Antibodies

Front 1

What are antibodies?

Back 1

Proteins made by B lymphocytes, also called ummunoglobulins (Igs)
-Circulate in blood and other fluids

Front 2

What is Humoral immunity?

Back 2

Immunitiy that is due to antibodies is called humoral immunity because humoral means fluids

Front 3

What are the functions of antibodies?

Back 3

They have numerous protective roles
-Prevent virus, bacteria or toxins from binding to cells (binding is an important step in infectioN) (Preventing them from entering cells)
-Target antigens for phagocytosis by neutrophils and macrophages (opsonization)
-They allow more types of bacteria to be killed efficiently by complement proteins (Activate Complement)

Front 4

Where do antibodies bind to?

Back 4

Single antibody molecule binds to only a small portion of the antigen molecule called the epitope or antigenic determinant. Epitopes are unique three dimensional structures
-Antigen binding site of the antibody has a shape that is complementary to that of the epitope and it fits like a lock and key model

Front 5

Different antibodies have antigen binding sites with different shapes and

Back 5

will therefore bind epitopes with different three diemnsional structures

Front 6

Describe epitopes

Back 6

-Have distinct 3d shape
-About 4-5 amino acids in size
-Amino acids do not have to be in a linear sequence
-Antigens have many different eptiopes (could be on the same antigen)

Front 7

Describe the antigen binding site of anitbodies

Back 7

-Antigen binding site is a three dimensional pocket made by the combination of the Vh and VL regions
-Side chains of the amino acids in the pocket play an important role in antigen binding (size, charge of R group)

Front 8

What is the structure of antibodies?

Back 8

All antibodies have 4 polypetide chains, 2 identical heavy chains and 2 identical light chains
-

Front 9

What are the two types of light chains?

Back 9

Kappa chain
lambda chain

Front 10

What are the five types of heavy chains?

Back 10

Gamma (y)
mu (u)
epsilon (e)
alpha (a)

Front 11

What determines the immunoglobulin class?

Back 11

The type of H chain determines this

Front 12

List the antibody classes and what chains they have

Back 12

IgG Abs have gamma heavy chains
IgM have u heavy chains
IgD has sigma delta heavy chains
IgE has epsilon heavy chains
IgA has alpha heavy chains

Front 13

What are some properties of immunoglobuins?

Back 13

They have different functions in the immune system
-All can be membrane bound or secreted (except IgD which is only found on the membrane of naive B cells)

Front 14

Immoglobulins of each type can have what?

Back 14

Either L chain (Kappa) or lambda but not both
-Ex: gamma2kappa2 antibodies are IgG antibodies as well as gamma2lambda2 since they have the same gamma heavy chain

Front 15

What are the two heavy and two light chains held together by?

Back 15

disulfide bonds

Front 16

What various from one to another in the antibodies?

Back 16

the N-terminal portions of the H and L chains are the variable regions (Vh and VL) and vary from one antibody to another

Front 17

What stays constant from one to another in antibodies?

Back 17

The rest of the H and L chains are the constant regions that are identical for all chains in that type (all gamma chains have similar constant regions)

Front 18

What are hypervariable regions?

Back 18

These are regions of the Vh and VL make up the antibody binding sites of the antibody
-These regions contribute signically to the antigen binding site and are part of the antibody that contacts the antigen

Front 19

What enhances antigen binding?

Back 19

Epitopes with different shapes that do not make close contact with surface of antigen binding site will not bind to antibody

Front 20

What is the constant region?

Back 20

WIthin a given species of mammals, the amino acid sequences are identical for all antibodies with that type of immunoglobun chain