Cells: Cell recognition and the immune system

Question 1

What is antigen?

Answer 1

A protein in the cell surface membrane that triggers an immune response.

Question 2

Where are B cells produced?

Answer 2

Bone marrow

Question 3

What are non-self cells?

Answer 3

Not our body’s cells and molecules

Question 4

Name two pathogens can stimulate an immune response:

Answer 4

• Virus
• Bacterium

Question 5

What are the two types of phagocytes?

Answer 5

Neutrophils
Macrophages

Question 6

What does a neutrophil do?

Answer 6

Engulfs and digests pathogens

Question 7

What does a macrophage do?

Answer 7

• Punch holes in bacteria.
• Stick proteins to the outside of bacteria to make them more appealing for the neutrophils to destroy.

Question 8

What is phagocytosis?

Answer 8

Engulfing pathogens.

Question 9

Describe how phagocytes destroy non-self antigens in the blood:

Answer 9

1) Complementary protein receptors on the cell-surface membrane of the phagocyte binds to non-self antigens.
2) Cell membrane forms around the pathogen, engulfing it.
3) The pathogen is internalised in a phagosome.
4) Lysosomes fuse with the phagosome, releasing lysozymes, which digest the pathogen.
5) Non-self antigens are presented on the cell-surface membrane of the phagocyte.

Question 10

Why must patients who receive organ donations take anti-rejection medicines?

Answer 10

Donor cells are non-self antigens, which will be destroyed by phagocytes.

Question 11

State the four types of non-self cells that lymphocytes can recognise:

Answer 11

• Toxins
• Tumour cells
• Transplanted cells
• Pathogens

Question 12

What are cells that belong to us called?

Answer 12

Self cells

Question 13

What are cells that can trigger an immune response called?

Answer 13

Non-self cells

Question 14

What are pathogens?

Answer 14

Any microorganism that causes disease

Question 15

Lymphocytes are _________ to one antigen.

Answer 15

Specific

Question 16

How are lymphocytes able to recognise antigens?

Answer 16

They have complementary receptors that bind to antigens

Question 17

How many antigens can a lymphocyte recognise?

Answer 17

One (specific antigen)

Question 18

When lymphocytes bind to an antigen, they trigger a _______ immune response.

Answer 18

Specific

Question 19

Why are phagocytes non-specific?

Answer 19

Their receptors are complementary to the molecular patterns found on all pathogens.

Question 20

When a pathogen invades the body, the pathogen releases _______ that attract phagocytes towards it.

Answer 20

Chemicals

Question 21

When a pathogen has released chemicals that attracts the phagocyte, the phagocyte moves towards it along a _____________.

Answer 21

Concentration gradient

Question 22

When the phagocyte reaches the pathogen, it binds to the pathogen via complementary _________.

Answer 22

Receptors

Question 23

How to lysozymes aid in the digestion of a pathogen?

Answer 23

They speed up the hydrolysis reaction.

Question 24

Do phagocytes or lymphocytes carry out a nonspecific response against a pathogen?

Answer 24

Phagocytes

Question 25

Where are B cells matured?

Answer 25

Bone marrow

Question 26

Where are T cells matured?

Answer 26

Thymus

Question 27

What is the role of the disulphide bridge in forming the quaternary structure of an antibody?

Answer 27

Holds and stabilises the polypeptides together

Question 28

What are the two types of white blood cells that lymphocytes can differentiate into?

Answer 28

T lymphocytes B lymphocytes

Question 29

If lymphocytes mature in the bone marrow, they are __-lymphocytes.

Answer 29

B

Question 30

If lymphocytes mature in the thymus, they are __-lymphocytes.

Answer 30

T

Question 31

Which type of lymphocytes are involved in humoral immunity?

Answer 31

B-lymphocytes

Question 32

What is meant by humoral immunity?

Answer 32

Immunity involving the body's humours, such as blood plasma or lymph.

Question 33

Humoural immunity involves the production of ________ antibodies.

Answer 33

Monoclonal

Question 34

Which type of lymphocytes are involved in cell-mediated immunity?

Answer 34

T-lymphocytes

Question 35

What do T lymphocytes deal with?

Answer 35

Cells that have antigens on their cell surface membranes only.

Question 36

What are the 4 types of T cells that T cells can differentiate into?

Answer 36

- T memory cells - T helper cells - Cytotoxic T cells - Suppressor T cells

Question 37

Role of T-helper cells:

Answer 37

- Releases cytokines (chemicals) to active B cells.

Question 38

Role of cytotoxic T cells:

Answer 38

- Perforate cell walls. - Destroy infected cells

Question 39

How does cytotoxic T cells perforating cell walls cause the antigen to die?

Answer 39

- Osmosis will occur. - Water will move into the antigen and cause it to burst.

Question 40

What is the role of B plasma cells?

Answer 40

Produce and secrete antibodies.

Question 41

What makes the non-specific immune response non-specific?

Answer 41

Response occurs immediately to infection and is carried out in the same way regardless of the pathogen.

Question 42

What stimulates the production and secretion of B cells.

Answer 42

- When T helper cells produce cytokines - When antibody molecules on their CSM bind to a complementary antigen.

Question 43

Phagocytosis is an example of a _______ immune response.

Answer 43

Non-specific

Question 44

What do B-memory cells do when infection is rencountered?

Answer 44

Stimulate the rapid production of plasma B cells.

Question 45

Antibodies have a _____ structure.

Answer 45

Quaternary

Question 46

Antibodies have a quaternary structure made up of 4 _____ chains.

Answer 46

Polypeptide

Question 47

Describe 2 features of the 4 polypeptide chains in an antibody:

Answer 47

- 2 dense chains, 2 light chains - Connected by disulfide bridges

Question 48

Antibodies are composed of a ____ region and an ________.

Answer 48

- Variable - Antigen binding site

Question 49

Why is it called the variable region?

Answer 49

It is different in different antibodies.

Question 50

What makes an antibody specific to an antigen?

Answer 50

The antibody's antigen-binding site is specific to the complementary antigen.

Question 51

The constant region is ___ ____ for all antibodies.

Answer 51

The same

Question 52

What is the role of the constant region of an antibody?

Answer 52

Contains another binding site which allows the antibody to bind to immune cells.

Question 53

Name the 3 ways that antibodies work to destroy pathogens:

Answer 53

1) Agglutination 2) Neutralising toxins 3) Blocking access to human cells

Question 54

Explain agglutination as a way that antibodies work to destroy pathogens:

Answer 54

- Antibodies will use their two binding sites to bind to two pathogens. - Clumps pathogens together. - Allows for phagocytes to efficiently engulf pathogens.

Question 55

Explain neutralising toxins as a way that antibodies work to destroy pathogens:

Answer 55

- Antibodies will bind to toxins which neutralises them - Antibody-toxin complex can be destroyed by phagocytes.

Question 56

Explain blocking access to human cells as a way that antibodies work to destroy pathogens:

Answer 56

- Antibodies will bind to antigens to prevent antigens from binding to human cells

Question 57

Immunity can either be ____ or _____.

Answer 57

Active or passive.

Question 58

What are the two types of active immunity?

Answer 58

- Natural - Artificial

Question 59

What is natural active immunity?

Answer 59

When you become immune after catching a disease.

Question 60

What is artificial active immunity?

Answer 60

When you become immune after you've been given a vaccination containing an antigen.

Question 61

What is active immunity?

Answer 61

Immunity you get when your immune system makes its own antibodies after being stimulated by an antigen.

Question 62

What is passive immunity?

Answer 62

Immunity you get from being given antibodies produced by a different organism.

Question 63

What are the two types of passive immunity?

Answer 63

- Natural - Artificial

Question 64

What is natural passive immunity?

Answer 64

When a baby becomes immune due to the antibodies it receives from its mother, through the placenta and breast milk.

Question 65

What is artificial passive immunity?

Answer 65

When you become immune after being injected with antibodies from someone else.

Question 66

A person has contracted tetanus. Explain how artificial passive immunity can help treat the illness:

Answer 66

- Person can be injected with antibodies against the tetanus toxin, collected from blood donations.

Question 67

Name the 4 features of active immunity:

Answer 67

- Requires exposure to an antigen - Protection develops over time - Memory cells are produced - Protection is long-term as the antibody is produced in response to the complementary antigen being present.

Question 68

Name the 4 features of passive immunity:

Answer 68

- Doesn't require exposure to an antigen - Protection is immediate - Memory cells are not produced - Protection is short-term as the given antibodies are broken down.

Question 69

What is the disadvantage of orally taking vaccines?

Answer 69

- May be broken down by enzymes in the gut - Molecules may be too large to be absorbed into the blood.

Question 70

What is antigenic variation?

Answer 70

When pathogens change their surface antigens.

Question 71

What is the impact of antigenic varitation?

Answer 71

Means memory cells will not recognise the antigen and the primary response will occur again.

Question 72

What are monoclonal antibodies?

Answer 72

Antibodies produced from a single group of genetically identical plasma B cells.

Question 73

What does the ELISA test stand for?

Answer 73

Enzyme-linked immunosorbent assay

Question 74

What does the direct ELISA use?

Answer 74

A single antibody that is complementary to the antigen that is being tested for.

Question 75

What are the two types of ELISA test?

Answer 75

- Direct - Indirect

Question 76

What does the indirect ELISA test use?

Answer 76

Two different antibodies.

Question 77

Define an antigen:

Answer 77

A protein found on the cell surface membrane which triggers an immune response.