Antibodies 2

Question 1

each variable region has 3 small regions called …

Answer 1

Hypervariable or Complemantarity
Determining regions

Question 2

hypervariable regions are responsible for …

Answer 2

antigen interaction + binding

Question 3

extreme aa sequence variability of hypervariable regions provides…

Answer 3

more than 108 different antigen binding specificities

Question 4

hypervariable regions of both chains make…

Answer 4

initial contact with antigen

Question 5

hypervariable loops

Answer 5

when hypervariable regions fold together into a 3D shapes to create loops

Question 6

when do hypervariable regions have the same structure?

Answer 6

when they are within the 2 arms of an antibody molecule

Question 7

hypervariable regions on antibody contact a region of antigen called ….. which has complementary shapes

Answer 7

epitope

Question 8

initial contact b/w antigen and antibody is stablisised by what bonds?

Answer 8

• H bonds
• electrostatic
• hydrophobic
• van der waals forces

Question 9

antigen/antibody

what is affinity?

Answer 9

strength of Ag/Ab binding

Question 10

higher affinity comes from…

Answer 10

closeness of fit

Question 11

antibodies can be made from different B cell clones to interact with :

Answer 11

• different epitopes on different antigens
• different epitopes on single antigen
• same epitope on one antigen

Question 12

antibodies bind to epitopes with different affinities depending on :

Answer 12

• number of complementary shapes b/w HV regions and antigen
• nature of forces existing b/w complementary shapes

Question 13

half life of an antibody?

Answer 13

few weeks

Question 14

what does half life of an antibody mean?

Answer 14

survival time of antibodies after being made by B cells

Question 15

B cell primary + secondary response

Answer 15

notes :0

Question 16

complement activation

Answer 16

• effector response
• plasma proteins activated by Ab/Ag complexes
• release of cytokines + proteases
• further activates complement system
• formation of membrane attack complex
• creating channels
• disrupting fluid/ions balance
• cell lysis

Question 17

opsonisation

Answer 17

• Ab/Ag complexes recruit phagocytes such as macropahges, neutrophils + APCs
• phagocytosis + destruction of Ag

Question 18

antibody dependent cell mediated cytotoxicity ( ADCC )

Answer 18

• binding of Fc to FcR on NK cells
• activation
• release of cytolytic granules
• cell lysis
  *

Question 19

conformational change

Answer 19

• Ab/Ag binding changes conformational shape of antigen
• modulates its biological effect or inhibit its entry to cell
• antigen becomes inactive

Question 20

function of IgG

Answer 20

• main class
• can cross placenta to protect foetus
• longest half-life
• excellent at activating complement system
• efficient & diverse opsonin
• main class in secondary response

Question 21

function of IgM

Answer 21

• first antibody made by plasma cells
• main class in primary response
• first antibody class made by foetus
• high affinity
• good opsonin

Question 22

function of IgA

Answer 22

• fist line protection for external surfaces
• mediates localised mucosal response
• secretory piece protects from degradation
• doesn’t activate complement system
• binds Fc receptor on immune cell - initiates inflammation

Question 23

function of IgD

Answer 23

• not known
• lowest circulatory concentration
• does not activate complement system

Question 24

function of IgE

Answer 24

• harmful + useful functions
• allergies - harmful - binds FcR on mast cells of basophils - degranulates histamine
• parasitic infections - protective - binds FcR on mast cells on eosinophils - release cytokine and inflammatory mediators
• low conc except allergies and infections