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AQA AS Biology > Immunity > Flashcards

Immunity Flashcards

1
Q

What is the process of phagocytosis?

A

Engulfing of pathogens

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2
Q

Define pathogen

A

An organisms that causes disease in another organism

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3
Q

What are the methods used by antibodies to get rid of/kill pathogens?

A
  • Labelling the pathogen for phagocytosis- Neutralisation of toxins- Agglutination of pathogens
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4
Q

Define monoclonal antibodies

A

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

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5
Q

What are the methods the body uses to prevent the entry of pathogens?

A
  • Mucus- Stomach acid- Enzymes
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6
Q

In phagocytosis, whar is the last thing done by the macrophage?

A

Presents the antigens of the pathogen on its membrane

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7
Q

What are the methods in which pathogens cause disease

A
  • Rupturing them to release nutrients- Breaking down nutrients within cells- Replicating inside of cells and bursting them when released
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8
Q

How are pathogens able to cause disease?

A

Release toxins

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9
Q

What do antibodies consist of?

A

Protein

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10
Q

A protein or polysaccharide found on the surface of cells that stimulates the production of antibodies is also known as?

A

An antigen

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11
Q

What is an antigen?

A

A protein on the surface of cells which causes an immune response

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12
Q

What do antigens allow the immune system to recognise?

A
  • Pathogens- Cells from organisms of the same species- Abnormal body cells e.g. tumors- Toxins
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13
Q

What is a pathogen?

A

An organism that causes disease e.g. Bacteria/Fungi/Viruses

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14
Q

What do pathogens do?

A
  • Destroy host cells- Produce toxins
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15
Q

What makes up the immune response?

A
  • Phagocytosis- T-cells- B-cells- Plasma cells
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16
Q

What are examples of cellular immune responses?

A
  • Phagocytosis- T-cells
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17
Q

What are examples of humoral immune responses?

A
  • B-cells- Plasma cells
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18
Q

What does a humoral response involve?

A
  • Antibodies- Clonal selection- Monoclonal antibodies
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19
Q

What is phagocytosis?

A
  • First line of defence- General immune response
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20
Q

How is phagocytosis carried out?

A
  • Phagocyte identifies foreign antigen- Phagocyte engulfs pathogen into its phagocytic vacuole- Lysosomes fuse with the phagocytic vacuole and release lysosomes which hydrolyse the pathogen- Phagocyte (antigen presenting cell) presents the antigens of the pathogen on its membrane which activates T-cells
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21
Q

How are T-lymphocytes activated?

A

By antigens presented on phagocytes

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22
Q

What are the two types of T-lymphocyte?

A
  • T-helper cells- Cytotoxic T-cells
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23
Q

What do T-helper cells do?

A

Activate B-cells and cytotoxic T-cells

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24
Q

What do cytotoxic T-cells do?

A

Kill pathogens (cellular response)

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25
Q

What are antibodies?

A

Proteins that bind to antigens to kill pathogens

26
Q

What do B-cells do?

A

Undergo clonal selection

27
Q

What is clonal selection?

A

The B-cell with the complimentary antibody to the pathogens antigen (and can therefore form an antigen-antibody complex) is selected and divides into many copies called plasma cells

28
Q

What are plasma cells?

A

Clones of the selected B-cell with the complimentary antibody to the pathogens antigen

29
Q

What do plasma cells do?

A
  • Make monoclonal antibodies (that can form an antibody-antigen complex with pathogens antigen)- Monoclonal antibodies can then stick pathogens together (agglutination) so phagocytes can engulf many pathogens at once
30
Q

What happens to plasma cells post infection?

A

Some plasma cells are saved as memory B-cells which are reactivated If there is a secondary response

31
Q

What is the structure of an antibody?

A
  • Antibodies are proteins with a specific primary, secondary and tertiary structure- Antibodies have a variable region and a constant region which are joined by a hinge and held together by disulphide bridges- The antibodies tertiary structure is responsible for the specific variable region which allows the antibody to form antibody-antigen complexes with its complementary antigen
32
Q

What happens in the primary immune response?

A
  • First immune response- Slow because immune response has to under go phagocytosis -> T-cells -> B-cells -> plasma cells and then the production of antibodies - Whilst the immune response is taking place the pathogen is able to multiply and you feel symptoms - When infection is over you save some plasma cells as memory cells incase of a secondary infection
33
Q

What happens in a secondary immune response?

A
  • The same pathogen with the same antigen infects you- The immune response is faster and stronger because you already have the memory B and T-cells which can divide and carry out the humeral and cellular responses in order to kill pathogens (T) and produce antibodies (B) - Because the pathogen has less time to replicate you fell no symptoms - Antigenic variation and various pathogen strains can prevent this
34
Q

What are monoclonal antibodies?

A

Identical antibodies made from the same B-cell/plasma cell

35
Q

How are monoclonal antibodies used in targeting medication?

A
  • Monoclonal antibodies used to deliver drugs- All cells have specific antigens on their surface - Monoclonal antibodies can be made to bind to any target cell- Attach the drug to the specific antibodies which will then form an antigen-antibody complex with the target cells antigens- Drug and antibody will only bind to target cells
36
Q

How are monoclonal antibodies used in medical diagnosis?

A
  • Monoclonal antibodies fixed to a plate- Sample e.g. blood plasma added- if sample contains the complimentary antigen and antibody-antigen complex will form and the antigens will bind to the antibody- Rinsed to remove unbound antigens- The same monoclonal antibody is added with an enzyme/colour marker - New antibody will also be able to bind to the antigen if it was present in the sample- Sample rinsed to remove unbound antibodies and enzymes- Observing will give a positive/negative. Either a colour change or if an enzyme was used a substrate will need to be added to identify whether or not it was catalysed
37
Q

What is a vaccine?

A

It contains antigens from a dead/weakened pathogen which stimulate the immune response to produce antibodies/plasma cells/memory cells

38
Q

What happens if you are infected post vaccination?

A

It is a secondary response because you already have memory B-cells for the complimentary antibody therefore you don’t feel symptoms

39
Q

Why are vaccines usually injected?

A

If taken orally they may be to big to absorb or they can be broken down by the stomach acid

40
Q

What is antigenic variability?

A

The ability of a pathogen to change the antigens on its surface so the antibodies produced by your memory B-cells are no longer complimentary are upon reinfection you have to go through the primary immune response

41
Q

How can the same pathogen have different antigens?

A
  • Antigenic variability- Pathogen may have multiple strains
42
Q

What is active immunity?

A

When you produce your own antibodies

43
Q

What is passive immunity?

A

When you are given antibodies by another organism

44
Q

Give an example of natural active immunity

A

You get infected by a pathogen and undergo a primary immune response

45
Q

Give an example of artificial active immunity

A

You receive a vaccine and undergo a primary immune response

46
Q

Give an example of natural passive immunity?

A

You are given antibodies by your mother either in breast milk or the placenta

47
Q

Give an example of artificial passive immunity?

A

You receive someone else antibodies through a blood transfusion

48
Q

Compare active and passive immunity

A

Active:- Slow- Long term- Make memory cells- Exposed to antigen Passive:- Fast - Short term (foreign antibodies are broken down by the body) - No memory cells- Not exposed to antigen

49
Q

What is ELISA?

A

Enzyme LinkedImmunoSorbent Assay

50
Q

What is an ELISA used for?

A

Testing whether patients have a specific antibody or antigen

51
Q

How do ELISAs give results?

A

They use antibodies bound to enzymes which when the complimentary substate is added a colour change can be observed

52
Q

What is a Direct ELISA?

A
  • Test for antigens - Immobilised antibodies are fixed to a well
53
Q

What is an Indirect ELISA?

A
  • Test for antibodies- Immobilised antigens are fixed to a well
54
Q

How is a direct ELISA carried out?

A

1 - Immobilised antibodies are fixed to a well2- Sample added (blood plasma)3- If blood plasma contains complementary antigens then an antigen-antibody complex will form4- Rinse to remove unbound antigens5- Same antibody with an enzyme is added6- Rinse to remove unbound antibodies7- Add substrate 8- Observe

55
Q

How is an indirect ELISA carried out?

A

1 - Immobilised antigens are fixed to a well2- Sample added (blood plasma)3- If blood plasma contains complementary antibodies then an antigen-antibody complex will form4- Rinse to remove unbound antibodies5- Different antibody with an enzyme is added which will only bind if the first antibody is present 6- Rinse to remove unbound antibodies and enzymes 7- Add substrate 8- Observe

56
Q

What is HIV?

A

Human Immunodeficiency Virus

57
Q

What does HIV do?

A

Infects helper T-cells weakening immune system which leads to the development of AIDS

58
Q

What is AIDS?

A

Acquired Immune Deficiency Syndrome

59
Q

How can people die from HIV?

A

HIV doesn’t directly kill you, your immune system becomes so weak it cannot fight any pathogens and you usually die from pneumonia/TB

60
Q

How does HIV replicate?

A
  • Virus attachment protein binds to a receptor on the TH-cell- Reverse transcriptase makes double stranded DNA from the viruses RNA- DNA enters the nucleus through the nuclear pore- TH-cell makes more copies of the viruses RNA and reverse transcriptase - Capsid reforms- Virus (RNA and reverse transcriptase) leaves host cell and takes an envelope from hosts membrane

AQA AS Biology (18 decks)

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