Antibody Function

Question 1

What are the two jobs of antibody?

Answer 1

Recognise Ag and help eliminate it or eliminate it on their own

Question 2

2 ways to find Ab are:

Answer 2

Transmembrane and secreted

Question 3

Regions of secreted:

Answer 3

Fab binds Ag, Fc is tail

Question 4

Which bit of Ab interacts with Ag? how?

Answer 4

CDRs have AAs complementary to Ag Epitope

Question 5

What size should the epitope be?

Answer 5

About 2.5nm^2

Question 6

Can more than 1 ab bind a pathogen?

Answer 6

Yes - different epitopes

Question 7

What are discontinuous epitopes?

Answer 7

When binding a protein Ag, the tertiary structure is important (conformation rather than sequence)

Question 8

How many CDRs used in binding?

Answer 8

Usually all 6 contribute, some are more important

Question 9

4 forces involved in Ab Ag binding:

Answer 9

H bond, Electrostatic, VdW, Hydrophobic

Question 10

Property of these bonds:

Answer 10

Reversible so need close interaction

Question 11

What is multivalent bonding, why is it better?

Answer 11

When both fab arms of 1 Ab or 5/6 of a polym Ab bind - stronger

Question 12

Amount of Ab in order

Answer 12

GAMDE

Question 13

How do you switch from membrane to secreted Antibody?

Answer 13

in the Cmue bit, mue 1 and mue 2 exons encode a stretch of hydrophobic AA - antibody gets stuck to cell surface
If plasma cell - stop using them so secreted

Question 14

3 things Antibodies can act on their own to do:

Answer 14

Neutralise Bacterial Toxins
Block viruses binding to their cellular receptor
Block adherence of bacteria to mucosal surfaces

Question 15

What do antibodies mainly do?

Answer 15

Bridge between Ag and other cells

Question 16

Which antibodies are good at direct neutralisation?

Answer 16

IgM, IgA, IgG

Question 17

How do RBCs clear immune complexes?

Answer 17

Have CR1 which recognises C3b to Ab/Ag - clears it

Question 18

Example of opsonisation by Ab

Answer 18

FcgammaR on phag cells bind IgG on path - engulf path

Question 19

Which antibodies activate complement?

Answer 19

IgG and IgM

Question 20

Killer cells and Ig?

Answer 20

FcR recognises Ab on path - kills it

Question 21

Which Ab contributes to inflammation? how?

Answer 21

IgE - mast cells

Question 22

What is the most abundant antibody in blood?

Answer 22

IgG1

Question 23

Which Abs can cross placenta?

Answer 23

IgG1, IgG3 and 4

Question 24

What does IgA do?

Answer 24

protects mucousal surfaces