im (not) muing system

Question 1

what happens during the cell mediated response

Answer 1

receptors on t cells will bind to antigen presenting cells (toxins, pathogens) and cause the t cell to divide via mitosis. once divided the t-cells can differentiate into any cell
memory cells - to enable a rapid response if ever to come into contact with the same antigen ( shortens the time of clonal selection because memory cells are already in the blood)
- cytotoxic t-cells - contain a protein called perforin which perforates the cell membrane of a pathogen and this will allow all substances to move into the cell and therefore causes apoptosis

helper t cells - this will stimulate b-cells to divide and secrete antibodies

t-cells also stimulate phagocytosis of pathogens

Question 2

what happens during the humoral response

Answer 2

helper t cells stimulate b -cells to divide and initiate the humoral response which involves antibodies . antibodies are complementary to to the antigens of pathogens. the binding site is described as the variable region because the active site will change for each antigen. the rest of the antibody is made of 4 polypeptide chains 2 of which are heavy 2 of which are light. and when an antigen binds to an antibody it forms and antigen antibody complex

Question 3

where are t cells matured

Answer 3

thymus gland

Question 4

where are b-cells matured

Answer 4

bone marrow

Question 5

where are t and b cells produced

Answer 5

bone marrow

Question 6

define antigenic drift

Answer 6

involves minor variations in antigenic structure which result in the production of new strains of a particular virus

Question 7

define antigenic shift

Answer 7

involves major variations in antigenic structure usually leading to the development of entirely new types of viruses

Question 8

what is active immunity

Answer 8

develops when the body illicits an immune response antigenic exposure

Question 9

what is passive immunity

Answer 9

to generate an immune response the body does not exposure to a antigen

Question 10

do preg tests use monoclonal antibodies

Answer 10

yes

Question 11

how does a preg test work

Answer 11

pregnancy tests use monoclonal antibodies to detect the human chorionic gonadotrophin. HcG if a woman is preg HcG eill be found in her urine the HCG tot he free antibody which has an enzyme attached to it
- HCG bound to the free antibody enters the test site. here the HCG free antibody complex will bind to another fixed antibody using HCG. this will bring the enzyme that is attached to the complex close tot he dye substrate. if there is a reaction there will be a colour change.

Question 12

how do you get a negative preg test

Answer 12

the free antibody moves through the test site and instead binds to the fixed antibody in the control site causing a colour change there. some free antibodies will still pass to the control site, so you will see 2 stripes

Question 13

what are the steps to creating a monoclonal antibody

Answer 13

a mouse is injected with an a dead or inactive version of a virus. complementary antibodies will be produced in response to this antigen by b-cells. the antibodies will then be fused with myeloma which is rapidly reproducing. this will create a hybridoma to create a rapidly reproducing antibody. they will be cloned collected and purified.

Question 14

how are monoclonal antibodies used to deliver cancer drugs

Answer 14

herceptin is a monoclonal antibody used to treat cancer, it recognises receptor proteins on the surface of cancer cells and binds to them, allowing the immune system to identify and destroy them

Question 15

what does ELISA stand for

Answer 15

enzyme linked immunosorbent assay

Question 16

what is direct ELISA testing

Answer 16

tests a single antibody that is complementary to an antigen

Question 17

what is indirect ELISA testing

Answer 17

uses two different antibodies known as the primary and secondary antibody

Question 18

how are monoclonal antibodies used inELISA testing

Answer 18

can be used to test if the patient has certain antigens or allergies.
- an enzyme will attach to the antibody
- when this enzyme reacts with the certain substrate a coloured product is formed causing the solution to in the reaction vessel to change colour. if a change in colours occurs the antigen or antibody or interest is present.

Question 19

what is the structire of HIV

Answer 19

attachment proteins
capsid (protein coat)
nucleic acid or RNA
reverse transcriptase
another layer or protection in the form of a lipid envelope that normal viruses dont have

Question 20

what are the difference between active and passive immunity

Answer 20

active immunity requires the presentation of an antigen to illicit an immune response where passive does not
- passive immunity has shorter lasting effect whereas active immunity is a long term line of defence
- in active immunity memory cells are produced whereas in passive immunity they are not

Question 21

how does an ELISA test work

Answer 21

• apply the sample to a surface, for example to a slide to which antigens in the sample will attach
• wash the surface several times to remove any unattached antigens ( to prevent false negatives)
• add the antibody that is specific tot he antigen we are trying to detect and leave the two to bind together
  -wash the surface to remove the excess antibody
• add a second antibody that binds with the first antibody. this second antibody will have an enzyme attached to it
• add the colourless substrate of the enzyme. the enzyme acts on the substrate to change the colour
• the amount of the antigen to present is relative to the intensity of the colour

Question 22

what is herd immunity

Answer 22

when a sufficiently large percentage of the population have been vaccinated so it makes it difficult for a pathogen to spread its antigens

Question 23

why may vaccines not eliminate disease

Answer 23

• vaccinations fails to induce immunity in certain individuals for example those with defective immune systems
• individuals may develop the disease immediately after vaccination but before their immunity levels are high enough to prevent it
  0 the pathogen may mutate frequently into multiple different strains and therefore antibodies are no longer able to form complexes

Question 24

what are some ethical issues with vaccines

Answer 24

vaccines may have long term side effects that cause harm
- the development of the vaccine using animal trials
- who should trials be tested out on and should they have to bear the consequences in the benefit of public health

Question 25

how does HIV cause AIDS

Answer 25

HIV specifically attacks helper T-cells. without a sufficient number of helper t-cells the body cannot stimulate enough b-cells to produce antibodies to fight infection or to produce cytotoxic t-cells that kill cells that are infected by pathogens. memory cells may also become infected and destroyed. as a result the body is not able to produce an adequate immune response and the patient suffers intensely from minor illness.

Question 26

how does the replication of HIV occur

Answer 26

• HIV enters the bloodstream
  -attachment proteins bind to the helper t cell
  -the protein capsid fuses with the cell surface membrane. the RNA and the reverse transcriptase enter the helper t cell.
  -reverse transcriptase will convert hivs rna into dna
  the newly made dna is moved inti the helper t cells nucleus where it is inserted into the cells dna
  -more replicatpiuon hiv dna using the helper t cells protein synthesis mechanisms (ribosomes) to make more hiv particles.