immunology

Question 1

what is an antigen

Answer 1

a molecule (protein) that stimulates an immune response that results in the production of a specific antibody

Question 2

examples of antigens

Answer 2

glycoproteins
glycolipids

Question 3

phagocytes definition

Answer 3

-groups of white blood cells which are capable of distinguishing between cells self/nonself
-capable of detecting chemical signals produced by pathogens

Question 4

phagocytosis process

Answer 4

-pathogen is engulfed by phagocyte
-engulfed pathogen enters the cytoplasm of the phagocyte in a vesicle
-called a phagosome
-lysosome fuse with phagosome releasing digestive enzymes
-lysosomal enzymes hydrolyse the pathogen
-waste materials are released via exocytosis
-phagocyte becomes an antigen presenting cell

Question 5

what is specific immunity

Answer 5

a specific response to a specific antigen on the surface of a cell that has been recognised as non-self

Question 6

the primary immune response

Answer 6

• phagocytosis and presents antigens on the cell surface membrane
  -T helper cells with specific receptor molecules bind to antigen
  -once the T helper cell binds to the presented antigen, it is activated
  -T helper cells then clone via mitosis to produce many T helper cells
• specific T helper cell binds to the the presented antigen and activates a specific complementary B cell
  -The specific T helper cell releases cytokine chemicals that signal the specific B cell to clone by mitosis
  -B cells differentiate into plasma cells and memory cells

Question 7

plasma cells function

Answer 7

produce and secrete vast quantities of specific antibodies into the blood plasma

Question 8

memory cells

Answer 8

remain in the body to allow for a greater and faster secondary immune response if re-infection

Question 9

antibodies definition

Answer 9

protein made in response to foreign antigen

Question 10

draw and label the structure of an antibody

Answer 10

-heavy chain
-light chain
-antigen binding site
-variable region
-constant region

Question 11

how do antibodies assist in the destruction of pathogens?

Answer 11

agglutination
opsonization
anti-toxin & anti-venom

Question 12

agglutination process

Answer 12

Specific antibodies bind to the antigens on pathogen and clump them together

Question 13

opsonisation process

Answer 13

marking pathogens so phagocytes recognise and destroy the pathogen more efficiently

Question 14

anti-toxin & anti-venom process

Answer 14

Bind to toxins or venom (both usually proteins) to prevent these molecules from binding to their complementary target receptors

Question 15

How is the secondary response different to the primary response

Answer 15

-quicker
-more extensive

Question 16

what is antigenic variability

Answer 16

antigens mutate and change shape
pathogen will not be recognised by the memory cell

Question 17

two types of immunity

Answer 17

passive
active

Question 18

passive immunity means?

Answer 18

no exposure to the antigen
antibodies are received elsewhere
eg. by mother or antiserum
no production of memory cells

Question 19

active immunity means?

Answer 19

antibodies are produced in response to exposure of antigens
memory cells are produced

Question 20

herd immunity definition

Answer 20

If enough individuals in the population are vaccinated (85%), then there is little chance of the disease spreading, therefore even non-vaccinated individuals will be protected.

Question 21

Describe the difference between active and passive immunity

Answer 21

1. Active involves memory cells, passive does not
2. Active involves production of antibodies by plasma cells
3. Passive involves antibody introduced into body from outside eg. mother
4. Active long term, because antibody produced in response to antigen
5. Passive short term, because antibody is broken down
6. Active can take time to work whereas is passive fast acting

Question 22

ELISA Test process

Answer 22

uses monoclonal antibody to detect a certain substance in a sample of liquid
1. Monoclonal antibodies fixed to the surface of the test well
2. Sample containing molecule to be detected
binds to antibody due to complementary shape
3. Second monoclonal antibodies (with enzyme attached) added and also binds to molecule
4. Washed soany unbound antibody with enzymes is washed away
5. substrate is added
7. colour change shows a positive result

Question 23

HIV replication process

Answer 23

1. Protein on HIV binds with a protein commonly found on T helper cells
2. Capsid fuses with cell-surface membrane and releases Viral mRNA and enzymes into the helper T helper cell.
3. The HIV reverse transcriptase converts viral mRNA into cDNA using host nucleotides.
4. Viral cDNA moves into nucleus of T cell and is inserted into host cell genome. The person is now INFECTED.
5. Transcription and translation of this DNA occurs so the T cell starts to manufacture HIV particles.
6. Particles break away from T cell with a section of host cell surface membrane which forms their lipid envelope, with T helper receptor proteins
7. Over time this leads to a reduction in the number of T cells

Question 24

AIDS points

Answer 24

• as few as 200 T cells per mm-3 of blood
• AID’s is screened for by checking the no. T helper cells

Question 25

ethical issues of vaccines

Answer 25

• animal testing
• human testing
  -free or expensive (only first world?)
  -side effects against benefit
  -compulsory or not