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AQA Biology A-level > Immunity > Flashcards

Immunity Flashcards

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1
Q

What is a pathogen?

A

A disease causing microrganism

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2
Q

What does a cell-mediated response involve?

A

T lymphocytes

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3
Q

What does a humoral repsonse involve?

A

B lymphocytes

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4
Q

What is an innate response?

A

First line of defense, attacks generic classes of pathogens

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5
Q

What is an adaptive immune response?

A

A specific defence system that eliminates almost any pathogen or abnormal cell in the body through immonulogical memory

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6
Q

What is an infection?

A

Interaction between the pathogen and the bodys various defence mechanisms

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7
Q

What is immunity?

A

The ability to ward off disease

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8
Q

What do all immune cells come from?

A

Hematopoietic stem cells

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9
Q

What do hematopoietic stem cells differentiate into?

A

Lyphoid progenitor or myeloid progenitor

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10
Q

What is the lymphoid lineage?

A

Lymphocytes

—>T-cells, B-cells and natural killer cells

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11
Q

What is the myeloid lineage?

A

Ganulocytes,monocytes

—>macrophages and neutrophils

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12
Q

What does the 1st line of defence include/do?

A

Physical and chemical barriers

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13
Q

What does the 2nd line of defence do/include?

A

Non-specific inflammatory response & phagocytosis

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14
Q

What is the 1st immune response?

A

B+T cells

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15
Q

What is the 2nd immune response?

A

Memory cells

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16
Q

Where are all immune cells derived from?

A

Bone marrow

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17
Q

What is the specific immune response?

A

Defense response against a specific foreign or abnormal cell

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18
Q

What is a non-specific immune response?

A

Initital, immidiate immune reponse against forein antigens vis non-specific antibodies and immune cells
Ie physical barriers and phagocytosis

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19
Q

What are some examples of physical barriers?

A
  • skin
  • mucous membranes
  • sebaceous + sweat glands
  • tears, saliva + secretions
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20
Q

How does the skin act as a barrier?

A

It contains keratinocytes that act as an impentrable barrier

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21
Q

What do mucous membranes do?

A

It lines body cavities like the digestive, respiratory and genitourinary tracts.
The epithilial layer has goblet cells which secrete mucous and ciliated cells.
The cilia waft the mucous along sweeping any microorganisms into the stomach where the acid denatures any enzymes that the pathogen may have

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22
Q

What does the sebaceous gland do?

A

It gives the skin an acidic pH (3-5) which prevents most pathogens from reproducing

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23
Q

What does the stomach acid do?

A

It has a highly acidic enviroment which breaks down any microbes found in food or drinks

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24
Q

What do tears, saliva and mucous do?

A

They continually wash away microbes from the surface.

Lysozyme is found in tears which is an antimicrobial and will break down bacteria cell walls

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25
Q

What is the most abundant type of immune cell?

A

Neutrophil

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26
Q

What is the function of neutrophils?

A

Phagocytise bacteria

Give pus a white colour

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27
Q

What do dendritic cells do?

A

They capture antigens and deliver them to the lymph nodes where they are presented to T-cells which mulitply and attack the pathogen

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28
Q

What helps the body to identify self and non-self cells?

A

Antigens

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29
Q

What are the two types of WBC?

A

Phagocytes and lymphocytes

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30
Q

Where do B-cells mature?

A

Bone marrow

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31
Q

Where do T-cells mature?

A

Thymus gland

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32
Q

What are antigens?

A

Proteins(glycoproteins or glycolipid) that are on the cell surface of pathogens that stimulate an immune repsonse

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33
Q

What are examples of non-specific immune repsonses?

A
  • inflammation
  • lysozyme action
  • interferon
  • phagocytosis
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34
Q

What happens if an antigen on a pathogen changes?

A

Lymphocytes and memory cells can’t bind so the host cell becomes infected

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35
Q

What do macrophages develop to become?

A

Antigen presenting cells

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36
Q

What causes inflammation to occur?

A

Histamine and other chemicals released by damaged tissues

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37
Q

What does inflammation cause?

A

Vasodilation of blood vessels

Leaky blood vessels

Increases blood flow to the infected site

More phagocytes are delivered

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38
Q

What does interferon do?

A

Stops viruses spreading to uninfected cells by preventing protein synthesis in viruses

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39
Q

What do phagocytes do?

A

Ingest and destroy pathogens

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40
Q

What are the types of phagocytic cells?

A

Macrophages and neutrophils

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41
Q

What are neutrophils?

A
  • Made in the bone marrow with a lobed nucleus
  • Travel in the blood + tissues
  • Patrol the body tissues
  • Released in large numbers but are short lived
  • Engulf and digest pathogens into the phagocytic vacuole
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42
Q

What are macrophages?

A

-Large long lived WBCs which move into organs and travel in the blood as monocytes
-Don’t destroy the pathogen completely by display it on the surface
(APC)

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43
Q

What is endocytosis?

A

The process by which cells take in substances from outside of the cell by engulfing them in a vesicle.

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44
Q

What are the stages of phagocytosis?

A
  1. The phagocyte is attracted to the pathogen by chemical products on the pathogen. It then moves along the conc. gradient via chemotaxis
  2. The chemical recptors on the surface of the phagocyte attach to the pathogen
  3. The phagocyte engulfs the pathogen and encloses it into a phagosome vesicle
  4. Lysosomes within the phagocyte migroate towards the phagosome and fuse to form a phagolysosome
  5. The lysosomes release lysozyme which release lytic enzymes into the phagosome to hydolyse the pathogen
  6. The pathogen is digested and the products are absorbed by the phogocyte into the cytoplasm
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45
Q

What is chemotaxis?

A

The movement of an organism in reponse to a chemical stimulus

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46
Q

What is the role of antigen presenting cells?

A

To stimulate other cells involved in the specific immune response system

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47
Q

How is the specific immune response activated?

A
  1. Antigen presenting cells interact with T-helper cells that have a complementary receptor
  2. Macrophages release interlukin 1 which stimulates T-helper cells to release interlukin 2
  3. Interlukin 2 causes the bone marrow to release wither T or B cells
  4. If T cells are released it will need the exact receptor
    If B cells are released it will need the exact plasma for antibodies
  5. Increased number of cells needed
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48
Q

What is interlukin 1&2?

A

Cytokines that act as a chemical messenger

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49
Q

Why are B memory cells better than T memory cells?

A

The antibodies dont destroy pur cell whereas killer T cells attack our cells and immune system

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50
Q

What do cytokines stimulate?

A
  • B cells maturing into plasma cells that secrete antibodies
  • Formation of B memory cells
  • Activation of cytotoxic T cells which destroy tumour cells and virus infected cells
  • Actibation of phagocytes
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51
Q

What do B cells do?

A

Differentiate into plasma cells that secrete antibodies

52
Q

What do T cells do?

A

Cell-mediated immune response

53
Q

What can T cells differentiate into?

A

T-helper cells
Killer T cells
T memory cells

54
Q

What do B cells differentiate into?

A

Plasma cells

B memory cells

55
Q

Why is it called the humeral response?

A

As it involves antibodues which are soluble in blood and tissue

56
Q

What is clonal selection?

A

The process through which immature B & T cells go though sp that only certain types are permitted to mature

57
Q

What is clonal expansion?

A

An increase in the number of the exact lymphocyte needed by mitotic cell division

58
Q

What do plasma cells do?

A
  • Secrete antibodies imto blood plasma
  • Short lived
  • Antibodies destroy enzyme
  • Known as primary immune response
59
Q

What do memory B cells do?

A

They are part of the seconary immune response. They dont produce antibodies directlybut circulate in the blood and tissue, whenthey encounter a previous antigen, they divide rapidly into the correct plasma cells

60
Q

What organelles would there be a high quantity of in plasma cells?

A

rER
Golgi apparatus
Ribosomes

61
Q

What makes blood cells leaky and causes them to dilate?

A

Histamines

62
Q

What indicates that your cells are self?

A

MHC proteins

63
Q

What does MHC stand for?

A

Major Histocompatibility Complex proteins

64
Q

What do cytotoxic T cells do?

A

Kill infected cells by producing perforin proteim that makes holes in the cell surface membrane causing the cell to die

65
Q

What do T helper cells do?

A

Release substances to activate B lymphocytes and T killer cells

66
Q

What are antibodies?

A

Immunoglobulin proteins that have a quaternary structure synthosised by B cells and bind to antigens

67
Q

What is the structure of antibodies?

A

Quaternary structure with two heavy and two light polypeptide chains bonded by disulphide bonds
Each chain has a constant and variable region

68
Q

What is the constant region on an antibody?

A

Its the same in all antibodies and allows antibody binding

69
Q

What is the variable region of an antibody?

A

Antigen binding site which is different on every antibody

70
Q

What is the variable region made up of?

A

Sequence of amino acids forming 3D structures

71
Q

What do antibodies form?

A

Antigen-antibody complexes

72
Q

What is the hinge region of sn antibody?

A

Allows flexibility when the antibody binds to the antigen allowing more than one antigen to bind

73
Q

What does the antigen binding cause?

A

It immobilises the antigen

74
Q

How do antibodies inactivate antigens?

A
  • Neutralisation
  • Agglutination
  • Precipiation of soluble antigens
  • Actibation of complement
  • Attach to the flagella immobilising the bacteria
  • Opsonisation
75
Q

What is neutralisation?

A

The pathogen may use the antigen to bind to a host cell. If an antibody binds to the antigen it prevents it happening

76
Q

What is agglutination?

A

Some antibodies have several variable regions allowing it to bind to multiple antigens. This sticks pathogens together preventing them from entering the host cell.

77
Q

What is precipitation of soluble antigens?

A

Soluble antigens stuck together to form precipitate to be engulfed

78
Q

What is activation of complement?

A

Tag foregin cells for destruction by phagocytes.
Produce complement protein which ruptures the cell walls of the pathogen which causes water to enter and the cell to burst

79
Q

What is opsonisation?

A

The process by which a pathogen is marked for ingestion and destruction by a phagocyte

80
Q

What is active immunity?

A

When the body is exposed to a pathogen and produces its own antibodies

81
Q

What is passive immunity?

A

Short term immunity using antibodies produced from outside the body from another human or animal ie vaccination

82
Q

What do hybridoma cells do?

A

Divide endlessly to produce a clone of one specific type of hybridoma cell

83
Q

What is the role of an activated B cell?

A

To multipy to form clones of plasma B cells

84
Q

How does HIV affect the immune system adversely?

A

Progressive reduction in number of active lymphocytes which causes a reduction in antibody productin

85
Q

What 2 cells fuse together during monoclonal antibody production?

A

Plasma and tunmour cells

86
Q

What is an example of active immunity?

A

Antibodies being produced after defence mechanisms have been stimulated by antigens

87
Q

What do RNA molecules in a virus do?

A

Carry genetic instructions and information to make DNA/new viral proteins

88
Q

How are new viruses produced after HIV has infected the T cell?

A
  1. DNA copy made up of viral RNA through reverse transcriptase reversing RNA INTO DNA
  2. DNA moves into the nucleus and uses viral DNA to make viral proteins and mRNA
  3. mRNA provides instructions to make new viral proteins which pass out of the nucleus and use the cells protein synthesis to make new HIV viruses which bud off
89
Q

How does antihen variation affect the use of vaccines?

A

-Memory B/T cells cannot recognise the antigen so the previous antibodies arent effective as they dont have a complementary shape

90
Q

What is an autoimmune disease?

A

A disease in which the body’s immune system attacks healthy cells

91
Q

What are some examples of autoimmune diseases?

A

Lupus, rheumatoid arthritis

92
Q

What is natural active immunity?

A

The productionof ones own antibodies or T cells as a result of infection or natural exposue to antigen

93
Q

What is artificial active immunity?

A

Acquiring ones own immunity against an attenuated pathogen

94
Q

Example of natural passive immunity?

A

Breastfeeding

95
Q

Example of natural active immunity

A

Infection

96
Q

Example of artificial passive immunity

A

Injection of antibodies or antitoxins

97
Q

Example of artificial active immunity

A

Vaccination

98
Q

What are the different types of vaccine?

A

Inactivated
Attenuated
Preparation made from antigens only

99
Q

What is an attenuated vaccine?

A

Alteration of the virus to make it less harmful

100
Q

How do vaccines work?

A

Once the vaccine is injected, an immune response is triggered
Memory cells produced remain in the blood
Secondary response allows for rapid production of antibodies
The pathogen is destroyed before causing symptoms

101
Q

What does the success of a vaccination programme depend on?

A
  • Economically avaliable quantities
  • Few less severe side effects
  • Ease in transport, storage, production and administation
  • Number needed for herd immunity
  • Cost
102
Q

What are the ethical issues around the use of vaccines?

A
  • Production may involve animals
  • Long term side effects
  • Clinical tests may be fatal
  • Should they be compulsory
  • Expensive
103
Q

What does HIV stand for?

A

Human Immunodeficiency Virus

104
Q

What type of virus is HIV?

A

Retrovirus

Catalyse DNA from RNA to replicate

105
Q

How is HIV transmitted?

A

Blood, semen, vaginal secretions, breast milk, sharing needles

106
Q

What does HIV do?

A

Destroys the immune system and causes AIDS

107
Q

What does AIDS stand for?

A

Aquired Immune Deficiency Syndrome

108
Q

What is the structure of HIV?

A 
Two single strands of RNA 
Attachement proteins
Lipid envelope
Protein capsid
Reverse transcriptase
109
Q

How does HIV replicate?

A 
HIV binds to CD4 receptor on t
helper cell
-capsid fuses w/ cell surface membrane
-RNA + enzymes enter t cell
-reverse transcriptase reverses RNA into
HIV DNA
-DNA moves into T cell nucleus
creating mRNA
-mRNA has instructions making
viral proteins
-viral particles assembled + break away
from T cell w/ piece of membrane to
make lipid envelope
110
Q

What is the course of the HIV infection?

A

Acute HIV syndrome
Chronic phase
Disease stage
Advancd AIDS

111
Q

How does HIV cause the symptoms of AIDS?

A

It reduces the number of T-helper cells so very few B cells are activated which means the body cannot fight off infections - AIDS

112
Q

Why are antibiotics ineffective against viruses?

A

Viruses use host cells to carry out metabolic processes as they lack their own metabolic pathways therefore antibiotics cannot disrupt it.
Viruses have a protein coat not a cell wall.

113
Q

How are antibiotics effective against bacterial infections?

A
  1. Inhibit enzymes needed for synthesis and assemble peptide linkages in bacterial cell walls
  2. They weaken the cell wall as they cannot withstand the pressure causing water to enter and the bacterium to burst
114
Q

What are monoclonal antibodies?

A

Antibodies produced from a single group of genetically identical B-cells

115
Q

How are monoclonal antibodies produced?

A 
- Mouse is injected with an injection of antigens
to stimulate production of
antibodies
- Plasma cells isolated from spleen
- Plasma cells fuse with tumor cells to
form a hybridoma through detergent
breaking down membranes
- Hybridoma divides produces large
amounts of identical antibody
molecules required
116
Q

How are monoclonal antibodies used?

A

Targeting medication to specific cell types

Medical diagnosis

Pregnancy testing

ELISA tests

117
Q

How are monoclonal antibodies used to target medication?

A

Antibodies produced are specific to the antigen allowing receptors to attach
These block chemical signals
Eg cancer signals leading to uncontrolled cell growth

118
Q

How are monoclonal antibodies used in medical diagnosis?

A 
-produce AB specific to antigen +
interacts w/ antigen -> wash
removing unbound
-antibody w/ enzyme attached ->
bind to antigen
-substrate added
-enzyme converts colourless
substrate to colored product if
present
119
Q

How are monoclonal antibodies used in pregnancy tests?

A 
-strip coated w/ antibodies specific
to hormone, HCG w/ coloured
particles
-HCG binds to antibodies when
dipped in urine + diffuses up strip
-immobilised MA bind with HCG
giving appearance of fixed blue Line
-small window w/ immobilised AB
bind with coloured mobile AB
120
Q

What does ELISA stand for?

A

Enzymes-linked Immunosorbent Assay

121
Q

What are the ethical uses of monoclonal antibodies?

A

Production involves the use of mice
Drug trials against arthritis and leukaemia resulted in multiple organ failure
Some deaths in trials and treament plans

122
Q

How are monoclonal antibodies used in seperating one type of molecule from a mixture?

A

MA immobilised on resin beads
Mixture is poured over beads
Target molecules attach to AB
Beads washed with substance releasing molecules

123
Q

How does the direct sandwich ELISA test work?

A

Antigens bound to well
Wash to remove the excess and unattched antigens
Add the antibody specific to the antigen
Wash the surface to remove excess AB
Add the entibodies with an enzyme conjugated
Substrate added
Changes colour if present

124
Q

How does the direct ELISA test work?

A

Antigen or sample is immobilised directly on the plate
Conjugated antibody binds to the antigen
Substrate added, producing a colour change if the enzyme substrate complex is formed

125
Q

How does the indirect ELISA test work?

A 
Antibody added to the well
The sample is then added, allowing antigen antibody complexes to form
Enzymes conjugated AB
Added binding
Substrate added=colour change
126
Q

How do anti-viral drugs work?

A

They block receptors, preventing viruses from binding with healthy cells
This lowers the viral load supressing them form dividimg and infecting
This reduces virus transmission
Inhibits molecular interactions and the functions that viruses need to replicate

AQA Biology A-level (1 decks)

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