UNIT 2 (topic 4) antibodies and vaccines

Question 1

what is the structure of an antibody

Answer 1

• 4 polypeptide chains - quaternary structure
• two heavy and two light chains
• two antigen-binding sites (variable region)
• rest of the antibody = constant

Question 2

what is agglutination

Answer 2

clumping pathogens together so easier for phagocytes to act

Question 3

what is neutralisation

Answer 3

antibodies act as a marker to stimulate phagocytosis ( constant region binds to phagocyte membrane, antigens bind to variable region)

Question 4

define polyclonal antibodies

Answer 4

• pathogens have different antigens on the surface
• different B cells are activated and divided by mitosis
• secrete antibodies with different active sites

Question 5

define monoclonal antibodies

Answer 5

antibody made in a lab from the cloning of one B-lymphocyte with a tumour cell (hybridoma)

Question 6

how are monoclonal antibodies used in pregnancy tests

Answer 6

• monoclonal antibodies bind to HCG on test strip
• monoclonal antibodies move up the test strip
• bind to another monoclonal antibody in the results window
• if no HCG, no binding until the control window

Question 7

what would a positive and negative pregnancy test look like

Answer 7

positive - 2 lines
negative - 1 line (only control window)

Question 8

differece between active and passive immunity

Answer 8

passive - infectd by disease under normal conditions
active - artificial - vaccinations

Question 9

define antigenic variability

Answer 9

a pathogen that can mutate frequently causing the antigens to change (new strands)

Question 10

define herd immunity

Answer 10

when a large proportion has been vacccinated - makes it difficult for pathogens to spread