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yr 1 uni work > 121 > Flashcards

121 Flashcards

1
Q

pros of microbes on food

A

food materials may require microbiologival activity such as yogurt

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2
Q

cons of microbes in food

A

food spoilage
food borne disease

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3
Q

why dont we know the true diversity of sample by culture

A

as we cannot culture all bacteria from a sample

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4
Q

3 domains of life

A

euksryotes
archea
bacteria

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4
Q

eukaryote

A

include fungi,animals,plants
an organism that consists of one or more cells each of which has a nucleus and other well developed compartments

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5
Q

bacteria

A

constitute a large domain of prokarytotic microorganisms
range from spheres to rods and sprirals

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6
Q

archaea

A

similar to bacteria in size
intermediate between bacteria and eukaryotes

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7
Q

archea characteristics

A

presence of tRNA and ribosomal RNAs
peptidoglycan cell walls
linked lipids built from phytanyl chains
occur in unusual habitats

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8
Q

virus size

A

0.01-0.2 um

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9
Q

bacteria size

A

0.2-5 um

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10
Q

eukaryotes size

A

5-100um

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11
Q

yeast size

A

5-10um

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12
Q

protists size

A

50-1000um

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13
Q

algae size

A

10-100um

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14
Q

cell volume importance

A

high SA:V of smaller cells leads to fast nutrient exchange
smaller cells = faster growth
lots of cells=mutation risk

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15
Q

barrier function

A

separation of cell from its environment

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16
Q

selectively permeable barrier

A

controls movements of molecules in or out a cells (transport proteins)

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17
Q

functions of bacterial cell membrane

A

barrier function
selectively permable membrane
site of respiration/photosynthesis
energy conservation(proton motive force)

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18
Q

diplococci

A

2 cells in line

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19
Q

streptococci

A

chain of cells

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20
Q

clump of cocci

A

clumps of cells

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21
Q

gram stain

A

stain with crystal violet
add iodine forms a complex
wash with ethanol
counterstain with safranin

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22
Q

why does lysozyme lyse and penicillin kill archaea

A

lack peptidoglycan , have variety of cell walls including ppseudo-peptidoglycan

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23
Q

gram + cell wall

A

almost 90% peptidoglycan - thick layer- with a cytoplasmic membrane layer as well on the inside. many have teichoic acids embedded. negatively charged so surface is negative so can bind to divalanet cations like mg and ca

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24
Q

gram- cell wall

A

thin layer of peptidoglycan surrounded by an outer membrane composed of lipids, proteins and lipopolysaccharides and porins . only 10% peptidoglycan

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25
Q

peptidoglycan structure

A

only found in bacteria
rigid layer glycan strands linked by glycosidic bonds. crosslinked strands by peptides.
lysozymes break G-M bonds bursting the cell

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26
Q

fimbriae

A

short, thin, hair like, proteinaceous appendages ( up to 1000/cell)
recognition and attachment to surfacs

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27
Q

pili

A

similar to fimbriae except onger thicker and less numerous (1/10), required for mating

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28
Q

polar flagellum

A

flagellum at end of cell

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29
Q

monotricheous

A

1 flagellum

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30
Q

amphitrichous

A

1 flagellum at each on of cell

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31
Q

lophotrichous

A

cluster of flagella at 1 or both ends

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32
Q

peritrichous

A

flagellum spread over entire surface of cell x

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33
Q

bacterial cytoplasm

A

contains ribosomes and nucleoid, cellular inclusions sometimes, macromolecules( rna, proteins), organic materials eg carbs + lipids
inorganic ions

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34
Q

the nucleoid in bacteria

A

irregularly shaped region, is location of singular chromosome or sometimes 2

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35
Q

plasmids

A

usually small closed circular dna molecules
exist and replicate independently of chromosome
not required for growth and reproduction
may carry genes that confer selective advantage eg drug resistance

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36
Q

cellular inclusions

A

granules of organic or inorganic material that are reserved for future use
may contain:
glycogen
poly-b-hydroxybutyrate (PHB)
polyphosphate granules
sulpher granules

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37
Q

cellular inclusions magnetism

A

specialist bacteria with magnetosomes
contain iron in form of magnetite
use is to orient cells in magnetic fields

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38
Q

gas vesicles- cellular inclusions

A

used for buoyancy in some aquatic bacteria

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39
Q

advantages of endospores

A

survive 100-1000 years- produced under unfavourable conditions
highly resistible to heat, drying. radiation and chemicals very low water content
contain calcium dipicolinate
special proteins protect dna

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40
Q

calcium dipicolinate

A

binds free water and helps dehydrate cell

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41
Q

halophillic bacteria

A

250 million year old crystal salt

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42
Q

culture media definition

A

nutrient solution that provide all the elements required for growth

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43
Q

chemically defined media

A

the exact chemical composition is known

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44
Q

complex media

A

exact chemical composition not known made of digests fo complex material such as milk protein beef yeast etc

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45
Q

binary fission

A

how bacterial cell divides into 2
dna replication
cell elongation
septum formation

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46
Q

doubling time/generation time

A

time needed for a population to double
exponential growth

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47
Q

batch culture

A

culture that is grown in a closed system, no additional nutrients are added and no waste products removed during culture period

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48
Q

lag phase in bacterial population

A

time interval between inoculation and maximal division rate ( cells adjusting to new environment )

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49
Q

log phase in bacterial growth

A

bacteria growing exponentially , constant doubling, maximum growth rate

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50
Q

stationary phase in bacteria growth curve

A

bacteria no longer reproduces but are still alive , no nutrients left…

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51
Q

viable but nonculturable bacteria

A

bacteria in a very low metabolic activity state where they dont divide but are alive and have the ability to become culturable once resuscitated
(or they just cant grow on conventionalble media )

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52
Q

total count

A

non specific dye that stains all bacteria , in most cases dead cells too

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53
Q

viable count

A

uses fluorescent activity dyes which counts all cells with activity

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54
Q

culturable count

A

count cells that can form colonies on solid media or increase turbidity in liquid media

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55
Q

advantages of total cell count

A

easy and fast

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56
Q

disadvantages of total cell count

A

uses special microscope counting slide
does not differentiate between live and dead bacteria

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57
Q

heterotrophs

A

require organic molecules made by other organisms

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58
Q

autotrophs

A

co2 is principal carbon source

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59
Q

phototrophs

A

use light as energy sourve to produce atp

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60
Q

chemotrophs

A

oxidise organic or inorganic compounds

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61
Q

where do obligate aerobes grow

A

need o2 for growth so grow close to top of test tube

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62
Q

abligate anaerobes

A

cannot grow in presence of o2 so grow at bottom of a test tueb

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63
Q

facultative anaerobes

A

can grow with and without o2

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64
Q

aerotolerant anaerobes

A

do not need o2 but can tolerate it

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65
Q

microaerophillic

A

need o2 but tolerate it at a low concentration

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66
Q

mesophile

A

grow best between 20-40 degrees
most bacteria in our body are these

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67
Q

thermophiles

A

grow bet between 45-80 degrees
live in hot springs compost heaps etc

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68
Q

hyperthermophiles

A

grow best above 80 degrees
live in hot springs

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69
Q

facultative aerobe

A

not required but grows better with oxygen

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70
Q

a useful enzyme produced by thermophilic bacteria

A

taq polymerase from thermus aquaticus used for pcr

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71
Q

histology

A

study of animal and plant tissues

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72
Q

cytology

A

study of cells under microscope

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73
Q

light microscope mag res ect

A

x1000 magnification
200 nm resolution
brightfield
phase-contrast
fluorescent

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74
Q

electron microscope

A

1 x 10^6
resolution down to 0.2nm
scanning EM
transmission EM

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75
Q

resolution

A

separation distance at which 2 objects in an image can be apart and still distinguished as separate

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76
Q

whats a host

A

organisms that supports growth of viruses, bacteria and parasites

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77
Q

pathogen

A

organism that causes disease, by impairing or interfering with the normal physiological activities of the host

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78
Q

pathogenicity

A

the ability to cause disease

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79
Q

virulence

A

the degree or intensity of pathogenicity (determined by toxicity and invasiveness)

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80
Q

infection

A

bacteria persist in host without necassarily causing tissue damage

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81
Q

disease

A

overt damage to the host, parts of body cannot fulfill their normal function

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82
Q

why did miasma theory sometime works

A

it was based on theory of bad smells causing disease so lots of cleaning and diverting of sewage was done and it prevented cholera. Dr. William Farr was convinced by this theory and that cholera was transmitted by air

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83
Q

robert koch

A

1843-1910
established germ theory
tried to prove specific microorganisms caused disease (kochs postulates)
developed simple methods for obtaining disease in pure culture

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84
Q

kochs postulates

A

infecting mice or collecting microorganisms from dead animals
led to discovery of causes for anthrax, TB and cholera

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85
Q

opportunistic pathogens

A

only cause serious disease when host defences are impaired
e.g. pseudomonas aeruginosa
often exist in envrionment

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86
Q

primary pathogens (obligate)

A

capable of causign diseae in absence of immune defects
e.g. syphilis- treponema pallidum
need to cause disease to survive
human-human and animal-human transmission

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87
Q

reservoirs

A

bacterial pathogens need at least 1 reservoir
such as other humans, animals and environment

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88
Q

reservoir examples for anthrax

A

agent= bacillus anthracis
reservoir in livestock and soil

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89
Q

reservoirs examples for legionnaires disease

A

agent= legionella pneumophila
reservoir in high moisture environments like air con

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90
Q

direct host-host transmission

A

airborne= aerosols like coughing
body contact like kissing and touching

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91
Q

indirect host-host transmission

A

vector-borne- living organisms like arthropods(insects,tics), vertebrates (rats,dogs)
non living- food, water, soil, fork, bedding, surgery instruments

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92
Q

colonisation

A

establishment of a stable population of bacteria in the host
body naturaly has this- microflora
pathogen must be able to compete for nutrients/surface attachment sites

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93
Q

why do bacteria adhere to tings

A

to overcome flushing mechanisms
e.g. streptococci to tooth surface and staphylococci to plastic catheters

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94
Q

how do bacteria adhere to things

A

association- involves non-specific forces like charges/ hydrophobicity
then adhesion- specfic host receptors. can form biofilm from aggregation which can disperse and spread

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95
Q

adhesions

A

fimbriae and pili
capsules and slime layer
flagella
(lipo) teichoic acids (gram+)

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96
Q

host receptors for adhesion include

A

blood group antigens
extracellular matric proteins e.g. fibronectin, collagen

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97
Q

invasion of bacteria

A

some bacteria penetrate through/between cells
some invade epithelial and some invade phagocytic cells

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98
Q

invasion of bacteria using lytic compounds

A

often accomplished by lytic compounds that attack the host tissue
e.g. collagenase
also determined by evasion of host defences

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99
Q

invasins

A

virulence factors

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100
Q

resisting phagocytosis

A

bacteri produce structures preventing effective contact. capsules, special surface proteins

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101
Q

bacteria surviving inside phagocytic cells

A

often very pathogenic bacteria

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102
Q

antibody avoidence

A

capsules
antigenic variation- switch between different types of surface structure
sometime degradation of antibodies

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103
Q

avoidance of complement

A

capsules can prevent complement activation
lipopolysaccharides (gram - ) sometimes hinder pore formation

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104
Q

how does tissue damage occur

A

irone acquisition
direct effect of bacterial toxins
indirect effects of bacterial toxins
induction of autoimmune response

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105
Q

nutrient acquisition- iron uptake

A

essential element for bacteria growth
bacteria express high affinity iron uptake systems to get the iron as iron levels too low in tissues
siderophores- bind iron with high affinity
direct binding of iron transport proteins like transferrin

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106
Q

exotoxin

A

act on specific targets e.g. protein synthesis
made by gram + and -
protein
secreted by living bacteria
heat labile
highly immunogenic
potential lethal

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107
Q

endotoxins

A

(LPS) bound to cell
action is indirect- activates many host systems that cause damage
made by gram-
lipopolysaccharide
part of cell membrane
heat stable
weakly immunogenic
lethal at high concs

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108
Q

human exposure to exotoxins

A

ingestion of preformed exotosin e.g. food poisoning

colonisation of mucosal surface or tissue like cholera

colonisation of wound- e.g. clostridium perfringens grows in wounds or abscess causing tissue degradation

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109
Q

whys is called endotoxin

A

as they are bound to cells and released when bacterium lyses or during cell growth
activates host systems leading to fever, shock, blood coagulation, inflammation

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110
Q

prokaryotes in summary

A

circular chromosome with plasmids
fimbria adhesion
capsule adhesion/evasion
no nucleus
no membrane enclosed organelles
rapid reproduction
binary fission
benefit or harm- mutualist, commensal, pathogen

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111
Q

3 domains of protists

A

prokaryotes- bacteria and archaea
eukaryotes- eukarya

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112
Q

4 eukaryote supergroups

A

excavata
SAR
archaeplastida
unikonta

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113
Q

ER simple

A

protein glycosylation
membrane factory
lipid synthesis

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114
Q

photoautotrophic

A

‘plastids’
green plastid= chloroplast
photosynthesis
algae- some have a cell wall

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115
Q

heterotrophic protists

A

feed on bacteria, fungi, and other protists
termed protozoa- non have cell wall

116
Q

mixotrophic

A

do both photoautotrophic and heterotrophic
non have a cell wall

117
Q

direct microscopic count- viewing protist cells

A

easy and fast
however uses special microscope counting slide
and does not differentiate between live and dead
known as total cell count
need to fix motile cells beforehand

118
Q

protists divide by what

119
Q

doubling time for protists

A

hours/days at 37 degree

120
Q

protist daughter cells

A

genetically identical but may vary in other components

121
Q

lag time - protist

A

time interval between inoculation and maximal division rate- cells adjust to new environment

122
Q

log phase- protists

A

constant doubling time
growth rate is maximal

123
Q

stationary phase- protists

A

can no longer reproduce but are still alive

124
Q

death phase- protist

A

death or cyst formation

125
Q

advantages of cyst

A

-Produced under unfavourable conditions
-Highly resistant to heat, drying & radiation
-Very low water content
-Can survive for 20 years in the environment
-Good resistance to antibiotics/disinfectants
-Effective dispersal mechanism
Can be transmitted to others via faeces

126
Q

where are cell walls always present in protists

A

non- motile photosynthetic protists
cysts

127
Q

cell walls are not present in what protists

A

motile photosynthetic protists
heterotrophic protists
mixotrophic protists
need to overcome osmosis

128
Q

obligate aerobes- o2

A

need o2 for growth
so top of tube

129
Q

obligate anaerobes - o2

A

cannot grow in presence of o2
so bottom of tube

130
Q

faculatative anaerobes - o2

A

can grow with and without o2
so spread out tube but collected at top slighlty

131
Q

aerotolerant anaerobes- o2

A

do not need o2 but tolerate it
spread evenly through tube

132
Q

microaerophilic - o2

A

need o2 but tolerate is only at low concentration
collected just under top of surface of tube

133
Q

endosymbiont theory

A

-For mitochondria and plastids
-Bacteria originally living as endosymbiont in cells
-Dependency then became permanent
-Alpha-proteobacterium became a mitochondrion
Hydrogenosome evolved from a mitochondrion
-Cyanobacterium became a chloroplast

134
Q

evidence for endosymbiont theory

A
  • size of organelle= size of bacterium
  • phylogeny analysis relates their DNA to their bacterial origin
  • have own circular DNA and replicate by binary fission
  • contain same ribosomes as bacteria
  • have double membrane- engulfing mechanism
135
Q

organellar mixotrophy

A
  • selective digestion
    -eat algal cells
  • doesnt digest plastids (kleptoplastids)
    -plastids fix co2
    -plastids do not encode for polymerases
    -die and need replenishing so eats more
    protists can live without the plastids
136
Q

cellular mixotrophy

A
  • no digestion
  • eats algal cells
  • no digestion of algae
    -algae fix co2
    -algae divide in cell
  • endosymbiosis
  • protists can live without the algae
137
Q

constitutive mixotrophs

A
  • algae evolve into organelles
  • over time
  • through complicated genetic transfer events
  • endosymbiotic algae become true organelles
    -protists cannot live without them
  • only seen in flagellates
138
Q

organellar mixotrophy seen in

A

ciliates and amoebae

139
Q

cellular mixotrophy seen in

A

ciliates and amoebae

140
Q

constitutive mixotrophy seen in

A

flagellates

141
Q

mixotrophy feeding vs photosynthesis

A

high light- photosynthesis> feeding
low light- feeding > photosynthesis

142
Q

whats the most developed protozoan

143
Q

ciliates mouth and anus

A

cytostome- mouth
cytoproct- anus

144
Q

2 types of nucleus and ciliate

A

macronucleus and micronuclei

145
Q

cilia

A

microtubule-based hair-like organelles
free swimming
usually attached (sessile)

146
Q

motile cilia

A

9+2 dynein motor protein
ciliates
human- bronchia; and oviduct epithelium

147
Q

non-motile cilium

A

9+0 no dynein motor protein
primary cilium on all human cells

148
Q

what do some cilia fuse to form

149
Q

what are cilia used for

A

movement
feeding- direct prey to mouth
sieve
filter feeding
cytostome contains stiffer cilia

150
Q

vorticella

A

prey drawn towards cell
vortex at cell mouth
very large feeding currents
no swimming so use cilia only for feeding
looks like a moon cup

151
Q

suctorian ciliates

A

exception to rule
numerous microtubule tentacles
each tentacle ends with a cytostome
extrusomes- secrete toxins
dissolve prey contents and suck out
raptorial feeding
can look like dandelions

152
Q

mixotrophic ciliates

A

do not contain their own plastids
acquire photoautotrophic ability 2 ways:
- organellar mixotrophy
- cellular mixotrophy

153
Q

do ciliates reproduce asexually or sexually?

A

both
asexual- transverse binary fission, involves mitosis
sexual- conjugation, involves mitosis an meiosis, micronuclei swap, allows for genetic variation

154
Q

are flagellum in flagellates forwards and backwards

A

no
they are propeller like motion (9+2)

155
Q

where are flagellates found in humans

156
Q

do flagellates possess macronucleus

A

yes this only

157
Q

how do flagellates divide

A

longitudinal binary fission

158
Q

flagellates are mainly anaerobic true or false

A

false they are mainly aerobic

159
Q

how do flagellates feed

A

heterotrophy
photoautotrophy
mixotrophy

160
Q

heterotrophic flagellates

A

mostly aerobic
consume pre-formed organic carbon
organic carbon (sugar) to inorganic carbon (co2)
use flagella for movement
raptorial feed and filter feeding

161
Q

hispid flagellum

A

hair = hispid
swim backwards kinda

162
Q

raptorial feeding with hispid flagellum

A

create feeding current when moving flagellar
prey is drawn to base of flagellum
ingested via cytoplasmic extensions (pseudopodia)

163
Q

raptorial feeding with naked flagellum

A

created currents due to flagellar movement
less contact with the base of the flagellum
less efficient capture pray cause they are swimming headfirst into prey not tail first

164
Q

increasing prey capture with naked flagellum

A

filter feeding
collar of tentacles (microvilli)
contain actin- contractile

165
Q

choanoflagellates

A

only group with a collar of tentacles
all have single naked flagellum
attach to surface by stalk
more closely related to animals than other protists

166
Q

photoautotrophic flagellates

A
  • also called phytoflagellate
    own plastids- green/golden
    photosynthesise
    inorganic carbon (co2) to organic carbon (glucose)
    all are aerobic
    use flagella for movement towards light and nutrients
167
Q

euglena - photoreception

A

eyespot/stigmas- organelle containing carotenoid lipid globules. shading device for photoreceptors to detect light direction

168
Q

mixotrophic flagellates

A

phytoflagellates that eat
constitutive mixotrophy- have own plastids
all aerobic
can ingest prey - raptorial
use flagella for movement and prey capture
one type of feeding is normally over-riding
depends on the genus and light climate

169
Q

mixotrophic flagellates as solitary cells

A

ochromonas
few plastids
prefers to feed on prey

170
Q

mixotrophic flagellates and colonys

A

some form colonys
dinobryon
plastids dominate cell
prefer to photosynthesise

171
Q

amoebae nucleus

A

one macronucleus

172
Q

are amoebae anaerobic or aerobic

173
Q

most amoebae or mixotrophic t/f

A

false - most are heterotrophic and some are mixotrophic

174
Q

amoebae reproduce asexually t/f

175
Q

whats the most publicised protozoan

176
Q

all amoebae are stationary t/f

A

false
some move but some are stationary

177
Q

naked amoebae- how they move and what do they produce

A

amoebae proteus
move by cytoplasmic streaming
produce pseudopodia on surfaces

178
Q

how do naked amoebae feed

A

feed by direct interception of prey
raptorial feeding
no specific location for ingestion- can be anywhere

179
Q

3 cell forms of naked amoebae

A

trophozoites- feeding form
cysts- produce resting phase
floating form- stiffened pseudopodia for dispersal

180
Q

shelled amoebae

A

enclosed in shell
can be made of anything- the shell
intrashellular cytoplasm within shell
project extrashellular cytoplasm to move/ feed
raptorial or diffusion feeding
can produce cysts

181
Q

testate amoebae

A

freshwater, marine and terrestrial
rapotiral

182
Q

foraminiferans

A

marine only
CaCO3 tests
diffusion feeding

183
Q

diffusion feeding

A

stationary predator captures prey with sticky extrashellular cytoplasm (axopodia)

184
Q

radiolarians

A

marine only
silica tests
diffusion feeding

185
Q

heliozoans

A

freshwater
silica tests
diffusion

186
Q

good ecological impacts of protists

A
  • all of the protists
    microbes- base of every food chain
    keep bacterial populations healthy
    important in nutirent cycling
187
Q

bad ecological impact of protists

A

mainly amoebae
allow evolution of new bacterial pathogens
act as a reservoir for them too

188
Q

what does predation stop bacteria from reaching

A

the stationary phase
keeping bacteria in log phase

189
Q

what ratio to protists have to keep their cellular C:N:P

A

50:10:
co2, nh4, po4

190
Q

what % of human cells are bacterial

191
Q

what protist is naturally present in humans

A

amoebae- entamoeba coli
exists in gut- not pathogenic

192
Q

gut infections caused by what protists examples

A

amoebae- entamoeba histolytica
one ciliate- balantidium coli
flagellates- giardia lamblia
cause dysentery and produce cysts
reservoir- water and animals/humans
transport- water, faecal-oral
treatable- takes months due to cysts

193
Q

eye infection caused by protists

A

amoebae- genus acanthamoeba
causes keratitis
reservoir- water
transport- dirty contact lenses
treatable but can lead to glaucoma

194
Q

brain infection caused by protists

A

amoeba- naegleria fowleri
primary amoebic meningoencephalitis (PAM)
reservoir- warm water
unusual flagellate stage
transmission- up nose
fatal within 2 weeks

195
Q

STDs caused by protists

A

trichomonas vaginalis
anaerobic, no cysts
infects urethra, vagina, prostate
reservoir- humans
males asymptomatic
transmission- sexual intercourse
treatable

196
Q

blood/tissue infections caused by protists

A

flagellates e.g leishmania mexicana
aerobic, no cysts
reservoir- dogs
transmission- sand fly
attacks tissues e.g. liver
cutaneous- infects macrophages
treatable

197
Q

whats a virus

A

simple
miniscule infectious
obligate
intracellular
parasite comprising of genetic material surrounded by protein coat or envelope derived from host cell membrane

198
Q

average size of viruses

A

20-300nm
can be seen with an electron microscope

199
Q

giant viruses- mimiviruses

A

750nm
bigger than bacteria
seen under light microscope

200
Q

pandoravirus

A

> 1000nm in length
biggest known virus
2.9megabyte genome
enclosed 2556 genes
only infect amoeba

201
Q

2 phases of a virus

A

extracellular virion (outside host cell)- for transmission
intracellular virus (after infecting host cell)- for replication

202
Q

whats viral replication

A

the formation of biological viruses during the infection process in the target host cell

203
Q

what is bacterial multiplication

A

the asexual reproduction or cell division of a bacterium into 2 daughter cells by binary fission

204
Q

virion

A

virus particle

205
Q

virus nucleocapsid

A

capsid- protein coat, made up of many proteins, subunits= capsomers
nucleic acid (DNA or RNA)

206
Q

helical capsomers

A

bond together in a spiral fashion

207
Q

polyhedral capsomers

A

capsi is roughly spherical. icosahedran symmetric carry 20 faces and 12 corners

208
Q

binal (complex) capsomer

A

neither helical or polyhedral. have irregular shapes or have complex structures. may have both helical and isometric symmetries

209
Q

function of capsid

A
  • protects the nucleic acid from enzyme digestion
  • special sites that allow virion to attach to host cell
  • proteins that enable virion to penetrate the host cell membrane
210
Q

groups of organisms that can be infected by viruses

A

bacteria
protozoa
algae
fungi
plants
animals
viruses- virophages

211
Q

whats a bacteriophage

A

viruses of bacteria
a particle weights a femtogram (10^-15)
10^30 bacteriophage particles in worlds water
biomass of bacteriophages outweighs elephants by 1000fold

212
Q

bacteriophage genome

A

only a few with envelopes
most have dsDNA
many are complex

213
Q

replication steps of lytic bacteriophage T4 (6 steps)

A

adhesion
penetration
replication
maturation
release
reinfection`

214
Q

Bacteriophage T4 is virulent and kills the host: it is a lytic phage. t/f

215
Q

Many bacteriophages have an alternative life cycle where they don’t kill the host: temperate phages or lysogenic phages. t/f

216
Q

prophage- bacteriophages

A

genome of temperaete phage integrates into host chromosome and becomes prophage.
produces a repressor protein which blocks lytic genes
also replicates with host chromosome- lysogeny or lysogenic cycle
immune against infection of same phage because of repressor

217
Q

Stresses (UV light, toxin) initiate induction to resume lytic cycle
t/f

218
Q

use of phages in biomedicine

A

EBI- listeria bacteriophage - on unprocessed foods like cheese, meats and fish

a bacteriophage enzyme detects and kills bacillus anthracis spores

biomarkers for disease

as delivery vectors

disease therapy

219
Q

what are some viruses named after

A
  • host organism
    -location
  • scientists
  • site in body
  • how contracted
  • cytopathology
  • a combination
    causes a lot of issues when classifying
220
Q

internal committee on the taxonomy of viruses (ICTV)

A

established by federation of European microbiology societies (FEMS) virology division
1 of the main methods for taxonomy of viruses

221
Q

Baltimore system of virus classification

A

system developed by David Baltimore
1 of the main methods for taxonomy of viruses

222
Q

phenotypic criteria for ICTV taxonomy

A
  • molecular composition of genome
  • virion/capsid structure
  • presence of an envelope
    -host range
  • pathogenicity
223
Q

genotypic criteria for ICTV for taxonomy of viruses

A
  • sequence similarity
    -gene contents
  • gene synteny
  • gene expression system
  • phylogenetic relationships
224
Q

ICTV- highest and lowest levels of classification

A

species- 9110 -lowest
genus - 2224 genera
family- 189
order- 59
class- 39
phylum- 17
kingdom- 10
realm- 6- highest level

225
Q

Baltimore system of virus classification

A

viral genome must make mRNA that can be read by host ribosomes
all viruses follow this rule to date
all viruses make mRNA
- dsDNA
- gapped dsDNA
- ssDNA
- dsRNA
-+ssRNA
- -ssRNA
- +ssRNA with DNA intermediate

226
Q

possible ways viruses can infect cells

A

transformation into tumour cell
lysis- death then release
persistent infection
latent infection- virus present but no harm till later

227
Q

virus lifecycle 3 steps

A

entry- attachment and uncoating
replication- replication, biosynthesis
exit- assembly, budding

228
Q

attachment stage of virus lifecycle

A

different viruses can attach to same receptors
but some viruses of same family may bind to different ones
one virus can bind to multiple receptors

229
Q

entry stage of virus lifecycle

A

3 possible mechanisms
1. injection of nucleic acid
2. fusion of envelope with host membrane
3. endocytosis

230
Q

replication of viruses purposes

A
  1. viral proteins - synthesis of mRNA (unanimous)
  2. viral genome- generation of viral genetic material (virus-dependent)

viral proteins + genome = assembled virus

231
Q

true pathogens

A

healthy host
adapted to high temp and low o2 tension
restricted to geographic location
display thermal dimorphism
usually asymptomatic
not obligate parasites

232
Q

true pathogens dont display thermal dimorphism t/f

A

false- they do

233
Q

true pathogens are normally asymptomatic in healthy host t/f

234
Q

true pathogens are obligate parasites t/f

A

false they arent

235
Q

thermal dimorphism- true pathogens

A

if you increase temp- animal habitat- yeast form, reproduction via budding or endospores, parasitic

decrease in temp- natural habitat, hyphal form, reproduction via spores saprophytic

236
Q

histoplasmosis

A

true pathogen
histoplasma capsulatum
most common
500 000 cases/yr in USA
<50 deaths
leads to pneumonia and sometimes spreads to internal organs

237
Q

coccidiodomycosis

A

true pathogen
coccidiodes immitis
most common in alkaline desert soils in US
60% no symptoms
40% fever
0.5% growth in lungs

mild lung infections which can spread to meningitis and skin rashes

238
Q

opportunistic

A

immunocompromised host
distributed worldwide
lots of species always increasing
no specific adaptation to host environment
superficial/benign to chronic systemic infections
prognosis- poor

239
Q

candidiosis- candida albicans

A

20% of us are inhabited
immunocompetent- non invasive local infection
immunocompromised- systemic causing organ failure
most common fungal pathogen causing death
4th biggest killer in tertiary car hospitals
invades wounds/burns
dimorphic yeast- hyphal form is aggressive

240
Q

dermatophytes

A

superficial infections on healthy host
worldwide
most common = ringworm, atheltes foot
not life-threatening just discomfort and unsightly

241
Q

why are human mycoses a rising clinical problem

A

more immunocompromised hospital patients
a poor understanding of fungal biology and limited antifungal treatments

242
Q

how do we control myocoses of humans

A

azoles- ketoconazole, fluconazole

polyenes- nystatin, amphotericin B

243
Q

what does 5 fluorocytosine do

A

inhibits RNA synthesis fungistatic

244
Q

pathogens of immature tissue

A

broad host range
soil-borne attack roots
water-logged soils

245
Q

pathogens of mature tissue

A

usually high degree of host specificity.
necrotrophic pathogens
biotrophic pathogens

246
Q

whats an example of a necrotrophic pathogen

A

armillaria mellea
major root rot pathogen of broad-leaved trees
excrete ligninases, cellulose and pectinases

247
Q

necrotrophic pathogens

A
  • excrete toxins and cell wall digesting enzymes
  • host cell death
  • tissue invasion
  • evoke host resistance mechanism
248
Q

biotrophic pathogens

A

maintain host viability
limited tissue invasion
do not evoke resistance mechanisms
life cycle depend on living host
arrive as spores on leaves

249
Q

haustorial biotrophs

A

biotropic pathogens
puccinia graminis- via stomatal openeing, infect mesophyll cells
erysiphe graminis- infect directly through cuticle epidermal layer

250
Q

fungi to control insect pests

A

> 1billion dollars spent in USA to control insect pests
over 400 species of fungi attack insect and mites

251
Q

verticillium lecanii

A

produces spores in liquid fermentors
fresh pores are sticky so attach insects which become contagious
spores do not need to be ingesed
germination needs rh>95% at 15-18c for 12h

252
Q

mechanisms to control phytopathogenic fungi

A

parasitism of the pathogen by the BCA
production of antibodies, BCA poisons the pathogen
competition for nutrients water and space

253
Q

parasitism

A

fungi that parasitize other fungi - mycoparasites

254
Q

trichoderma - trichodermin gliotoxin

A

produce antibiotics
trianum- sold for control of fungal diseases

255
Q

yeast in food and drink

A

baking and brewing
saccharomyces cerevisiae
C6H12O6–> 2C2H5OH + 2CO2
S. cerevisiae yeast extract paste marmite

256
Q

soya bean products- food and drink

A

has positive and negatives
fermentation of beans with aspergillus oryzae
beans soaked for 16hrs
aerobic fermentation 3d-3m
20% salt
anaerobic fermentation with zygosaccharomyces 3m-3yr
drained and pasteurised

257
Q

quorn- food and drink yeast

A

developed after concerns in protein content in food
grows on glucose syrup
ammonia- nitrogen source
filaments spun and flavoured to resemble meat

258
Q

enzymes produced commercially by aspergillus niger

A

glucoamylases- liquid starch to high glucose syrup
pectinases- breakdown pectins in plant cell wall for juices
glucose oxidase- food preservation and diagnostic tests
phytases- improvement of animal feed

259
Q

problems with fungal cell factories

A

starch-based food cooked at high temp recently discovered to have high levels of acrylamide a carcinogen

260
Q

fungal cell factories- antibiotics

A

penicillin
alexander flemming 1928
used at end of WW11
improved yields from 2mg to 30gl-1
chemically altered semi-synthetic penicillins

261
Q

statins

A

fungal metabolites that inhibit the biosynthesis of cholesterol and are used to reduce plasma cholesterol levels

262
Q

examples of old disease

A

polio
hepatitis
smallpox
influenza
warts
rabies
measles
rubella
leukemia

263
Q

examples of re-emerging diseases

A

west nile fever, dengue fever, ebola, aids, monkeypox, sars-cov-2

264
Q

what does rhabdovirus cause disease in

A

animals humans and plants

265
Q

what shape is rabies virion

A

bullet shape
170nm long

266
Q

replication of rabies virus

A
  1. RNA-polymerase
  2. translation into protein by host
  3. transcription of viral RNA
  4. assembly
267
Q

what group is the rabies virus

A

group V virus (-ssRNA)

268
Q

how many deaths does rabies causes worldwide /yr

269
Q

where does rabies virus enter

A

peripheral nervous system and then migrates to the central nervous sytem to the brain

270
Q

how does rabies kill person

A

causes swelling of the brain (encephalitis)

271
Q

furious rabies

A

80-90% of cases
change in behaviour and voice
paralytic stage
death

272
Q

dumb rabies

A

10-20% of cases
predominantly paralytic
lapse into stage of sleepiness
death within 3 days

273
Q

where is monkeypox endemic

A

central and west africa

274
Q

monkey pox group classification

A

group 1 virus, dsDNA

275
Q

how many cases of monkeypox in 29 EU countries

A

20455
and 73604 total cases

276
Q

how is monkey pox transmitted

A

animal-animal- bites/scratches

human-human- direct skin contact with lesions on skin or indirect with contaminated domites such as bedding/clothing

277
Q

ACAM2000- live vaccinia virus - smallpox(mokeypox) vaccine

A

single dose
not recommended for immunocompromised/pregnant as can replicate
lesion at innoculation site

278
Q

modified ankara (MVA) smallpox vaccine

A

2 doses 4 weeks apart
no lesion at site
does not replicate

279
Q

LC16m8 licensed in japan smallpox vaccine

A

single does
less replication than other viruses and so safer

280
Q

viroids

A

infectious agent that resemble viruses
small circular ssRNA
naked
no capsid
resistant to proteases and nucleases
only infects plants
doesn’t encode proteins
replicate autonomously

281
Q

whats a prion

A

small proteinaceous infectious particles which resist inactivation and contain no genetic material
often called spongiform encephalopathies

282
Q

cellular prions

A

localise on the neurons synapses between neurons or facilitate the uptake of copper into the cell
caused by the accumulation of the misfolded protein scrapie prion protein

283
Q

do we know how prions cause disease

A

no
most likely infection with prion protein (=PrP^sc) produces more copies of PrP^sc, leading to disease

284
Q

scrapie - sheep

A

a degenerative fatal disease of the CNS of sheep and goats
symptoms of ataxia and recumbency
no treatment
selective breeding for genetic resistance, surveillance and depopulation

285
Q

BSE (bovine spongiform encephalopathy)- cattle

A

mad cow disease- erratic behaviour
4 million cows killed during eradication programme in uk
3 different presentations- classical BSE, H-type atypical BSE and L-type atypical BSE
classical BSE is the only form that can be transmitted to humans through consumption of meat causing creutzfeldt-jakob disease

286
Q

kuru- human

A

means trembling
caused by prions
reported in fore tribe of papau new guinea via funerary cannibalism

287
Q

CJD (creutzfeld-jacob disease)

A

lose ability to think and move properly and suffer from memory loss
always fatal usually within 1yr
lots of types like sporadic which is most common
familial CJD- rare genetic condition
varient CJD- consuming meat
latrogenic CJD- when infection is accidentally spread from someone with CJD through medical or surgical treatment

yr 1 uni work (13 decks)

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