Specific+Immunity+HW3+MC

1. B cells and T cells have antigen receptors on their surface. What is an antigen receptor? (p. 130) - They are plasma membrane receptor proteins, whose shape allows them to combine with particular antigens. 2. If the antigen is the key, what is the lock? (p.130) If the antigen is the key, then the lock is the receptor. Its often said that the receptor and the antigen fit together like a lock and key. 3. How many types of antigen receptors does one T cell or B cell have? (p. 130) We encounter a million different antigens during our lifetime, we need diversity of B cells and T cells to protect us against them. 4. How many different types of B cells and T cells do we need? Why? (p. 130) There are 2 types of B cells and 3 types of T cells. We need them because we need to be protected from the million different antigens during our lifetime. T cells regulate immune response and produce cytotoxic T cells and helper T cells. B cells produce plasma cells and memory cells. 5. How many different types of B cell and T cells do we have? (p. 130) We have 2 types of B cells and 3 types of T cells. 6. What is the special name for the antigen receptor on a B cell? (p. 131) The receptor on a B cell is called B-cell receptor or BCR. 7. If an antigen and a B-cell receptor make a lock and key match, what does the B-cell do? (p. 131) The B- cell produces multiple copies of itself. 8. What does clonal expansion of the B-cells mean? When does this occur? (p. 131) During clonal expansion, cytokines secreted by helper T cells stimulate B cells to clone. Most of the cloned B cells become plasma cells. This occurs when only the B cell with a BCR has a shape that fits the antigen. 9. What are plasma cells? (p. 131) Plasma cells circulate in the blood and lymph. 10. What is an antibody with respect to the B-cell receptor? (p.131) They are identical to the BCR of the B cell that was activated. 11. What are memory cells? (p. 131) It’s the means by which long-term immunity is possible. 12. Why is B-cell defense called antibody mediated defense? (p.131) Because activated B cells become plasma cells that produce antibodies, as many as 2 million different antibodies. 13. How do antibodies fight infection? (p.132) The antibodies in an immune complex are like beacon that attracts white bloods that move in for the kill. Antigens combine with antibodies, termed an immune complex. 14. What is the name for the antigen receptor on a T-cell? (p. 134) It’s called a T-cell receptor or TCR. 15. T cell receptors cannot recognize antigen alone, the antigen must be attached to a self protein on a self cell. This protein is called the... (p. 134) This protein is called the HLA or human leukocyte antigens. 16. If the T cell lock matches an antigen key, what happens to the T cell? (p. 134) The T cell does the same thing that the B cell did. It produces activated T cells or multiple copies of the activated T cell are made 17. What do cytotoxic T cells do to cells that have antigens that match their T-cell receptor? (p. 135) They kill them. 18. How do helper T-cells indirectly fight disease? (p. 135) they help specific T cells and kill cyototoxic cells.

19. Which of pertain(s) to B cells? a. have specific receptors b. are responsible for antibody mediated immunity—correct answer c. synthesize and liberate antibodies

20. Which of these pertain(s) to cytotoxic-T cells? a. have specific receptors b. are more than one type c. are responsible for cell-mediated immunity—correct answers d. stimulate antibody production by B-cells