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Bio Module 4 > Communicable Disease > Flashcards

Communicable Disease Flashcards

1
Q

What is a communicable disease?

A

An infectious disease that can be passed from organism to organism

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2
Q

What are the 4 types of pathogen?

A

Bacteria
Virus
Fungi
Protoctista (protista)

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3
Q

What are bacterium?

A

They are prokaryotes as they have no membrane-bound organelles.

They can be spherical, rod-shaped or corkscrew in shape.

They also have a cell wall (cellulose)

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4
Q

What is the process by which bacteria reproduce called?

A

Binary fission

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5
Q

What are viruses

A

They are regarded as non-living and are 50x smaller than the average bacteria.

They use host cells to reproduce rapidly and evolve accordingly to their host.

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6
Q

What are protoctista/protista?

A

They are eukaryotic organisms. A small group of of protoctista act as pathogens. They are parasites which means they use the host organism for their own benefit.

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7
Q

What is TB and who does it affect?

A

It affects humans, cattle and other animals

It is a bacteria

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8
Q

What is ring rot and who does it affect?

A

It affects potatoes and tomatoes

It is a bacterium

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9
Q

What is HIV/aids and who does it affect?

A

It is a virus that only affects humans

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10
Q

What is influenza and who does it affect?

A

Influenza is a virus that affects animals and humans

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11
Q

What is tobacco mosaic virus and who does it affect?

A

Tobacco mosaic virus (TMV) is a virus that affects plants

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12
Q

What is black sigatoka and who does it affect?

A

It is a fungi that only affects bananas plants

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13
Q

What is athletes foot and who does it affect?

A

It is a fungi that affects humans

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14
Q

What is potato/tomato blight and who does it affect?

A

It is a protoctist that affects potatoes and tomatoes

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15
Q

What is malaria and who does it affect?

A

It’s a protoctist that affects animals and humans

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16
Q

How do pathogens cause disease?

A

Damaging host cells or tissues directly

Producing toxins which damage host tissues

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17
Q

What are exotoxins?

A

Toxins produced and secreted by a normal pathogen

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18
Q

What are endotoxins?

A

They are toxins that are produced when a pathogen is damaged and toxins are released

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19
Q

Can fungi photosynthesise?

A

They can’t photosynthesise. They must digest their food extracellularly before absorbing nutrients. They are sacrophytes which means they feed on dead and decaying matter.

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20
Q

What are the two types of disease transmission?

A

Direct and indirect transmission

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21
Q

What is direct transmission?

A

The pathogen/disease is transmitted from one organism to another

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22
Q

What are examples of direct transmission?

A

Physical contact (sexual intercourse)
Droplet infection (coughing/sneezing)
Inoculation (break in skin/needle use)
Ingestion (eating contaminated food)

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23
Q

How can you reduce the risk of direct transmission?

A

Washing hands regularly
Cleaning and disinfecting cuts
Sterilising surgical instruments
Using condoms

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24
Q

What is indirect transmission?

A

When a disease is transmitted from one organism to another via and intermediate (vectors or fomites)

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25
What is a vector?
An organism that spreads disease by carrying the pathogen
26
What is a fomite?
Inanimate objects that harbour and transfer disease
27
What factors affect transmission?
Living conditions (over-crowding, poor nutrition, poor disposal of waste) Social factors (traditional remedies can increase transmission, poorly trained health workers) Climate change
28
What is a zoonosis?
A zoonosis/zoonotic disease is an infectious disease that is transmitted from animals to humans Eg. Swine flu
29
How can pathogens be transmitted to other plants?
Direct transmission (contact of a healthy plant with any part of an infected plant) Vectors (soil contamination, wind, water, contaminated farming tools)
30
In plants where does the fungus often live?
The fungus often lives in the vascular tissue to easily acquire nutrients. They hyphae releases extracellular enzymes to digest surrounding tissue causing decay.
31
What is a pathogen?
A disease-causing organism
32
Give an example of a disease caused by a protoctist?
Malaria
33
What are passive defences?
They are defences against pathogens that are always present eg. waxy cuticle
34
What are examples of physical defences in plants?
Cellulose cell wall & bark Lignin thickening Stomatal closure Waxy cuticles prevent build up of water
35
How is an attack recognised in plants?
Receptors respond to molecules from pathogens or chemicals released when the cell wall is attacked. The plant cells then release signalling molecules which switch on genes in the nucleus. This then triggers cellular responses.
36
What are the cellular responses in plants?
Producing defence chemicals Sending alarm signals to other cells Strengthening the cell wall
37
What is the role of callose in plant defence?
A large polysaccharide that is deposited in the sieve tubes blocking them, and closing up the plasmodesmata. This stops the pathogen from moving from cell to cell.
38
What is the role of tylose in plant defence?
Tylose causes a balloon like swelling that fills the xylem vessel thus preventing the spread of pathogens. The tylose also contain chemicals such as terpenes that are toxic to pathogens.
39
What is necrosis in a plant?
Necrosis is deliberate cell suicide, cells are sacrificed to save the rest of the plant. Intracellular enzymes are released
40
What is canker in plants?
A sunken necrotic lesion in the woody tissue of the plant caused by pathogens. It results in the death for the cambium bark tissue.
41
How is the skin a useful non-specific defence in mammals?
It covers the entire body The pH of the skin is slightly acidic The skin is made up of dead cells The skin harbours healthy microorganisms that outcompete pathogens
42
What is sebum?
Sebum is an oily/waxy substance produced by sebacious glands. It coats and protects the skin with anti microbial properties.
43
What are expulsive reflexes?
They occur when pathogens irritate the airways. Expulsive reflexes eject pathogens from upper airway tract. Eg. Sneezing, coughing, vomiting, diarrhoea
44
What are lysozymes?
They are secreted in bodily fluids. It acts as an antibacterial agent by breaking down bacterial & fungal cell walls. They exist in tears, sweat, urine, mucus, blood and breastmilk
45
What are intestinal flora?
They are healthy microorganisms in our gut
46
Why are intestinal flora so important to our health?
They outcompete pathogens thus preventing infection. They also assist with digestion and the production of some vitamins.
47
What is the process of blood clotting?
1) collagen from outside the skin is detected 2) inactive platelets in blood become active 3) clotting factors 4) prothrombin + Vitamin K + calcium —> thrombin 5) thrombin —> soluble fibrinogen —> insoluble fibrin
48
How are mast cells involved in allergic responses?
Antibodies to the allergen bind to mast cells & the allergen. This causes the mast cells to release chemicals eg. Histamines.
49
What are the roles of opsonins?
They bind to antigens on pathogens, tagging them. This makes them more recognisable for phagocytosis. They also act as binding sites for phagocytic cells
50
What are cytokines?
They are signalling molecules
51
How can pathogens reduce plant growth and yield?
Reducing the rate of photosynthesis by blocking light or destroying chloroplasts. Increasing rate of respiration Feeding on the plants sugars Blocking xylem and phloem
52
What are antigens?
Antigens are found on the surface of all cells. The immune system uses antigens to recognise the difference between self and non-self
53
Where do B lymphocytes mature?
B lymphocytes mature in the bone marrow
54
Where do T lymphocytes mature?
Thymus gland
55
What are the two types of response in the immune system?
Cell mediated response and Humoral response
56
What chemical is released when an antigen-presenting cell interacts with a specific T-helper cell?
Interleukin-1
57
What does interleukin-1 stimulate the release of?
Interleukin-2 which stimulates the growth and development of T-killer cells
58
Describe the structure of an antibody?
Antibodies are Y-shaped glycoproteins that bind to specific antigens or toxins They are made up of 2 heavy chains and 2 light chains joined by disulfide bonds
59
What are the two ways which antibodies destroy pathogens?
Neutralisation and Agglutination
60
What is neutralisation (antibodies)
Antibodies bind to antigens on pathogens and prevent them from attaching to and entering host cells. The antibodies also encourage macrophages to phagocytose the pathogen.
61
What is agglutination (antibodies)
Antibodies bind to the antigens of several pathogens, clumping them together. Macrophages then recognise and easily destroy the pathogens via phagocytosis.
62
How do antitoxins help to protect cells?
Antibodies combine with toxins secreted by bacteria to neutralise them eg. Tetanus
63
Why don’t vaccines cause illness?
Vaccines contain an attenuated version of the pathogen. The vaccine may only contain a pathogens antigens & not the entire pathogen
64
What is active immunity?
Your immune system responds to the presence of foreign antigens and produces antibodies
65
What is passive immunity?
Your immune system does not respond to antigens; you receive the antibodies from another source. No immune response whatsoever
66
What are the two types of active immunity?
Natural - eg. Infection Artificial - eg. Vaccination
67
What are the two types of passive immunity?
Natural - maternal antibodies Artificial - monoclonal antibodies
68
What is the difference between vaccination and immunisation?
Vaccination is when a vaccine is administered to you where as immunisation is what happens in the body after the vaccination
69
What is herd immunity?
To achieve herd immunity - almost all people in a community must be vaccinated. Those who are unable to be vaccinated or choose not to are also protected.
70
What is antigenic variation?
Antigenic variation is when pathogens mutate and change their surface antigens/proteins and a new strain of the pathogen is formed.
71
What are the problems antigenic variation causes?
If you are exposed to the pathogen again, the memory cells from the first infection will not recognise the different antigens
72
What is an epidemic?
An epidemic is when an infectious disease spreads rapidly to a large population
73
What is a pandemic?
A pandemic is when an infectious disease is global
74
What is an autoimmune disease?
An abnormal immune response that occurs when antibodies start to attack self antigens. The attack may be aimed at a single organ, tissue or the whole body
75
What are some sources of medicine?
Accidental discovery eg. Penicillin Traditional remedies Plant research Observation of wildlife
76
When was penicillin discovered?
1928
77
Who discovered penicillin?
Alexander Fleming
78
What do antibiotics do?
They attack bacteria by interfering with their metabolism without affecting the metabolism of human cells. This is called selective toxicity
79
How does antibiotic resistance occur?
1) Genetic variation in bacteria due to mutations 2) A mutation may allow resistance to an antibiotic 3) Those with the advantageous allele survive and reproduce 4) most bacteria in a population now have this advantageous allele
80
What is the purpose of the disulfide bond in antibodies?
The disulfide bond joins the light and heavy chains together
81
In plants where does the fungus often live and why?
The fungus often lives in the vascular tissue in order to acquire nutrients
82
Where are t-lymphocytes produced?
The are produced in the bone marrow but mature in the thymus gland before being released into the bloodstream
83
What is the role of t-lymphocytes?
They detect antigens on body cells Eg. Cancer cells , APC and virus antigens on infected cells
84
Where are b-lymphocytes produced?
They are produced in the bone marrow and mature there. Unlike t-lymphocytes which mature in the thymus gland
85
How does cell mediated response happen?
1) a macrophage destroys a pathogen and displays its antigen (APC) 2) The APC interacts with a specific T-helper cell causing the release of interleukin-1 3) Interleukin-1 stimulates the release of interleukin-2 which stimulates the growth of T-killer cells (the process of activating a t helper cell is called clonal selection) 4) the t killer cells detect the antigen and release perforin which forms pores in the membrane so water and ions flood in causing lysis 5) T memory cells are formed, ready to respond if the antigen is present again
86
What is humoral response?
1) macrophage destroys pathogen and becomes APC 2) APC interacts with a t helper cell, releasing interleukin-1 which stimulates interleukin-2 to be released 3) interleukin-2 stimulates the differentiation of a b-effector cell into a plasma cell 4) plasma cells divide by mitosis producing several clones which have the correct antibodies that can destroy the pathogen by agglutination or neutralisation 5) B memory cells are produced and are ready to release antibodies upon a second infection

Bio Module 4 (3 decks)

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