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Biology-topic 2 cells > Immunity, antibodies, and monoclonal antibodies > Flashcards

Immunity, antibodies, and monoclonal antibodies Flashcards

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1
Q

What is an antigen?

A

a protein located on the surface of cells that triggers the immune response

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2
Q

What is a pathogen?

A

a microorganism that causes disease

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3
Q

What are the four types of pathogens?

A

-bacteria
-virus
-fungi
-protist

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4
Q

What are antigens made of?

A

they’re large complex proteins/chemical markers

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5
Q

Where are different antigens found?

A

-on the surface of pathogens
-on the surface of abnormal cells (like cancer)
-on the surface of cells from other organisms in the same species
-on toxins produced by microorganisms

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6
Q

What are examples of the first line of defence?

A

physical barrier- skin
chemical barrier- stomach acid

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7
Q

What are examples of the second line of defence?

A

-inflammation
-blood clot
-phagocytosis

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8
Q

What is the blood made up of?

A

55% plasma, 45% red blood cells, <1% white blood cells and platelets

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9
Q

What are the two (broad) types of white blood cells?

A

phagocytes
lymphocytes

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10
Q

What are the two types responses in the specific immune response?

A

cellular- T lymphocytes
humoral- B lymphocytes

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11
Q

What do phagocytes do?

A

they are part of the non-specific, immediate response and they travel in the blood to the site of infection/trauma

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12
Q

How do phagocytes deal with pathogens?

A

by the process of phagocytosis

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13
Q

Explain the process of phagocytosis

A

pathogens release chemicals/debris that attract the phagocyte towards it along a concentration gradient via chemotaxis

the phagocyte has several receptors on it’s cell surface that attach to the pathogen

the phagocyte then engulfs the pathogen, making a phagosome

the lysosomes inside the phagocyte bind to the phagosome, creating a phagolysosome

the enzymes released (lysozymes) hydrolyse the pathogen which destroys it

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14
Q

What do lymphocytes do?

A

they are involved in the specific immune response, and result in immunity, although their response is slower but more long term

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15
Q

Give two differences between specific and non-specific immune responses

A

ns- same process for all pathogens
s- specific pathogens

ns- immediate response
s- longer process

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16
Q

What is an antigen presenting cell?

A

any cell that presents a non-self antigen on it’s surface

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17
Q

What is antigen variability?

A

the antigen on a pathogen changes frequently due to genetic mutations

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18
Q

Why is antigen variability a problem for the immune system?

A

our immune system produces a specific immune response due to it’s memory cells- the lymphocytes and memory cells are complementary in shape to only one antigen, which means they can no longer bind if the antigen changes shape due to mutations. this means that there is no secondary immune response and the host gets infected and suffers symptoms of the disease again

19
Q

Where are phagocytes produced and stored?

A

in the bone marrow

20
Q

Where do phagocytes do their job?

A

in the blood

21
Q

What are the two types of phagocyte?

A

neutrophil/macrophage

22
Q

Where are lymphocytes produced and matured?

A

produced in the bone marrow and mature in the thymus

23
Q

How many different types of lymphocytes exist in your body?

A

around 10 million

24
Q

Why is infection in the foetus rare?

A

it is protected by the mother and the placenta

25
Q

What happens with the lymphocytes in a foetus?

A

infection is rare in a foetus so the lymphocytes collide almost exclusively with self cells, and some lymphocytes will have receptors that are complementary to the body’s own cells, and these lymphocytes either die or are supressed
the lymphocytes that remain only have receptors complementary to non-self cells

26
Q

Which cells are involved in the humoral response and why?

A

B-cells as they deal with immunity involving pathogens in bodily fluids

27
Q

Which cells are involved in the cell mediated response and why?

A

T-cells as they deal with immunity involving body cells

28
Q

Explain the cell mediated response

A

pathogens invade the body or are taken in by phagocytes

the phagocytes present the antigens from the pathogen on its cell membrane

receptors on a specific T helper cell are complementary to these antigens

this attachment activates the T cell to divide rapidly by mitosis to form genetically identical clones

the cloned T cells then:
-develop into memory cells
-stimulate phagocytes to engulf pathogens by phagocytosis
-stimulate B cells to divide and secrete their antibody
-activate cytotoxic killer T cells

29
Q

What do memory cells do?

A

enable a rapid response to future infections by the same pathogen (after a pathogen is dealt with some lymphocytes remain in the blood)

30
Q

How do cytotoxic killer T cells kill infected cells?

A

they produce a protein called perforin which makes holes in the cell surface membrane, making it become freely permeable to all substances, causing the cell to die

31
Q

What are 2 differences between T cells and B cells?

A

1- T cells mature in the thymus and B cells mature in the bone marrow
2- T cells are involved in cell mediated immunity and B cells are involved in humoral immunity

32
Q

Explain the humoral response

A

the antigens of an invading pathogen are taken up by a B-cell

the B cell processes the antigens and presents them on its surface

helper T cells attach to the antigens presented on the B cell which activates the B cell

this makes the B cell divide by mitosis to give clones of plasma cells

the plasma cells produce and secrete the specific antibody that is complementary to the pathogen’s antigen

these antibodies then bind to 2 pathogens causing agglutination

phagocytes can then engulf and destroy the pathogens

some B cells develop into memory cells also that can divide rapidly to produce a secondary immune response if the same pathogen infects again

33
Q

What are antibodies?

A

a protein that a B cell secretes in response to a non-self antigen

34
Q

What type of structure do antibodies have?

A

a quaternary structure

35
Q

How many polypeptide chains do antibodies have and what are they called?

A

they have 4 polypeptide chains and the longer ones are heavy chains whereas the shorter ones are light chains

36
Q

Where is the binding site on the antibody?

A

in the variable region

37
Q

How is the binding site unique on each antibody?

A

because each binding site consists of a unique sequence of amino acids that forms a specific 3D tertiary shape/binding site

38
Q

How can monoclonal antibodies be used for treating cancer?

A

direct monoclonal antibody therapy-
MABs are produced that are specific to the antigens on the cancer cells
these are then given to the patient and can attach themselves to the cancer cells’ receptors
by attaching to the cancer cells’ surface they block the chemical signals that stimulate their uncontrolled growth

indirect monoclonal antibody therapy-
involves attaching cytotoxic/radioactive chemicals to the MABs that when they attach to the cancer cells they kill them

39
Q

How can monoclonal antibodies be used in medical diagnosis?

A

they can produce specific antibodies that will bind to a specific antigen, and also use dye, so that if the antigen you are testing for is present then the dye will show up. ELISA tests are often used

40
Q

Explain the problems to do with ethics within the use of monoclonal antibodies

A

production of MABs involves the use of mice

although there has been many successes with using MABs to treat diseases like cancer/diabetes, there have been some deaths associated with their use in treating multiple sclerosis- patients should have informed consent

41
Q

What is clonal selection?

A

the process of matching the antigens on antigen presenting cells to the receptors on T and B lymphocytes

42
Q

What is the primary response?

A

after the 1st contact with an antigen, the time for the random collision of the complementary B cell to with the antigen, then the B cells divide to produce plasma and memory cells to deal with the pathogen

43
Q

What is the latent period?

A

the time from infection to antibody production

44
Q

What is the secondary response and how do we not show symptoms?

A

the 2nd exposure to the SAME pathogen, and it can be triggered by a smaller amount of antigen
it is a more rapid response as the memory cells in the blood are more likely to collide with the antigen and bind to it, then the memory B cells start to divide to produce more plasma cells (hence more antibodies)
the pathogen is therefore destroyed before it can fully infect- secondary response leads to more antibodies produced and faster

Biology-topic 2 cells (9 decks)

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