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A-Level Biology- Y12 > 3.2.4- Cell Recognition- Immunity & Response > Flashcards

3.2.4- Cell Recognition- Immunity & Response Flashcards

1
Q

non-specific barriers

A

prevent pathogens from getting in- immediate and works for most pathogens

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2
Q

specific barriers

A

immune response to kill pathogens- slower and pathogen specific

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3
Q

non-specific barrier examples

A

skin, stomach, eyes, breathing system- physical barrier or phagocytes

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4
Q

specific barrier examples

A

Immune system: white blood cells, antitoxins, memory lymphocytes. Cell mediated or humoral response

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5
Q

Pathogen

A

A microorganism that causes disease

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6
Q

Infection

A

interaction or invasion of the body by a pathogenic organism. Cannot be killed by medication

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7
Q

immunity

A

the ability of an organism to resist a particular infection or toxin by the action of specific antibodies or sensitized white blood cells.

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8
Q

2 options upon infection

A
  1. pathogen overwhelms defences-> death
  2. defences overwhelm the pathogen->recovery
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9
Q

What must lymphocytes be able to do?

A

distinguish between self and non-self cells

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10
Q

what would happen if lymphocytes were unable to distinguish between self and non-self?

A

our immune system wouldn’t combat pathogens and would destroy our own tissues

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11
Q

how can lymphocytes distinguish between pathogens and self-cells?

A

markers are present on cell surfaces

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12
Q

antigen

A

molecule on the surface of pathogens that triggers an immune response.

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13
Q

clonal selection

A

antigens bind to specific receptors, causing a fraction of lymphocytes to clone themselves

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14
Q

Why do we not want lymphocytes to be complementary to self cells?

A

Because the lymphocytes would attack self cells and leave our immune system weak

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15
Q

Lymphocyte production in adults

A

In the bone marrow

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16
Q

Apoptosis

A

programmed cell death

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17
Q

How does cell recognition impact transplant patients?

A

The organ may often get rejected as the lymphocytes see it as a non-self cell. This causes the person to be very ill due to the strong immune response so they have to take immunosuppressant drugs.

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18
Q

Immunosuppressant drugs

A

drugs which suppress the immune system of the recipient of a transplanted organ to prevent rejection

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19
Q

White blood cells

A

fight infection and combat pathogens

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20
Q

Types of WBC

A

Lymphocytes and Phagocytes

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21
Q

Phagocytes

A

White blood cells that attack invading pathogens, non-specific and travel in blood but can move out to other cells due to segmented nucleus

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22
Q

Phagocytosis

A

Process in which a pathogen is engulfed

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23
Q

Phagocytosis step 1

A

Pathogen releases chemoattractants and the phagocyte is attracted to them so moves towards the pathogen.

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24
Q

Phagocytosis step 2

A

Receptors on the phagocyte attach to chemicals on the pathogen surface.

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25
Q

chemoattractants

A

chemical signals and products of a pathogen

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26
Q

Phagocytosis step 3

A

formation of phagosome because the bacteria is engulfed. Lysosomes move closer to the phagosome

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27
Q

Phagocytosis step 4

A

Lysosomes fuse with the phagosome, and they release lysozymes (lytic enzymes) into the phagosome which hydrolyses the bacterium.

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28
Q

Phagocytosis step 5

A

The hydrolysis products of the bacterium are absorbed by the phagocyte. Antigens are presented on cell membrane of phagocyte

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29
Q

Purpose of presenting bacterium products

A

signals other areas of the immune system that there is an infection that they must fight & also they can produce antibodies.

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30
Q

Impact of pH change on immune response

A

could alter charges on the active site which break down pathogens so this could prevent pathogen hydrolysis.

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31
Q

What is a specific response?

A

A slower response that is specific to each pathogen

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32
Q

Advantage of specific response

A

Develops immunity in the long term

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33
Q

Disadvantage of specific response

A

Slower as it targets certain pathogens

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34
Q

Which cells are required to initiate a specific response?

A

Requires lymphocytes

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35
Q

T lymphocytes

A

cell-mediated immunity

Mature in thymus gland

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36
Q

What do t lymphocytes respond to?

A

Responds to foreign material inside body cells so it only responds if pathogen is directly affecting body cells

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37
Q

Antigen presenting cells

A

Cells that display foreign antigens on their surface

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38
Q

T cells and phagocytes

A

When phagocytosis occurs, the pathogen is engulfed by a phagocyte and displays antigens. This means the T cells can bind

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39
Q

T cells and body cells invaded by viruses

A

They would display the antigens of the virus to alert the body to the virus invasion. Acts as a distress signal

40
Q

T cells and cancer cells

A

They are different from healthy cells as they present antigens on the surface

41
Q

T cells and transplanted cells

A

These are bodily cells but look completely different because they come from elsewhere so they contain different antigens

42
Q

cell mediated immunity stage 1

A

pathogen invades body cells/taken in by phagocytes or engulfed

43
Q

cell mediated immunity stage 2

A

phagocyte presents pathogen’s antigens on it’s cell surface membrane

44
Q

cell mediated immunity stage 3

A

receptors on specific helper T cells fit exactly onto antigens because they are complementary

45
Q

cell mediated immunity stage 4

A

activates the T cell to undergo clonal selection (divide through mitosis)

46
Q

4 things cloned T cells can do

A

develop into memory cells

stimulate the phagocytes

stimulate the B cells to divide

activate cytotoxic t cells

47
Q

Cytotoxic T cells

A

attack abnormal body cells.

Produce a protein called perforin that makes holes in the cell surface membrane and make it a freely permeable membrane

48
Q

Perforin

A

One of the proteins released by cytotoxic T cells on contact with their target cells. It forms pores in the target cell membrane that contribute to cell killing.

49
Q

B lymphocytes

A

form in the bone marrow and release antibodies that fight bacterial infections, respond to foreign material outside body cells

50
Q

How do T and B cells work together?

A

B cells find an antigen in the body and join with it to form an antigen-antibody complex. It is taken up through endocytosis.

B cells present the antigens on the surface and the T cells attach to B cells and help B to divide in clonal selection.

51
Q

What happens in the second part of humoural immunity?

A

cloned B plasma cells produce specific antibodies for a quick response and they attach to the antigen of the pathogen and destroy it (primary response)

52
Q

Humoural immunity

A

The type of response which involves B lymphocytes and antibodies.

53
Q

what happens in the third stage of humoural immunity?

A

some B cells remain and become memory cells. They respond in the future and create the secondary response

54
Q

Plasma cells

A

secrete antibodies into blood plasma but survive for only a few days. Part of primary response

55
Q

Memory cells

A

live for decades, circulate in blood and tissue fluids. dont produce antibodies directly - divide into both plasma and memory cells for secondary response

56
Q

Secondary immune response

A

memory cells facilitate a faster, more efficient response

57
Q

Issues with memory cells?

A

Many pathogens have many cell surface proteins which acts as antigens and they can change and mutate meaning memory cells may not always recognise cells

58
Q

Antigen variation

A

changing its appearance by altering surface antigens

59
Q

antibodies

A

Specialized proteins that aid in destroying infectious agents

60
Q

Where are antibodies found?

A

plasma cells

61
Q

Describe the structure of an antibody in terms of protein hierarchy

A

They have a quaternary structure (3d shape and formed of many polypeptide chains). Two heavy polypeptide chains bonded to two light chains.

62
Q

variable region of antibody

A

antigen binding site

63
Q

constant region of antibody

A

terminal that contains 2 heavy chains; binds to receptors on cells

64
Q

Explain why the Antibody will only detect a certain antigen (3 marks)

A

Antibody and it’s variable region has a specific amino acid sequence

This gives a specific shape (tertiary structure) which is complementary to the antigens

It forms a complex between antigen and antibody

65
Q

Do antibodies directly destroy antigens?

A

No they lead to antigen structure through other means

66
Q

Agglutination

A

Clumping of microorganisms or blood cells, typically due to an antigen-antibody interaction. Easier for phagocytes to locate and engulf as they are less spread out

67
Q

Markers (roles of antibodies)

A

Antibodies act as markers that stimulate phagocytes making it easier to engulf the pathogen

68
Q

Monoclonal antibodies

A

Antibodies produced by a single clone of B lymphocytes and that are therefore identical in structure and antigen specificity. Single type. Often produced outside the body

69
Q

Polyclonal antibodies

A

a series of antibodies are produced responding to a variety of different sites on the antigen. Produced from a variety of B cells

70
Q

Monoclonal antibody therapy

A

A type of treatment by which monoclonal antibodies are administered, the antibodies form an antibody-antigen complex with cancerous cells which prevents further growth and stimulates chemical destruction of the cancer

71
Q

Herceptin

A

Antibody for treating:

Ovarian Cancer

Breast cancer

72
Q

What can Herceptin do?

A

Engulf cancer cells and mark them for destruction

Block the chemical signals that stimulate uncontrolled growth

73
Q

Advantages of antibody therapy

A

Non-toxic

Highly specific

74
Q

Indirect monoclonal antibody therapy

A
  • a radioactive or cytotoxic drug is attached to a monoclonal antibody that is bound to antigens

Kills cancer cells

75
Q

How do pregnancy tests work?

A

1) Monoclonal antibodies are used to detect human chorionic gonadotropin (hCG) found in the urine of a pregnant woman

2) When urine is applied to the application area, the antibodies bind to any hCG, forming antigen-antibody complexes

  • these antibodies are attached to blue-coloured beads

3) The urine moves up to the test strip, where immobilised antibodies bind to any hCG antigen-antibody complexes

  • the test strip turns blue from the concentration of coloured beads
76
Q

What can antibodies identify?

A

Flu, hepatitis, cancer, chlamydia

77
Q

ELISA test

A

Enzyme Linked Immunosorbent Assay uses antibodies to detect presence and quantity of a protein in a sample

78
Q

1st stage of ELISA test

A

Apply sample to well surface.

Antigens in sample attach to surface

Wash to remove any unattached antigens

79
Q

2nd stage of ELISA test

A

Add the antibody that is specific to the antigen we wish to detect.

Leave to allow binding then wash.

80
Q

3rd stage of ELISA test

A

Add a second antibody to bind with the 1st. This one will have an enzyme attached to it. Wash again.

81
Q

4th stage of ELISA test

A

Add substrate to enzyme (must be colourless)

This enzyme acts on substrate and causes a colour change for a positive result

82
Q

ELISA positive result

A

Colour change

83
Q

Ethical implications of monoclonal antibodies

A

Mice are used to test- animal cruelty

Deaths associated with use of monoclonal antibodies

Drug testing can impact even healthy people

84
Q

Passive immunity

A

the short-term immunity that results from the introduction of antibodies from an outside source. No memory cells produced so it is short term but immediate.

85
Q

Active immunity

A

production of antibodies stimulated by the individual. Requires direct contact with pathogen and takes time. Has 2 forms.

86
Q

natural active immunity

A

production of one’s own antibodies or T cells as a result of infection or natural exposure to antigen

87
Q

artificial active immunity

A

Production of one’s own antibodies or T cells as a result of vaccination against disease

88
Q

Vaccines

A

A preparation that prevents a person from contracting a specific disease- contain small amounts of weakened or dead forms of a pathogen

89
Q

When a vaccine is given to a person, it leads to the production of antibodies against a disease-causing organism. Describe how.

A
  1. Vaccine contains antigen from pathogen;2. Macrophage presents antigen on its surface;3. T cell with complementary receptor protein binds to antigen;4. T cell stimulates B cell;5. (With) complementary antibody on its surface;6. B cell secretes large amounts of antibody;7. B cell divides to form clone all secreting / producing same antibody
90
Q

Corona Virus vaccine

A

Developed a synthetic version of some of the virus’ mRNA. Our cells read it as an instruction to start building spike proteins (antigens). The body then ammounts an immune response against them

91
Q

How do you make a vaccination programme successful?

A

Cheap

Few side effects

Be able to produce, store and transport vaccines

Administer them correctly

92
Q

Herd immunity

A

The resistance of a group to an attack by a disease to which a large proportion of the members of the group are immune

93
Q

How do you achieve herd immunity?

A

Vaccinate large amounts of a population all at the same time

94
Q

Why are vaccination programs rarely 100% successful?

A

Some people have defected immune systems

Pathogens can mutate and change their antigens

Pathogens have different strains

Some hide from immune systems

People object to vaccinations

95
Q

Ethics of vaccinations

A

Production uses animals

Side effects

Who should be tested on?

Can people be forced to get a vaccine?

Should expensive vaccination programmes still continue if a disease is eradicated?

96
Q

Ethics of vaccinations

A

Production uses animals

Side effects

Who should be tested on?

Can people be forced to get a vaccine?

Should expensive vaccination programmes still continue if a disease is eradicated?

A-Level Biology- Y12 (14 decks)

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