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AS Biology - Unit 1 > Unit 3.2.6 - The Bodies Defense System > Flashcards

Unit 3.2.6 - The Bodies Defense System Flashcards

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1
Q

What on pathogens trigger an immune response?

A

The foreign antigens on its surface

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2
Q

What is an antigen?

A

A large complex molecule that triggers an immune response - like a glycoprotein

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3
Q

What is an antibody?

A

A protein secreted by B cells in response to a non-self antigen

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4
Q

Describe the structure of an antibody?

A

Four polypeptide chains joined together by disulphide bond, two of the chains are long heavy longs and two of the chains are short lighter chains.

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5
Q

What is the same about all antibodies?

A

The constant region

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6
Q

What is different between all antibodies?

A

The variable region

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7
Q

What is the shape of the variable region determined by?

A

The sequence of amino acids which make up the primary structure of the protein

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8
Q

Draw the structure of an antibody?

A

See flash card 21

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9
Q

What type of white blood cell carries out phagocytosis?

A

A phagocyte

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10
Q

What are the five steps in phagocytosis?

A
  1. ) The phagocyte recognises the foreign antigens on the pathogen
  2. ) It moves its cytoplasm around the pathogen engulfing it in a phagosome
  3. ) A lysosome fuses with the phagosome
  4. ) It releases lysosomal enzymes
  5. ) These enzymes begin to break down the pathogen
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11
Q

What is the pathogen contained in during phagocytosis?

A

A phagosome

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12
Q

How do phagocytes activate T cells?

A

After phagocytosis they present the foreign antigens on their surface which activates the T cells

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13
Q

Name two other types of white blood cells, not including phagocytes?

A

B cells and T cells

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14
Q

What type of response do the T cells form?

A

The cellular response

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15
Q

What type of response do the B cells form?

A

The humoral response

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16
Q

What cells form the cellular response?

A

T cells

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17
Q

What forms the humoral response?

A

B cells and the production of antibodies

18
Q

What are the two types of T cells?

A

Killer and helper cells

19
Q

What do the killer T cells do?

A

They attach to antigens on the pathogen and kill the cell

20
Q

What do helper T cells do?

A

They activate the B cells

21
Q

How do B cells becomes activated?

A

They have antibodies on their surface, when they bind with foreign antigens they form antigen-antibody complexes and so become activated

22
Q

When the B cells become activated what cells do they produce and how?

A

They divide by mitosis, so that the new cells are genetically identical and have the same antibodies which are specific to the antigens on the pathogen, these are called plasma cells

23
Q

What three ways do antibodies help the immune response?

A
  1. ) coating the pathogen to make it easier for the phagocyte to engulf
  2. ) coating the pathogen to prevent it from entering host cells
  3. ) bind to and neutralise toxins produced by the pathogens
24
Q

What do both B and T cells produce which mean you become immune to a pathogen after coming in contact with it?

A

Memory cells

25
Q

Why do memory cells mean you are immune to a pathogen?

A

If you ever come in to contact with the same antigen again they recognise it and produce plasma cells much faster than before so you don’t get ill and so you are immune

26
Q

What type of response are plasma cells known as?

A

Primary response

27
Q

What type of response are memory cells known as?

A

Secondary response

28
Q

If the primary or secondary response slower and why?

A

Primary because there aren’t many B cells making the correct antibody so they have to divide which all takes time

29
Q

Why are you usually given a second injection?

A

To boost the number of memory cells in your blood so that you can still quickly produce plasma cells to fight of the pathogen

30
Q

What is meant by antigenic variation?

A

When pathogens can change their antigens on their surface

31
Q

What is bad about antigenic variation?

A

If the antigens change it means you will no longer have memory cells that will recognise the pathogen and so you will no longer be immune

32
Q

Why do you have to have a new flu vaccination each year?

A

The influenza virus shows antigenic variation and so the antigens keep changing so even though you have memory cells for the pathogen one year they may have changed by the next so you need a new vaccination

33
Q

What is a vaccine?

A

It is when dead or weakened pathogens or antigens are put into the body (often by an injection) to provide protection for individuals and populations against disease

34
Q

Describe how a vaccine gives you immunity to a certain pathogen?

A

When the body comes into contact with the foreign antigens it activates the T cells which then activate the B cells
The B cells then divide to produce plasma which they produce antibodies to destroy the pathogen
Memory cells are also produced by the B and T cells so that the secondary response happens much faster and you don’t get ill from the pathogen and so are immune

35
Q

What is herd immunity?

A

When a high percentage of the population is vaccinated so that there are fewer people to carry the disease and pass it on so fewer people will develop the disease

36
Q

What is a monoclonal antibody?

A

An antibody that is specific to one particular antigen and can be mass produced for medical purposes

37
Q

How can monoclonal antibodies be used to treat cancer?

A

You can attach anti-cancer drugs onto the end of the monoclonal antibodies, this means when the antibody binds to the specific antigens on the surface of the tumour the drug can be delivered to the cancerous cells

38
Q

Why is it good to use monoclonal antibodies to treat cancer?

A

The drug will only accumulate where there are cancer cells and so reducing damage to normal cells in the body, reducing the side effects

39
Q

Other than to treat cancer what is another use for monoclonal antibodies?

A

They are used in pregnancy tests to detect very small amounts of the hormone HCG

40
Q

Why are babies often immune to diseases which they haven’t had yet?

A

They have the antibodies from their mother for the first few months of their lives

41
Q

Why are babies only protected with their mothers antibodies for the first few months of their lives?

A

They will have foreign antigens on their surface and so the babies immune system will start to destroy the antibodies

AS Biology - Unit 1 (6 decks)

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