

Answer 1

1. Quaternary structured protein (immunoglobin)
2. Secreted by B lymphocytes and produced in response to a specific antigen
3. Binds specifically to antigens (monoclonal) forming an antigen-antibody complex

Question 2

Describe and explain how the structure of an antibody relates to its function:

Answer 2

1. Primary structure of protein = sequence of amino acids in a polypeptide chain
   - Determines the folds in the secondary structure as R groups interact
   - Determines the specific shape of the tertiary structure and position of hydrogen, ionic and disulfide bonds
2. Quaternary structure is comprised of 4 polypeptide chains (tertiary structured) held together by hydrogen, ionic and disulfide bonds
   - Enables the specific shaped variable region (binding site) to form which is a complementary shape to a specific antigen
   - Enables antigen-antibody complex to form

Question 3

How do antibodies work to destroy pathogens e.g. bacterial cells?

Answer 3

1. Binds to two pathogens at a time (at variable region/binding site) forming an antigen-antibody complex
2. Enables antibodies to clump the pathogens together – agglutination
3. Phagocytes bind to the antibodies and phagocytose many pathogens at once

Note: the hinge region means an antibody can bind to antigens / pathogens different distances part

Question 4

What are antigens?

Answer 4

Antigens are molecules present on the surface of cells, which trigger an immune response.