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infection and response Flashcards

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Biology 101 flashcards
1
Q

define pathogens

A

microorganisms that cause infectious disease

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2
Q

what can pathogens be, what can they infect and how are they spread

A

they may be viruses, bacteria, protists or fungi; they may infect plants or animals and can be spread by direct contact, by water or by air

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3
Q

how do bacteria and viruses spread

A

they reproduce rapidly inside the body (they divide every 20 minutes under ideal conditions)

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4
Q

how do bacteria make us feel ill

A

they produce toxins that damage tissues

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5
Q

how do viruses cause cell damage

A

because they live and reproduce inside cells

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6
Q

what is a communicable disease

A

a disease that can be spread from person to person; they are infectious and are spread via pathogens

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7
Q

what is the difference between bacteria and viruses

A

unlike bacteria, viruses themselves cannot reproduce, but can reproduce once they enter a host cell

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8
Q

how do viruses make us feel ill

A

once inside, the virus reproduces using the cell’s resources and increases in number so much until the cell bursts and gets damaged

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9
Q

what are protists and how are they spread

A

they’re eukaryotic pathogens which are sometimes parasitic; they’re often transferred between organisms by vectors

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10
Q

what are vectors

A

animals that carry a disease but do not get the disease themselves

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11
Q

what are fungi and how are they spread

A

some are single-celled and others have a body made up of hyphae that grow and penetrate human skin and the surface of plants, causing diseases; hyphae can produce spores that spread to other plants and animals. these spores can travel through the wind and infect organisms

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12
Q

how are pathogens spread in the air

A

via droplet transmission e.g. in sneezes and cough, whereby droplets are carried in the air and inhaled

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13
Q

how are pathogens spread in water

A

water can become contaminated, causing the spread of pathogens e.g. cholera

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14
Q

how are pathogens spread by direct contact

A

through contact or change of bodily fluids e.g. HIV is spread by sexual contact and some viruses can be spread by handshaking

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15
Q

6 main ways of reducing the spread of pathogens

A
  • implementing simple hygiene measures, e.g., washing hands before eating and before cooking food
  • vaccination; this allows for herd immunity so that less people are able to be infected by that disease
  • isolation; in highly-infectious diseases, patients may be isolated to prevent them spreading the disease to others
  • vector control; for example, with malaria, you could use insecticides to kill off the mosquito vectors
  • use condoms to prevent transmission of STIs
  • provide clean drinking water rather than that containing cholera
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16
Q

measles symptoms

A

fever, and after around 3 days, the patient develops a red skin rash

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17
Q

how can measles be fatal

A

in some cases, complications can arise that cause damage to the respiratory system and the brain. otherwise, measles is already a serious illness

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18
Q

how is the measles virus spread

A

droplets in the air when an infected person coughs or sneezes are inhaled by another person

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19
Q

how can measles be prevented

A

because of the seriousness of this illness, most young children are vaccinated against it

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20
Q

symptoms of HIV

A

the first symptoms are often a flu-like illness, but this disappears after one or two weeks

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21
Q

what happens if HIV isn’t successfully controlled

A

the virus attacks the patient’s immune cells, and over time, the immune system becomes severely damaged. at this point, the immune system becomes so badly damaged, that it is unable to fight off other infections, meaning the patients can now easily contract infections like tuberculosis and cancer

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22
Q

what is late-stage HIV called

A

AIDS; at this point, the disease is fatal

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23
Q

how do antiretroviral drugs work in HIV

A

they prevent the virus from multiplying inside the patient so the virus does not damage the patient’s immune system any further; patients who take these antiretroviral drugs do not go on to develop AIDS and can lead a normal life expectancy

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24
Q

are antiretroviral drugs a cure for HIV/AIDS? why?

A

no they’re not; they must be taken for the rest of the patient’s life, otherwise the viruses will start reproducing again and damage the immune system

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25
Q

how is HIV spread

A

via sexual contact or exchange of body fluids e.g. blood, which occurs when drug users share needles

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26
Q

what is TMV

A

a widespread plant pathogen affecting many species of plants including tomatoes

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27
Q

symptom of TMV

A

gives a distinctive ‘mosaic’ pattern of discolouration on the leaves

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28
Q

why is TMV bad for a plant

A

due to the discolouration on the leaves, there is less chlorophyll in those areas, meaning the rate of photosynthesis reduces. this has a negative effect on the growth of the plant, because less glucose is produced, therefore less amino acids and proteins can be produced

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29
Q

how is salmonella spread

A

it’s spread by bacteria ingested in food, or by food prepared in unhygienic conditions

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30
Q

symptoms of salmonella

A

fever, abdominal cramps, vomiting and diarrhoea are caused by the bacteria and the toxins they secrete

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31
Q

how is salmonella prevented

A

in the UK, poultry are vaccinated against salmonella to control the spread of the disease

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32
Q

symptoms of gonorrhoea

A

a thick yellow or green discharge from the vagina or penis and pain when urinating

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33
Q

how is gonorrhoea treated now vs. before and why

A

now, it’s treated using antibiotics and, in the past, it was treated easily using the antibiotic penicillin but antibiotic-resistant strains of bacteria are now becoming more common, so different drugs are used

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34
Q

how is gonorrhoea spread

A

it’s spread via sexual contact

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35
Q
A
36
Q

how is the spread of gonorrhoea controlled

A
  • by treatment with antibiotics
    OR
  • by the use of a barrier method of contraception e.g. condoms to stop the bacteria spreading from person to person
37
Q

what is rose black spot

A

a fungal disease where purple or black spots develop on the leaves of a plant, which often turn yellow and drop early

38
Q

why is rose black spot bad for a plant

A

just like TMV, the rate of photosynthesis is reduced due to a lack of chlorophyll in the yellow areas of the leaves, which reduces the rate of growth of the plant (less photosynthesis = less glucose = less amino acids and proteins = less growth)

39
Q

how is rose black spot spread

A

in the environment by water or by wind

40
Q

how is rose black spot treated

A
  • by using fungicides
    AND/OR
  • removing and destroying the affected leaves to prevent the fungus spreading to the other parts of the plant
41
Q

the three examples of viral diseases, two of bacterial diseases, one of fungal diseases and one of protist diseases

A

VIRAL; measles, HIV and TMV
BACTERIAL; salmonella and gonorrhoea
FUNGAL; rose black spot
PROTIST; malaria

42
Q

what pathogens cause malaria

A

protists

43
Q

symptoms of malaria

A

recurrent episodes of fever and can be Fata;

44
Q

process of the spread of malaria

A
  • the infected person is bitten by a mosquito
  • the blood of the person containing malarial pathogen passes into the mosquito
  • the infected mosquito bites a different person and passes the malaria protist to them
45
Q

how is the spread of malaria controlled

A
  • preventing the vectors, mosquitos, from breeding. we can do this by draining areas of still water (this is where many mosquitoes breed) or by spraying insecticides in these areas of still water to kill the mosquitos. however, it is impossible to kill all mosquitos
  • using mosquito nets to avoid being bitten (these nets may be covered in insecticides)
46
Q

the 4 non-specific human defence systems

A

skin, nose, trachea and bronchi, stomach

47
Q

how does the skin protect the human body against pathogens

A
  • acts as a protective physical barrier to prevent pathogens entering the body, as it has a layer of dead cells which is difficult for pathogens to penetrate
  • secretes antibacterial substances that kill pathogens on its surface
  • forms scabs when it is damaged
48
Q

how does the nose protect the human body against pathogens

A

it’s lined with nose hair and mucus that trap and prevent pathogens from entering the respiratory system

49
Q

how do the trachea and bronchi protect the human body against pathogens

A

they’re lined with cilia and mucus; the mucus traps the pathogens in it, and the cilia wafts the pathogen-containing mucus up the trachea and bronchi to the mouth, where it can be swallowed and killed by stomach acid

50
Q

how does the stomach protect the human body against pathogens

A

it contains hydrochloric acid that kills pathogens and microorganisms found in food, preventing them from entering the blood via the digestive system

51
Q

what happens if a pathogen enters the body

A

the immune system tries to destroy it and any toxins they produce, and it protects us in case the same type of pathogen invades us in the future

52
Q

what happens if the non-specific defence systems are unable to prevent and kill the pathogen and it gets into the blood

A

we rely on white blood cells to defend our body from infection

53
Q

what 3 ways can white blood cells defend our bodies against pathogens

A

phagocytosis, antibody production, antitoxin production

54
Q

describe how phagocytosis defends our body against pathogens

A

white blood cells called phagocytes detect the foreign antigen and engulf, ingest and destroy pathogens using enzymes

55
Q

describe how antibody production defends our body against pathogens

A

antibodies are proteins that have a specific shape to the antigen of the pathogen so that they can bind to the pathogen and destroy it

56
Q

describe how antitoxin production defends our body against pathogens

A

these neutralise the toxins produced by bacteria by binding to the toxins and preventing them damaging cells to prevent us feeling ill

57
Q

how do vaccinations work

A
  • they contain small quantities of dead or inactive forms of a pathogen into the blood
  • the pathogen is dead so it will not infect the patient
  • the foreign antigen stimulates the white blood cells to produce antibodies against the dead or inactive pathogen – these antibodies will be specific in shape to the antigen binding site of the pathogen
  • these lymphocytes become memory cells, divide by mitosis and remain in the body for years
  • when re-exposed to the real pathogen, the memory white blood cells (lymphocytes) then produce the correct antibody very quickly, destroying the pathogen quickly, preventing the person being infected
58
Q

why is it important that a very large number of people are vaccinated against pathogens

A

it helps to introduce herd immunity whereby most people are vaccinated, so they even protect the unvaccinated people from being infected. this is because there is no one who can pass the pathogen onto the unvaccinated person – hence herd immunity

59
Q

evaluate the global use of vaccinations in the prevention of disease

A

PROS:
- vaccines have helped control lots of infectious diseases that were once common and deadly e.g. smallpox and polio
- epidemics are prevented if the population is vaccinated and has herd immunity, thus reducing death and costs of diseases

CONS:
- vaccines sometimes don’t work and can sometimes have side effects; some people may react badly to particular vaccines, e.g., having swelling or fevers

60
Q

how do antibiotics treat disease

A

antibiotics, such as penicillin, are medicines that help to cure bacterial disease by killing infective bacteria inside the body. it’s important that specific bacteria should be treated by specific antibodies

61
Q

evaluate the use of antibiotics

A

PROS:
- greatly reduced deaths from infectious bacterial diseases

CONS:
- the emergence of strains resistant to antibiotics is of great concern

62
Q

how can you treat viral pathogens (include what doesn’t work)

A
  • antibiotics cannot kill viral pathogens
  • painkillers and other medicines are used to treat the symptoms of disease but do not kill pathogens
63
Q

why is it difficult to kill viruses

A

it is difficult to develop drugs that kill viruses without also damaging the body’s tissues

64
Q

what were drugs traditionally extracted from, and give the 3 examples

A

plants and microorganisms, e.g.,
- the heart dug ‘digitalis’ originates from foxgloves
- the painkiller ‘aspirin’ originates from willow
- the antibiotic ‘Penicillin’ was discovered by Alexander Fleming from the Penicillium mould

65
Q

how are most new drugs made

A

most new drugs are synthesised by chemists in the pharmaceutical industry. however, the starting point may still be a chemical extracted from a plant

66
Q

caution for new medical drugs

A

new medical drugs have to be tested and trialled before being used to check that they are safe and effective

67
Q

what are new drugs extensively tested for

A

toxicity, efficacy (the ability to produce a desired, intended result) and dose

68
Q

describe how clinical trials take place

A
  • healthy volunteers and patients are used
  • very low doses of the drug are given at the start of the clinical trial
  • if the drug is found to be safe, further clinical trials are carried out to find the optimum dose for the drug
  • in double blind trials, some patients are given a placebo
69
Q

what are antibodies produced by

A

a type of white blood cell called a B-lymphocyte

70
Q

what do lymphocytes produce

A

they produce antibodies against anything that the body detects as foreign (has a foreign antigen)

71
Q

what is an antigen

A

a protein on the surface of all cells, specific to each cell; so, white blood cells can detect when a foreign antigen of a pathogen is present

72
Q

what are monoclonal antibodies produced from and how do they work

A

they’re produced from a single clone of cells; the antibodies are specific to one binding site on one protein antigen and so are able to target a specific chemical or specific cells in the body

73
Q

how to produce monoclonal antibodies

A
  • inject a mouse with the desired antigen to stimulate mouse lymphocytes to produce antibodies against that antigen (they will be specific to the shape of the antigen binding site)
  • the lymphocytes are then collected from the mouse
  • the lymphocytes will not divide by mitosis so - to overcome this - we fuse the lymphocytes with tumour cells to form a hybridoma cell which produces antibodies and divides rapidly by mitosis
  • the hybridoma is left to multiply and produce lots of antibodies in a culture medium, which are then collected and purified; these are monoclonal antibodies as they come from the same clone of hybridoma cells, and they are all the same type of antibody, specific to the antigen that you injected with the mouse
74
Q

evaluate the use of monoclonal antibodies

A

PROS:
- we can use them to target a specific chemical or specific cells in the body, so they have a wide range of uses e.g., they can be used to cure diseases like cancer without harming other cells

CONS:
- in certain trials they have been found to produce very harmful side-effects, so they aren’t as widely used as everyone hoped when they were first developed
- more side effects than expected
- very expensive to produce, research and use

75
Q

uses of monoclonal antibodies

A
  • for diagnosis, such as in pregnancy tests
  • in labs to measure the levels of hormones and other chemicals in blood, or to detect pathogens
  • in research to locate or identify specific molecules in a cell or tissue by binding to them with a fluorescent dye, so that when it binds to the antigen of the cell, the cell can clearly be detected
  • to treat some diseases; for cancer, the monoclonal antibody can be bound to a radioactive substance (or an anti-cancer drug), a toxic drug or a chemical which stops cells growing and dividing. it delivers the substance to the cancer cells without harming other cells in the body
76
Q

what can plants be attacked by

A
  • pathogens e.g., TMV and rose black spot
  • insects e.g., aphids, which extract nutrients like sugars from the plant by piercing phloem with their mouthpiece. lack of glucose = less amino acids can be produced = less proteins produced = stunted growth
77
Q

what makes up amino acids

A

glucose and nitrate ions

78
Q

ways plant diseases can be detected

A
  • stunted growth
  • spots on leaves
  • areas of decay (rot)
  • growths e.g., crown galls
  • malformed stems or leaves
  • discolouration
  • the presence of pests
79
Q

ways plant diseases can be identified

A
  • reference to a gardening manual or website
  • taking infected plants to a laboratory to identify the pathogen
  • using testing kits that contain monoclonal antibodies
80
Q

what can plants be infected by, and what can plants be damaged by

A

INFECTED BY a range of viral, bacterial and fungal pathogens, as well as by insects

DAMAGED BY a range of ion deficiencies

81
Q

how can plants be damaged by nitrate deficiency

A

nitrate ions are needed to make amino acids, so are needed to make proteins; a lack of nitrate ions therefore means less proteins are synthesised, leading to stunted growth in plants

82
Q

how are plants damaged by magnesium deficiency

A

magnesium ions are needed to make chlorophyll, hence magnesium ion deficiency leads to chlorosis which is where leaves of the plant become yellow

83
Q

why is the understanding of ion deficiencies important

A

it allows horticulturists (people that cultivate plants) to provide optimum conditions for plants

84
Q

3 different types of plant defences

A

physical, chemical and mechanical responses

85
Q

physical plant defence responses

A
  • strong cellulose cell walls which act as a physical barrier against microorganisms
  • thick, tough waxy cuticle on leaves which stop their cells from becoming infected by bacteria and fungi
  • layers of dead cells around stems (bark on trees) which form a physical barrier against microorganisms and fall off
86
Q

chemical plant defence responses

A
  • many plants produce antibacterial chemicals which deter animals from consuming the plant
  • many plants produce poisons to deter herbivores
87
Q

mechanical plant defence adaptations

A
  • plants like roses have evolved specialised hardened cells which form large thorns to avoid being eaten
  • leaves which droop or curl when touched
  • mimicry to trick animals

bio spec (9 decks)

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