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Biology 6.1 > Bacteria and disease > Flashcards

Bacteria and disease Flashcards

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1
Q

What are pathogens

A

Microorganisms that cause disease

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2
Q

How can you investigate microorganisms even though they are small

A

By culturing them

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3
Q

What is culturing

A

Growing large numbers of the microorganisms so they can be measured in some way

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4
Q

What are the most cultured organisms

A

Bacteria and fungi

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5
Q

Why is important to take great care when culturing

A

There’s a risk a mutant strain can grow that may be pathogenic
there is a risk of contamination
When culturing a pure strain anything from the air will contaminate it

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6
Q

What are some health and safety precautions that must be followed when culturing

A

Making sure the equipment is sterile
Once the culture has grown it cannot leave the lab
Sterilize culture at 121 degrees got 15mins

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7
Q

What are the steps needed for culturing microorganism

A

1) Find microorganism you want to culture
2) Right nutrients to grow microorganisms (medium)
3) Introduce microorganism to medium
4) The sterile broth in the flask
5) Flsk is then stoppered again with cotton wool
6) Flask is incubated

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8
Q

What is the nutrient medium

What form does it come in

A

Usually nutrient agar

Can come in nutrient broth (nutrients in liquid) or solid form

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9
Q

What is agar

Why is agar useful

A

A jelly extracted from seaweed

It doesn’t melt until it is heated to 90 degrees

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10
Q

How are most microorganisms grown

A

Medium enriched in good protein such as blood yeast or meat

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11
Q

What is a selective medium

A

A medium in or on which only a select group of microorganisms with particular requirements will grow

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12
Q

What is a selective medium important for

A

Identifying the particular mutant strain of microorganisms and antibiotic resistance
Identifying microorganisms that have been genetically modified

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13
Q

What is inoculation

A

Getting bacteria onto your agar or into your broth

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14
Q

How do you get a pure culture

A

isolation is needed

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15
Q

How does isolation take place

A

1) Growing a culture under anaerobic conditions
2) Indicator media that cause certain types of bacteria to change color
3) Different nutrients to grow different microorganisms

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16
Q

How can bacteria or single-celled fungi cultured in a nutrient broth be counted

A

Using a microscope and haemocytometer

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17
Q

What is a haemocytometer

A

Consists of a specialised thick microscope slide with a rectangular chamber that holds a standard volume of liquid

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18
Q

Why is the sample of nutrient broth diluted with trypsin blue

A

The dye stains dead cells blue so you can identify them and count the living organisms

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19
Q

What does the corner of the haemocytometer have

A

Squares divided into 16 smaller squares

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20
Q

Why is the haemocytometer calibrated

A

So the number of bacterial and fungal cells in one set of 16 squares equates to the number of cells X10 to the ower of 4 of broth

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21
Q

What is turbidimetry

What happens

A

An alternative way of measuring the number of cells in culture (a specialized form of colorimetry)
As the number of bacterial cells in a culture increase, it becomes increasingly cloudy)

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22
Q

What does a colorimeter measure

A

How much light passes through a sample

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23
Q

How is a calibration curve produced

What does it help us measure

A

By growing a control culture and taking samples at regular time intervals
The number microorganisms using turbidimetry

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24
Q

What is diluting plating

What is used to find

A

Another way of counting microorganisms in a culture

used to find total viable cell count

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25
What is the technique dilution plating based on
The idea that each colony on an agar plate have grown from a single, viable microorganism on the plate
26
What happens if the number of colonies is multiplied by a dilution factor
Then the total viable count for the original sample can be determined
27
How can the accuracy of dilution plating after finding the mean measured
by using a haemocytometer to count the original culture
28
What is a simple way to assess the growth of a cultured fungi
To measure the diameter of the patches of mycelium
29
Explain the process if finding the growth of cultured fungi
1) Different petri dish at different temperature 2) measure the diameter of each fungal colony 3) The temperature that has resulted in the largest mean for growth is the optimum temperature
30
What is the generation time
The time between bacterial division
31
Do bacteria rapidly divide
Yes they always divide very quickly
32
Why do we use log to deal with bacteria
Because bacteria divide rapidly and log makes it easier to deal
33
How is log represented on the graph
Y-axis is in powers of 10 and x-axis is time/hrs
34
What is the exponential growth rate formula What does each stand for
``` K=log10Nt -log10N0 ---------------------------- log102 x t k=exponenyial growth rate Nt=no.of organs at time t No=No.of organisms at time 0 k = exponential growth rate constant t= the time the colony has been growing ```
35
What are the 4 stages for this growth curve
1. lag phase (When bacteria are adapted to their maximum environment and are not yet reproducing at their maximum rate) 2. log phase (When the rate of bacterial production is close to or at theoretical maximum) 3. stationary phase (As the no. of new cells formed by binary fission is equal t the no. of cells dying) 4. death phase (when reproduction has almost ceased)
36
Give two reasons why the exponential growth of bacteria doesn't continue
1) Reduction of nutrients available | 2) Build up of waste products
37
Give an example of some diseases caused by bacteria
Tonsillitis, tuberculosis, and pneumonia
38
What does understanding bacteria acts us agents of infections help us avoid
Infections and treat bacterial diseases effectively
39
What happens once pathogenetic bacteria gets into the body
They cause the signs and symptoms of disease in a number of ways
40
How do most bacteria make people sick
Through the toxins, they make as a by-product of their metabolism
41
What are toxic classified as
Endotoxins and Exotoxins
42
What are endotoxins
Endotoxins are lipopolysaccharides that are an integral part of the outer layer of the cell wall of Gram-negative bacteria
43
What acts as the toxin in Endotoxins
The lipid part of the lipopolysaccharides
44
What effect do endotoxins have | Whats the pathogenic effect
Have an effect around the site of infection by the bacteria. | The pathogenic effects produced are things such as diarrhoea, fever, and vomiting
45
What can antibiotics lead to
Further endotoxin release, due to the lipopolysaccharides component of the cell wall
46
How does the salmonella bacteria act
The bacteria invade the lining of the intestine and the endotoxins cause inflammation The cell no longer absorbs water so the faeces become liquid The gut then goes into spasms of peristalsis that results in diarrhoea
47
How is salmonella spp. spread
By ingestion of food and water contaminated with infected faeces
48
Where does the salmonella bacteria live
Live in the gut of many food animals and easily contaminates the meat
49
Why is salmonella rare in the UK
The chicken is vaccinated of the disease
50
Why are antibiotics useless for this disease
Even though it allows them to feel better it acts as a carrier for longer
51
How can salmonella be avoided
Cooking the meat thoroughly Washing hands after handling raw meat Washing hands after using the toilet
52
What are you Exotoxins
Are usually soluble proteins that are produced and released into the body by bacteria as they metabolise and reproduce in the cells of their hosts
53
How are exotoxins produced
Gram-positive and Gram-negative bacteria
54
Give examples of that some exotoxins do
Some damage cell-membrane causing cell breakdown internal bleeding competitive inhibitors to neurotransmitters Directly poison cells
55
When do Staphylococcus spp. cause disease
If they get inside the tissues of the body, if the skin flora is changed or if the person has a compromised immune system or has been receiving treatment such as chemotherapy
56
What kinda bacteria is Staphylococcus spp.
Gram-bacteria positive
57
What does s.aureus cause
Skin infections | Infections of the joints in septic arthritis
58
What do both s.aureus and s.epidermis cause
Bacterial meningitis
59
What are third-way bacteria acts as a pathogen
invading host tissues and damaging the cells
60
What are the bacteria that causes tuberculosis
Bacterium mycobacterium tuberculosis
61
How is Mycobacterium tuberculosis spread
By droplet infections
62
Whose more vulnerable to tuberculosis (TB)
People who are malnourished, ill or have problems with their immune system
63
How are people infected by Mycobacterium bovis
by drinking infected milk or living and working in close contact with cattle
64
What does TB affect
The respiratory system, damaging and destroying lung tissues suppresses the immune system making it less able to fight diseases
65
What are the well-known symptoms of coughing
Coughing up blood and weakness
66
What happens once the bacteria for tb is inhaled
It sits in the lungs and multiples
67
What is a tubercle
Localised inflammatory response forming a mass of tissue when the immune system is healthy
68
When does primary tb often take place
During childhood
69
What adaptation does Mycobacterium tuberculosis have
Enables it to avoid the immune system, allowing some bacteria to survive the primary infection stage
70
What are antibiotics
Medicines that either destroy microorganisms or prevent them from reproducing
71
What is the principle of selective toxicity
A principle in which all modern antimicrobial drugs work against microorganisms
72
What was the first successful antibiotic | Is it still used
Penicillin | Yes used globally
73
Why are antibiotics effective
They disrupt the biochemistry of the bacterial cells
74
What does bacteriostatic mean
The antibiotics used completely inhibits the growth of the microorganism
75
What is tetracycline
Used to cure acne
76
Give examples of a bacteriostatic antibiotic
respiratory tract infections and chlamydia
77
What does bactericidal
It means it'll destroy almost all the pathogens present
78
when are bactericidal used
To treat severe and dangerous diseases | Also used to treat infections where the immune system is suppressed
79
Give an example of bactericidal antibiotics | What does it treat
Penicillin | Used to treat skin infections, chest infections, and urinary tract infections
80
Which one out of bactericidal and bacteriostatic kills all bacteria What's the difference in percentage
Bacteriostatic 100% bacteriostatic 99% bactericidal
81
What factors does the effectiveness of antimicrobials depend on
1) Conc of the drug 2) PH 3) The susceptibility of the pathogen 4) Whether either the pathogen o the host tissue destroys the antibiotic
82
When is an antibiotic only effective
If the microorganisms have a binding site for the drug and metabolic process or biochemical pathway with which the antibiotic interferes
83
How does antibiotic resistance bacteria come about
By mutation to the antibiotic
84
What is MRSA
An example of a superbug
85
How can we reduce the number of antibiotic resistance
By using antibiotics sparely only when needed
86
Where are superbugs commonly found
Hospitals and care homes
87
What happens to patients that develop superbugs
They need to stay in hospital much longer
88
How are Staphylococcus infections cured
Treated very effectively with methicillin
89
What is Clostridium difficile
An anaerobic bacterium that is found in small numbers in the large intestine
90
When does Clostridium difficile cause problems
When an antibiotic that damages the gut flora
91
What are the rules that doctors have made to stop widespread of healthcare-associated diseases
1) Control the use of antibiotics 2) Hygiene measures 3) Isolation of patients 4) Prevention of infection coming into the hospital 5) Monitoring levels of healthcare-associated infections
92
What has happened ever since rules were put up about healthcare-associated diseases
There has been a decrease in the disease spread

Biology 6.1 (1 decks)

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