topic 11.1- antibody production and vaccination

Question 1

every organism has —– ——– on the surface of their cells

Answer 1

unique molecules

Question 2

antigens on the surface of red blood cells

Answer 2

stimulate antibody production in a person with a different blood group

Question 3

describe the presence and absence of antigens on the surface of blood cells from different blood groups

Answer 3

• all three alleles involve a basic antigen sequence called antigen H
  A: this is modified by the addition of molecule N-acetylgalactosamine
  B: additional molecule is galactose
  AB: both types of antigen
  O: neither surface glycoprotein

Question 4

what happens if a recipient is given a transfusion involving the wrong type of blood?

Answer 4

an immune response occurs. antibodies are produced, agglutination (clumping) occurs, followed by hemolysis where red blood cells are destroyed and blood may coagulate in vessels

Question 5

describe an immune response

Answer 5

1. macrophage ingests pathogen and displays antigens on it
2. helper T cell specific to the antigen is activated by the macrophage
3. B cell specific to the antigen is activated by proteins from the helper T cell
4. B cell divides repeatedly to produce antibody-secreting plasma cells
5. B cell also divides to produce memory cells
6. antibodies produced by the clone of plasma cells are specific to antigens on the pathogen and help destroy it

Question 6

how does activation of helper T cells work?

Answer 6

they have an antibody-like receptor protein in their plasma membranes, which can bind to antigens displayed by macrophages

Question 7

how does the structure of plasma cells relate to their function?

Answer 7

• the cytoplasm contains an extensive network of rough endoplasmic reticulum (rER), which manufactures, modifies, and transports proteins (antibodies).
• The range of genes expressed is lower than a typical cell as the cell produces a lot of the same protein

Question 8

define clonal selection

Answer 8

the generation of large numbers of plasma cells that produce one specific antibody type

Question 9

give and explain 4 ways in which antibodies aid the destruction of pathogens

Answer 9

1. opsonisation- make the pathogen more recognisable to phagocytes so they are more readily engulfed. also, once bound, they can link the pathogen to phagocytes
2. neutralisation of viruses and bacteria: antibodies prevent viruses from docking to / entering host cells
3. neutralisation of toxins- bind to the toxins produced by pathogens, preventing them from affecting susceptible cells
4. activation of complement- antibodies activate a complement cascade which leads to the formation of a membrane attack complex that forms a pore in the membrane of the pathogen allowing water and ions to enter the cell and causing lysis
5. agglutination of pathogens, preventing cell entry and aiding ingestion by pathogens

Question 10

what is the complement system?

Answer 10

a collection of proteins which ultimately lead to the perforation of the membranes of pathogens

Question 11

what does immunity depend upon?

Answer 11

the persistence of memory cells

Question 12

describe how vaccines lead to immunity

Answer 12

they contain antigens that trigger immunity by causing a primary immune response but do not cause the disease

if the actual pathogen enters the body, it will be destroyed by the antibodies in a secondary immune response

Question 13

what was the first infectious disease of humans to have been eradicated by vaccination?

Answer 13

smallpox

Question 14

give 3 reasons why the smallpox eradication campaign was successful

Answer 14

• only humans can catch and transmit smallpox. there is no reservoir where the disease could be maintained and re-emerged
• symptoms of infection emerge quickly and are readily visible allowing teams to ‘ring vaccinate’ all of the people who might have come into contact with the afflicted person
• immunity is long-lasting

Question 15

pathogens can either be

Answer 15

species-specific or able to cross species barriers

Question 16

define a zoonosis

Answer 16

a pathogen which can cross a species barrier
these are a growing health concern

Question 17

Sensitization: Initial exposure to allergen and

Allergic Reaction: Secondary exposure to same allergen

Answer 17

1. when a specific B cell first encounters the allergen, it differentiates into plasma cells and makes large quantities of antibody (IgE)
2. the IgE antibodies attach to mast cells, effectively ‘priming’ them towards the allergen
3. upon re-exposure to the allergen, the IgE-primed mast cells release large amounts of histamine which causes inflammation

Question 18

when and how are histamines released?

Answer 18

• by mast cells (immune cells found in connective tissue) secrete histamine in response to infection
• by basophils which circulate in the blood

Question 19

state the effect of histamine on blood vessels

Answer 19

causes the dilation of the small blood vessels in the infected area causing the vessels to become leaky. This increases the flow of fluid containing immune components to the infected area and allows for some of the immune components to leave the blood vessel resulting in both specific and non-specific responses.

Question 20

symptoms of an allergic reaction

Answer 20

nose: itching, fluid build-up, sneezing, mucus secretion and inflammation
allergic rashes and dangerous swelling (anaphylaxis)

Question 21

define monoclonal antibodies

Answer 21

highly specific, purified antibodies that are produced by a clone of cells derived from a single cell. they recognise only one antigen

Question 22

what is the use of monoclonal antibodies?

Answer 22

the treatment and diagnosis of diseases; eg the test for malaria or the creation of antibodies for injection into rabies victims

Question 23

define a hybridoma cell

Answer 23

the cells formed by fusion of antibody-producing plasma B cells and myeloma (tumour) cells, which produce monoclonal antibodies

Question 24

describe how hybridoma cells are created

Answer 24

1. antigen recognised by the antibody is injected into a mouse or other mammal
2. the mouse’s immune system makes plasma B cells that are capable of producing the desired antibody
3. plasma cells are removed from the spleen of the mouse and fused with cancer cells called myeloma cells

Question 25

describe how pregnancy tests work with a diagram

Answer 25

kits use monoclonal antibodies to detect hCG, which is produced during pregnancy by the developing embryo and the placenta. the urine of pregnant women contains detectable levels of hCG

1. free monoclonal antibodies specific to hCG are conjugated to an enzyme that changes the colour of a dye
2. a second set of monoclonal antibodies specific to hCG are immobilised to the dye substrate
3. if hCG is present in urine, it will interact with both sets of monoclonal antibody (forming an antibody ‘sandwich’)
4. when both sets of antibody are bound to hCG, the enzyme is brought into physical proximity with the dye, changing its colour
5. a third set of monoclonal antibodies will bind any unattached enzyme-linked antibodies, functioning as a control