Immunoglobulins

Question 1

What are immunoglobulins?

Answer 1

A type of antibody

Produced by plasma (B) cells

Question 2

Name the immunoglobulins.

Answer 2

IgG
IgA
IgM
IgD
IgE

Question 3

Which immunoglobulin is the main effector of humoral immunity?

Answer 3

IgG

Question 4

What shape is IgG?

Answer 4

Monomer

Question 5

Which immunoglobulin is the main line of defence against foreign antigens?

Answer 5

IgG

Question 6

Which immunoglobulin crosses the placenta?

Answer 6

IgG

Question 7

Which immunoglobulin is associated with mucosal surfaces?

Answer 7

IgA

Question 8

Which immunoglobulin is found in body secretions like colostrum and tears?

Answer 8

IgA

Question 9

What shape is IgA?

Answer 9

Dimer

Question 10

What shape is IgM?

Answer 10

Pentamer

Question 11

Where is IgM found?

Answer 11

Just floating in the circulation

Question 12

Which immunoglobulin is the first line of defence?

Answer 12

IgM

Question 13

Describe IgM.

Answer 13

Low affinity and specificity

Question 14

Which immunoglobulins are associated with the B cell membrane?

Answer 14

IgM

Mostly IgD

Question 15

What shape is IgD?

Answer 15

Monomer

Question 16

Which immunoglobulin is associated with allergic responses?

Answer 16

IgE

Question 17

What shape is IgE?

Answer 17

Monomer

Question 18

What is the structure of immunoglobulins?

Answer 18

Fc fragments: they all have similar Fc fragments

Fab fragments: diverse, they all have different Fab fragments

Question 19

What is an epitope?

Answer 19

The portion of the antigen that binds to the antibody

Question 20

What forces help antibodies & antigens interact?

Answer 20

Ionic
Covalent
H bonds
Van der Waals
Hydrophobicity

Question 21

Describe the clonal selection theory!

Answer 21

There is a vast array of B-cells in the body which would each make a different antibody, these are called naïve B cells

The ones that recognise self are destroyed during development

When a B cell is exposed to an antigen, it changes and becomes a mature B cell. It changes such that it can produce high affinity antibodies.

Question 22

What is opsonisation?

Answer 22

Antibodies coat the pathogen, binding to it via their Fab fragments.

Phagocytes have Fc receptors, so they recognise the Fc fragments on the antibodies coating the pathogen.

The phagocyte binds to the Fc fragments and engulfs the pathogen

Question 23

What is meant by complement fixation?

Answer 23

Antibodies binding to multiple molecules of antigens brings lots of Fc regions together

This assembly of Fc regions causes the binding of components of the complement pathway and initiates the formation of the membrane attack complex

Question 24

What is the membrane attack complex?

Answer 24

Formation of channels in the cell wall of the pathogen which disrupt the membrane causing cell lysis and death

Question 25

What is 'antibody-dependent cell-mediated cytotoxicity' (ADCC)?

Answer 25

The target pathogen is coated with antibodies Lymphocytes lyse the antibody coated pathogen when their Fc receptors bind to the Fc fragments of the antibodies

Question 26

What immunoglobulins are formed by newly formed B cells?

Answer 26

IgM

Question 27

What immunoglobulins are formed by mature B cells?

Answer 27

IgM and IgD

Question 28

How do T and B cells work together?

Answer 28

Antigens are captured by B cells The B cells are processed and digested into peptides The B cells then present the peptides to the T cells (T cells can only recognise peptides rather than whole antigens)