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Flashcards in Microbiology Deck (104)
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1
Q

What are the four main groups of microorganism?

A
  • bacteria
  • viruses
  • protozoa
  • fungi
2
Q

Which of the microorganisms are eukaryotes?

A
  • fungi
  • protozoa
3
Q

Which of the microorganisms are prokaryotes?

A
  • bacteria
4
Q

What are the features of bacteria?

A
  • prokaryotes / no true nucleus
  • contain cytoplasm
  • have flagellum (some)
  • DNA is in circular strand
  • peptidoglycan cell wall
  • lack of membrane-bound organelles
5
Q

What are the features of viruses?

A
  • non-living & acellular
  • protective shell called a capsid, contains genetic material
  • rely on the host to reproduce
  • very small, much smaller than bacteria
  • viral envelope surrounds capsid
  • shapes - helical, complex & polyhedron
6
Q

What are the features of fungi?

A
  • eukaryotic
  • disperse by producing spores
  • saprophytic
  • reproduce sexually and asexually
  • cell walls of chitin
  • form hyphae (multicellular)
    • many = mycelium
7
Q

What are the features of protozoa?

A
  • eukaryotic
  • unicellular
  • can reproduce asexually and sexually (think it’s mostly asexual)
  • heterotrophic
  • some have flagella
  • can be multinucleate
8
Q

What are the main differences between bacteria and viruses?

A
  • bacteria are larger
  • bacteria are prokaryotic cells, viruses are acellular
  • bacteria have a cell wall made of peptidoglycan or liposaccharide, viruses have a capsid
  • bacteria have ribosomes, viruses do not
  • bacteria reproduce asexually, viruses require a host cell
9
Q

What are the similarities between bacteria and viruses?

A
  • do not have a nucleus
    *
10
Q

Label the bacterial cell

A
11
Q

What is the structure of the bacterial cell wall?

A
  • contains peptidoglycan - made from polysaccharides cross-linked with unusual peptides
  • can be gram positive or gram negative
12
Q

What is the function of the bacterial cell wall?

A
  • great mechanical strength
  • responsible for strength, rigidity, shape
    *
13
Q

What is the structure of the bacterial plasma membrane?

A
  • phospholipid
    • phosphate heads
    • fatty acid chains
14
Q

What is the function of the bacterial plasma membrane?

A
  • selectively permeable
  • barrier
  • protective
  • controls metabolism of the cell
15
Q

What is the structure of the bacterial flagella?

A
  • long & thin
  • made of protein
  • attached to the cell through the cell wall & the membrane
  • could have one or many
16
Q

What is the function of the bacterial flagella?

A
  • movement
17
Q

What is the structure of the bacterial capsule?

A
  • capsule is located outside the cell wall
  • usually consists of polysaccharides
18
Q

What is the function of the bacterial capsule?

A
  • provide strength
  • protects against the body’s defences
  • increases resistance to disinfectants and antibiotics
19
Q

What is the structure of the bacterial pili?

A
  • thin rigid fiber
  • made of protein
  • protrudes from the bacterial cell surface
  • smaller than flagella
  • densely packed
20
Q

What is the function of the bacterial pili?

A
  • responsible for adhesion
  • allows bacteria to stick together to form clumps
  • stick to mucous membranes
  • allows to attach to human cells to spread disease
21
Q

What is the function of the bacterial cytoplasm?

A
  • where metabolism, and replication are carried out
22
Q

What is the structure of the bacterial cytoplasm?

A
  • viscous fluid
  • contains nuclear mass and ribosomes
23
Q

What is the structure of a bacterial inclusion?

A
  • numerous inclusion bodies, or granules, in the bacterial cytoplasm
  • never enclosed by a membrane
24
Q

What is the function of a bacterial inclusion?

A
  • storage vessels.
    • Glycogen is stored as a reserve of carbohydrate and energy.
25
Q

What is the structure of the bacterial mesosome?

A
  • Mesosomes or chondrioids are folded invaginations in the plasma membrane of bacteria
26
Q

What is the structure of the bacterial ribosomes?

A
  • two subunits
  • smaller than eukaryotic ribosomes
27
Q

What is the function of the bacterial ribosomes?

A
  • protein synthesis
28
Q

What is the structure of the bacterial nucleoid?

A
  • irregularly shaped region that contains all or most of the genetic material
  • not surrounded by a nuclear membrane
  • the genome of prokaryotic organisms generally is a circular double-stranded piece of DNA
29
Q

What is the function of the bacterial nucleoid?

A
  • contains genetic material
  • essential for controlling the activity of the cell and reproduction
  • where transcription and replication of DNA take place
30
Q

What is the difference between gram positive and gram negative bacteria?

A
  • gram negative cell wall contains lipoproteins - give the wall greater strength compared to gram positive.
31
Q

What occurs during binary fission?

A
  1. bacterial cell elongates
  2. bacteria replicates its DNA
  3. cell membrane/envelope then pinches inwards around the DNA
  4. cell membrane meets in the middle
  5. divide is formed, two distinct cells can be seen
  6. cells separate to form two separate cells
32
Q

Is binary fission sexual or asexual?

A

asexual

33
Q

How do viruses reproduce?

A
  • attachment - virus binds to a specific receptor on the host cell surface
  • penetration - the viral nucleic acid enters the cell
  • synthesis of new components - viral nucleic acid takes control of the cell metabolism stopping the cells normal nucleic acid and protein synthesis. Viral nucleic acid is replicated using nucleotides from the host cell. Protein coats are manufactured using amino acids of the host cell.
  • assembly - whole virus particles are made when the nucleic acids are surrounded by the protein coats
  • release - many viral particles are released when the cell bursts open (lysis) or by slow leakage
34
Q

Label a growth curve

A
35
Q

What occurs during the lag phase of a growth curve?

A
  • slow growth due to time and lack of energy
36
Q

What occurs during the log phase of a growth curve?

A
  • exponential growth
  • lots of nutrient medium
  • more cells = more replication = more cells…
37
Q

What occurs during the stationary phase of a growth curve?

A
  • number of living = number of dying
  • nutrients being depleted, toxic products beginning to accumulate
38
Q

What occurs during the death phase of a growth curve?

A
  • more dying than viable
39
Q

What factors affect the growth of bacteria?

A
  • nutritional factors
  • temperature
  • pH
  • oxygen concentration
  • osmotic requirements
40
Q

What elements are required for nutrition for bacterial growth?

A
  • nitrogen - for amino acids (proteins)
  • carbon - main constituent of cellular material
  • potassium - required for chemical reactions within the cell
  • magnesium - for chemical reactions
  • calcium - for chemical reactions & for endospore production
41
Q

What are organisms who obtain their energy from light called?

A

Phototrophs

42
Q

What are bacterial pigments?

A
  • some bacteria produce pigments during growth
  • gives colonies characteristic colour
  • might give some bacteria some protection from effects of sunlight
43
Q

What are bacteria who obtain their energy source from an organic form of carbon called?

A

Heterotrophs

44
Q

What are bacteria who obtain their source of energy from inorganic compounds called?

A

Lithotrophs

45
Q

What are species who thrive in temperatures between 1-25oC (optimum=<20oC) called?

A

Psychrophiles

46
Q

What are species who thrive in temperatures between 20-45oC (optimum= 25-37oC) called?

A

Mesophiles

47
Q

What are species who thrive in temperatures betweem 45-65oC (optimum=55-65oC) called?

A

Thermophiles

48
Q

What is the optimum growth range of acidophiles?

A

1 - 5.5

49
Q

What is the optimum growth range for neutrophiles?

A

5.5-8

50
Q

What is the optimum growth range of alkalophiles?

A

8.5 - 11.5

51
Q

What do fungi produce spores for?

A

Fungi produce spores for reproduction.

52
Q

What do bacteria produce spores for?

A

Bacteria produce spores for protection.

53
Q

What does a culture media provide?

A

A culture media provides the ideal conditions for organisms to grow. It provides the nutritional needs of the organism.

54
Q

What are culture media used for?

A
  • growth of microorganisms
  • identification
  • transport of specimens
55
Q

What are the different types of culture medium?

A
  • selective
  • differential
  • enriched
56
Q

Give an example of enriched medium.

A

Tryptone soy agar (TSA)

57
Q

What is the purpose of an enriched medium?

A
  • specially fortified to encourage lots of growth
58
Q

Give an example of selective medium.

A

mannitol salt agar (MSA).

  • used to isolate pathogenic staphylococci
  • contains 7.5% NaCl - inhibits growth of most bacteria
  • fermentation of agar by staphylococci produces area of yellow
59
Q

What is the purpose of selective mediums?

A

used to isolate and identify. Allows certain types of organisms to grow and inhibits the growth of others.

60
Q

Give an example of differential medium.

A

Eosin Methylene Blue Agar (EMB agar).

Used to differntiate between organisms that ferment lactose and those that do not.

61
Q

What is the purpose of differential mediums?

A

differential mediums are used to differentiate different microorganisms. Contain a dye or chemical that will produce characteristic changes which are used to identify.

62
Q

What are the advantages of using a liquid media?

A
  • useful for growing batch cultures
63
Q

What are the disadvantages of using a liquid medium?

A
  • hazardous - more likely to spill
  • not easy to count colonies of an organism
64
Q

What are the advantages of using a solid medium?

A
  • enables growth of clear colonies
  • easier to count colonies
  • can observe colony growth and characteristics amd use this information to identify organisms
  • solid media can be selective or differential, which means that solid medium can grow/identify specific organisms or differentiate between two closely related organisms
65
Q

What are the disadvantages of using a solid medium?

A
  • not very good at producing batch cultures
66
Q

What are different ways we can carry out microbial monitoring?

A
  • settle plates
  • contact plates and swabs
  • active air sampling
  • finger dabs
67
Q

Which media should be present in the agar for settle plates?

A

Tryptone soy agar (TSA) for total count & Sabouraud dextrose agar (sabs) for yeasts and moulds

68
Q

Where are contact plates used?

A

Contact plates are recommended to be used on flat accessible surfaces

69
Q

Where should surface swabs be used?

A

Surface swabs should be used when a surface isn’t flat and accessible.

70
Q

When are finger dabs performed?

A

Finger dabs are performed at the end of the session.

71
Q

What are characteristics of a desirable disinfectant?

A
  • cost
  • effective on pathogen + on surface
  • smells nice
  • colour
  • availability
72
Q

What are some different chemical agents for disinfecting?

A
  • phenols
  • halogens
  • alcohols
  • quaternary ammonium compounds
73
Q

What are the advantages of using phenols?

A
  • work by denaturing proteins and disrupting membranes
  • are tuberculocidal
  • remain on surfaces long after application
74
Q

What are the disadvantages of using phenol disinfectants?

A
  • hexachlorphene can cause brain damage
    • only used in staphylococcal outbreaks in hospital nurseries
  • unpleasant odour
  • can cause skin irritation
75
Q

TRUE or FALSE

Alcohol is bactericidal and fungicidal?

A

TRUE!

Alcohol is bactericidal and fungicidal,

it is NOT sporicidal.

76
Q

How do alcohol disinfectants work?

A

Alcohol denatures proteins and also possibly dissolves membrane lipids

77
Q

Which are the two most important anti-microbial halogens?

A

Chlorine and iodine

78
Q

What is iodine used for?

A

Iodine is used as a skin antiseptic and kills by oxidising cell constituents.

79
Q

What are the disadvantages of iodine?

A
  • may damage the skin
  • stains the skin
  • iodine allergies may result
80
Q

What is an improved version of iodine?

A

Iodophor is iodine complexed with an organic carrier. Releases iodine slowly to minimise skin burns and irritation.

81
Q

What does chlorine kill?

A

Chlorine destroys bacteria and fungi but not spores.

82
Q

What is quaternary ammonium compound?

A

Quaternary ammonium compound is a detergent

83
Q

What are the advantages of detergents?

A
  • stable
  • non-toxic
84
Q

What are the disadvantages of detergents?

A
  • inactivated by hard water and soap
85
Q

Define sterility

A

Sterility is the total absence of viable organisms in an absolute state. In pharmacy achieved by aseptic technique or terminal sterilisation

86
Q

Define sterilisation

A

the process that products are subjected to whereby all viable organisms are killed or removed.

87
Q

Define aseptic technique

A

Aseptic technique means preparing products from sterile starting materials whilst using procedures that prevent the access of viable organisms into the product.

88
Q

What are the methods of sterilisation?

A
  • moist heat sterilisation in autoclaves
  • dry heat sterilisation
  • sterilisation by filtration
  • gaseous sterilisation
  • sterilisation by radiation
89
Q

What is the process of moist heat sterilisation in autoclaves?

A
  • 121oC for 15 minutes
  • pressure of 15lbs
90
Q

What is the process of dry heat sterilisation?

A
  • 180oC for at least 30 minutes
  • 170oC for at least 1 hour
  • 160oC for at least 2 hours
91
Q

What is a host?

A

an organism that supports the growth of another organism

92
Q

What are the features of normal flora?

A
  • do not harm us
  • do not cause disease
  • large numbers within the body
  • perform tasks essential for human survival
93
Q

Define a pathogen

A

A pathogen is a microorganism capable of causing disease

94
Q

What is an opportunistic pathogen?

A
  • generally harmless in normal environment
  • can be pathogenic in immunocompromised host
95
Q

What is an obligate pathogen?

A
  • depend on hosts for key nutrients but live outside host cells
  • to be transmitted must cause disease
96
Q

What is the infectious disease cycle?

A

pathogen

source

transmission

susceptibility

exit

97
Q

What is an active carrier?

A

An active carrier is diagnosed with the disease

98
Q

What is a convalescent carrier?

A

recovered from the disease but still harbors pathogen

99
Q

What is a healthy carrier?

A

harbors pathogen, asymptomatic (typhoid Mary)

100
Q

What is an incubatory carrier?

A

Incubates pathogen, not yet ill

101
Q

Which ways can pathogens be transmitted?

A
  • airborne
  • contact
  • vehicle
  • vector-borne
102
Q

What is vehicle transmission?

A

vehicle is an inanimate object. Spreads the pathogen but is not responsible for the reproduction of it.

103
Q

What is vector-borne transmission?

A

refers to living transmitters. Pathogen can exist on either the inside or the outside of the vector.

104
Q
A