Microbio Quiz 1

tyndallization

heat resistant endospores survive pasteurization so boil, allow for spor germination, then boil again before sporulation

Robert Koch

final proof of microbes causing disease

made petri dishes

proved anthrax and TB were caused by bact

avg size of viruses

0\.1 micrometer

avg size of bacteria

1 micrometer

avg size of microeukaryotes

200 micrometers

oil immersion lenses

increase refractive index (n), decrease d(res) which means increas in resolution

fluorescent microscope

shows bright image of object from fluorescent light emitted by object

what filter size should you use for bacteria

0\.2 micrometers

pure culture method

koch invented

sterile surface

solidified nutrient media

counting methods

MPN method (CFUs)

dilute to extinction

great plate count anomaly

discrepency btw # of microbial cells observed by microscopy (overestimate) and # of colonies that can be cultivated from the same sample (underestimate)

molecular techniques

blackbox approach

in situ approach

molecular techniques (based on genes- ssu rRNA)

small subunit rRNA

biomarker

very conserved thru all life

16S in prok

18S in euk

bacteria shapes- cocci

speres

diplococci

pairs

streptococci

chains

staphylococci

grape-like clusters

tetrads

4 cocci in a square

bacilli

rods

coccobacilli

very short rods

vibrios

resemble rods, comma shaped

spirilla

rigid helices

spirochetes

flexible helices

mycelium

network of long multincleate filaments

bacteria cell envelope features

plasma membrane

cell wall

capsule

plasma membrane has cholesterol

only in eukaryotes

phospholipids

polar hydrophilic head and hydrophobic fatty acid tail

phospholipid head and tail held together by

ester bond in bacteral and euk

ether bond in archaea

membrane proteins

peripheral

integral

gram negative cell wall

outer membrane

thin layer of peptidoglycan

large periplasmic space

cytoplasmic membrane

no techoic acid

gram positive cell wall

thick peptidoglycan layer

periplasmic space

cytoplasmic membrane

also lots of techoic acid

peptidoglycan structure

mesh-like polymer of identical subunits forming long strands

2 alternating sugars

alternating D and L aa

chains crosslinkid by peptide strength

gram-neg periplasmic space

larger than gram +

20-40% of cell volume

more enzymes present

gram outer membrane permeability

more permeable than other plasma membranes bc of porin protiens and transporters

capsule

outside cell wall

usually made of polysaccharides

sticky sugar coat

well organized

relatively thick (vs slime layer)

slime layer

similar to capsules but diffuse, inorganized and can be easily removed

aid in motility

help biofilm formation

s layer

surface layer not slime layer

regulary structured layers of protein or glycoprotein that self-assemble

not easily removed

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bacteria ribosomes

70S (large)

16 S (small)

bacteria genome

closed circular chromosomes

double stranded DNA

also plasmids

plasmids

extrachromosomal DNA

found in bacteria, archaea, some fungi

usually small circular DNA molecules

exist and replicate independently of chsome

contain low # of genes that are non-essentail

confer selective advantage to host

pili and fimbriae

short, thin, hairlike protein tubes

mediate attachment ot surfaces, help w motility

pilin protein

also sex pili

sex pili

similar to fimbriae except larger, thicker, less numerous

required for conjugation

genes for formation found on plasmids

unidirectional horizontal gene transfer

flagella

threadlike appendages

structure:

filament- hollow, rigid cylinder. composed of protein flagellin

hook- links filament to basal body

basal body-series of rings that drive flagella motor

(G- lots of rings in diff layers, G+ only 2 rings)

chemotaxis

cell crawling

move towards chem attractants like nutrients and away from harmful substances

archaeal structure similarities to bact

cell size

cell shape and arrangement

genome shape (circular), size, plasmid

ribosomes (16S small subunit)

archaea diff than bact

abundance- lower

distribution- many in extreme environments

cell envelope structure

have not found pathogenic archaea

archaea cell envelope

membranes: unique lipids- branched, so more stable under heat than unbranched

ether linkages rather tahn ester linkages

some have monolayer rather than bilayer

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cell wall: lack peptidoglycan

pseudomurein (peptidoglycan like)

S layer most common (capsule and slime layer rare

archaeal flagella

thinner

NOT HOLLOW

hook and basal body difficult to distinguish

eukaryotic microbes

2 groups

fungi

protists

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10 micrometers

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membrane-delimited nucleus

membrane-bound organelles

more structurally complex

generally larger than bact or arch

protist def

euk unicellular organism that is not plant, fungi or animal

diff btw eku and prok

euk cell envelopes:

plasma membrane- has cholesterol

many euk lack or have chemically distinct cell wall (photosynthetic algae have cellulose, pectin and silica

fungi have cellulose, chitin or glucan

viruses

not alive

infect both prok and euk

avg 0.1 micrometer

no cell membrane

cant replicate

protein cover

genetic material: ss, dsRNA, DNA

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other virulent particles

virion: complete virus particle

genome and capsid made of protein

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prion: protein infection

virus capsid

protein coat

very diff from cell membrane

protect genetic material

lots of shapes

viral envelopes

outer flexible membranous layer

usually arise from host cell membraes

virus spikes/peplomers

proteins (viral encoded) various functions:

attachment to host

SARS-CoV-2

0\.06-0.14 micrometer (huge range)

single stranded RNA

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ACE2 receptor: present in epithelium in nose, mouth, and lungs

viral infection

entry: fusion and uncoating

exit: exocytosis, budding

viral attachment

adsorption

receptor mediated (on host cell membrane) very specific

spikes (ligands) look for receptros

viral multiplication

attachment to host

entry

synthesis

assembly

release

virion release

enveloped- budding (host membrane becomes part of envelope)

non-enveloped- lyse the host cell

bacterial virus multiplication

different from others

phage:

virulent or temperate

virulent virus

one reproductive choice

multiply immediatedly upon entry and lyse bacteria host cell to exit

temperate virus

two reproductive options:

lytic cycle and lysogenic cycle

lysogenic cycle

remain within host w/o destroying it

no exit

integrate into host DNA (called prophage gene) and replicate w host

but when exposed to UV light triggers or other stress, is excised from host and enters lytic cycle

viral gene transduction

horizontal gene transfer

when enter lytic cylce and cut out dna from host cell, not careful and sometimes take bacterial genes too

result of infection

in euk:

cell death/lysis

no obvious change- latent- slow infection + release

transformation to malignant cell (cancer)

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prok:

cell death

getting new genes

lysogenic conversion

\-bact become immune to superinfection

phage may express pathogenic toxin or enzyme

virioids

RNA only

circular ssRNA, non protien coding

satellite

dna or rna

capsid

need helper virs to replicate

prions

protein only

have odd structure that can change conformation of normally folded proteins

bacterial reproduction

binary fission

duplication

asexual

exceptiosn to binary fission in bact

budding- one cell becomes 2 but mother is diff size from daughter

multiple fission-

uneven fission-

spore formation-

batch culture

closed system- diff from open system like bioreactor

lag phase

lag phase

stationary phase

death phase

long-term stationary phase

lag phase

cell synth new components

replenish spent materials

adapt to new medium

varies in length-can be absent

log/exponental phase

rate of growth is constant and maximal

population is most uniform in terms of chem and phsy propertis and size

stationary phase

reproductive rate=death rate

nutrient limitation

limited oxygen

toxic waste accum

limited space

death phase

2 alt hypotheses

\-cells are viable but not culturable (VBNC)

alive but dormant, capable of new growth when conditions are right

\-programmed cell death

mathematics of growth

generation time

2^n

for populations reproducing by binary fission

Nt= N0 x 2^n

pop @ time t = initial pop x # of generations in time t

mean growth rate (mu)

\# of generatiosn per unit time

=n/t

= (log Nt - log N0) / 0.301t

direct cell counts

counting chamber

on membrane filters

electronic counters

measurement of cell mass

dry weight

(time consuming and not very sensitive)

tubidometric measures

(quick easy and sensitive, optical density (OD))

microbes cannot regulate their internal temp

enzymes have optimal temp which they function

adaptations of thermophiles

protein structre stabilized by lots of stuff

\-more H bonds

\-more proline

\-more chaperones

histone-like proteins stabilize DNA

\-also more G-C than A-T bc 3 bonds instead of 2

membrane stabilized by lots of stuff

\-more saturated and branched and higher molecular weight lipids

\-ether linkages in archaeal membranes

oxygen conc

e- transport chain, terminal e- acceptor used

nutrient levels

oligotrophic (low- deserts and oceans(

mesotrophic (lake water)

copiotrophic (lake erie)

eutrophic (LOTS of nitrogen and phosphorus)

environmental factors

water

temp

ph

pressure

microbial growth in natural environments

free-living

attach to surface- very good for them cause stable environemt

biofilm (like on teeth)

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numerical aperture (NA)

light gathering capacity of lens

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(n)(sin theta)

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increase NA, decrease d(res), increase resolution

resolution equation

d(res) = (0.5 x wavelength) / NA

types of microscopes images

light field- dark image, cell w pigment

dark-field- light image, black background

phase contrast- different shade

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fluorescence microscope- bright image on black background

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gram stain process

1) stain cells purple

rinse

2) iodine (mordant)

rinse

3) alcohol decolorizer

\*G+ remain purple, G- become colorless

rinse

4) safranin counterstain

\*G+ stay purple, G- become red

G- outer membrane

made of lipopolysaccharide (LPS)

lies outside the thin peptidoglycan layer

Braun’s lipoprotiens connect outer membrane to peptidoglycan

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lipopolysaccharides (LPSs)

embedded in outer membrane

contribute to negative charge on cell surface

may help w attachment to surfaces and biofilm formation

protect from host defenses

can act as endotoxin

gram- outer membrane permeability

more permeable than others due to porin protiens

archaeal cell walls

dont have peptidoglycan!

plasmids present in

bact and archeaa

rare in euk

membrane bound nucleus present in

bact- no

arch- no

euk - yes

DNa complexed w histones

bact- no

arch- some

euk- yes

chromosomes

bact- usually one circular chromosome

arch- one circular chromosome

euk- more than one linear chromosomes