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AQA A Level Biology > Immune Response > Flashcards

Immune Response Flashcards

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1
Q

Define antibody

A

Protein produced by white blood cells that help break down a pathogen

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2
Q

Define immune

A

When you are no longer able to catch a disease

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3
Q

Define vaccination

A

The insertion of a dead or weakened pathogen in order to cause an immune response

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4
Q

Describe the basics of an antigen

A

.On the surface of all cells are chemical markers called antigens.Your body recognises the antigens on your cells as your own.Anything with different antigens to yours stimulates an immune response.In an immune response, your body will recognise the antigen as foreign and will attack it

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5
Q

Which molecules can act as anitgens?

A

. Proteins. Glycoproteins

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6
Q

Why are antigens important?

A

. Initiate immune response to pathogens. Allowing recognition of faulty cancer cells. Recognition of cells from other organisms of the same species

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7
Q

How does antigenic variation work?

A

.Some pathogens can mutate which causes changes in the surface antigens.The memory cells from the first infection won’t recognise the different antigens.The immune system must carry out a primary response against the new antigens

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8
Q

What is phagocytosis?

A

Phagocytosis is when phagocytes (a type of white blood cell) engulf and break down an invading pathogen in order to protect the body, it is a part of the immune system.

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9
Q

What type of response is phagocytosis?

A

Phagocytosis is a non-specific response

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10
Q

Describe the steps of phagocytosis

A
  1. The phagocyte is attracted to the pathogen by detecting the toxins it is releasing2. The phagocyte moved towards one of the pathogens3. The phagocyte begins to surround the microbe. A vacuole forms around it.4. The phagocyte engulfs the pathogen5. The pathogen is inside a vacuole like phagosome in the phagocyte6. Lysosomes fuse with the phagosome and secrete digestive enzymes into the phagosome7. The pathogen inside the phagosome is digested by these enzymes and destroyed
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11
Q

What are the roles of T cells?

A

.Produces memory T Cells.Stimulates phagocytosis.Kills infected cells – making holes in their membranes.Stimulates B cells to divide

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12
Q

How does an antigen presenting cell come about?

A

B cells with an antibody that is complementary to the antigen of invading pathogens takes up the surface antigenThis antigen is presented on the surface of the B cell

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13
Q

What happens to an antigen presenting cell?

A

A T helper cell attaches to the processed antigens on the B cells thereby activating the B cell meaning it produces by mitosis to produce clones

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14
Q

When B cells divide by mitosis what is formed?

A

They can either become memory cells or plasma cells

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15
Q

Where are memory cells found and what are ready to do?

A

Memory cells circulate in blood and tissue fluid in readiness to respond to a future infection by the same pathogen whos antigen was used in the process of forming them

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16
Q

What do plasma cells do?

A

Plasma cells produce antibodies that exactly fit the antigens on the pathogens surface

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17
Q

What do antibodies do?

A

The antibodies attach to antigens on the pathogen and destroy them

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18
Q

If the same infection occurs again what do memory B cells do?

A

If the same infection occurs again the memory B cells divide and develop into plasma cells that produce antibodies

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19
Q

List 3 functions of antibodies

A

.Coat the pathogen with antibodies to make it easier for the phagocyte to engulf it.Coat the pathogen with antibodies to prevent it from entering host cells.Antibodies bind to and neutralise (inactivate) toxins produced by the pathogen

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20
Q

How are B cells and C cells both needed to remove a pathogen from the body?

A

The responses interact with each other.T cells activate B cells and antibodies coat pathogens making it easier for phagocytes to engulf them

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21
Q

If you see the word humoral in the exam what do you think?

A

B cells

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22
Q

What produces antibodies?

A

B cells, more specifically plasma cells

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23
Q

Are antibodies specific?

A

yes

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24
Q

Name 6 parts of an antibodies structure

A
  1. Antigen binding sites2. Variable region3. Constant region4. Light chains5. Heavy chains6. Receptor binding sites
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25
Q

Draw and label antibodies

A

idk check your revision guide or google if its right?

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26
Q

Why are the variable regions on antibodies called that?

A

As the binding sites differ

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27
Q

What gives the variable region its specific 3d shape in antibodies?

A

The sequence of amino acids

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28
Q

In antibodies, where does the constant region bind to?

A

receptors

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29
Q

Each binding site on an antibodie is c____________ to a specific antigen

A

complementary

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30
Q

When an antibodies binding site binds to an antigen what is formed?

A

forms an antigen-antibody complex

31
Q

Roles of antibodies

A

.Antibodies do not directly destroy antigens.Agglutination.Markers

32
Q

What happens in agglutination

A

Antibodies clump bacteria cells together which is helpful as it means they can be taken in by phagocytes for digestion much more easily since they are easier to locate as they are less spread out

33
Q

How do antibodies act as markers?

A

They can act as markers that stimulate phagocytosis

34
Q

How do pregnancy tests work?

A

A hormone called HCG is found in the urine of women only when they are pregnant, pregnancy tests can detect these hormones..Monoclonal antibodies that attach to HCG can be mass produced and stuck down to a test strip on a pregnancy test, while on a separate part of the pregnancy test antibodies attached to blue heads can be placed..If your pregnant and wee on it, the HCG in your urine will attach to the antibodies on the blue heads and the urine will carry them down to the test strip where they will attach to the stuck down antibodies and change the colour of the strip – showing a positive result..If you are not pregnant and wee on it, the urine still carries the blue beads and antibodies down the test to the test strip but they won’t attach to the stuck down antibodies, and so a colour change does not occur – a negative result.

35
Q

How do monoclonal antibodies help diagnose PSA?

A

.men with prostate cancer tend to have high levels of the protein PSA (prostate specific antigen) in their blood due to the fact they produce so much of it. Through the use of a monoclonal antibody that can interact with it, it is possible to get a measure of the level of PSA in a sample of blood.

36
Q

Name 3 ethical implications of monoclonal antibodies?

A

.Use of mice.Death of patients with MS.Drug trials are dangerous

37
Q

How is the use of mice in the production of monoclonal antibodies an ethical issue? Has any help been put in place?

A

.Production of monoclonal antibodies includes the use of mice.The formation of tumour cells includes the deliberate inducing of cancer in mice.Guidelines have been drawn up to reduce suffering but many people still believe it is unethical

38
Q

How is the death of people with MS in treatment with monoclonal antibodies an ethical issue? Has any help been put in place?

A

.Monoclonal antibodies have saved many lives through diagnosis and treatment.But they have also led to the deaths of some people with multiple sclerosis.Informed consent is needed, where people know all the details of treatment including possible death before they consent to it

39
Q

How are drug trials with monoclonal antibodies an ethical issue? Has any help been put in place?

A

.March 2006, 6 healthy volunteers underwent a test for a new monoclonal antibody in London.They all suffered from organ failures, as a result of T cells overproducing chemicals that stimulate an immune response or attack body tissues.All 6 survived, but it still raises questions about the ethics of drug trials

40
Q

What is immunity?

A

The ability of an organism to resist immunity

41
Q

What are the two types of immunity?

A

.Passive.Active

42
Q

What is passive immunity, with examples

A

.Antibodies introduced from an outside source.Abs are not produced by the individual so they are broken down.No memory cells.Short livedFor example – .Anti-venom.Immunity acquired by a foetus from the mother

43
Q

What is active immunity

A

.Production of abs is stimulated by the individual.Direct contact with the pathogen/antigen.Takes time to develop.Long lasting

44
Q

What two forms does active immunity come in?

A

.Natural – met the disease yourself, normal immune response.Artificial – from a vaccine, induced immune response, few symptoms

45
Q

Define huminisation

A

making the monoclonal antibodies suitable for human use (since they come from mouse tissue)

46
Q

Uses of monoclonal antibodies

A

.Separating chemicals from mixtures.Immunoassay (detecting concentrations of macromolecules in solutions).Cancer treatment.Transplant surgery

47
Q

What can antibodies be used to identify?

A

Antibodies can be used to identify flu, hepatitis, chlamydia and types of cancer

48
Q

What is a non-specific response?

A

immediate and same for all pathogens

49
Q

What are the two nonspecific responses?

A

.Physical Barrier (skin).Phagocytosis

50
Q

What is a specific response?

A

slower and pathogen specific

51
Q

What are the two specific responses?

A

.Cell – mediated response (T-Lymphocytes).Humoral response (B-Lymphocytes)

52
Q

Where do T cells mature?

A

.T Lymphocytes mature in the thymus gland

53
Q

What do T cells respond to?

A

own cells altered by viruses/cancers (foreign material inside body cells) or transplanted tissues

54
Q

How can different cells display antigens on their surface?

A
  1. Phagocytes that have engulfed and hydrolysed a pathogen present some of the pathogens antigens on their surface2. Body cells invaded by a virus present viral antigens on their surface as a distress signal3. Cancer cells are different from normal cells and present antigens on their surface4. Transplanted cells from the same species have different antigens on their cell surface
55
Q

What are cells that display foreign antigens known as?

A

antigen-presenting cells

56
Q

How do T cells become activated?

A

The phagocyte places antigens from the pathogen on its own cell-surface membraneReceptors on certain helper T-cells fit exactly onto these antigensThis activates other T cells to divide rapidly by mitosis and form a clone

57
Q

What do cloned T-cells do?

A

.Develop into memory cells that allow a fast future response to the same pathogen .Stimulate phagocytes to engulf pathogens via phagocytosis .Stimulate B-cells to divide and secrete their antibody .Activate cytotoxic T cells

58
Q

What do cytotoxic T cells do?

A

.Cytotoxic T cells kill abnormal body cells

59
Q

How do cytotoxic T cells kill abnormal body cells?

A

.They produce a protein called perforin that makes holes in the cell surface membrane.This makes the cell freely permeable, killing it

60
Q

What are cytotoxic T cells effective against?

A

.This action is very effective against viruses as they replicate inside cells

61
Q

Define pathogen

A

Disease causing microbe

62
Q

Define phagocyte

A

WBCs that travel in the blood and tissues, destroying pathogens

63
Q

Define phagocytosis

A

Mechanism where phagocytes engulf pathogens and hydrolyses them using enzymes

64
Q

Define immune

A

Resistant to a particular infection or toxin owing to the presence of specific antibodies

65
Q

Define antigen

A

Molecule that triggers an immune response

66
Q

Define antibody

A

A protein made by lymphocytes in response to the presence of an antigen

67
Q

Define t lymphocyte

A

Type of WBC produced in the bone marrow but matures in the thymus. Coordinates immune response and kills infected cells – cell mediated response

68
Q

Define helper t cell

A

Bind to antigens presented by antigen presenting cells. This binding stimulates T cell to divide rapidly.

69
Q

Define antigen presenting cell

A

Cells that display foreign antigens on their cell-surface membrane.

70
Q

Define b lymphocyte

A

Type of WBC produced by and matures in the bone marrow. Present in bodily humour. Humoral immunity. Produce antibodies.

71
Q

Define memory cell

A

Produced by B cells. Live for decades. Provide long-term immunity. When they encounter the same pathogen again they divide rapidly into more plasma and memory cells to immediately fight the infection - secondary immune response

72
Q

Define plasma cell

A

Secrete antibodies into blood plasma. Survive for only a few days. Destroy pathogens and toxins. Immediate defence only - primary immune response

73
Q

Define cytotoxic T cell

A

Kills infected cells by introducing perforin molecules into their CSM, causing them to take in water and burst.

74
Q

Define vaccination

A

Introduction of a vaccine subcutaneously or orally that contains pathogen antigens capable of initiating an immune response.

AQA A Level Biology (19 decks)

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