L4 Bacteria, structure, function & taxonomy Flashcards
1
Q
what do unicellular microorganisms rely on
A
hosts
2
Q
where do unicellular microorganisms live
A
free living
3
Q
what is monera
A
single cell
4
Q
what is protists
A
single cell
5
Q
what is grouped in monera
A
prokaryotes
6
Q
what are prokaryotes
A
eubacteria
archaeobacteria
7
Q
what is grouped in protists
A
eukaryotes
8
Q
what are eukaryotes
A
protozoa
algae/slime moulds
9
Q
what is the structure of a typical bacterial cell
A
pili flagellum outer membrane cell wall inner membrane ribosomes genome of DNA folded and organised no nucleus/nuclear membrane
10
Q
how does the bacteria move
A
flagellum for motility anchored in cytoplasmic membrane – needs energy from cytoplasmic membrane (electron transport chain)
11
Q
where is the peptidoglycan
A
cell wall
12
Q
do prokaryotes or eukaryote protist have nucleic acids
A
both do
13
Q
do prokaryotes or eukaryote protist have structured nucleus
A
prokaryotes -
eukaryotes +
14
Q
do prokaryotes or eukaryote protist have mitochondria
A
prokaryotes -
eukaryotes +
15
Q
do prokaryotes or eukaryote protist have ribosomes
A
both do
16
Q
do prokaryotes or eukaryote protist have cell membrane
A
both do
17
Q
do prokaryotes or eukaryote protist have rigid PG cell wall
A
prokaryote +
eukaryotes -
18
Q
do prokaryotes or eukaryote protist have mesosome
A
prokaryote +
eukaryotes -
19
Q
do prokaryotes or eukaryote protist have ER/Golgi
A
prokaryote -
eukaryotes +
20
Q
what is a mesosome
A
invagination of cytoplasmic membrane important for cell division to make daughter cells
21
Q
what is the binomial system for naming bacteria
A
genus + species
22
Q
why is bacterial taxonomy important
A
handling info learning communication identification evolution
23
Q
what are the phenotypic characteristics
A
morphology - macro/micro-scopic biotyping - biochemical tests serotyping antibiogram patterns
24
Q
macroscopic growth characteristics
A
shape margin elevation size texture appearance pigmentation optical density
25
what is beta hemolysis
complete hemolysis = yellow no red on blood agar
26
what is alpha hemolysis
degraded partially, characteristic green/brown colour
27
microscopic growth characteristics
shape
size
staining
arrangement
28
what are the shapes of microscopic growth
```
rod
club
coccus (round)
curved (vibrio)
spirillum
spirochaete
```
29
what are the staining charactersitics
gram stain - true bacteria
| acid fast stain - mycobacteria
30
how are the genotypic characteristics tested
```
% GC ratios
DNA hybridisation
chromosomal DNA fragment analysis
ribotyping
MALDI_TOF
```
31
what is MALDI TOF
Matrix-Assisted Laser Desorption/Ionization-Time Of Flight
sample mixed in liquid matrix with solvent (maybe acid) break up any vegetative bacteria, crystallise and hit with a laser = desorbs the material, ionises it and put through a vacuum column and hit detector = mass spectra gram of the sample
32
what is ribotyping
extract DNA and break up enzymatically into smaller linear units and probs single stranded DNA that has been enzymatically broken up into ribosomal RNA genes that are unique to specific organisms - rRNA-based phylogenetic analyses
33
what is DNA hybridisation
species specific probes that are specific to specific bacteria = if makes ds then it is the organism that you think it is
34
what is the difference between gram + and - cell wall
gram + is thick
| gram - is thin
35
how does a gram stain work
crystal Violet stain
gram’s Iodine (mordant, fixes crystal violet)
decoloriser
(alcohol/acetone)
(gram+ve PG too thick so not stripped)
safranin red (counter stain, gram-ve gets stained)
36
do gram + and gram - have an outer membrane
gram +ve has no outer membrane
| gram -ve has got an outer membrane
37
do gram + and gram - have and LPS (endotoxin)
gram +ve doesnt
| gram -ve does
38
do gram + and gram - have teichoic acid
gram +ve does
| gram -ve doesnt
39
do gram + and gram - sporulate
some strains of gram +ve do
| gram -ve dont
40
do gram + and gram - have a capsule
sometimes
41
are gram + and gram - lysozyme sensitive
gram +ve are
| gram -ve are not
42
what is lysozyme function
hydrolyses PG
43
which of the gram + and gram - are more susceptible to penicillin
gram +ve most susceptible
44
what is teichoic acid interlinked with
PG
45
what is LPS made up of
lipid A, outer core made of carbohydrate, O antigen
46
what is the function of cell wall
```
maintain rigidity, cell shape/structure
maintain osmolarity (prevent osmotic lysis)
survival - interacts with host membranes
cell division - form cross wall separating 2 daughter cells
```
47
what is a cell wall made up of
two disaccharide sugars - N-acetylglucosamine and N-acetylmuramic acid alternating
48
what form are amino acids in - in cell wall
natural form of amino acid is L isomeric form
49
where are D isomeric forms found
cell wall there is a D isomeric form only form in nature where D isoform is made
50
how are adjacent stem peptides linked to the cell walls
linked directly by transpeptidase reaction (e.g. in E. coli) whereas in some gram positive have penta-glycine (5 glycine amino acids) form a cross bridge between adjacent stem peptides – where AB work
51
how do antibiotics with beta lactam structure work
molecular mimic for the stem peptide amino acid, interact with pencillin binding protein or transpeptidase enzyme and prevent that enzyme binding to amino acids ion stem peptide to form cross bridge
no cross bridge = no PG effective structure no cell wall and bacteria die (bactericidal)
52
how does vancomycin work
binds to terminal D-ala molecular inhibition - also prevents transpeptidation of adjacent stem peptides
53
how does the bacterial cell wall synthesise
PG precursor synthesised inside cell
exported across cell membrane
site is created in existing wall by enzymic action (PBPs)
new nucleotide minus terminal D-ala is encorporated
cell ‘grows
54
how are mycobacterium different
modified PG layer
covalently attached to arabinogalactan polymer
mycolic acid waxy coat - lipids
poor gram stain
55
why cant mycobacterium be gram stained
arabinogalactan polymer
56
how are mycobacterium stained
acid fast gram stain (Zeihl-Neelsen stain) - carbolfuchsin
57
how are mycoplasma different
no cell wall
| cell membrane has steroids from host membrane
58
what are cell membranes generally like
```
lipid bilayer - hydrophobic
no steroids (except mycoplasma)
ion transport and energy production (mitochondria)
mesosomes
electron transport
```
59
what are spores like
cell survival in adverse conditions
| desiccation, heat, starvation
60
what are capsules for
protect against phagocytosis
61
what are capsules
gelatinous material,polysaccharide/polypeptide
62
what are flagella for
cell motility
63
what are flagella like
1-20; peritrichous or polar
| coiled in structure
64
where are flagella
anchored into bacterial membrane
65
what is the flagella protein
flagellin
66
what do flagella do
chemotaxis
67
how do flagella move
ATP driven motor membrane potential
68
what are fimbriae like
smaller length and diameter than flagella
69
how are fimbriae arranged
peritrichous arrangement
70
are fimbriae or flagella coiled
only flagella are
71
what is the fimbriae protein
pilin
72
what is the sex pili
F plasmid
73
what kind of infection do fimbriae cause
e. coli UTI
| N.gonorrhoeae
74
what is LOS
LPS with no O antigen
75
what has LOS
neisseria
76
what happens to LPS in cell
shed LPS into constituent moietys, lipid A = inflammatory response, activates cytokines for e.g. increased temp, create fever, organ failure through lack of blood flow
77
which bacteria have porins
gram -ve
78
which bacteria have pili
N.gonnorrhea
79
what are the surface proteins in gram +ve
```
afimbrial adhesins
protein F (Strep. pyogenes)
```
80
what do gram +ve bacteria cause on infection
inflammatory response
| cytokines/shock
81
what affect the growth of bacteria
```
O2/CO2
temperature
water
pH
light
osmolarity (5-12%)
```
82
what are the nutritional requirements for bacterial growth
carbon and nitrogen source
inorganic salts
organic compounds
83
what are inorganic salts bacteria require for growth
Fe/Na/K/P/Ca/Mg
84
what are auxotrophs
can't make essential nutrient have to get from environment
85
what is the medical relevance of cell wall synthesis
antibiotics
86
what is the medical relevance of capsules
vaccines
87
what is the medical relevance of cell membranes
antibiotics
| vaccines
88
what is the medical relevance of ribosomes
antibiotics
89
what are monera and protists
| like
unpaired chromosomes
| no nucleus
