12.9.1 B Cells: The Humoral Response

Question 1

B Cells: The Humoral Response

Answer 1

• Antigens activate B cells to clone antibody-producing plasma cells and memory B cells that are specific for that antigen.
• T-dependent antigens rely upon helper T cells to stimulate antibody production.
• T-independent antigens elicit a response from B cells without the aid of IL-2 from helper T cells. This response is somewhat weaker than the T-dependent immune response.
• Antibodies are proteins that recognize and bind to specific antigens.

Question 2

humoral response

Answer 2

• The humoral response, shown in the diagram to the left, involves the activation of B cells and the production of antibodies. Free antigens activate B cells to clone
  plasma cells and memory B cells that are specific for that antigen.
• T-dependent antigens require cytokines secreted from
  activated helper T cells to elicit a humoral immune response from B cells.
• Some antigens elicit a response from B cells without the aid of IL-2 secretions from activated helper T cells. These are known as T-independent antigens. The T-independent response is generally weaker than the T-dependent response and no memory cells are produced.
• Some T-independent antigens include polysaccharides of bacterial capsules and proteins in the flagella of bacteria.

Question 3

antobodies

Answer 3

• Antibodies are a class of proteins known as
  immunoglobulins. A basic antibody molecule consists of
  four polypeptide chains—two light chains and two
  heavy chains. The chains are joined together by disulfide bonds to form a “Y-shaped” molecule. The two ends of the antibody consist of variable regions, which form the antigen-binding region that is unique for that antibody. The third end, which consists of the constant regions of the heavy chains, does not vary greatly between antibodies and is responsible for determining the class of the antibody

Question 4

A(n) _____________________ is a harmless variant of a pathogen that stimulates an immune response against the actual pathogen.

Answer 4

• vaccine

Question 5

True or false?
When someone is vaccinated, an immune response to a pathogen is triggered even though the person does not get sick. Memory B cells are then present in the body resulting in an immunity to the disease.

Answer 5

• true

Question 6

True or false?

A B cell doesn’t clone unless its antigen is present.

Answer 6

• true

Question 7

Which statement regarding B lymphocytes is incorrect?

Answer 7

• B lymphocytes mature in the blood.

Question 8

In the late 1700s, Edward Jenner’s discovery of the vaccine was linked to what observation?

Answer 8

• People who milked cows and came down with cowpox did not come down with small pox.

Question 9

An epitope is

Answer 9

• the site on an antigen that binds on to an antibody.

Question 10

_________________ are examples of T-independent antigens.

Answer 10

• Polysaccharides in bacteria cell walls.

- Proteins in the flagella of bacteria