Antibody Structure & Function

Question 1

What are antibodies produced by?

Answer 1

A type of B lymphocyte called Plasma cells

Question 2

What is the antibody produced in response to

Answer 2

Exposure to a foreign antigen

Question 3

Describe the Primary Immune Response in relation to antibody levels

Answer 3

• At time of initial exposure to a foreign antigen, there is no antibody in blood and levels do not begin to increase for a numner of days
• The level of antibody rises slowly towards a low peak and then gradually declines towards baseline

Question 4

Describe the Secondary Immune Response in relation to antibody levels

Answer 4

• On subsequent exposure to same antigen, the level of antibody begins to increase within 24 hours and reaches a high level which is sustained

Question 5

The 3 different fractions that plasma proteins are made of?

Answer 5

1. Albumin
2. Globulins
3. Fibrinogen

Question 6

What are antibodies and what may they be referred to as?

Answer 6

Antibodies are proteins. They are referred to as gamma (Immuno) globulins.

Question 7

What does each immunoglobulin consist of

Answer 7

Two heavy chains and two light chains

Question 8

What is contained within the variable region of antibodies

Answer 8

Antigen combining bond sites

Question 9

What are the light and heavy chains held together by

Answer 9

Disulfide bonds

Question 10

What happens at the variable regions of the antibodies

Answer 10

The antibody binds to its specific antigen at the variable region

Question 11

What are the other regions/domains called?

Answer 11

The constant region

Question 12

Function of the constant region

Answer 12

• Anchors the antibody to the surface of the cells of the reticuloendothelial system (monocytes and macrophages) that are involved in the destruction of the cell carrying a foreign antigen
• Important in binding complement
• Determining the ability of an antibody to cross the placenta

Question 13

What does the Hinge Region of the antibody do

Answer 13

Gives the molecule flexibility so the antigen binding sites may operate independently

Question 14

What is the J-chain of an antibody

Answer 14

An additional protein found in IgM pentamer and IgA dimers which, along with the disulfide bonds, is involved in holding the Immunoglobulin (Ig) units together

Question 15

Properties of IgG vs IgM antibodies

Type of heavy chain IgG

Answer 15

Gamma

Question 16

Properties of IgG vs IgM antibodies

Type of heavy chain IgM

Answer 16

Mu

Question 17

Properties of IgG vs IgM antibodies

No. of antigen combining sites per molecule IgG

Answer 17

2

Question 18

Properties of IgG vs IgM antibodies

No. of antigen combining sites per molecule IgM

Answer 18

10

Question 19

Properties of IgG vs IgM antibodies

Placental transfer IgG

Answer 19

YES

Question 20

Properties of IgG vs IgM antibodies

Placental transfer IgM

Answer 20

NO

Question 21

Properties of IgG vs IgM antibodies

Opt temp for rxn IgG

Answer 21

37 degrees C

Question 22

Properties of IgG vs IgM antibodies

Opt temp for rxn IgM

Answer 22

4-20 degrees C

Question 23

Properties of IgG vs IgM antibodies

Primary immune response involvement IgG

Answer 23

RARE

Question 24

Properties of IgG vs IgM antibodies

Primary immune response involvement IgM

Answer 24

YES

Question 25

Properties of IgG vs IgM antibodies

Secondary immune response involvement IgG

Answer 25

YES

Question 26

Properties of IgG vs IgM antibodies

Secondary immune response involvement IgM

Answer 26

RARE