cell recognition and immunity

Question 1

what can our immune system identify by their organisms

Answer 1

-pathogens
-cell surface structures
-cellls from other organisms of the same species
-cancerous cells
-toxins

Question 2

main defence mechanisms of the body

Answer 2

non specific and specific

Question 3

non specific response

Answer 3

response is immediate and the same for all pathogens

Question 4

specific response

Answer 4

response is slower and specific to each pathogen

Question 5

non specific response methods

Answer 5

primary method eg skin
secondary methods eg phagocytosis

Question 6

specific response methods

Answer 6

-cell mediate response - t lymphocytes
humoral response - b lymphocytes

Question 7

two immune system

Answer 7

non specific - all animals
specific-only vertebrates

Question 8

what iOS the immune system

Answer 8

complex networks of cells tissue and organs and molecules

Question 9

cells of immune system

Answer 9

white blood cells

Question 10

inflammation

Answer 10

1)injury cut or graze
2)damaged white blood cells and mast cells from connective tissue releases histamines
3)dilation of arterioles in the area
4)increases blood flow in capillaries and capillary cells separate slightly
5)plasma white blood cells and antibodies leak into tissues causing oedema
6)white blood cells can destroy microbes

Question 11

phagocytosis

Answer 11

1)neutrophils arrive first and engulf 5-20 bacteria but then die
2)macrophages arrive and destroy up to 100 bacteria

Question 12

phagocytosis stages

Answer 12

1)chemotaxis
2)Adhesion
3)ingestion and intracellular digestion
4)disposal

Question 13

chemotaxis

Answer 13

actively seek foreign antigens stimulated by chemicals released by the pathogen or lymphocytes

Question 14

adhesion

Answer 14

firm connection between phagocytes membrane and the antigen

Question 15

ingestion and intracellular digestion

Answer 15

pathogen engulfed and surrounded by a membrane e lines vacuole where lysosomes containing enzymes break it down

Question 16

disposal

Answer 16

the parts that cannot be used in metabolism are ejected by exocytosis

Question 17

specific immune repose - clonal expansion

Answer 17

-specific lymphocytes are not produced in response to an infection they already excst
-there are so many different types there is high probability that one of these will have a protein on surface that is complementary to an antigen
-when infection occurs the one type of cell that recognises the antigen will divide to build up the numbers of that particular type

Question 18

apotosis

Answer 18

cell death

Question 19

when lymphocytes recognise and rwespsond to cells in our own body

Answer 19

-in the foetus lymphocytes rarely come into contact with pathogens so collude exclusively with self cells
-some of the receptors fits those pf the body cells these lymphocytes are then suppressed
-this leaves only lymphocytes that might recognise non-self antigens

Question 20

t lymphocytes

Answer 20

mature in thymus gland
-cell mediated immune its ie. immunity requiring the cell to be present
-have receptor proteins that can detect antigens and form antigen receptors complexes
-helped T cells th
cytoxic T cells tc
-antigen recognition site binds to antigens

Question 21

b lymphocytes

Answer 21

form and mature in bone marrow

Question 22

activTION of t helper cell

Answer 22

1)bacterium with antigen on surface
2)bacterium engulfed by macrophage
3)macrophage presents antigens on major hustocompatability complexes becomes an antigen presenting cell

Question 23

Explain why the secondary immune response is much more rapid than the primary one

Answer 23

Because of the production of memory cells the secondary response is much more faster than the primary one . The memory cells differentiate into plasma b cells rapidly to produce much more antibodies at a faster rate against the pathogens .

Question 24

Primary immune response - B cell clonal selection

Answer 24

B cells bind to antigens the antigen enters by endocytosis and then is presented on surface of cell it has become an antigen presenting cell

Question 25

Humoral immune response

Answer 25

Plasma cells secrete lapse amount of antibodies
Antibodies bind to antigens and stop disease by stickin cells together into large clumps targeting them for destruction by phagocytes
Preventing viruses and bacteria from infecting cells
Binding to free toxin proteins

Question 26

Antibodies

Answer 26

Composed of four polypeptide chains
2 heavy chains
2light chains
Joined by disulphide bonds
Form a Y shaped structure
The stem =constant region
The ends of the arms =variables regions that bind to the antigen

Question 27

Contrast the cell mediated and humoral response to pathogens

Answer 27

Humoral response produces antigen specific antibodies
Humoral response also more rapid whereas cell mediated is delayed

Question 28

Monoclonal antibodies

Answer 28

Antibodies produced from a single group of genetically identical B-cells specific to one type of antigen
They are all identical in structure

Question 29

Why are monoclonal antibodies same in structure

Answer 29

They have the Same primary structure as they are coded for by the same genes so they have the same secondary and tertiary structures as a results

Question 30

Uses of monoclonal antibodies

Answer 30

1)cancer treatments to target cytotoxic drugs to the cancer cells
The monoclonal antibody carries a cytotoxic drug to the cancer cells it is specific to the antigen on the cancer cells the drug is activated to kill the cancer cells
2)cancer treatment to block the growth factors that stimulate cell division
3)medical diagnosis -eg.hiv test ,pregnancy test,Covid lateral flow
4)transplant surgery to knock out T cells targeting the foreign antigen

Question 31

Pregnancy testing

Answer 31

-the placenta in a pregnancy women produces a hormone hcg in mothers urine
-monoclonal antibodies immobilised in coloured beads on a test strip
-when urine is applied hcg will bind to antibodies to form complex
-hcg antibody colour complex along the strip until trapped by a different type of antibody
Completed accumulate t produces a coloured trace

Question 32

ELISA test

Answer 32

-detects the presence of specific antibodies or antigens in the blood
Uses antibodies with an enzyme attached
-an Elisa test may be used to diagnose diseases such as HIV,Lyme diseases ,syphilis
-the test is extremely sensitive and therefore can detect a small quantity of molecule

Question 33

Ethical issues

Answer 33

-use of mice
-informed consent
-dangers in trialling the drug

Question 34

Pronlem of using mice

Answer 34

Mice used to produce antibodies and tumour cells so deliberately induce cancer in the mice there are guidelines drawn up to minimise suffering

Question 35

Deaths using monoclonal antibodies

Answer 35

When treating multiple sclerosis’s
It is important that patients have full knowledge of the risks and benefits of these drugs before giving permission for them to be used

Question 36

Testing the safety of new drugs

Answer 36

200( healthy volunteers trial of new antibody caused multiple organ failure all volunteers survived but it raises issues about the conduct of drug trials

Question 37

Two forms of immunity

Answer 37

Active and Passive

Question 38

Herd immunity

Answer 38

If enough people are immune to a pathogen then the remaining people are often protected due to a lack of hosts for the pathogen to reproduce in

Question 40

Antibiotics

Answer 40

Prevent growth of bacteria
Two types -bacteriocidal + bacteriostatic

Question 41

Why antibiotics have no effect on eukaryotic cells

Answer 41

They don’t have a cell wall and their ribosomes are a different size which means antibiotics can’t bind to them

Question 42

Why antibiotics have no effect on viruses

Answer 42

They do not possess either cell wall or ribosomes
Replicate inside host cells