Antibodies!

Question 1

Antibodies

Answer 1

Proteins produced by cells of the immune system responsible for identifying non-self molecules and microbes

Tag microbes as invaders for others parts of immune system to destroy, or directly neutralize invader

Question 2

Antigens

Answer 2

Non-self molecules and microbes

Question 3

What kinds of antibodies exist?

Answer 3

IgM, IgG, IgA, IgE, IgD

IgG makes up 80% of total antibodies in serum

Question 4

IgG

Answer 4

Main antibody, Y-shaped, 80% of antibodies in serum, neutralizes toxins, opsonization

Question 5

Where do antibodies come from?

Answer 5

B cells differentiate into plasma cells and plasma cells produce antibodies

Question 6

Differences between B cell receptor and antibody?

Answer 6

B cell receptor has a part of the protein that anchors the protein to the cell membrane, which secreted antibody lacks

Question 7

Opsonization

Answer 7

Facilitation of phagocytosis

Question 8

Various ways antibodies inactivate antigens

Answer 8

Phagocytosis, cell lysis

Phagocytosis:

1. Viral neutralization, opsonization
2. Agglutination of antigen-bearing particles
3. Precipitation of soluble antigens

Cell lysis:
4. Activation of complement system

Question 9

Immunological Memory

Answer 9

B cells differentiate into both plasma cells and memory cells, which in future can respond rapidly to infections by producing antibodies

Question 10

Passive Immunity

Answer 10

Transfer antibodies from one person to another. Temporary, leaves no immunological memory.

e.g. breast feeding

Question 11

Active immunity

Answer 11

Immunity provided by B cell differentiation, including immunological memory

Question 12

Structure of IgG antibodies

Answer 12

1. Two heavy chains and two light chains
2. Two antigen binding sites (each tip of the Y)
3. Constant region (Fc) - same in all antibodies from a given animal
4. Variable region (Fab) - gives specificity to antigen binding site

Each B cells makes antigens with UNIQUE binding site

Question 13

Generation of antibody diversity

Answer 13

V, D, and J segments are chosen from a whole list of options for each, known as VDJ Recombination.

There are three for the light chain and three for the heavy chain, so for each antigen there is a unique combination of six proteins.

Question 14

Where do antibodies mediate immune response

Answer 14

Lymph nodes, spleen

Question 15

How do antibodies mediate immune response

Answer 15

Macrophage pathway, B cell pathway

Question 16

Macrophage Pathway

Answer 16

1. Processed antigen presented by macrophage
2. Helper T cells activated
3. Helper T cells secrete cytokines, stimulating B cells

Question 17

B cell pathway

Answer 17

1. Antigen binds to B cell receptor
2. Plasma cells activated and secrete specific antibodies
3. Antibodies do their thang!

Question 18

How are antibodies used in Western blot?

Answer 18

Primary antibodies specific to a particular protein are introduced into solution and bind to that protein.

Then secondary antibodies that bind to the Fc region of those primary antibodies, and that typically introduce an accompanying color change or light release when they bind, are introduced.