houmoural response

Question 1

Where do B-lymphocytes mature

Answer 1

-B-lymphocytes mature and are produced in the Bone marrow

Question 2

What are the steps in humoral response

Answer 2

• T helper cell stimulates by binding to B lymphocytes

• T lymphocytes have specific receptors that allow it to bind to the antigen

• Once the B lymphocyte has been stimulated by binding to both the antigen and specific T helper cells, this activates cloning of B cells into
– memory B cells with the specific antibodies.
- plasma cells which secrete the specific Antibodies.

Question 3

what is the primary response

Answer 3

• The B cells begin to divide by mitosis (clone themselves) to form plasma cells and memory cells this is known as clonal selection. Plasma cells produce antibodies that are complimentary to the antigens.

Question 4

What is secondary response

Answer 4

• The memory cells stay in the blood stream circulating. If they come into contact with the antigen again they divide to form plasma cells and memory cells again.

Question 5

What is the structure of antibodies

Answer 5

•Four polypeptide chains which are held together by disulphide bridges.

•Constant region : the same for all antibodies; enables antibodies to attach to phagocytic cells; helps the process of phagocytosis.

•Variable region : specific shape (differs from one antibody to the next) due to its amino acid sequence – ensures that the antibody can only attach to the correct antigen. Variable region shape is complementary to the antigen shape.

•Hinge regions : allow flexibility so that the molecule can move further apart and attach to more than one antigen.

Question 6

What is an antibody

Answer 6

-Antibodies are large quaternary structure proteins also known as immunoglobulins.

Question 7

What is the evidence that antibodies are quaternary structure

Answer 7

-More than one polypeptide chains

Question 8

How do antibodies defend the body?

Answer 8

1. Agglutination
   Antibodies can cause antigen-antibody complexes to clump together.This makes it easier for phagocytes to engulf them.
2. Opsonin production
   Antibodies can act as opsonins (markers), which aids phagocytosis.
3. Neutralisation
   Some pathogens make us ill by producing toxins.Some antibodies work by binding to the toxins and
   neutralising them.

Question 9

What is a vaccine

Answer 9

A low dose of an inactive/dead pathogen are injected-contain antigens to trigger immune response, creating protective memory cells

Question 10

What is herd immunity

Answer 10

If more members of a population have had a vaccine, more people are then protected as a disease can spread less rapidly, even if they haven’t had the vaccine themselves.

Question 11

Why don’t vaccinations fully eliminate diseases?

Answer 11

1. Fails to induce immunity in some people (immunodeficiency)
2. Antigenic variability - pathogens can mutate
3. Many different strains - can’t vaccinate against all
4. Objections to vaccinations based on moral, religious and ethical grounds