cell recognition

Question 1

pathogen

Answer 1

any organism that causes a disease

Question 2

4 types of pathogens

Answer 2

bacteria
virus
fungus
protozoan

Question 3

How do pathogens cause disease?

Answer 3

release toxins
kill/damage cells/tissues
pathogens might have complementary shaped antigens to bodies cell receptor proteins enabling them to bind to target cells

Question 4

antigen

Answer 4

any part of an organism or substance that is recognised as ‘non-self’ by the immune system and stimulates an immune response

Question 5

what does an antigen stimulate the production of

Answer 5

antibodies

Question 6

what type of molecules on the surface of pathogens might act as antigens

Answer 6

proteins and glycoproteins

Question 7

antibody

Answer 7

large y shaped proteins with specific binding sites
each has a specific shape complementary to an antigen

Question 8

what are antibodies produced by

Answer 8

white blood cells called B lymphocytes in response to infection

Question 9

Why do you think that the most important molecules used in cell identification are proteins?

Answer 9

huge variety of proteins
highly specific tertiary structure

Question 10

What cells in your own body could stimulate immune response?

Answer 10

cancer cells are abnormal cells that have different antigens

Question 11

defence mechanisms

Answer 11

non-specific : immediate response, same for all pathogens
specific : slower response, specific to each pathogen

Question 12

non-specific

Answer 12

physical barriers
phagocytosis

Question 13

specific

Answer 13

cell mediated response- T lymphocytes
humoral response- B lymphocytes

Question 14

Primary defences- barriers to pathogen entry

Answer 14

skin
mucous membranes
HCL in stomach
tears in eyes
wax in ear canal

Question 15

inflammatory response

Answer 15

1. physical barriers are breached by pathogens
2. pathogens release chemicals
3. cause the dilation of local blood vessels so that blood flow to the area increases
4. also increase the permeability of capillaries causing fluid to leak out the blood causing swelling
5. means many phagocytic white blood cells move to the area

Question 16

stages of phagocytosis

Answer 16

1. chemicals released by pathogens attract phagocytes to the injury
2. phagocyte attaches to the receptor molecules on the surface of the pathogen
3. pathogen is engulfed by the phagocyte into a phagosome
4. phagocytes lysosomes fuse with the phagosome
5. hydrolytic enzymes are released from the lysosome into the phagosome which hydrolyse the pathogen
6. soluble products of digestion are absorbed into the cytoplasm of the phagocyte or released from the cell by exocytosis
7. some of the antigens from the pathogen are placed on the cell surface membrane of the phagocyte