Chapter 5

Question 1

what lymphocytes are incorporated in cell-mediated responses

Answer 1

T Lymphocytes

Question 2

what lymphocytes are incorporated in humoral responses

Answer 2

B Lymphocytes

Question 3

Clonal Selection

Answer 3

The process of matching the antigens on an antigen presenting cell with the antigen receptors on B and T lymphocytes and replicating it

Question 4

Defence Mechanisms photo

Answer 4

see phone camera roll

Question 5

speed of a non-specific response

Answer 5

fast

Question 6

speed of a specific response

Answer 6

slow

Question 7

6 steps of phagocytosis

Answer 7

chemotaxis - the chemical products of damaged and abnormal cells attract the phagocyte, phagocytes attach to the receptors, they then engulf the pathogen making a phagosome, lysosomes move towards the phagosome and fuse with it, lysozymes hydrolyse the bacterial walls, the products from the breakdown are absorbed into the phagocyte’s cytoplasm

Question 8

where are T-lymphocytes matured

Answer 8

thymus gland

Question 9

where are B-lymphocytes matured

Answer 9

bone marrow

Question 10

what is an antigen

Answer 10

specific molecules found on the surface of cells that identify it

Question 11

5 steps of cell-mediated immunity

Answer 11

Pathogens invade the body and are engulfed by phagocytes, a slightly different phagocyte will present the foreign antigen on its surface membrane, the antigen is presented to T helper cells, the antigen complementary binds to a T helper cell receptor, the T helper cell stimulates the correct T lymphocyte causing rapid division and simultaneously triggers more phagocytosis, the humoral response and cytotoxic T cells

Question 12

what are cytotoxic T cells

Answer 12

kill infected cells by puncturing their membranes

Question 13

7 steps of humoral immunity responses

Answer 13

the surface antigens of the pathogen are taken up by B lymphocytes, the B lymphocytes present the antigens on their cell surface membranes, T helper cells from the cell-mediated response bind to the processed antigens and activate the B lymphocytes, the activated B lymphocytes divide by mitosis into short-living plasma cells and longer-living memory cells, the plasma cells produce antibodies, in the primary immune response the antibodies attach to the antigens on the pathogen causing agglutination and phagocytosis, in the secondary immune response some remaining B lymphocytes convert into memory cells that stay in the bloodstream

Question 14

2 main roles of antibodies

Answer 14

bind to antigens and cause agglutination, bind to antigens as markers to stimulate phagocytosis

Question 15

antibodies definition

Answer 15

globular protein produced by a plasma cell with a complementary shape to match an antigen

Question 16

what are antibodies made of

Answer 16

four polypeptide chains - 2 heavy, 2 light

Question 17

what shape are antibodies

Answer 17

Y shape held together by disulphide bridges

Question 18

vaccination definition

Answer 18

introduction of a dead or weakened pathogen into the body to stimulate active immunity against a disease

Question 19

what is herd immunity

Answer 19

transmission of the pathogen is interrupted preventing the infection of unvaccinated individuals

Question 20

what is passive immunity

Answer 20

introducing ready-made antibodies

Question 21

Monoclonal antibody definition

Answer 21

antibody that has been isolated and cloned

Question 22

3 uses of monoclonal antibodies

Answer 22

drug delivery, medical diagnosis and ELISA tests

Question 23

what is a retrovirus

Answer 23

virus containing reverse transcriptase

Question 24

what can reverse transcriptase do

Answer 24

able to synthesise single stranded DNA (cDNA) from a RNA template

Question 25

5 main structures within HIV

Answer 25

RNA, attachment proteins, reverse transcriptase, lipid membranes, capsid

Question 26

5 steps of HIV replication

Answer 26

HIV attaches to T - helper cells and injects reverse transcriptase and RNA into a cell, reverse transcriptase uses the RNA as a template to make cDNA that is inserted into the host’s chromosome, the viral DNA is transcribed to make viral mRNA and is then translated to make viral proteins, viral proteins and RNA form new HIV particles which burst out to go and infect more T-helper cells, this eventually leads to the destruction of T-helper cells

Question 27

process of the ELISA test

Answer 27

well is washed, coat with the sample so suspected antigen can attach, wash to remove unattached antigens, add the antibody that is specific, wash to remove excess antibody, add a second antibody with an enzyme attached that will bind to the 1st antibody, wash to remove excess antibody, add a colourless substrate that will change colour if enzyme is present