1. Topic 11.1

2. Every organism has unique molecules on the surface of their cells
Define antigens-
A: any foreign molecule that can trigger an immune response
What do these two antigens do for the flu virus:
a. Hemagglutinin- allows the virus to stick to host cells.
b. Neuraminidase- helps with the release of newly formed virus particles.

3. Antigens on the surface of blood cells stimulate antibody production in a
Describe what happens if a person is given a transfusion with an incorrect blood type.
A: Agglutination followed by hemolysis where the blood cells are destroyed.

4. B Lymphocytes are activated by T lymphocytes in mammals
Explain the principle called “challenge and response”.
A: It explains how antibodies are formed without producing all the other antibodies that could be produced. The challenge are the antigens on the pathogens and the response is antibody production.

5. Antigen presentation and T lymphocyte activation
11.1.U3 B lymphocytes are activated by T lymphocytes in mammals.
Antigen presentation and T lymphocyte activation
Helper T cells are the major driving force and the main regulators of the immune defense. Their primary task is to activate B-cells and killer T cells (not dealt with in this syllabus).
n.b. there are many different Helper T cells and B-cells which response to different antigens.
B lymphocyte activation
The B-cell searches for antigen matching its receptors. If it finds such antigen it connects to it, but the B-cell needs proteins produced by helper T cells to become fully activated.

6. Plasma cell and antibody production
11.1.U4 Activated B cells multiply to form clones of plasma cells and memory cells. AND 11.1.U5 Plasma cells secrete antibodies. AND 11.1.U6 Antibodies aid the destruction of pathogens.
Plasma cell and antibody production
Plasma cells are specialized in producing a specific antibody that matched the B-cell receptor. Plasma cells can produce tens of thousands of antibodies per second!!
Pathogen destruction and the formation of memory cells
T-cells can also produce memory cells with an even longer life span than B memory cells. Subsequent infections by the same pathogen therefore provoke a much more rapid immune response. If little or no symptoms are experienced the organism is said to be immune.

7. B Lymphocytes are activated by T lymphocytes in mammals
Draw and annotate the steps the steps of a response.
1. A macrophage ingest the pathogen and displays its antigens.
2. A helper T cell specific to that antigen is activated.
3. The helper T cell activates B cell specific to the antigen.
4. B cell divides to produce plasma cells and memory cells
5. Antibodies specific to the pathogen help to destroy it.

8. Plasma cells secrete antibodies
What is the role of plasma cells in the immune response?
a: To produce and secrete a large number of antibodies during an immune response.
Why does the plasma cells cytoplasm contain extensive rough endoplasmic reticulum?
A: Because the ER transports proteins (antibodies).

10. Activated B cells multiply to form a clone of plasma cells and memory cells
What is clonal selection? How long do they last?
A: The generation of large numbers of plasma cells that produce antibodies. They last a few weeks or months.
How are memory cells different from the clone of the B cells?
A: They remain long after the infection and are inactive until that same pathogen infects the body.

11. Antibodies aid the destruction of pathogens
Describe the following ways in which antibodies aid in the destruction of a pathogen:
1. Opsonization- make the pathogen more recognizable.
2. Neutralization of Viruses- prevent the viruses from attaching to the host cells.
3. Neutralization of Toxins- bind to the toxins to keep them from entering the cells.
4. Activation of Compliment- forms a membrane attack complex that puts pores in the membrane.
5. Agglutination- sticking together of pathogens making them easier to destroy.

12. Immunity depends upon the persistence of memory cells
Describe how a primary and secondary response are different.
A: Secondary occurs more rapidly and produces more antibodies.