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Biology > Immunity > Flashcards

Immunity Flashcards

1
Q

What is a pathogen?

A

A pathogen is any disease causing microorganism

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2
Q

How is each type of cell identified?

A

Each cell has a specific molecule on it’s surface usually a protein which in pathogens is called an antigen thi0s has a specific tertiary structure only complementary to one antibody

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3
Q

How do surface molecules help to identify foreign cells?

A

All have specific antigens on their surface which allow them to identify the cells as foreign

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4
Q

What are the bodies physical barriers to disease?

A

Skin, membrane linings, cilia, scabs on injuries

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5
Q

What are the bodies chemical barriers?

A

Sweat, oils, saliva, stomach acid, urine, tears and mucus

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6
Q

What is immunity?

A

When we can fight off disease without getting ill because we already have the antibodies

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7
Q

What type of cells produce a non specific response?

A

Phagocytes

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8
Q

What type of cells produce a specific immune response?

A

Lymphocytes

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9
Q

How do lymphocytes recognise self cells?

A

In the foetus lymphocytes constantly collide with self cells as very little infection some lymphocytes fit specifically with the own body cells these are suppressed and die so the only remaining ones will fit and respond to foreign cells. In adults in the bone marrow lymphocytes are produced and only encounter self cells any that bind with the antigen undergo aptosis- programmed cell death.

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10
Q

What is an antigen?

A

A molecule often a protein that the body recognises as foreign and triggers an immune response.

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11
Q

What is the effect of antigen variability?

A

Where the antigen mutates which alters it’s tertiary structure so the antibodies are no loner complementary so disease will have a greater effect on the immune system and spread more. It also means we can’t develop vaccines because the antigen injected will not be the same as the pathogen so the incorrect antibodies will be made and stored.

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12
Q

What is the process of phagocytosis?

A
  1. Pathogen releases chemicals which attracts the phagocyte
  2. Phagocytes have several receptors on their cell surface membrane which recognise and attach to chemicals on the surface of the pathogen
  3. Phagocyte engulfs pathogen by endocytosis/ phagocytosis and digests pathogen to form a phagosome
  4. Lysosomes fuse with the phagosome and release hydrolytic enzymes lysozymes which hydrolyse the pathogen and the products are absorbed
  5. Phagocyte displays important antigens on the cell surface
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13
Q

How does the specific immune response work?

A
  1. Pathogen is engulfed by phagocyte by phagocytosis and the pathogen displays the important antigens on it’s cell surface membrane
  2. A specific T helper cell with complementary receptor binds to antigen which activates the T cell
  3. T cell proliferates by mitosis to form many clones
  4. Specialise to become T helper cells, stimulate phagocytosis, killer T cells and memory T cells
  5. Specific helper T cell activates a B cell with complementary antibody on it’s surface to the pathogen
  6. B cells proliferate by mitosis to form many clones
  7. Most of the B cells specialise to become plasma cells which produce and secrete monoclonal antibodies and some memory B cells
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14
Q

What is an antibody?

A

A protein produced by lymphocytes in response to the presence of an appropriate antigen.

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15
Q

What is the structure of an antibody?

A

4 polypeptide chains - 2 light and 2 heavy with two binding sites in the variable region and the rest is made up of a constant region.

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16
Q

What are the two ways that antibodies help to fight off disease?

A
  1. Cause agglutination of bacteria cells so they are easier for phagocytes to locate and engulf
  2. Serve as markers which stimulate phagocytes to engulf the bacterial cells
17
Q

How is a antigen antibody complex formed?

A

Antigens bind to the variable region of the antibody each antigen is only complementary to one antibody due to the antigen and antibodies variable region having a specific tertiary structure and they form a complex.

18
Q

What is the role of plasma and memory cells in producing a primary and secondary response?

A

Plasma cells produce antibodies which are broken down but they differentiate into memory cells so more antibodies can be produced at a faster rate in the secondary response.

19
Q

What are monoclonal antibodies?

A

Antibodies with the same tertiary structure produced from same plasma cells so they are all clones for a specific antigen.

20
Q

How are monoclonal antibodies used in targeting medication?

A
  1. Direct therapy is where monoclonal antibodies are produced complementary to a specific antigen on cancerous cells then given to patients and they bind and block signalling pathways preventing uncontrolled growth.
  2. Indirect therapy a cytotoxic drug is attached to monoclonal antibodies and when given to the patient they attach to the antigen on the cancerous cells and kill them.
21
Q

How are monoclonal antibodies used in medical diagnosis?

A

Used in pregnancy and COVID lateral flow tests.
Pregnancy tests rely on HCG being produced on the reaction site antibodies attach to HCG at test site enzyme attaches and causes die to bind then the unbound AB1 enzymes activate more dye at the control site.

22
Q

How are monoclonal antibodies used in ELISA?

A

They are used to diagnose disease and the concentration of the antigen or antibody do this by using a multi well plate and antigen coats a well then wash and add antibody to measure, wash, add enzyme, wash then add substrate to form E-S complex which releases dye and observe the colour. The darker the colour the higher the concentration of antigen or antibody.

23
Q

What are the ethical issues associated with monoclonal antibodies?

A

Use of mice, risks or death, side effects, testing of new drugs lead to deaths

24
Q

What is a vaccination?

A

Use a liquid that is injected into the body containing one or more antigens we induce an immune response in an individual without them suffering the symptoms

25
Q

How does a vaccination prevent disease?

A

Antibodies are produced to fight the antigens in the vaccine which are broken down but memory cells remain which can differentiate to become plasma cells when needed this makes the secondary immune response a lot faster.

26
Q

What is the concept of herd immunity?

A

When a sufficiently large proportion of the population has been vaccinated to make it more difficult for a pathogen to spread even to those not immunised.

27
Q

What is passive immunity and how is it different to active?

A

Where monoclonal antibodies are inserted into an organism from an outside source so there is no direct contact with the pathogen. This means it is faster but short lasting because no memory cells are produced e.g. mothers milk and antivenom

28
Q

What is active immunity and how is it different to passive?

A

Direct contact with the pathogen or it’s antigens which stimulates the bodies immune response to produce antibodies this is slower but lasts longer as memory cells are produced e.g. illness and vaccination.

29
Q

What are the features of a successful vaccination programme?

A 
Financially available
Few side effects
Ways to produce, store and transport
Staff trained to administer
Enough people can get it to create herd immunity
30
Q

What are the ethical issues of vaccinations?

A
  1. Use of animals
  2. Side effects
  3. Price
  4. Testing
  5. When they should be stopped
31
Q

What is the structure of HIV?

A

Reverse transcriptase enzyme, RNA, capsid, matrix, lipid envelope and attachment proteins

32
Q

Why is HIV a retrovirus?

A

Contains reverse transcriptase

33
Q

How does HIV replicate in T cells?

A
  1. Reverse transcriptase converts RNA to DNA
  2. Binds to CD4 receptor on T helper cell
  3. Cuts and inserts itself into DNA in the nucleus of the T cell
  4. Protein synthesis occurs and viral proteins are also produced
34
Q

How does HIV cause the symptoms of AIDS?

A

Not enough helper T cells so can’t stimulate the B cells to produce antibodies or cytotoxic T cells to kill the infected cells. This means the body can’t produce an adequate immune response so will die of infections and cancer.

35
Q

Why are antibiotics ineffective against viruses?

A
  1. Usually work by inhibiting cell wall synthesis but viruses have no cell wall
  2. Usually prevent protein synthesis but viruses rely on host cells to carry out metabolic processes and antibiotic can’t get into the host cell
36
Q

How do you evaluate standard deviation?

A

If error bars don’t overlap there is no statistically significant difference
If error bars do overlap there is a statistically significant difference

37
Q

How do you decide if there is a difference using the T test?

A

If p is less than 0.05 it is statistically significant

If p is greater than 0.05 it is not statistically significant

Biology (22 decks)

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