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Biology > 2C Cells and the Immune System > Flashcards

2C Cells and the Immune System Flashcards

1
Q

Where are antigens found and what do they do?

A

They’re on the outside of all cells and generate an immune response

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2
Q

What type of biological molecule are antigens?

A

Proteins (glycoproteins)

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3
Q

What do foreign antigens do?

A

Stimulate an immune response

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4
Q

What is special about the shapes of foreign antigens?

A

Certain/specific shapes stimulate white blood cells

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5
Q

Are self antigens good or bad?

A

Good. Foreign antigens are bad

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6
Q

What are antibodies and what do they do?

A

Proteins made by white blood cells that attach to antigens

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7
Q

What are pathogens?

A

Disease causing organisms, they all have antigens on their surface and recognised by immune system

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8
Q

What can happen to abnormal body cells?

A

They can turn cancerous

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9
Q

What do cancerous cells have?

A

Abnormal antigens that stimulate immune response

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10
Q

What are viruses and how do they infect people?

A

Pathogenic, they invade host cells and inject their DNA so that the cell replicates the virus instead of itself

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11
Q

What are toxins and what are they produced by?

A

They are molecules poisonous to the body which some pathogens produce and release

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12
Q

What kind of cells perform phagocytosis?

A

Phagocytes, a type of white blood cell

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13
Q

Describe phagocytosis

A
  • first stage of immune response
  • phagocyte engulfs and digests foreign cell
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14
Q

What do phagocytes do during phagocytosis?

A
  • recognise foreign antigens
  • moves towards pathogen and engulfs it
  • pathogen is packaged into phagocytic vesicle (phagosome)
  • lysosome fuses with phagosome to form phagolysosome
  • lysozymes digest pathogen and remains are excreted (may be presented on white blood cell’s surface)
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15
Q

What is an APC?

A

Antigen-presenting cell

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16
Q

Where do T-cells mature?

A

Thymus

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17
Q

What are T-cells?

A

A type of white blood cell, sometimes referred to as T-lymphocytes

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18
Q

What is the role of the receptor proteins on the surface of a T-cell?

A

They bind to complementary antigens presented by APCs which activates the T-cell

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19
Q

What are the different types of T-cells?

A
  • helper T-cells: release chemical messengers to activate and stimulate phagocytes, Tc cells and B cells
  • cytotoxic T-cells: kill pathogens directly
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20
Q

What is the name of the chemical messengers released by T helper cells?

A

Cytokines

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21
Q

What are B-cells and what are they also known as?

A

Type of white blood cell, aka B-lymphocytes

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22
Q

What are B-cells covered in?

A

Proteins called antibodies (every B-cell has a different shaped antibody on its surface)

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23
Q

What is formed when the antibody on a B-cell’s surface binds with an antigen?

A

An antigen-antibody complex

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24
Q

What is clonal selection?

A

When B-cells are stimulated to divide by mitosis because they have complementary antibodies to an antigen that enters the body

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25
Q

What happens to B-cells after they’re activated?

A

They divide into B plasma cells which make antibodies

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26
Q

Describe the structure of an antibody

A
  • y-shaped
  • protein with 2 binding sites for antigens
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27
Q

What are all activated plasma cells?

A

Clones of the B-cell progenitor (where the clones descend from)

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28
Q

What do plasma cells do?

A

They secrete antibodies into the blood which are specific to a particular antigen

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29
Q

Are antibodies clones?

A

Yes, aka monoclonal antibodies

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30
Q

How many binding sites do antibodies have and what does this allow?

A

2, this allows for agglutination (clumping pathogens together)

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31
Q

How does agglutination make phagocytosis more efficient?

A

Phagocytes can engulf multiple pathogens at once rather than one at a time

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32
Q

What is opsonisation?

A

Signalling for phagocyte due to constant regions, complementary to phagocyte binding region

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33
Q

What is neutralisation?

A

Antibodies neutralise pathogens, they’re rendered harmless

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34
Q

What is active immunity?

A

When the organism creates its own antibodies

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35
Q

What is natural active immunity?

A

When an organism creates its own antibodies after being infected with a disease

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36
Q

What is artificial active immunity?

A

When you create your own antibodies after a vaccination

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37
Q

What is passive immunity?

A

When antibodies are donated from another organism

38
Q

What is natural passive immunity?

A

When a baby is immunised from antibodies through the breast milk it receives from its mother

39
Q

What is artificial passive immunity?

A

When an organism is injected with antibodies from another individual

40
Q

State 4 features of active immunity

A
  • requires direct exposure
  • protection develops after a period of time
  • produces memory cells
  • protection for years, memory cells remain in blood in case of reinfection
41
Q

State 4 features of passive immunity

A
  • doesn’t require exposure
  • protection is immediate
  • memory cells not produced
  • protection only lasts for days/weeks (antibodies are broken down over time)
42
Q

Describe the forms a vaccination could come in

A

Antigenic material: live, dead, weakened (attenuated) or fragmented

43
Q

What is vaccine hesitancy?

A

The unwillingness to have a vaccine

44
Q

What significance did Edward Jenner has in vaccination?

A

He pioneered the concept of vaccination, he used a strain of cowpox to immunise against smallpox

45
Q

When did Edward Jenner carry out his first vaccination?

A

1796

46
Q

How many people must be vaccinated within a population to achieve herd immunity?

A

It depends on the R value of the disease (its transmissibility) however not the entirety of the population must be vaccinated

47
Q

Why do many people disagree with the testing of vaccinations?

A

They are tested on animals such as rabbits and mice

48
Q

Why may vegetarians not agree with having certain vaccines?

A

Animal products such as gelatin may be used

49
Q

What risk does human testing of vaccinations include?

A

Serious side effects

50
Q

Why may some people refuse to have vaccines (not for ethical beliefs) and why do many others see this as unfair?

A

They think vaccines will give them side effects and that they will be protected through herd immunity which others believe is unfair

51
Q

What is a major issue when outbreaks of disease occur?

A

Prioritisation of who gets the vaccination first

52
Q

How are antigens involved with primary and secondary response?

A
  • they stimulate primary response and memory cells are produced
  • they stimulate the secondary response if someone is reinfected and symptoms aren’t seen
53
Q

What is antigenic variation?

A

Some pathogens can change the shape of their antigens and memory cells won’t recognise these, therefore primary response will be stimulated again so symptoms will show

54
Q

Why does antigenic variation cause issues with vaccination?

A

A vaccine can’t include all varieties of antigen that may be present on a pathogen

55
Q

Name 3 diseases that exhibit antigenic variation

A
  • HIV
  • influenza
  • COVID-19
56
Q

What are monoclonal antibodies made from?

A

A single group of B-cells which are clones of each other

57
Q

How can monoclonal antibodies be designed and what can they be used for?

A
  • they can be designed to bind to specific substances eg. antigen or toxin
  • can be used to target cancer cells as cancerous cells have antigens called tumour markers
58
Q

How can anti-cancer drugs be manufactured into healthcare?

A

They can be attached to complementary antibodies of tumour markers which allows for more specific targeting of cancer and fewer side effects

59
Q

How are monoclonal antibodies used in molecule detection?

A

Pregnancy tests rely on monoclonal antibodies detecting the hormone hCG

60
Q

What does hCG stand for?

A

Human Chorionic Gonadotropin

61
Q

Describe how a pregnancy test works

A
  1. application area contains hCG-complementary antibodies
  2. they combine with hCG to form antigen-antibody complexes
  3. antibody is bound to coloured dye which moves down test strip
  4. antigen-antibody complex binds to fixed antibody in test site, free antibodies continue to control site
  5. free antibodies bind to fixed antibody at control site
62
Q

What does ELISA test stand for?

A

Enzyme Linked ImmunoSorbent Assay

63
Q

What are ELISA tests used for?

A
  • to test for the presence of antibodies
  • used for medical diagnosis of many things such as allergies and pathogenic infections
64
Q

What occurs during an ELISA test?

A

Antibodies are bound to enzymes, the enzyme will react with substrate to produce colour change but only if antibody associated with enzyme binds to an antigen

65
Q

What are the 2 types of ELISA test?

A

Direct and indirect

66
Q

Describe the process of a direct ELISA test?

A
  1. antigens are isolated from fluid sample and bound to a plastic well
  2. monoclonal antibodies that are bound to an enzyme and complementary to antigen are added and then the well is washed out
  3. coloured substrate solution is added and if a colour change occurs then the antigen antibody complex was present
67
Q

What is the difference between a direct and indirect ELISA test?

A

Direct: use of a single antibody
Indirect: use of 2 antibodies (common test for HIV)

68
Q

Describe the process of an indirect ELISA test

A
  1. HIV antigen attached to well
  2. blood serum added to well so if antibodies are present they bind to the HIV antigens
  3. well is washed out
  4. second antibody is added with enzyme attached to it
  5. 2nd antibody binds to 1st then well is washed again
  6. substrate solution added so if antibodies were present then colour change occurs
69
Q

Describe the ethics of monoclonal antibodies

A
  • they’re often produced using animals
  • mouse is injected with antigen to then create antibodies for it
  • antibodies are removed using surgery
    -many disagree with this on the grounds of cruelty
70
Q

What does HIV stand for?

A

Human immunodeficiency virus

71
Q

What does HIV do and what kind of virus is it?

A

Retrovirus that affects human immune system

72
Q

What does AIDS stand for?

A

Acquired immunodeficiency syndrome

73
Q

What does AIDS result in?

A

Results in a compromised immune system that is unable to fight off infectious diseases, makes person with it more vulnerable to tuberculosis and pnuemonia

74
Q

What kind of cell does HIV infect?

A

T helper cells, they act as host cells to the virus but they are supposed to run the immune system (activate Tc and B cells)

75
Q

What happens to a person when T helper cell quantity drops below a certain level?

A

The immune system begins to fail and critically low numbers leads to AIDS

76
Q

Describe the infection that HIV causes and how it is transmitted

A
  • sexually transmitted (primarily)
  • in initial infection, HIV replicates rapidly and flu-like symptoms occur for several weeks
  • after initial infection, HIV replication slows and no symptoms occur
77
Q

What is a latency period?

A

When the HIV replication slows

78
Q

What is in the core of an HIV particle?

A

It has an RNA core, this contains the enzyme reverse transcriptase which aids viral replication

79
Q

What is the protein coat of an HIV particle?

A

The capsid- often an outer envelope created from membranes collected from host T helper cells

80
Q

What is on the surface of an HIV particle?

A

Attachment proteins which help with adhering to T helper cells

81
Q

How do RNA and DNA switch between their two forms?

A

Reverse transcriptase converts RNA into DNA and transcriptase turns DNA into RNA

82
Q

How to B cells replicate?

A

By mitosis or clonal expansion

83
Q

What is the difference between humoral and cell-mediated responses?

A

Humoral involves B lymphocytes and cell-mediated involves T lymphocytes

84
Q

What types of particles can the immune system identify?

A
  • pathogens
  • non-self cells (eg. transplants)
  • toxins
  • abnormal body cells (eg. cancer cells)
85
Q

Name 2 non-specific responses and describe them

A
  • physical barrier eg. skin
  • phagocytosis
    The response is immediate and the same for all pathogens
86
Q

Name 2 specific responses and describe them

A
  • cell-mediated response
  • humoral response
    Response is slower and specific to each pathogen
87
Q

Describe the process of viral replication

A
  1. viral attachment proteins are complementary to receptors
  2. viral genetic info and enzymes are inserted into host cell
  3. RNA>DNA via reverse transcriptase
  4. DNA replicated/incorporated into host genome
  5. host cells produce viral proteins/lipids/particles and they’re assembled
  6. viral particles released/burst/budding
88
Q

Summarise the response of T lymphocytes to infection by a pathogen

A
  1. Pathogens invade body cells or are taken in by phagocytosis
  2. Phagocytes present antigens on their cell-surface membranes
  3. Receptors on a specific helper T cell fit exactly onto these antigens
  4. Attachment activates T cell to divide rapidly by mitosis
89
Q

What 4 things can cloned T cells do after their response to infection by a pathogen?

A
  • develop into memory cells
  • stimulate phagocytes to engulf pathogens by phagocytosis
  • stimulate B cells to divide and secrete their antibody
  • activate cytotoxic T cells
90
Q

How do cytotoxic T cells kill infected cells?

A
  • produce a protein called perforin that makes holes in the cell membrane of infected cells
  • the cell dies as a result as the membrane becomes permeable to every substance
91
Q

Why are antibiotics ineffective against viral diseases like AIDS?

A
  • antibiotics prevent bacteria from making cell walls
  • bacterial cell walls are made from murein
  • antibiotics weaken the wall so the cells burst when water enters them
  • viruses use host cells as their means to replicate, therefore, in viruses there are no metabolic mechanisms or cell structures for the antibiotics to interrupt
  • viruses also have a protein coat rather than a murein cell wall and so don’t have a site where antibiotics can work
  • when a virus is in an organism’s own cells, the antibiotics cannot reach them

Biology (17 decks)

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