Immunity AS

Question 1

define pathogen

Answer 1

microorganisms that cause disease

Question 2

how do pathogens cause disease

Answer 2

damage cells/tissues and produce toxins

Question 3

non specific defenses

Answer 3

barriers/phagocytes

Question 4

specific defence

Answer 4

lymphocytes

Question 5

how do lymphocytes learn to recognise your own body cells

Answer 5

proteins on surface allow cells to be distinguished from one another in foetus adult lymphocytes collide with own material. if lymphocytes fit with body cells they are deleted (apoptosis)

Question 6

what cells can lymphocytes distinguish between

Answer 6

pathogens, non-self material, toxins, cancer cells

Question 7

where do T cell develop

Answer 7

Thymus

Question 8

what are T cells associated with

Answer 8

cell mediated immunity

Question 9

where do B cells mature

Answer 9

bone marrow

Question 10

what are B cells associated with

Answer 10

antibodies/humoral immunity. memory and plasma cells

Question 11

function of memory cells

Answer 11

carry immunological memory of the specific antigen

Question 12

steps of cell mediated immunity

Answer 12

pathogen contains antigens. pathogen taken up by phagocyte and presented on surface. binds

Question 13

phagocytosis

Answer 13

phagocyte recognises antigens or chemicals on pathogen as foreign. phagocyte attaches to chemicals on pathogen. engulfs pathogen. bacteria in phagosome (vacuole) lysosome empties vacuole bacteria digested

Question 14

stages of humoural response

Answer 14

B cell presents antigen. T cell attaches and actives B cell. B cell divides by mitosis to form clones. cloned plasma cells secrete antibodies. on second exposure memory cells produce antibodies rapidly

Question 15

what are monoclonal antibodies

Answer 15

single clone of B cells, used in pregnancy tests

Question 16

what are monoclonal antibodies used in?

Answer 16

pregnancy testing, medication (cancer cells) medical diagnosis (PSA/mumps) (all variations of ELSA)

Question 17

what percentage vaccinated do you need for herd immunity

Answer 17

95%

Question 18

define antigen

Answer 18

foreign protein on the cell surface that stimulates an immune response

Question 19

role of antibodies in an ELISA test

Answer 19

antibody binds to complementary antigen.
second antibody with enzyme attached is added.
second antibody attaches to antigen
solution added and colour changes

Question 20

ethical issues with mabs

Answer 20

mice are used to produce both antibodies and cancer cells. some trials have been unsuccessful and some have been successful for cancer and diabetes.

Question 21

steps in vaccination

Answer 21

antigen injected. these bind to receptor on T helper cells. they release cytokines. B cells divide by mitosis. plasma cells make antibodies. memory cells produce antibodies rapidly at the next exposure

Question 22

natural active immunity

Answer 22

own antibodies produced from being exposed to a disease under normal circumstances

Question 23

artificial active immunity

Answer 23

own antibodies produced from vaccination

Question 24

passive immunity

Answer 24

temporary introduction of antibodies e.g. antivenom. faster.

Question 25

difference between primary and secondary immune response

Answer 25

primary after first exposure, secondary after second. after secondary memory cells produce antibodies more quickly after primary plasma cells produce antibodies

Question 26

structure of HIV

Answer 26

attachment proteins, lipid envelope, matric, capsid, RNA and reverse transcriptase

Question 27

replication of HIV

Answer 27

HIV binds to CD4 on T helper cells. protein capsid fuses with the cell membrane of T cell. RNA to DNA (reverse transcriptase). DNA inserted into T cells genetic material. mRNA created. mRNA can leave nucleus and use host cells material to make HIV particles

Question 28

why is it hard to develop a HIV vaccine

Answer 28

antigenic variability