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immunity Flashcards

1
Q

What are antigens?

A

molecules that can generate an immune response. Most are proteins often found on the surface of cells

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2
Q

what are foreign antigens with examples

A

Antigens that are not found in the body e.g.
Molecules on pathogens
Parts of pathogens
Abnormal body cells (cancerous)
Toxins
Molecules on cells from other organisms

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3
Q

what is the first defence in the immune system

A

phagocytes

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4
Q

explain phagocytes

A

Phagocytes are a type of white blood cell.
They are non specific.
They assist by engulfing pathogens and antigens.

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5
Q

what is the process of phagocytosis

A

1)binding and absorption
2)phagosome formation
3)phagosome and lysosome to form phagolysosome
4)digestion
5)release of microbial products

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6
Q

what are B cells

A

These are also a type of white blood cell.
Create antibodies, which can be secreted or found on their
cell surface.

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7
Q

what do the antibodies created from B cells form with antigens, and why

A

Antibodies are proteins.
This means they have a specific and complementary shape to certain antigens.
When they combine they create an antigen-antibody complex.

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8
Q

explain humoral immunity

A

Antigen-antibody complex is taken into the B cell by endocytosis.
The B cell then takes the antigen and presents it on the cell surface membrane to signal to other immune cells - T helper cells
T-helper cells stimulate B cells to undergo clonal selection to form plasma and memory cells.

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9
Q

explain plasma cells

A

Secrete antibodies
Only survive a few days
Responsible for primary immune response

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10
Q

explain memory cells

A

Live for a longer period of time
When they encounter same antigen, rapidly divide to produce B plasma cells
Involved in secondary immune response

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11
Q

what is clonal selection

A

Making many copies of the same B cell

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12
Q

what does clonal selection result in

A

This results in many of the same B cell creating many of the same antibody (monoclonal antibodies)

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13
Q

explain antibody structure

A

Antibodies are proteins (therefore made up of amino acids)
The protein overall is made of 4 polypeptide chains.
2 light chains
2 heavy chains
They have 2 binding sites
Have a variable region
Have a constant region

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14
Q

explain the role of antibodies

A

Allow the binding of 2 antigens to the variable regions

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15
Q

what is the binding of antigens called

A

agglutination

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16
Q

explain antibodies being variable

A

The specificity of an antibody depends on the structures of the variable region.
This is variable as the difference in amino acids will alter the tertiary structure.

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17
Q

how do b memory cells help fight a secondary infection

A

Because of mitosis now in the cell there are many memory cells with the specific antibody. This means if a secondary infection was to occur in the body the response would be:
Quicker
A greater antibody productions
Fewer/no symptoms
Quicker recovery time for patient

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18
Q

what are the 2 types of T cells

A

Cytotoxic T cells
Helper T cells

19
Q

explain the role of cytotoxic T cells

A

destroy antigen presenting cells (APC), by releasing a chemical called perforin, this creates holes in the APC’s membrane, destroying the cell.

20
Q

what are examples of antigen presenting cells

A

Viral infected cells
Phagocytes with pathogen antigens
Transplanted cell
Cancer cells

21
Q

explain the role of helper T cells

A

Activate phagocytes to become more aggressive
Activate cytotoxic T cells
Stimulate B cell division
Develop into T memory cells (long lived)

22
Q

What is passive immunity

A

Individual does not come into contact with the pathogen so receives an outside source of antibodies, doesn’t produce immunity

23
Q

Examples of passive immunity

A

Breast milk, anti venom

24
Q

What is active immunity

A

Immune response triggered by pathogen so own antibodies are produces, allows immunity as memory cells are produced

25
Examples of active immunity
Infection and vaccines
26
Explain how vaccines work
Inactive pathogen is injected into the body, antigens are detected by B lymphocytes which produce antibodies, lymphocytes with the specific antibody multiply to produce B memory cells (for next infection)
27
How does herd immunity protect the unvaccinated
Requires the majority of population vaccinated, reduces the likelihood of two unvaccinated people coming into contact
28
Why is herd immunity important
Protects those who cannot be vaccinated Reduces the chance of pathogens mutating
29
What is it important that a vaccine has/is
Economically available Minimal side effects Stored and transported easily Can be administered by suitable individuals in times of need
30
Why might vaccines not work
Ineffective with poor immune systems Pathogen may have mutated Individuals may reject the vaccine for religious/personal reasons
31
What are ethical implications of vaccines
Requires animal testing Animal based substances needed to make vaccines Social issues leading to people not wanting vaccines Risk to volunteers when developing new vaccine Expensive
32
What are monoclonal antibodies
Copy’s of a single antibody produced from a single clone of B cells
33
How can monoclonal antibodies be used in cancer treatment
Tumour cells express different proteins in their surface compared to normal body cells, mAbs specific to this antigen form an antigen antibody complex, the mAbs can carry drugs and fluorescent markers so toxic drugs only damage cancerous cells, and so that the markers can locate remaining cancerous cells left behind after surgery
34
How are monoclonal antibodies used in pregnancy tests
Pregnant women produce HCG which is complementary to the antibodies on the blue beads on the test Urine moves up the stick carrying blue beads, another binding zone in the HCG binds to the antibodies stuck down on the test strip, strip turns blue as antigen antibody complex is formed
35
Explain the direct ELISA test
1)A patient sample is bound to the inside of the well plate 2) ‘Detection’ antibody complementary to the antigen with an attached enzyme is added to the plate 3) if patient has the antigen, an antigen-antibody complex will form 4) plate is then washed to remove unbound antibodies 5)substrate solution is added and if the antibody is bound the attached enzyme reacts with the substrate to cause a colour change
36
What is the direct ELISA test testing for
Infection
37
Why must the plate be washed to remove unbound antibodies
To prevent false positives- enzyme substrate complexes would form with unbound antibodies
38
Explain indirect ELISA
1) antigen is bound to the bottom of the plate 2) patients fluid sample is added to the well 3) plate is washed to remove unbound antibodies 4) secondary antibody against the human antibody with attached enzyme binds to the patients antibodies 5)plate is washed to remove any unbound secondary antibodies 6)substrate solution is added an positive result cause colour change
39
What does HIV do
Infects and destroys T helper cells so immune system is unable to amount to an effective immune response Makes the person immunocompromised
40
Explain the process of HIV developing to AIDs
1)Initially virus is replicating rapidly so person displays flu like symptoms 2)As T helper cell number drops so does number of T helper cells able to be infected so disease enters latency period 3)Once T cells drop bellow a certain number the person has developed AIDs 4)Initial symptoms include respiratory infection and contracting other diseases 5)These secondary infections cause the patients death
41
What are the elements of the structure of HIV
Attachment protein Genetic material Capsid Lipid envelope Matrix Reverse transcription enzyme
42
How does HIV infect T helper cells
HIV enters and circulates around the bloodstream Attachment proteins bind to specific receptors on the surface of cells Capsid is released into the cell, releasing the RNA and enzymes from the virus HIV virus transcribes viral RNA into DNA using reverse transcriptase enzyme Viral DNA insert into the cells own DNA As viral DNA is incorporated, the genes will begin to make viral proteins due to transcription by mRNA These proteins release from the cell surrounded by a lipid envelope from host cell
43
What type of virus allows reverse transcription?
Retrovirus
44
What is used to treat HIV
Antiretrovirals Education

Biology (9 decks)

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