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AQA A level Biology > Cell recognition and the immune system > Flashcards

Cell recognition and the immune system Flashcards

1
Q

What is the biological name for white blood cells

A

Leukocytes

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2
Q

What are the 3 types of white blood cells, only 2 on spec

A
  • Granulocytes (not on spec)
  • Phagocytes
  • Lymphocytes
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3
Q

What are the 2 types of phagocytes

A
  • Neutrophil
  • Macrophage
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4
Q

What is the name of a macrophage before it’s developed

A

Monocyte

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5
Q

What are the 2 types of lymphocytes

A
  • B cell
  • T cell
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6
Q

What does a B cell mature into

A

Plasma cell

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7
Q

What does a T cell mature into

A
  • Either T helper cell
  • Cytotoxic cell
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8
Q

What type of stem cells are the ones found in bone marrow

A

Multipotent

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9
Q

What does a multipotent stem cell mean

A

The stem cell can only differentiate into a certain type of cell e.g. blood cells but can differentiate into any type of blood cell

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10
Q

Why don’t phagocytes provide immunity

A

Because they don’t have memory cells so they just destroy pathogens but don’t remember them

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11
Q

What type of white blood cells are part of the non-specific immune response

A
  • Granulocytes (not on spec)
  • Phagocytes
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12
Q

What are lymphocytes capable of recognising

A
  • Self and non-self recognition
  • Can differentiate cells that belong to the individual and those that are foreign
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13
Q

What type of white blood cell is part of the specific immune response and why

A

Lymphocytes because they have memory

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14
Q

What type of white blood cell provide immunity and why

A

Lymphocytes because they have memory

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15
Q

What shape nucleus does a neutrophil have

A

Lobe shape

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16
Q

What shape nucleus does a macrophage have

A

C shaped

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17
Q

What shape nucleus does a lymphocyte have

A

Nearly the entire cell is covered by nucleus

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18
Q

What type of leukocytes are antigen presenting cells

A
  • Macrophage
  • Lymphocytes
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19
Q

Which division process do immature T cells undergo, and what does this produce

A

Mitosis, producing genetically identical cells- clone

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20
Q

Where do T cell mature

A

In the thymus

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21
Q

What is produced when a T cell matures

A

Cell receptors

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22
Q

What type of biological molecule are the cell receptors on a T cell

A

Protein, tertiary structure

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23
Q

What are the 2 possible types of T cell after they have matured

A
  • T helper cells
  • Cytotoxic cells
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24
Q

When a T cell matures what is different on each T cell

A

The receptors

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25
Q

What division process do immature B cells divide by

A

Mitosis- producing genetically identical cells called a clone

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26
Q

Where do B cell mature

A

In the bone marrow

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27
Q

When B cell mature what do they produce

A

Antibody receptors

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28
Q

What type of biological molecule is the antibody receptor produced in the maturation of B cells

A

3D, Globular protein

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29
Q

Where are the 2 places where mature B cell circulate to

A
  • Liver
  • Spleen
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30
Q

When B cell mature what is different between each B cell

A

The antibody receptors

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31
Q

What are the 7 examples of barriers in immunity

A
  • Skin
  • Tears
  • Saliva
  • Sweat
  • Stomach acid
  • Mucus
  • Skin flora
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32
Q

How does skin act as a barrier

A

Contains collagen and keratin which are tough

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33
Q

How does tears, saliva and sweat act as a barrier

A

They contain an enzyme called lysozyme which disrupts bacterial walls

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34
Q

How does stomach acid act as a barrier

A

It denatures the proteins and kills the pathogen

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35
Q

How does mucus act as a barrier

A

It traps bacteria and waft it up the trachea and down into the stomach where the acid kills the bacteria

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36
Q

How does the skin flora act as a barrier

A

They compete with bad bacteria

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37
Q

What are the 4 actions that happen for a non-specific immune system

A
  • Phagocytosis
  • Blood clotting
  • Fever
  • Inflammation
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38
Q

How does blood clotting act as a line of defence in immunity

A

It prevents pathogens from entering the capillaries

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39
Q

How does a fever act as a line of defence in immunity

A

It increases the temperature to denture growth enzymes in pathogens

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40
Q

How does inflammation act as a line of defence in immunity

A

It increases the blood flow to the site of injury which helps carry more white blood cells - the immunity cells

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41
Q

What type of cells are involved in the specific immune system

A

Lymphocytes

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42
Q

What’s the difference between immunity and resistance

A

Immunity produces antibodies to fight the pathogen whereas resistance is a tolerance of the pathogen or an ability to withstand .

Immunity you gain from being exposed to the certain pathogen whereas resistance isn’t obtained the organism is born with it e.g. bacteria resist antibiotics

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43
Q

What are the 7 cells that have antigens

A
  • Viral capsids
  • Infected body cell
  • Toxin
  • Bacterial antigen
  • Macrophage
  • Transplanted organ
  • Cancerous cell
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44
Q

What happens during clonal selection

A

The lymphocytes with the complementary receptor/ antibody to the antigen are selected

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45
Q

What happens during clonal expansion

A

The lymphocyte with the complementary receptor/ antibody to the antigen are cloned over and over by mitosis

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46
Q

What cells are involved in cellular response

A

T cells

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47
Q

What are the 3 types of T cells involved in cellular response

A
  • T helper cells
  • Cytotoxic T cells
  • Memory T cells
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48
Q

During cellular response, what is the first thing that T helper cells do

A

They attach/ bind to the antigen on the antigen presenting cell - only the ones that are complementary to the antigens

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49
Q

During cellular response, what do the T helper cells do after they attach to the antigens

A

They divide by mitosis - clonal expansion

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50
Q

Once T helper cells have divided during cellular response, what is the final thing they do

A

They secrete cytokines which stimulate all other white blood cells

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51
Q

During cellular response, what do the T cytotoxic cells do first

A

The complementary cells attach to the antigen on the antigen presenting cell which activates them or they are activated via the T helper cells

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52
Q

After the complementary cytotoxic T cells bind to the antigens that they are complementary to, what do they then do

A

They divide by mitosis

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53
Q

Once cytotoxic T cells divide, what do they then do during cellular response

A

They then release perforin proteins - which create pores leading to cell lysis

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54
Q

What do perforin proteins do

A

They get inserted into the cell membrane of the infected cell or the bacteria cell and make a pore - which then allows water the enter the cell via osmosis which results in cell lysis

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55
Q

How long of T memory cells remain in the blood for

A

Decades

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56
Q

Why are T memory cells useful

A

So if the same antigen is encountered the response is much faster since there are already multiple cells with complementary receptors

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57
Q

What are the 3 types of B cells involved in humoral response

A
  • B cells
  • Plasma cells
  • Memory B cells
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58
Q

What type of lymphocyte is involved in the humoral response

A

B cells

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59
Q

What is the first thing that B cells do during a humoral response

A

The complementary B cell attaches to the antigen on the antigen presenting cell - clonal selection

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60
Q

After B cells have been clonally selected, what is the next process

A

Clonal expansion, via mitosis

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61
Q

Once B cells have divided what do they then do

A

They differentiate into plasma cells

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62
Q

What are the 3 organelles that a plasma cell is packed with

A
  • Mitochondria
  • RER
  • Golgi body
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63
Q

Why do plasma cells require a lot of mitochondria

A

To produce ATP for the synthesis of the antibodies and the secretion of the antibodies via exocytosis

64
Q

Why do plasma cells require a lot of RER

A

For the synthesis of antibodies

65
Q

Why do plasma cells require Golgi bodies

A

To package and secrete antibodies

66
Q

What is the difference between B memory cells and T memory cells

A

B memory cells secrete a small number of antibodies even after the pathogen has gone whereas T memory cells just stay dormant in the blood

67
Q

Why is there a longer lag time for the primary response than the lag time for the secondary response

A

Because clonal selection takes time to find the complementary antibody, then it takes time for clonal expansion

68
Q

Why are you more likely to express symptoms during the primary response

A

Because it’s a slower and weaker response - since it takes time for the complementary antibody to be found and then it takes for the antibody to be reproduced via mitosis

69
Q

Why is there a steeper gradient for the antibody concentration for the secondary response compared to the primary response

A

There is faster antibody production

70
Q

Why is there a higher maximum antibody concentration during the secondary response compared to the primary response, and why does this maximum concentration last longer than the primary’s maximum concentration

A

Because the clone is bigger due to memory cells and then all the cells with the complementary antibodies divide via mitosis

71
Q

What are the 2 circumstances when there is no secondary response

A
  • When the first pathogen exposure was fatal (the organism dies)
  • When the pathogen mutates it’s antigen - antigenic variability on the same pathogen (e.g. the common cold)
72
Q

What are the names of the 2 regions on an antibody

A
  • Constant region
  • Variable region
73
Q

What are the 2 types of polypeptide chains on an antibody

A
  • Heavy polypeptide chain
  • Light polypeptide chain
74
Q

What is the name of the bonds on an antibody

A

Disulphide bridges

75
Q

What is the name of the site at the top of an antibody

A

The antigen binding site

76
Q

What type of biological molecule is an antibody

77
Q

What structure protein is an antibody

A

Globular, quaternary structure

78
Q

What makes the region on an antibody variable, and where on the antibody is this region

A

Because it has a different amino acid sequence, its at the antigen binding site

79
Q

Why do antibodies need to have variable regions

A

Because antibodies need to be complementary to different antigens and in order for this to be the case antibodies need to have different antigen binding sites and the variable region makes these sites different

80
Q

How many types of antigens can one antibody bind to

81
Q

How many antigens can an antibody bind to at one time

A

2, there are 2 antigen binding sites

82
Q

What are the 5 actions of antibodies

A
  • Cause bacterial lysis
  • Prevent pathogens entering host cells
  • Coat pathogens to aid phagocytosis
  • Deactivate flagella to aid phagocytosis
  • Cause pathogens to agglutinate
83
Q

What does it mean when pathogens agglutinate

A

They stick together - so they can be consumed at once

84
Q

What word is motility fancy for

85
Q

What are monoclonal antibodies

A

Artificial antibodies that are produced in a lab specific to one type of antigen only

86
Q

How are monoclonal antibodies produced

A
  • The specific antigen is injected into small mammals which stimulates a humoral response
  • isolated the B plasma cells that secrete the antibodies that responded to the antigen
  • Plasma cells fuse with myeloma cell
  • Forming a hybridoma
  • clone the hybridoma
87
Q

What type of cell does the plasma B cell fuse with to make monoclonal antibodies

88
Q

What is formed when a plasma B cell binds to a myeloma cell during the process of making monoclonal antibodies

89
Q

What type of response is stimulated in the small mammal once the antigen has been injected into them during the process of making monoclonal antibodies

A

Humoral response

90
Q

What are the 2 types of monoclonal antibody treatments

A
  • Direct
  • Indirect
91
Q

How does direct monoclonal antibody cancer treatment work

A
  • You inject the patients cell into a small mammal - so the antibodies are specific to the individual
  • So the antibodies are complementary to the cancer’s antigens so they bind and this stops the uncontrolled cell division by mitosis
92
Q

How does indirect monoclonal antibody therapy work

A

A cytotoxic drug is attached to an antibody that is complementary to the cancer’s antigen so the cytotoxic drug only kills the cancerous cells instead of all the cells

93
Q

What are the advantages of monoclonal antibody treatments

A
  • Monoclonal antibodies are non-toxic
  • Monoclonal antibodies are specific so a lower dosage is needed: meaning there are fewer side effects and its cheaper
94
Q

When you reach this card look on the 2.4 powerpoint and look at the pregnancy testing with monoclonal antibodies

95
Q

What does PSA stand for

A

Prostate Specific Antigen

96
Q

In direct ELISA, what attaches to the well in the test plate

A

A monoclonal antibody that is specific to the antigen that is being tested for

97
Q

In the direct ELISA, after the monoclonal antibodies attach to the well in the test plate, what happens

A

Wash the test plate to remove any unattached monoclonal antibodies

98
Q

After washing the test plate to remove any unattached monoclonal antibodies the first time during the direct ELISA, what happens

A

You add the patients blood sample - if any of the antigens you’re testing for are in the sample then they bind to the antibodies

99
Q

After the patients blood sample if added to the test plate during direst ELISA, what happens

A

You wash the plate to remove any unattached antigens

100
Q

After the plate is washed after adding the patients blood during direct ELISA, what happens

A

You add another monoclonal antibody that has an enzyme attached and then wash to remove any unattached antibodies

101
Q

Why does the second monoclonal antibody need to have an enzyme attached during direct ELISA

A

It reacts with a colourless substrate to produce a coloured product and this shows a positive result

102
Q

What are the 3 ethical issues of using monoclonal antibodies

A
  • Small mammals are used to produce them and we induce diseases upon them
  • Requires informed consent from patients (being aware of the good and the bad)
  • Have been failed drug trials (people have gone into organ failure)
103
Q

What are the 4 types of immunity

A
  • Artificial active
  • Natural active
  • Natural passive
  • Artificial passive
104
Q

What induces artificial active immunity

A

Antigen injection

105
Q

What induces natural active immunity

A

Having the disease/ encountering the pathogen

106
Q

What induces natural passive immunity

A

Breastfeeding
Across from the placenta

107
Q

What induces artificial passive immunity

A

Antibody injection

108
Q

What type of immunity is obtained from an antibody injection, and why

A

Artificial passive immunity because it’s deliberate exposure but no memory cells are produced since the B cells don’t get activate

109
Q

What type of immunity is obtained from an antigen injection, and why

A

Artificial active immunity because it’s deliberate exposure and the B cells get activated to produce antibodies and memory cells are made

110
Q

What is the difference between active and passive immunity

A

Active immunity activates the B cells to produce the organisms own antibodies and memory cells
Passive immunity is when antibodies are retrieved from somewhere else - e.g. an injection

111
Q

What’s the difference between artificial and natural immunity

A

Artificial immunity is when there’s deliberate exposure to get immunity
Natural is when immunity is obtained through some kind of natural life process

112
Q

What does an attenuated pathogen mean

A

A weakened pathogen

113
Q

What is in a vaccine (6 options)

A
  • Dead/ inactive pathogen
  • Attenuated pathogen
  • Antibodies
  • Antigens
  • Toxoids
  • Live pathogens
114
Q

What 2 things make a vaccine successful

A
  • Antigen that’s highly immunogenic (produces high concentration of antibodies/ triggers strong immune response)
  • Only 1 antigenic type of pathogen (a none mutating pathogen)
115
Q

What type of vaccine is the most effective, what type of pathogen inside the vaccine, and why

A

Live pathogen because it’s living so it can continue to replicate so there’s continuous exposure to the pathogen

116
Q

What type of vaccine is the least effective, what type of pathogen inside the vaccine, and why

A

Dead pathogen since they can’t replicate so there’s limited exposure

117
Q

Why are booster vaccines useful

A

They trigger a secondary response which increase the antibody concentration in the blood so increases the number of memory cells

118
Q

What is herd immunity

A

The majority of the population are vaccinated to interrupt transmission of pathogen in population

119
Q

Who is protected when there’s herd immunity

A

Those who haven’t been vaccinated are also protected

120
Q

What is ring immunity

A

When the people around the infected individual are vaccinated

121
Q

What type of virus is HIV

A

Retro virus

122
Q

What is a retro virus

A

A virus that has RNA so has the enzyme reverse transcriptase

123
Q

How many RNA strands does HIV contain

A

2 RNA strands

124
Q

What does reverse transcriptase do

A

It uses an RNA template to make DNA copies

125
Q

Where does the lipid double membrane come from in a HIV molecule

A

The host cells membrane

126
Q

What cells are effected by HIV

A

T helper cells

127
Q

After HIV attaches to the receptor proteins on the surface of the T helper cells, binding, what happens

A

Fusion occurs where the HIV membrane fuses with the T helper cell membrane allowing entry of viral capsid and contents

128
Q

Once the HIV has fused with the T helper cell membrane what happens

A

Reverse transcription- uses viral RNA as template to make DNA

129
Q

Once reverse transcriptase has happened to HIV, what occurs

A

Integration- The viral DNA enters the T helper cells nucleus and becomes inserted into the T helper cells DNA

130
Q

How long does the HIV viral DNA stay in the T helper cells nucleus

A

For years and even decades

131
Q

What is the name of the process, where the HIV viral DNA is activated and uses the T helper cell to synthesise viral proteins and viral RNA

A

Activation

132
Q

After the HIV viral DNA has been activated, what happens

A

Assembly- viral proteins and RNA synthesised by the T helper cell moves towards the cell membrane and begin to assemble into HIV

133
Q

After HIV has been assembled in the T helper cell, what occurs

A

Budding- HIV pushes itself out of T helper cell taking a section of the T helper cell’s membrane with it

134
Q

Why does continuous budding off of HIV from T helper cells, decrease the number of T helper cells

A

Since T helper cells continue to shrink since the HIV takes part of the membrane and because there are many T helper cells undergoing this the number of T helper cells decreases

135
Q

Why does HIV spread

A

It gets into the T helper cells and these T helper cells undergo clonal expansion so divide by mitosis so the viral DNA is passed on into new cells

136
Q

Can you die from AIDS

A

No, it’s the weakened immune system that fails when the patients encounters a disease

137
Q

Why are antibiotics not effective against HIV

A

Antibiotics work by preventing cell wall synthesis and viruses don’t have a cell wall

138
Q

What is phagocytosis

A

An example of the non-specific immune response. Where pathogens are engulfed and digested by phagocytes

139
Q

What is the role of Helper T cells (4 things)

A
  • Develop into memory cells
  • Activate cytotoxic T cells
  • Stimulate phagocytes to carry out phagocytosis
  • Stimulate B cells to divide and secrete their antibodies
140
Q

Describe how HIV is replicated (4 marks)

A
  • Attachment proteins attach to receptors on helper T cell
  • RNA enters cell
  • Reverse transcriptase converts RNA to DNA
  • Viral protein produced
  • Virus particles assembled and released from cell
141
Q

Describe how the HIV is replicated once inside helper T cell ( 4 marks)

A
  • RNA converted into DNA using reverse transcriptase
  • DNA inserted into helper T cell DNA
  • DNA transcribed into HIV mRNA
  • HIV mRNA translated into new HIV proteins for assembly into viral particles
142
Q

Describe how a phagocyte destroys a pathogen present in the blood (3 marks)

A
  • Engulfs
  • Forming phagosome and fuses with lysosome
  • Enzyme digests
143
Q

Give 2 types of cells, other than pathogens, that can stimulate an immune response

A
  • Cells from other organisms/ transplant
  • Abnormal/ cancer / tumour
  • Cells infected by virus
144
Q

Explain how HIV affects the production of antibodies when AIDS develops in a person ( 3 marks )

A
  • Less/ no antibody produced
  • Because HIV destroys helper T cells
  • So few/ no B cells activated/ stimulated
145
Q

Determining the genome of the viruses could allow scientists to develop a vaccine. Explain how. ( 2 marks)

A
  • The scientists could identify proteins
  • They could then identify potential antigens
146
Q

Describe how the B lymphocytes of a frog would respond to a vaccination against a virus, assuming B cells act as they do in humans (3 marks)

A
  • B cells binds to viral, complementary antigen
  • B cells clones
  • Plasma cells release antibodies against the virus
  • B cells produce memory cells
147
Q

What is a monoclonal antibody

A

Antibodies with the same tertiary structure

148
Q

Describe the role of antibodies in producing a positive result in an ELIZA test (4 marks)

A
  • First antibody binds to antigen
  • Second antibody with enzyme attached is added
  • Second antibody attaches to antigen
  • Substrate added and colour changes
149
Q

Describe and explain the role of antibodies in stimulating phagocytosis (2 marks)

A
  • Binds to antigen
  • Antibodies cause aggluntination
150
Q

Describe how phagocytosis of a virus leads to presentation of its antigens ( 3 marks)

A
  • Phagosome fuses with lysosome
  • Virus destroyed by lysozymes
  • Antigens are displayed on the cell membrane
151
Q

Describe how presentation of a virus antigen leads to the secretion of an antibody against this virus antigen (2 marks)

A
  • Helper T cells binds to the antigen
  • This helper T cells stimulate to a specific B cell
  • B cell clones
  • Forms plasma cells that release antibodies
152
Q

What is an antigen (2 marks)

A
  • Foreign protein
  • That stimulates an immune response
153
Q

What is an antibody (2 marks)

A
  • A protein specific to an antigen
  • Produced by B cells
154
Q

Describe how vaccination can lead to protection against bacterial meningitis ( 6 marks )

A
  • Antigen binds to surface protein on a B cell
  • Activated B cell divides by mitosis
  • Division stimulated by T cells
  • B cells/ plasma cells release antibodies
  • Some B cells become memory cells
  • Memory cells produce plasma/ antibodies faster
155
Q

When a vaccine is given to a person, it leads to the production of antibodies against a disease-causing organism. Describe how. (5 marks)

A
  • Vaccine contains antigen from pathogen
  • Macrophage presents antigen on its surface
  • T cell with complementary receptor protein binds to antigen
  • T cells stimulate B cells
  • With complementary antibody on its surface
  • B cell secretes large amounts of antibody
  • B cell divides to form clone all secreting same antibody
156
Q

Describe the difference between active and passive immunity (5 marks)

A
  • Active involves memory cells, passive does not
  • Active involves production of antibody by plasma cells/ memory cells
  • Passive involves antibody introduced into body from outside
  • Active long term, becuase antibody produced in response to antigen
  • Passive short term, because antibody given is broken down
  • Active can take time to develop / work, passive fast acting

AQA A level Biology (41 decks)

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