Antibodies (year 2)

Question 1

define an antigen

Answer 1

any molecule that can bind specifically to an antibody or antigen receptor

Question 2

define an epitope

Answer 2

site in an antigen recognised by an antibody or antigen receptor

Question 3

define an antibody

Answer 3

protein that binds specifically to an antigen

Question 4

what is affinity?

Answer 4

binding of one antigen binding fragment (Fab) region to one epitope

Question 5

what is avidity?

Answer 5

overall attraction between antigen and antibody - able to bind to more than one epitope

Question 6

what does high avidity and affinity mean for the function of the antibody?

Answer 6

carries out its function well, if they don’t bind well to the pathogen then they won’t work properly

Question 7

what immune response are antibodies apart of?

Answer 7

humoral - produced by B cells

Question 8

what cells produce antibodies?

Answer 8

B cells

Question 9

name the 5 classes of immunoglobulin

Answer 9

IgM, IgG, IgA, IgE, IgD

Question 10

where are the three main classes of antibody produced?

Answer 10

IgM - spleen/lymph nodes
IgG - spleen/lymph nodes
IgA - locally in mucosal systems (GI/respiratory)

Question 11

what species of animal is IgD mainly found in?

Answer 11

fish

Question 12

describe the structure of IgG

Answer 12

Y shaped structure with hinge regions and two antigen binding sites

Question 13

describe the structure of IgM

Answer 13

pentameric structure with 5 subunits joined by glycoprotein bonds

Question 14

describe the structure of IgA

Answer 14

2 subunit structure joined by a J chain

Question 15

what are the two regions of an immunoglobulin subunit?

Answer 15

constant and variable

Question 16

what is the role of the constant region of an immunoglobulin?

Answer 16

interacts with the hosts cells and can alter the effector function, delivers antibody to specific areas and helps to initiate the compliment cascade and when it changes it is known as class switching

Question 17

what triggers class switching?

Answer 17

cytokines

Question 18

what is the role of the variable region on immunoglobulins?

Answer 18

free to interact with the pathogen

Question 19

what is the main isotope of immunoglobulin produced during a primary immune response?

Answer 19

M

Question 20

what is the main isotope of immunoglobulin present during a secondary immune response?

Answer 20

IgG and IgA

Question 21

describe the length and magnitude of primary and secondary immune responses

Answer 21

primary - short lived and low magnitude

secondary - rapid and longer duration with higher magnitude

Question 22

why does class switching from IgM to IgG and IgA occur?

Answer 22

IgA and IgG have a higher affinity for antigens than IgM

Question 23

where is the primary immune response initiated?

Answer 23

local lymph nodes

Question 24

where is the secondary immune response initiated?

Answer 24

local lymphoid tissue

Question 25

what are the two cells that synthesise antibody?

Answer 25

blasting B lymphocytes

plasma cells

Question 26

where are the plasma and blasting B lymphocyte cells that synthesise antibody located?

Answer 26

in germinal centres

Question 27

what are the three main functions of antibody?

Answer 27

neutralise pathogens
activate complement
opsonisation

Question 28

what does neutralisation of pathogens prevent?

Answer 28

pathogen attachment
invasion of host cells
replication
toxin production

Question 29

IgA is a tissue specific effector, describe this process?

Answer 29

secreted locally to mucosal tissue then binds to polymeric Ig receptor and passes into the lumen of the enterocyte
the receptor is then proteolysed to leave the secretory component protecting IgA