Antibodies: Structure and Function Flashcards Preview

PoD Test 1 > Antibodies: Structure and Function > Flashcards

Flashcards in Antibodies: Structure and Function Deck (21)
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1
Q

Describe the bonding between antigen and antibody.

A

Involves several weak forces active over short distances

Covalent bonds are not involved

2
Q

What is the B cell receptor?

A

Located on surface of B cells

Antibodies are a secreted form of the BCR

3
Q

What is the T cell receptor?

A

Located on surface of T cells

Binds MHC molecules presenting peptide on APCs

Key in the recognition of intracellular pathogens

4
Q

What are plasma cells?

A

Activated antibody producing cells

Make antibody in germinal centers locating in the white pulp of spleen, cortex of lymph nodes or in mucosal tissue

5
Q

What is an epitope?

A

Specific antigenic determinants on molecules

A single antigen may have multiple epitopes

6
Q

Describe the structure of immunoglobulins.

A

Consists of 2 identical light polypeptide chain and 2 identical heavy polypeptide chains

An antigen combining site is the result of the interaction between a heavy and light chain variable region

Typical antibody has 2 identical combining sites

7
Q

What happens to the b cell response over time?

A

It becomes better

Mutational events occur in the antigen binding regions during the life of the B cell which give rise to higher affinity binding

This is called somatic mutation

8
Q

What two processes are responsible for generation of antibody diversity?

A

Somatic recombination - gene segment recombination during B cell development

Somatic hypermutation - mutation that occurs at high frequency in the rearranged variable-region DNA segments of antibody genes in activated B cells

9
Q

What are the five classes of antibodies?

A

IgG

IgM

IgD

IgA

IgE

10
Q

Describe the structure and function of IgM.

A

Pentamer

First antibody made in the primary response

Fixes complement

11
Q

Describe the structure and function of IgA.

A

monomeric/dimeric

Major Ig in seromucous secretions

Fixes complement and mediates phagocytosis

12
Q

Describe the structure and function of IgG

A

Secondary antibody response

Fix complement, mediate phagocytosis, cross the placenta

13
Q

Describe the function and structure of IgE

A

Found on surface of mast cells and basophils

Major role in response to parasites and allergic reactions

14
Q

Describe the struccture and function of IgD.

A

Plays a role in eliminating B-lymphocytes generating self-reactive autoantibodies

15
Q

What are isotypic differences?

A

Differences reflect AA differences which make each antibody type different (e.g. IgG from IgE)

16
Q

What are allotypic differences?

A

Slight differences in AA sequence which make IgG from one individual slightly different from IgG in another individual

17
Q

What are idiotypic differences?

A

AA differences found in the variable regions which make up the antigen combining sight

18
Q

What three secondary effector functions are associated with antibody function?

A

Neutralization

Opsonization

Complement activation

19
Q

Describe the neutralization function of antibodies.

A

Neutralize bacterial toxins or prevent bacteria or viruses from binding to cells and entering them

Immune complexes removed by the spleen

20
Q

What is antibody dependent cellular toxicity (ADCC)?

A

Antibodies provide their function by serving as a bridge between an effector cell such as an NK cell or macrophage and a target cell

21
Q

How do eosinophils kill parasites?

A

IgE bind to parasite

Eosinophils bind to the bound IgE via Fc receptors and kill via ADCC