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Alevel Biology OCR > 4.1.1 - Disease and the Immune System > Flashcards

4.1.1 - Disease and the Immune System Flashcards

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1
Q

What is a communicable disease?

A

a disease caused by pathogens that can be passed from one organism to another
-are infectious

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2
Q

What are the 4 types of pathogens?

A
  • bacteria
  • viruses
  • protoctista
  • fungi
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3
Q

What are the 2 types of bacteria?

A

Gram positive bacteria
-look purple-blue (after gram staining) under light microscope
Gram negative bacteria
-look red (after gram staining) under light microscope

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4
Q

How do bacteria cause disease?

A

by producing toxins that poison or damage the host cells

eg. by breaking down cell membrane or interfering with genetic information

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5
Q

Are bacteria eukaryotes or prokaryotes?

A

prokaryotes

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6
Q

Name 3 examples of bacterial diseases

A

ringrot
tuberculosis
bacterial meningtisis

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7
Q

What type of pathogen causes ringrot?

A

bacteria

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8
Q

What type of pathogen causes tuberculosis?

A

bacteria

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9
Q

What type of pathogen causes meningtisis?

A

bacteria

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10
Q

What is the basic structure of viruses?

A

genetic material surrounded by protein

0.02-0.3μm

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11
Q

How do viruses cause disease?

A

By invading cells and taking over the cell’s mechanism
They insert their genetic information into the cell’s DNA
The virus uses the cell to produce new viruses, which burst out of the cell (destroying that cell) into other cells

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12
Q

What are bacteriophages?

A

viruses that attack bacteria by taking over their cells and using them to replicate, which destroys the bacteria in the process

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13
Q

Name 3 examples of viral diseases

A

TMV (tobacco mosaic virus)
HIV (AIDS)
Flu/influenza

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14
Q

What type of pathogen causes TMV?

A

virus

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15
Q

What type of pathogen causes HIV (AIDS)?

A

virus

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16
Q

What type of pathogen causes flu/influenza?

A

virus

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17
Q

Are protoctista eukaryotes or prokaryotes?

A

eukaryotes

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18
Q

How do protoctista cause disease?

A

By taking over cells and breaking them down by digesting and using the cell’s contents

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19
Q

Name 2 examples of protoctisa diseases

A

malaria (the protist is mosquito)

potato blight

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20
Q

What type of pathogen causes malaria?

A

protoctista

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21
Q

What type of pathogen causes potato blight?

A

protoctista

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22
Q

Are fungi eukaryotes or prokaryotes?

A

eukaryotes

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23
Q

How do fungi cause disease?

A

By digesting and destroying living cells

-some produce toxins that affect the host cells and cause disease

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24
Q

Name 3 examples of fungal diseases

A

black sigatoka
ring worm
athlete’s foot

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25
Q

What type of pathogen causes black sigatoka?

A

fungus

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26
Q

What type of pathogen causes ring worm?

A

fungus

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27
Q

What type of pathogen causes athlete’s foot?

A

fungus

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28
Q

What is direct transmission?

A

when the pathogen is directly transferred from one organism to another

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29
Q

What is indirect transmission?

A

when the pathogen travels from one organism to another through something else

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30
Q

Name the 6 methods of transmission in animals

A 
direct contact (contagious disease)
inoculation
ingestion
fomites
droplet infection (inhalation)
vectors
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31
Q

Describe how direct contact transmission can happen in animals

A
  • skin to skin contact
  • contact with bodily fluids of another person (eg. by kissing, sexual reproduction)
  • microorganisms from faeces
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32
Q

Describe how inoculation (transmission) can happen in animals

A
  • break in the skin
  • animal bites
  • puncture wounds, sharing needles etc
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33
Q

Is inoculation direct or indirect transmission?

A

direct

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34
Q

Describe how ingestion (transmission) can happen in animals

A

-taking in contaminated food/drink

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35
Q

Is ingestion direct or indirect transmission?

A

direct

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36
Q

Describe how fomites (transmission) can happen in animals

A

-inanimate objects transfer pathogens

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37
Q

Are fomites direct or indirect transmission?

A

indirect

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38
Q

Describe how droplet infection (transmission) can happen in animals

A

-tiny droplets of saliva/mucus come out of mouth as you speak/cough/sneeze. If they contain pathogens and people breathe them in, they will become infected

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39
Q

Is droplet infection direct or indirect transmission?

A

indirect

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40
Q

Describe how vectors (transmission) can happen in animals

A

-transmit pathogen from one host to another

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41
Q

Are vectors direct or indirect transmission??

A

indirect

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42
Q

Describe how direct transmission can happen in plants

A

-contact of a healthy plant with a diseased plant

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43
Q

Describe how soil contamination (transmission) can happen in plants

A
  • infected plants leave pathogens (bacteria or virus) or reproductive spores from pathogens (from fungi or protisits) in soil
  • this can affect the next crop that is grown in that soil
44
Q

Is soil contamination direct or indirect transmission?

A

indirect

45
Q

Describe how vectors (transmission) can happen in plants

A
  • pathogens carried by wind
  • spores swim on water
  • animals carry pathogens
  • humans (hands, clothing, farming products, etc)
46
Q

What factors affect the chance of animals catching a communicable disease?

A
  • living conditions (eg. overcrowding)
  • climate
  • socioeconomic factors (eg. lack of trained health workers)
  • poor nutrition
  • poor disposal of waste
47
Q

How to plants recognise an attack from a pathogen?

A

receptors in cells detect pathogen or chemicals pathogen has produced
-this stimulates the release of signal molecules and causes responses

48
Q

How do plants respond to pathogens?

A
  • send alarm signals to unaffected cells
  • physically strengthen cell walls
  • produces chemicals eg.
    - produces callose (polysaccharide that seals of infected areas and strengthens cell walls)
    - produces ligin (strengthens barriers)
49
Q

What chemicals do plants produce to defend themselves against pathogens?

A
  • callose
  • ligin
  • insect repellants
  • insecticides
  • antibacterial compounds containing antibiotics
  • antifungal compounds
  • anti oomycetes
  • general toxins
50
Q

What does callose do?

A
  • seals off infected cells from rest of plant
  • strengthens cell walls
  • seals off sieve plates in phloem and plasodesmata between cells
51
Q

What are the primary non-specific defences against pathogens in animals?

A
  • skin
  • mucous membranes
  • blood clotting
  • inflammation
  • expulsive reflexes
  • lysozymes
52
Q

What does skin do to prevent the entry/spreading of pathogens?

A
  • covers entire body
  • has lots of healthy microorganisms (flora) that outcompete with pathogens for space on body surface
  • produces sebum (oily substance that inhibits pathogen growth)
53
Q

What do mucous membranes do to prevent the entry/spreading of pathogens?

A

-line body tracts (eg. airways in gas exchange system) and produce mucus (which contains phagocytes and lysozymes and traps organisms)

54
Q

What are lysozymes?

A
  • enzymes found in tears, urine and stomach acid

- destroy bacterial/fungal cell walls

55
Q

What are expulsive reflexes and how do they prevent the entry/spreading of pathogens?

A

-coughs
-sneezes
eject mucus (containing pathogens) from gas exchange system

-vomiting
-diarrhoea
expel contents of gut alongside any pathogens

56
Q

How does blood clotting prevent the entry/spreading of pathogens?

A

rapidly seals wounds by platelets forming scabs that pathogens can not get through

57
Q

How does inflammation prevent the entry/spreading of pathogens?

A
  • red swelling of tissue
  • activates most cells, causing them to release histamines and cytokines
  • histamines dilate blood vessels, which causes temperature to raise to prevent pathogens reproducing
  • cytokines attract phagocytes
58
Q

How does a fever prevent the entry/spreading of pathogens?

A
  • body temp increases, stopping the reproduction of pathogens
  • immune system also works faster at higher temp
59
Q

What are phagocytes?

A

white blood cells that engulf and destroy pathogens through phagocytosis

60
Q

What are the two types of phagocytes?

A

neutrophils

macrophages

61
Q

What are neutrophils?

A

phagocytes made in the bone marrow which have a multi-lobed nucleus and are found in the blood

62
Q

What are macrophages?

A

large phagocytes made in the bone marrow

-they travel in the blood as monocytes, settle in lymph nodes and develop into macrophages

63
Q

Explain the stages of phagocytosis

A
  • phagocytes recognise antigens on pathogen’s cell surface membrane and identify the pathogen as non-self
  • phagocyte binds to pathogen
  • phagocyte engulfs the pathogen
  • pathogen becomes enclosed in a vacuole in the phagocyte and is called a phagosome
  • lysosomes in the cytoplasm of the phagocyte move towards the phagosome and combine with it, forming a phagolysosome
  • enzymes from lysosome are released to digest and destroy the pathogen
  • digested pathogen is absorbed into the cytoplasm of phagocyte
64
Q

What do macrophages do at the end of phagocytosis? (which neutrophils do not)

A
  • antigens from pathogen’s surface membrane combine with MHC (glycoprotein) in cytoplasm
  • MHC moves antigens to the macrophage’s surface
  • cell becomes an antigen presenting cell (APC), which alerts the immune system without being a threat
65
Q

What do cytokines do?

A
  • signal and attract phagocytes
  • increase body temp
  • stimulates specific immune response
66
Q

What do opsonins do?

A

-bind to pathogens and tag them so that they are easily recognised by phagocytes

67
Q

What are antibodies?

A

Y shaped glycoproteins that bind to a specific antigen

68
Q

What is formed when an antibody binds to an antigen?

A

antigen-antibody complex

69
Q

What are the antigen binding sites in an antibody?

A

the site where it binds to the antigen

70
Q

What is the function of the variable region in an antibody?

A

gives antibody its specificity for an antigen

71
Q

What is the function of the disulfide bridge in an antibody?

A

holds the polypeptide chains in shape

72
Q

What are the 4 ways an antibody works to defend the body (once it has formed an antigen-antibody complex)?

A
  • antibody in complex acts as opsonin -is easily engulfed and digested by phagocytes
  • most pathogens can’t invade body when they’re part of an antigen-antibody complex
  • antibody acts as an agglutinin -causes pathogens carrying complexes to clump together (can’t spread so much + phagocytes can engulf multiple at once)
  • antibody acts as antitoxin -binds to toxins produced to make them harmless
73
Q

What do agglutinins do?

A

bind to several antigens so that they clump together

  • can’t spread much
  • phagocytes can engulf multiple pathogens at once
74
Q

What do antitoxins do?

A

bind to toxins to make them harmless

75
Q

What are lymphocytes?

A

white blood cells involved in the specific immune system

76
Q

What are the two types of lymphocytes?

A

B lymphocytes
T lymphocytes

  • both produced in bone marrow
  • B mature in bone marrow but T mature in thymus gland
77
Q

What are the types of T lymphocytes?

A
  • T helper cells
  • T killer cells
  • T memory cells
  • T regulator cells
78
Q

What do T helper cells do?

A

produce interleukins (which stimulate B cells to increase antibody production)

79
Q

What do T killer cells do?

A

secrete perforin (which kills the pathogen by making holes in its cell membrane)

80
Q

What do T memory cells do?

A

provide immunological memory

-live for a long time

81
Q

What do T regulator cells do?

A

suppress the immune system (control and regulate it)
-stops immune system once pathogen has been eliminated to make sure the body doesn’t have an autoimmune response (start attacking its self antigens)

82
Q

What do B effector cells do?

A

divide to form plasma cells

83
Q

What do plasma cells do?

A

produces and releases antibodies specific to a particular antigen

84
Q

What do B memory cells do?

A

provide immunological memory

-live for a long time

85
Q

What happens in cell mediated immunity?

A
  • macrophage destroys a pathogen and becomes an antigen presenting cell (APC)
  • a specific T helper cell has receptors that compliment the antigens on the APC
  • these specific T helper cells bind to the antigens (so that the T helper cell becomes activated)
  • T helper cells produce interleukins which stimulate more T helper cells to divide via mitosis to produce clones
  • clones develop into T helper and T memory cells
  • interleukins also stimulates phagocytosis and B cells to divide
86
Q

What happens in humoral immunity?

A
  • B cell binds to pathogen’s antigen, engulfs the pathogen and processes the antigens to become an antigen presenting cell (APC)
  • an activated T helper cell binds to the B cell (clonal selection)
  • B cell divides by mitosis (clonal expansion)
  • B cells differentiate into B plasma cells and B memory cells
  • B plasma cells produce antibodies
  • B memory cells provide immunological memory
87
Q

What are the differences between cell mediated and humoral immunity?

A
  • cell mediated responds to changes in cells
  • humoral responds to antigens outside of cells
  • cell mediated mainly involves B cells
  • humoral mainly involves T cells
  • cell mediated detects cells altered by viruses
  • humoral detects pathogen’s antigens
88
Q

What is clonal selection?

A

an antibody on a B-cell binds to a complimentary antigen on a pathogen, which activates the B-cell, causing it to undergo clonal expansion (divide)

89
Q

What is clonal expansion?

A

mass rapid increase in antibody-producing B cells by mitosis

90
Q

What is active immunity?

A

immunity obtained when your immune system makes its own antibodies after being stimulated by an anitgen

91
Q

What is passive immunity?

A

immunity obtained from being given antibodies from a different organism
-body doesn’t produce the antibodies itself

92
Q

Give an example of natural active immunity

A

when you become immune after catching a disease

93
Q

Give an example of artificial active immunity

A

when you become immune after being given a vaccination containing a harmless form of the antigen which causes the immune system to produce antibodies

94
Q

Give an example of natural passive immunity

A

a baby becoming immune by being given antibodies from its mothers blood (through the placenta) or from colostrum (mother’s milk)

95
Q

Give an example of artificial passive immunity

A

having an injection of antibodies

-antibodies produced in one individual are extracted and injected into another individual

96
Q

What is an autoimmune disease?

A

a disease caused by an organism’s immune system being unable to recognise self antigens (treats them as foreign antigens) so acts against its own cells and destroys healthy tissues in the body

97
Q

Name some examples of autoimmune diseases

A
  • arthritis (immune system attacks cells in connective tissues, can affect skin, joints and organs)
  • lupus (immune system attacks cells in joints)
98
Q

What is a vaccine?

A

a safe form of an antigen injected into the blood stream to trigger the primary immunity response to the immune system produces antibodies specific to the antigens and memory cells so if you come into contact with the antigen again, the secondary immune response recognises it and destroys the pathogen

99
Q

What are routine vaccines?

A

injections offered to everybody

eg. MMR vaccine and Meningitis C vaccine

100
Q

What is a pandemic?

A

when a communicable disease spreads rapidly across several countries or continents

101
Q

What is an epidemic?

A

when a communicable disease spreads rapidly to a lot of people in a local/national area

102
Q

Why do vaccines sometimes need to be changed?

A

new strains of pathogens are produced (from mutations and natural selection) which have different antigens to previous strains, meaning new vaccines need to be made containing the correct antigens

103
Q

What are common sources of medicine?

A

-microorganisms and plants
-designing drugs using computer programmes
-using computer libraries of chemicals
future -personalised medicines
-synthetic biology

104
Q

What do antibiotics do?

A

damage and destroy bacterial cells by inhibiting their metabolism
-are selectively toxic (only destroy bacteria, not body cells)

105
Q

What is antibiotic resistance?

A

when bacteria becomes resistant to antibiotics
-mutations cause bacteria to be resistant and this is passed on via natural selection (resistant allele passed onto offspring)

106
Q

Name some examples of resistant bacteria

A

MRSA -resistant to meticillin

C.difficile

107
Q

What do parasites do?

A
  • live on host cell at expense of host (harms host)

- feeds on host to gain nutrition

Alevel Biology OCR (26 decks)

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