Cell Recognition And The Immune System

Question 1

What are types of specific defence mechanisms?

Answer 1

Cell mediated response
Humoral response

Question 2

What are types of non-specific defence mechanisms?

Answer 2

Physical barrier (e.g. skin)
Phagocytosis

Question 3

What is the difference between specific and non-specific defence mechanisms?

Answer 3

Specific- slower, specific to each pathogen
Non-specific- immediate, same for all pathogens

Question 4

What type of lymphocytes are used in the cell-mediated response?

Answer 4

T lymphocytes

Question 5

What type of lymphocytes are used in the humoral response?

Answer 5

B lymphocytes

Question 6

What does the skin do?

Answer 6

Barrier mainly consisting of keratin that microorganisms can’t penetrate

Question 7

How does the nose and gas exchange system form a barrier?

Answer 7

Lined with cilia (waft mucus up throat to be swallowed to stomach), bathed in mucus (pathogens trapped)

Question 8

How is the stomach a barrier?

Answer 8

HCL (pH 1.5-3.5) kills pathogens

Question 9

How are tears a barrier?

Answer 9

Contain lysozymes- digest cell wall in bacteria

Question 10

What are two types of phagocyte?

Answer 10

Macrophage, neutrophil

Question 11

What causes phagocyte to arrive at site of infection via bloodstream?

Answer 11

Chemical products (cytokines) of pathogen act as attractants

Question 12

How do phagocytes attach themselves to the surface of pathogens?

Answer 12

Receptor on phagocyte binds to antigens on pathogen

Question 13

What’s it called when phagocyte engulfs pathogen?

Answer 13

Endocytosis

Question 14

What the vesicle called that’s formed after endocytosis

Answer 14

Phagosome

Question 15

What fuses with the phagosome?

Answer 15

Lysosomes, containing hydrolytic enzymes

Question 16

What do the enzymes released in the phagosome do?

Answer 16

Hydrolyse molecules that make up pathogen into smaller soluble products. Digest pathogen

Question 17

What happens to the antigens of the pathogen after it’s digested

Answer 17

Presented on cell membrane of phagocyte

Question 18

What happens at the site of infection during phagocytosis

Answer 18

Inflammation due to release of histamine

Question 19

What are two types of antigen

Answer 19

Self-antigen
Foreign antigen

Question 20

What are antibodies

Answer 20

Proteins synthesised by plasma cells, have specific tertiary structure and region complementary to antigen

Question 21

What is formed when the antigen and antibody bind

Answer 21

Antigen- antibody complex

Question 22

What’s the site of maturation of T lymphocytes

Answer 22

Thymus gland

Question 23

Do T lymphocytes secrete antibodies

Answer 23

No

Question 24

What’s the site of maturation of B lymphocytes

Answer 24

Bone marrow

Question 25

Do B lymphocytes secrete antibodies

Answer 25

Yes

Question 26

What happens on cell mediated immunity

Answer 26

-Pathogens ingested by phagocytes -Foreign antigen presented -Receptors of some T cells complementary to antigens -T cells activated and divide by mitosis to form clones -Clones specialised

Question 27

What 4 different functions do T cells specialise to?

Answer 27

Memory cells Helper T cells Killer T cells Suppressor T cells

Question 28

What are all cells that present antigens of other cells called

Answer 28

Antigen presenting cells

Question 29

How many different types of B lymphocytes are we born with approx

Answer 29

10,000,000

Question 30

What do clones of B lymphocytes differentiate to form

Answer 30

Plasma B Memory B

Question 31

What do plasma B cells do

Answer 31

Produce thousands of specific antibodies every second- released into bloodstream and bind to antigens- destroys pathogen (primary response)

Question 32

What do memory B cells do

Answer 32

Protect from future invasions by same pathogen (secondary response)

Question 33

What are the differences between primary and secondary responses

Answer 33

Primary- quantity and speed antibodies lower/ slower than secondary

Question 34

What’s the structure of an antibody

Answer 34

-Y shaped protein, 4 polypeptide chains (2 heavy, 2 light), disulphide bridge -variable region, constant region - antigen binding sites

Question 35

What is agglutination?

Answer 35

Pathogens clumped together by antibodies

Question 36

What’s the difference between polyclonal and monoclonal antibodies

Answer 36

Monoclonal- isolating+ cloning a single type of antibody-single type of plasma clone Polyclonal- many different clones

Question 37

What is the ELISA test?

Answer 37

Plasma sample added- primary antibody attached to secondary antibody attached to enzyme- substrate complementary to enzyme- colour change- positive result

Question 38

What is meant by vaccine?

Answer 38

Preparation/ injection of antigens/ attenuated (whole) microorganisms treated so they’re harmless. Stimulates memory cells- large scale= herd immunity

Question 39

What is herd immunity

Answer 39

Pathogen isn’t carried by vaccinated people and enough so non vaccinated are protected

Question 40

What’s the structure of the human immunodeficiency virus?

Answer 40

Matrix Attachment proteins Capsid Genetic material Lipid envelope Reverse transcriptase

Question 41

How is HIV transmitted

Answer 41

Unprotected sex Blood transfusion HIV infected mother Sharing needles

Question 42

Why are antibiotics ineffective against viruses

Answer 42

Viruses don’t have mute in cell walls Viruses hide in living eukaryotes

Question 43

How do antibiotics prevent bacteria dividing

Answer 43

Stop DNA replicating Stop DNA dividing