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biology - component 3 > immunology > Flashcards

immunology Flashcards

1
Q

define pathogen

A

an organism that causes a disease, damaging the host

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2
Q

define infectious

A

a disease that may be passed or transmitted from one individual to another

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3
Q

define carrier

A

a person who shows no symptoms when infected by a disease organism but can pass the disease to another individual

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4
Q

define disease reservoir

A

where a pathogen is normally found, this may be in humans or another animal and may be a source of infection

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5
Q

define endemic

A

a disease which is always present at low levels in an area

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6
Q

define epidemic

A

where there is a significant increase in the usual number of cases of a disease often associated with rapid disease spread

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7
Q

define pandemic

A

an epidemic occurring worldwide, or over a very wide area, crossing international boundaries and usually affecting a large number of people

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8
Q

define vaccine

A

uses non-pathogenic forms, products or antigens of micro-organisms to stimulate an immune response which confers protection again subsequent infection through memory cells

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9
Q

define antibiotics

A

substances produced by microorganisms which affect the growth of bacteria

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10
Q

define antibiotic resistance

A

where a microorganism which should be affected by an antibiotic is no longer susceptible to it

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11
Q

define vector

A

a living organism which transfers a disease from one individual to another

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12
Q

define toxin

A

a chemical produced by a pathogen which causes damage to cells and tissues of the host

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13
Q

define antigenic types

A

organisms with the same or very similar antigens on the surface
- such types are sub groups or strains of a microbial species which may be used to trace infections.
- they are usually identified by using antibodies from serum

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14
Q

define antigen

A

a molecule that causes the immune system to produce antibodies against it
- these may be individual molecules or those on the surface of cells

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15
Q

define antibody

A

a protein produced by immune cells (B cells) which binds to a specific antigen

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16
Q

what is immunology?

A

immunology concerns the immune system and how it protects the body.
- studies an organisms response to invasion by foreign microbes and their products

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17
Q

what is a disease?

A

the body acting as a host to other living organisms

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18
Q

how might E coli benefit from humans?

A

the human body provides E-coli with a safe, enclosed and comfortable living environment in which the bacteria receive the required nutrients (sugars) for reproduction and growth

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19
Q

what is the name and type of cholera?

A

NAME: vibrio cholerae
TYPE: gram negative bacterium

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20
Q

what is the site of infection and symptoms of cholera?

A

toxins affect the human gut lining causing a watery diarrhoea, severe dehydration and frequently death

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21
Q

what is the mode of transmission of cholera?

A

humans act as reservoirs or carriers and can contaminate water supplies with the pathogen
- the pathogen is transmitted by drinking contaminated water, although it only multiplies in the human host

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22
Q

how is cholera prevented and controlled?

A
  • treatment of waste water
  • good hygiene
  • provision of clean drinking water
  • vaccine (killed organism or possibly genetically engineered) may provide temporary protection
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23
Q

what is the treatment for cholera?

A

antibiotic treatment is possible but oral rehydration is the main method of treatment

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24
Q

what is the name and type of pathogen for tuberculosis?

A

NAME: mycobacterium tuberculosis
TYPE: bacterium

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25
Q

what is the site of infection and symptoms for tuberculosis?

A
  • most commonly affects lung and neck lymph nodes
  • symptoms include: coughing, chest pain and coughing up blood
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26
Q

what is the mode of transmission for tuberculosis?

A
  • can be spread rapidly in overcrowded conditions
  • transmitted in airborne droplets through coughing and sneezing of infected individuals in close proximity
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27
Q

how is tuberculosis prevented and controlled?

A
  • BCG vaccination programme for children
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28
Q

what is the treatment for tuberculosis?

A

a long course of antibiotics

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29
Q

what is the name and type of smallpox?

A

NAME: variola major
TYPE: virus

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30
Q

what is the site of infection and symptoms for smallpox?

A
  • small blood vessels of the skin, mouth, throat and lungs, causing a rash and blisters
  • 30 to 60% fatality rate
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31
Q

what is the mode of transmission for smallpox?

A

airborne droplets of infected individuals in close proximity

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32
Q

how is smallpox prevented and controlled?

A
  • now extinct due to immunisation programme. this was possible due to low rate of antigenic variation / mutation
  • in addition, there was no animal reservoir and people were keen to be immunised because of the devastating effects of the disease
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33
Q

what is the name and type of pathogen for influenza?

A

NAME : 3 main subgroups e.g H1N1
TYPE : virus

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34
Q

what is the site of infection and symptoms for influenza?

A

upper respiratory tract, causing:
- sore throat
- coughing
- fever

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35
Q

what is the mode of transmission for influenza?

A

airborne droplets through coughing and sneezing of infected individuals in close proximity

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36
Q

how is influenza prevented and controlled?

A
  • quarantine and hygiene but difficult to control
  • annual vaccination programmes, but due to new types this is not always effective
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37
Q

what is the treatment for influenza?

A
  • antibiotics are ineffective against influenza and are only used to treat the symptoms of secondary bacterial infection
  • rest, keep warm, drink water and take painkillers
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38
Q

what is the name and type of pathogen for malaria?

A

NAME : plasmodium spp.
TYPE : protoctistan

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39
Q

what is the site of infection and symptoms for malaria?

A
  • liver cells and red blood cells, causing them to burst when more parasites are produced

symptoms:
- severe bouts of fever and flu-like illness
- headache
- muscle aches
- tiredness
- nausea
- vomiting
- diarrhoea may also occur

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40
Q

how is malaria prevented and controlled?

A
  • knowledge of life cycles. nets, clothing & repellent
  • vaccines difficult to develop
  • drug treatment to reduce the chances of infection
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41
Q

what is the treatment for malaria?

A

drug that affect plasmodium outside cells are available but limited success and have side effects

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42
Q

how does transmission of malaria occur?

A

when the infected mosquito pierces the skin of a human to take a blood meal.

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43
Q

why are male mosquitos not vectors of the Plasmodium parasite?

A
  • male mosquitos feed on the nectar of plants to get sugar
  • they do not feed off blood like females
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44
Q

what is the primary and secondary host of malaria and describe.

A

primary host : adult female mosquito
- does not suffer from presence of parasites

secondary host : humans
- do show symptoms of infection

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45
Q

outline the life cycle of malaria

A
  1. the infected mosquito takes a blood meal and the plasmodium parasite enters the bloodstream
  2. plasmodium travels to and then invades liver cells, where the parasite matures
  3. liver cells rupture and release plasmodium parasites. they then invade red blood cells and multiply asexually. red blood cells then also rupture, releasing more plasmodium parasites, which invade other red blood cells. the rupture of red blood cells results in severe fever.
  4. if a female mosquito feeds on the blood of an infected individual, the Plasmodium parasites infect the mosquito, which acts as a vector to pass the disease onto another host
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46
Q

name preventative measures in relation to responding to mosquito behaviour

A
  • sleep under nets
  • nets are treated with the pyrethroid insecticide
  • spray indoor walls with insecticide
  • drain or cover stagnant water
  • film of oil on the water
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47
Q

name preventative measures in relation to responding to biological control

A
  • fish introduced into water
  • infecting mosquitos with bacterium
  • male mosquitos sterilised with x-rays
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48
Q

give a reason for sleeping under nets

A

mosquitos feed at night

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49
Q

give a reason for why nets are treated with the pyrethroid insecticide

A

pyrethroid kills mosquitos

50
Q

give a reason for spraying indoor walls with insecticide

A

kills mosquitos as they rest on walls after feeding

51
Q

give a reason for draining or covering stagnant water

A

removes female mosquitos access for egg-laying sites

52
Q

give a reason for filming of oil on water

A

prevents larvae piercing surface for oxygen

53
Q

give a reason for fish being introduced into water

A

larvae are aquatic and fish eat them

54
Q

give a reason for infecting mosquitos with bacterium

A

bacteria infection blocks plasmodium development in the mosquito

55
Q

give a reason for male mosquito being sterilised with x-rays

A

after they mate with females, no offspring are produced

56
Q

why have vaccines for malaria proved difficult to develop?

A

the plasmodium parasite has high mutation rates and there are many antigenic types

57
Q

what does inert mean, regarding viruses?

A

viruses outside the host cells

58
Q

how many types of reproduction cycle for viruses?
what are they?

A

TWO TYPES:
- lysogenic cycle
- lytic cycle

59
Q

describe what occurs in the lytic cycle

A
  • viruses immediately reproduce using the host’s metabolism to copy their nucleic acid and synthesise new coat protein
  • once new viral particles have been assembled in the host cell cytoplasm, they will then leave the host cell
60
Q

in what way do the virions leave the host cell cytoplasm?

A
  • lysis of the host cell e.g common cold virus
  • budding from the host cell surface (virus becomes enclosed by part of the host cell membrane) e.g influenza virus
61
Q

describe what occurs in the lysogenic cycle

A
  • following penetration of the host cell and shedding of the capsid, the viral nucleic acid is integrated into the host cell genome
  • this may remain there for many cell generations with NO EFFECT
  • the virus may then enter the lytic cycle at some later time, when symptoms are produced
62
Q

list how viruses can be pathogenic?

A
  • cell lysis
  • production of toxic substances
  • cell transformation
  • immune supression
63
Q

describe how cell transformation as a means of viruses being pathogenic

A

viral DNA can integrate into host chromosome
- if the DNA inserts into a proto-oncogene or tumour suppressor gene it can result in the cell undergoing rapid and uncontrolled cell division i.e becoming cancerous

64
Q

describe how new HIV particles are made after they enter the host cell
(4 marks)

A
  • viral DNA transcribes messenger RNA (mRNA) and new viral RNA
  • messenger RNA carried code for amino acids as triplets / codons to ribosomes
  • viral protein assembled
  • viral protein and viral RNA assembled into new viriones
65
Q

define antibiotic

A

a substance produced by a fungus which diminishes the population growth of bacteria

66
Q

what are the 2 modes of action for antibiotics.
describe them and give examples

A
  1. BACTERIOSTATIC - prevent population growth of bacteria e.g tetracyclin
  2. BACTERICIDAL - kill bacteria e.g penicillin
67
Q

describe broad-spectrum antibiotics

A

act against a wide range of disease-causing bacteria by targeting both gram positive and gram negative bacterial groups

68
Q

describe narrow spectrum antibiotics

A

active against a selected group of bacterial types
- they can act on either gram positive or gram negative but not both

69
Q

outline the structure of bacterial cell wall

A
  • contains peptidoglycan consisting of molecules of polysaccharide cross-linked by amino acid side chains. this provides strength and prevents osmotic lysis
  • in some bacteria this cell wall is surrounded by an outer layer of lipopolysaccharides
70
Q

how are gram negative and gram positive bacteria identified?

A
  • the gram statin reaction highlights cells with the addition layer in gram negative and they retain a counter stain and appear red
  • this layer gives protection from some antibacterial agents such a lysozyme and penicillin
71
Q

describe tetracycline

A

an antibiotic that affects protein synthesis, a metabolic process common to all bacteria
this means it is effective against a broader range of baceria, including gram +ve and some gram-ve species

72
Q

how does tetracycline affect protein synthesis?

A

acts as a competitive inhibitor preventing codon-anticodon complexes forming at the second anti-codon binding site on the smaller subunit of bacterial ribosomes
- prevents the binding of a tRNA molecule to its complementary codon

73
Q

what effect does the prevention of the binding of a tRNA molecule to its complementary codon?

A

adjacent amino acids won’t join by peptide bonds and translation and protein synthesis is prevented

74
Q

what does penicillin affect?

A
  • affects the formation of cross-linkages in the peptidoglycan cell wall during growth and division of bacterial cells
75
Q

how does penicillin affect the formation of cross linkages in the cell wall?

A
  • by binding to and inhibiting the enzymes (transpeptidase) responsible for the formation of these cross linkages.
  • binds irreversibly to transpeptidase and it is not complementary to the active site of the enzyme
76
Q

explain what type of inhibitor penicillin is.

A

penicillin is a non competitive inhibitor, as binding is irreversible.
- penicillin has a shape that is not complementary to the active site

77
Q

as a result of the penicillin the cell wall is weakened.
what effect would this have if the cells were placed in a hypotonic solution?

A

water will enter in by osmosis, the cell becomes turgid and eventually lysis occurs at

78
Q

why are viruses not affected by antibiotics?

A

viruses have no cell wall or metabolic pathway to disrupt

79
Q

why are gram positive bacteria more susceptible to penicillin?

A

due to their thick peptidoglycan cell wall

80
Q

what are the two sources of antibiotic resistance alleles?

A
  1. bacteria divide under optimum conditions and have a high mutation rate. naturally occurring mutations that confer resistance to antibiotics have given these bacteria a selective advantage in the presence of antibiotics
  2. plasmids containing the antibiotic resistance allele can be transferred from one bacterium to another via conjugation
81
Q

what is the passive immune response?

A

enables the body to resist disease.

82
Q

what does the passive immune response allow the body to do?

A

able to detect foreign antigens and distinguish them from self antigens in its own tissues

83
Q

name some natural barriers in the body

A
  • ciliated mucous membranes
  • blood clotting
  • tear ducts, saliva
  • stomach
  • phagocytosis
  • skin flora
  • skin
84
Q

describe ciliated mucous membranes as a natural barrier

A

mucus traps inhaled pathogens and cilia waft the mucus up and out of the trachea

85
Q

describe blood clotting as a natural barrier

A

prevents the entry of pathogens through broken capillaries

86
Q

describe tear ducts and saliva as a natural barrier

A

lysozyme
hydrolyses cell walls to kill bacteria

87
Q

describe the stomach as a natural barrier

A

stomach acid kills bacteria

88
Q

describe the skin as a natural barrier

A

covers the external surface of body

89
Q

describe phagocytosis as a natural barrier

A

a macrophage (phagocytosis) engulfs bacteria into vacuoles, which fuse with lysosomes which release hydrolytic enzymes into the vacuole

90
Q

describe skin flora as a natural barrier

A

commensal microorganisms on our skin compete with pathogenic bacteria
- the natural flora doesn’t wash off the body as easily as pathogenic bacteria

91
Q

what is the specific immune response?
what provides this?

A

in the adaptive immune response, the body produces a specific response to a foreign antigen
- lymphocytes provide this response

92
Q

what are lymphocytes?

A

a type of leucocyte (white blood cell)

93
Q

what are the two components to the adaptive immune response?

A
  • the humoral response
  • cell mediated response
94
Q

where do B lymphocytes originate from and where do they mature?

A

originate from = stem cells in the bone marrow
mature = spleen and lymph nodes

95
Q

describe the humoral response

A
  • B cells circulate in the blood stream and lymph vessel. each has a specific receptor on its surface which bind to one type of antigen
  • when a foreign antigen enters the blood or lymph vessels, specific B lymphocytes bind to the foreign antigens.
  • this causes B cells to activate which stimulates clonal expansion
96
Q

what does clonal expansion of B cells form?

A
  • plasma cells
  • memory B cells
97
Q

what do plasma cells do?

A

secrete antibodies specific to the foreign antigen

98
Q

what do memory B cells do?

A

remain dormant in the blood circulation ready to rapidly divide by clonal expansion to form more B lymphocytes if the same antigen is encountered in the future

99
Q

what are antibodies?

A

Y shaped globular proteins (immunoglobulins)
- made from four polypeptides and has two antigen binding sites

100
Q

what is the highest level of protein structure an antibody has?

A

quaternary

101
Q

what type of bond (covalent) holds the polypeptide chains together between sulphur containing variable groups?

A

disulphide bridges

102
Q

explain how the structure of an antibody ensures it only binds to one type of antigen?

A

complementary

103
Q

In agglutination microbes are clumped together. This allows them to be destroyed more efficiently.
How is the structure of an antibody adapted to help agglutination occur?

A

there are 2 binding sites so the antibody can bind to two antigens at once

104
Q

what is formed when the specific antibody binds to the antigen?

A

antigen-antibody complex

105
Q

what does agglutination prevents?

A

prevents antigens infecting cells/producing toxins and allows phagocytic cells to engulf them in phagocytosis

106
Q

where do T-lymphocytes originate from?
where are they activated?

A

originate - stem cells in bone marrow
activated - thymus gland

107
Q

how are antigen presenting cells formed?

A
  • when macrophages engulf a pathogen, the pathogen is hydrolysed into component parts
  • the macrophage can then present some of these parts (antigens) on its membrane surface
  • it is now an antigen presenting cell
108
Q

what are some other cells that can present antigens on their surfaces?

A
  • B lymphocytes
  • infected body cells
109
Q

what stimulates a T lymphocyte to go under clonal expansion?

A

when a T lymphocyte detects a specific antigen on an antigen presenting cell

110
Q

how many different types of cells are made when T lymphocytes undergo clonal expansion?
what are they?

A

THREE
1. T helper cells
2. T memory cells
3. Cytotoxic T cell (killer cells)

111
Q

describe T helper cells

A

produce chemicals called cytokines
cytokines:
- stimulate more phagocytic cells to migrate to the infected tissue, which then engulf more pathogens
- stimulate clonal expansion of plasma B cells to make and secrete antibodies specific to that particulate antigen
- (attracts T killer cells)

112
Q

describe T memory cells

A

remain dormant in the circulation and then divide rapidly by clonal expansion to form more T lymphocytes if the same antigen is encountered in the future

113
Q

describe cytotoxic T cell (killer)

A

destroy infected body cells (that have specific antigens on their surface) by LYSING the cells

e.g a normal body cell infected by a virus

114
Q

explain why the latency period is much shorter and the antibody production much greater in the secondary immune response

A
  • on re-exposure to the same antigen, after a very short latent period, memory cells undergo rapid clonal expansion
  • a small amount of antigen stimulates rapid production of plasma B cells
  • antibodies are made much more quickly and more concentrated than in the primary response
  • the antibodies remain at high concentrations for longer and no symptoms develop
115
Q

outline the steps in primary immune response

A
  1. antigen-presenting cells engulf pathogens and display antigens
  2. these antigen presenting cells activate specific T cells which undergo clonal expansion to form T helper cells which release cytokines
  3. cytokines stimulate B cells to undergo clonal expansion forming B plasma cells which secrete antibodies against the antigen. memory cells produced
  4. B lymphocyte with a specific receptor can also bind to an antigen on the pathogen and is stimulated to undergo clonal expansion
  5. antibodies are specific to antigen and bind to it, holding the pathogen in place
  6. the B plasma cells secrete a low levels of antibodies for about 3 weeks, after which the infection usually subsides
116
Q

describe passive immunity

A

the body may receive antibodies that have been produced by another individual
- protection is short lived because the antibodies are recognised as non-self and are destroyed so no memory cells are produced

117
Q

name examples of passive immunity

A
  • when antibodies are transferred to the foetus via the placenta, or to the baby in breast milk
  • artificial when pre-synthesised antibody is injected into an individual
118
Q

describe active immunity

A

the individual produced their own antibodies
- protection is long-lasting due to production of antigen-specific memory cells

119
Q

name some examples of active immunity

A
  • natural production following infection
  • artificial production following vaccination e.g against Rubella
120
Q

why are antibody injections used?

A
  • provide rapid protection against a pathogen
  • used with people who do not develop a strong immune response to a vaccination or who have a weakened immune system

biology - component 3 (8 decks)

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