immunity

Question 1

define pathogen

Answer 1

microorganism that causes disease

Question 2

give examples of barriers in the immune system

Answer 2

• conjunctiva (eye)
• tear fluid
• ciliated epithelium
• stomach acid
• skin
• gut bacteria
• saliva

Question 3

what is a non-specific immune system response

Answer 3

response is immediate and the same for all pathogens

Question 4

what is the aim of non-specific immunity

Answer 4

stop pathogens getting into blood

Question 4

what does cell-mediated response include

Answer 4

T lymphocytes

Question 4

what is a specific immune system response

Answer 4

response is slower and specific to each pathogen

Question 5

what are the 2 types of non-specific defence mechanisms

Answer 5

physical barriers e.g. skin
phagocytosis

Question 6

what are the 2 types of specific defence mechanisms

Answer 6

cell-mediated response
humoral response

Question 7

what does humoral response include

Answer 7

B lymphocytes

Question 8

how is the skin an effective barrier

Answer 8

many layers of cells
sebum contains fatty acids which are toxic to many microorganisms

Question 9

how do the lungs prevent infections

Answer 9

mucus production in trachea, bronchi and bronchioles traps microorganisms so they can’t enter lungs
movement of cilia removes mucus by allowing it to be moved up, swallowed and killed by stomach acid

Question 10

how does the digestive system prevent infections

Answer 10

saliva contains antibacterial enzymes

Question 11

what are the antibacterial enzymes in saliva

Answer 11

lysozymes

Question 12

describe the stages in phagocytosis

Answer 12

phagocyte recognises pathogen as foreign
engulfs pathogen and ingests it
Phagosome (vesicle) forms with pathogen inside
phagolysosome then forms after phagosome and lysosome fusing together
Lysosome then releases digestive hydrolytic enzymes which break down pathogen by hydrolysis

Question 13

what can occur after phagocytosis

Answer 13

an antigen presenting cell can bind onto the surface receptors on a T helper cell

Question 14

what does cell mediated specific immunity mean

Answer 14

T-cells directly attack and destroy infected or cancerous cells, rather than fighting pathogens in the body fluids

Question 15

what occurs in cell-mediated specific immunity after antigen presenting cell binds to T-helper cell

Answer 15

• T-helper cells divide by mitosis, by clonal expansion
  then either:
  1) cytotoxic T cells form
  2)T memory cells form

Question 16

what do cytotoxic t cells do

Answer 16

release perforin protein which lyses the pathogen

Question 17

what do T memory cells do

Answer 17

they have immunological memory
meaning faster secondary immune response

Question 18

what stages can b cells form from

Answer 18

-phagocytosis
-antigen presenting cells
- t helper cells

Question 19

how does a b cell form from a t helper cell

Answer 19

clonal selection
causes specific b cell to form
as it activates cytokinesis

Question 20

wat happens to the b cells (2)

Answer 20

they divide by mitosis using clonal selection and expansion
or directly produce plasma cells

Question 21

how do plasma cells form from b memory cells

Answer 21

they differentiate by clonal selection and expansion

Question 22

what do plasma cells do

Answer 22

they produce and release antibodies specific to original pathogen

Question 23

how do the plasma cells work to destroy pathogen

Answer 23

antibodies are complimentary to pathogen to bind to it they then neutralise the pathogen

Question 24

what does monoclonal mean

Answer 24

antibodies specific to one antigen

Question 25

can 1 antibody bind to multiple pathogens at once

Answer 25

yes

Question 26

what is agglutenation

Answer 26

a clump of antibodies and pathogens

Question 27

give the two types of active immunity and give examples

Answer 27

natural - infetion artificial -

Question 27

what is phagocytosis

Answer 27

non-specific immune response a phagocyte engulfs and destroys a pathogen

Question 28

describe the structure of an antibody

Answer 28

(quaternary protein structure) constant region (bottom straight bit) variable site (antigen binding site (complimentary to binding site)

Question 29

give an example of active immunity for natural artificial

Answer 29

natural - infection artificial - vaccination

Question 30

give an example of passive immunity natural artificial

Answer 30

natural - maternal antibodies artificial - monoclonal antibodies

Question 31

describe herd immunity

Answer 31

vaccinates most people reducing spread so people without it are less likely to get it

Question 32

what monoclonal antibody is used to detect breast cancer

Answer 32

Herceptin it helps recognise where cells are

Question 33

describe the process of using monoclonal antibodies to identify prostate cancer

Answer 33

PSA protein is released with prostate cancer take a blood sample add antibodies antibodies would show up with fluorescent test

Question 34

what protein is detected for in pregnancy tests how is it produced what doe it cause

Answer 34

hCG hormone produced by embryo in pregnancy causes morning sickeness

Question 35

name the things ELISA can be used to detect

Answer 35

HIV TB Hepatitis Drugs Allergens

Question 36

what does ELISA stand for

Answer 36

enzyme linked immunosorbent assay

Question 37

describe the process of direct ELISA (presence of a protein)

Answer 37

immobilise antibody wash add antigen add second antibody with enzyme attached (bound to antigen) wash add substrate and observe colour change measure absorbance

Question 38

describe the process of indirect ELISA

Answer 38

immobilise antigen wash add antibody (blood sample) wash add secondary antibody with enzyme attached (bound to constant region) wash add substrate and observe colour change measure absorption

Question 39

what is the main difference between direct and indirect ELISA

Answer 39

1 immobile antibody, 1 mobile 2 immobile antibodies

Question 40

describe viral replication

Answer 40

1) HIV attachment proteins bind to receptors on cell membrane of a T helper cell 2) The lipid envelop of the virus fuses with the T helper cell, emptying contents in cell (RNA and reverse transcriptase) 3) Reverse transcriptase makes a copy of Viral RNA, as a DNA copy 4) Viral DNA is incorporated into t helper cell DNA 5) Transcribe viral DNA in nucleus, then translate it at the ribosome coding for viral proteins e.g. - Capsid - Attachment proteins - Reverse transcriptase 6) … sometimes Th cells will express viral protein on its membrane : destroyed

Question 41

how can HIV be passed on

Answer 41

- Sexual intercourse - Shared needles - Blood contact/transfusions - Across placenta

Question 42

how to detect aids

Answer 42

the antibodies in blood

Question 43

how does reverse transcriptase work

Answer 43

- Copies RNA to DNA - Using spare bases in cell Complimentary based pairing occurs

Question 44

define monoclonal antibody - real definition

Answer 44

antibodies with same tertiary structure