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Biology > Mrs H bio 8 Immunology and HIV > Flashcards

Mrs H bio 8 Immunology and HIV Flashcards

1
Q

what are the 3 major types of pathogenic organisms?

A

bacteria, viruses and fungi

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2
Q

what is a pathogen?

A

an organism, usually a micro-organism, which causes a disease

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3
Q

what are the 3 defence mechanisms our bodies have against pathogens?

A

1, preventing the entry of pathogens by a variety of physical and chemical defences, such as the skin, mucus membranes, tears and saliva
2. inflammation of the region invaded by the pathogen, a process known as non-specific inflammatory response
3.recognising ‘foreign’ cells and targeting any pathogenic cells, a process known as a specific immune repsonse

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4
Q

what is an antigen?

A

a molecule that stimulates an immune reponse resulting in the production of specific antibodies

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5
Q

why does an immune response occur?

A

the surface of our own cells and of pathogens are covered in antigens that act as markers to help identify the type of cell so if the antigens arent recognised then the body will treat the cell/pathogen as non-self and initiate an immune response

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6
Q

what is an antibody?

A

protein/glycoprotein made in response to foreign antigen- has binding sites which bind specifically to antigen and are produced by B cells

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7
Q

what is the structure of an antibody?

A

antibodies are complex quaternary structures made up of four polypeptide chains. overall shape= Y-shaped. main part of antibody (heavy chain) is the same in all antibodies, it is the light chain and therefore the binding site that changes from antibody to antibody

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8
Q

what is formed when an antibody binds to a specific antigen?

A

antigen-antibody complex

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9
Q

what is phagocytosis?

A

carried out by white blood cells called phagocytes, where, early in an infection, the WBC collect at the site of infection and begin to breakdown pathogens

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10
Q

describe the process of phagocytosis

A

1) pathogen engulfed by phagocyte
2) engulfed pathogen enters the cytoplasm if the phagocyte in a vesicle
3) lysosomes fuse with vesicle releasing digestive enzymes
4)lysosome enzymes break down the pathogen
5)waste materials are ejected from the cell

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11
Q

what is specific immunity?

A

a specific repsonse to a specific antigen on the surface of a cell or pathogen that has been recognised as non-self

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12
Q

what type of white blood cell does specific immunity involve?

A

lymphocytes

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13
Q

what are lymphocytes?

A

smaller than phagocytes and have a large nucleus. produced in the bone marrow before birth

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14
Q

what are the 2 types of lymphocytes?

A

T cells and B cells

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15
Q

what is the structure of a T cell?

A

specific cell surface receptors called T cell receptors which have a similar structure to antibodies and are each specific to one antigen

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16
Q

How do T cells respond to a pathogen or it antigen?

A

require other cells to process the antigens and present them to the T cell. the antigen presenting cell will present the cells on its surface and the T cells are activated when they encounter their specific antigen

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17
Q

how do T cells increase in no.?

A

divide via mitosis

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18
Q

what two main types of T cell can they differentiate into?

A

helper T cells and cytotoxic T cells

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19
Q

what do helper T cells do?

A

assist other white blood cells in the immune response. they release cytokines which stimulate:
-the maturation of B cells into antibody- secreting plasma cells
-production of memory B cells
-activation of cytotoxic T cells, which destroy virus infected cell and tumour cells
-an increased rate of phagocytosis

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20
Q

what do cytotoxic T cells do?

A

kill infected cells

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21
Q

how are B cells activated?

A

surface antigens of an invading pathogen are taken up by a specific B cell, specific B lymphocyte presents these antigens on its surface, a helper T cell with complementary receptor binds to presented antigens and activates the B cell to clone, B cell now activated and divides by mitosis to give a clone of plasma cells

22
Q

what do B plasma cells do?

A

produce and secrete the specific antibody that fits on to the pathogens surface, the antibody attaches to the antigens and destroys it

23
Q

what do B memory cells do?

A

remain circulating in the blood for a long time and can respond to the pathogen quicker if there was to be future re-infection

24
Q

how do antibodies help to destroy pathogens?

A

bind to the antigens and clump them together (agglutination) which allows phagocytes to recognise and destroy the pathogen more efficiently. this Is called enhanced phagocytosis

25
Q

how to antibodies help destroy bacteria?

A

antibodies bind to the surface of the bacteria and damage the bacterial cell membrane causing the bacterial cell lyses leading to its destruction

26
Q

what is the primary response?

A

the whole process form initially recognising a pathogen as non self to producing antibodies

27
Q

what is the secondary response?

A

the activation of memory cells to produce antibodies which is much faster and more extensive

28
Q

describe the process of the secondary response

A

if memory cells encounter the antigen on another occasion, they are activated and divide rapidly, the memory cells clone into plasma cells and more memory cells, the plasma cells produce the specific antibodies for the invading pathogen

29
Q

what is antigen variability?

A

antigens presented on a pathogens surface can change frequently due tp genetic mutations

30
Q

why does antigen variability pose a problem for many mammal immune systems?

A

lymphocytes and memory cells produce a specific immune response and their surface receptors are only complementary in shape to one antigen so when the antigen changes, the secondary immune response longer works and the host gets infected again

31
Q

what are the 2 main ways immunity can be gained?

A

active or passive

32
Q

what is passive immunity?

A

antibodies are received from elsewhere (not produced by the individual), does not involve memory cells, short term as antibody is broken down, fast acting

33
Q

what is artificial passive immunity?

A

when people are given an injection/ transfusion of antibody

34
Q

what is natural passive immunity?

A

foetuses receive antibodies across the placenta from their mothers or when babies receive the initial breast milk from their mothers which delivers a certain isotope of the antibody

35
Q

what is active immunity?

A

type of immune provided by B memory cells produces after a primary response to a pathogens antigen

36
Q

what is a vaccine?

A

suspension of antibodies that are intentionally put into the body to induce artificial active immunity. will initiate a primary immune repsonse producing memory cells but no symptoms then if later infection occurs with real pathogen then secondary immune response occur before it can cause disease

37
Q

what are the two main types of vaccine?

A

live attenuated and inactivated

38
Q

what are the problems with vaccines?

A

side effects which in some individuals could have severe permanent effects, people could also have a poor response (e.g. malnourished and can’t produce the needed antibodies)

39
Q

why is antigenic variation an issue for vaccinations?

A

variation in the antigens of pathogens causes the vaccines not to trigger an immune response or diseases caused by eukaryotes (e.g. malaria) have too many antigens on their cell surface membranes making it difficult to produce vaccines that would prompt the immune system quick enough

40
Q

how is antigenic concealment an issue for vaccines?

A

when the pathogen hides from the immune system by living inside cells or when the antigen coats their bodies in host proteins or by parasitising immune cells such as macrophages and T cells or by remaining in parts of the body that are difficult for vaccines to reach

41
Q

what is herd immunity?

A

if enough individuals in the population are vaccinated then there is little chance of the disease spreading so even non-vaccinated individuals can be protected

42
Q

give the 10 mark points for how a vaccine causes an individual to develop immunity against a pathogen

A

1)vaccine contains pathogens with associated antigens
2)phagocyte presents antigen
3)binds to receptor on t-cells
4)pathogen engulfed by B-cell
5)T-cells activate B cell
6)B cell divides (clonal selection)
7)plasma B cells secrete antibody
8)memory cells formed
9)vaccine provokes primary immune response
10)memory cells give rapid response in future giving immunity

43
Q

what are monoclonal antibodies?

A

all have the same tertiary structure and are produced from cloned plasma cells

44
Q

what are the uses of monoclonal antibodies?

A

research, immune assays, diagnosis, targeting drugs, detecting cancer cells, killing specific cells, isolating specific chemicals

45
Q

what are the 2 types of ELISA tests?

A

direct and indirect

46
Q

what is the difference between direct and indirect ELISA tests?

A

direct= uses a single antibody that is complementary to the antigen being testes for
indirect= uses two different antibodies

47
Q

what are the steps of the direct ELISA test?

A

1) antigens from patient sample are immobilised to the inside of a well in a well plate
2)detection antibody that is complementary to the antigen of interest is added
3) if antigen is present the detection antibody will bind
4)well is washed to remove any unbound antibodies
5)substrate solution is added
6)if detection of antibody is bound, the enzyme converts substrate into coloured product

48
Q

what is the process of an indirect ELISA test?

A

1) HIV antigen is immobilised in the well
2)sample of patients blood plasma added
3)of there are HIV-specific antibodies in plasma, these will bind to the antigens immbolisedin the well
4)well is washed to remove any unbound antibodies
5)secondary antibody added which has an enzyme attached to it
6)secondary antibody can bind to the HIV specific antibody
7)well washed out to remove any unbound secondary antibody
8)substrate solution added to the well, if secondary antibody present, a coloured product will form

49
Q

what are the ethical issues surrounding monoclonal antibody testing?

A

techniques involve inducing tumours in mice, in many cases, mice re genetically engineered to produce human antibodies, there have been 1 or 2 examples of human volunteers suffering major, unexpected side effects

50
Q

what is the structure of HIV?

A

spherical in shape and has an envelope of lipids and glycoproteins. inside there is a cone shaped capsid containing RNA and an enzyme called reverse transcriptase

51
Q

how is HIV spread?

A

from one infected person to another when bodily fluids mix:
sexual intercourse
blood transfusion
drug needle string
mother to unborn baby
mother to Child (breastmilk)

52
Q

describe the process of HIV replication

A
  1. HIV enters the blood stream
  2. attachment protein attaches to a receptor molecule on the cell membrane of the host T helper cell
    3.capsid is released into the cell where it uncoats and releases the RNA into the cell’s cytoplasm
  3. reverse transcriptase is used to make a complementary strand of DNA from the viral RNA template
    5.doube stranded DNA is made and inserted into the human DNA
    6.host cell enzymes used to make viral proteins form the viral DNA found within the human DNA
  4. viral proteins assembled into new viruses, which bud from the cell and go on to infect other cells

Biology (18 decks)

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