caused by microorganisms

ex. smallpox - 1st disease eradicated by worldwide vacc. campaign (only possible b/c only in humans)

1. Archaea

2. Bacteria

3. Eukaryotes

1. microscopis (except for Thiomargarita & Epulopiscium)

2. unicellular

3. structurally simple (except viruses)

1. bacteria

2. some fungi

3. viruses

4. some algea

5. archaea

6. protozoa

-1st cells on earth

-evolution gives clues to progress of other evolution

-discovered in mid-17th C

-used to industrially produce food, alcohol, vitamins, hormones, etc

-evidence in writings from 3000 BC of infectious diseases that still exist today

idea of bad vapors:

Lucretius (55BC) & Fracastora (1400) - wrote things implying "seeds of disease" transmitted from one person to another to spread disease

FATHER OF MICROBIOLOGY

Anton von Leeuwenhoek (Holland)

mid 17th century

viewed "specimens" under handmade, primitive microscopes

saw in specimens "many small living animals" - called them animalcules

gets credit b/c he drew detailed drawings, wrote detailed descriptions & wrote letters to Royal Society of London

field couldn't advance for 200 yrs b/c couldn't study/grow orgs.

theory that living organisms can come into existence without previous living organisms having been there (come from decaying matter)

1600's - experiment w/ meat put idea to rest for larger orgs

BUT still though microorganisms could spontaneously generate b/c would put vegetables & water out uncovered, would putrify

John Needham

1700's

believed in spontaneous generation

organic matter had "life giving force" allowing spon. gen.

Spallanzani

1700's

experiments seemed to disprove Needham:

boiled broth (to killed microorganisms), sealed - nothing grew

PITFALL: opponents claimed boiling killed "life-giving force" & sealing kept oxygen out

Pasteur 

1800's

filtered air though cotton, cultured cotton, found micro-orgs = micro-orgs in air

swan-neck flasks: boiled broth but left flask open to air (to show flask still had ability to sustain life)

micro-orgs/particles got stuck in neck, grew there

wine-spoiling problems

took samples of wine - found yeast

yeast ferment sugars from grapes, make alcohol

spoiled wine - had yeast AND bacterial cells - bacteria converted alcohol to acetic acid

gentle heating of wine - kills bacteria but not yeast (pasteurization!)

invented rabies vaccine using attenuated virus

gentle heating of liquid to remove pathogens

products pasteurized: juice, milk, cans/bottles of beer (not kegs)

use of anaesthetics = more extensive surgery

after surgery, incision sites (or cpd fractures) would become red & pussy, cause disease or death

some thought good sign

idea of antisepsis:

sprayed phenol sol'n into air around surgery table, clean instruments w/ phenol, soak bandages for cpd fractures in phenol

-developed in women after childbirth, some died

-caused by bacteria

-if present during childbirth, can be dangerous for baby as well

spread b/c med students would examine women who died from it, then go & deliver babies in previously healthy women (didnt wash hands)

took blood from women w/ puerperal sepsis, saw bacteria

suggested hand-washing to remove orgs when moving btwn patients

worked with anthrax

proved certain bacteria caused specific disease

(ideas of how to prove laid out by Henle)

Koch's Postulates

~1876

process to prove specific organism causes certain disease

not outdated

first proof of bacteria causing disease

organism must be present in ALL people who have the disease and absent from healthy people

carriers make 2nd part false

-may not be able to culture organisms (uncultivable)

(would use molecular tools instead)

-some microorgs only cause specific disease in humans or very specific animal

ex. HIV - only causes disease in humans and special species of monkey - couldn't carry out Koch's Postulates until found specific species of animal that got sick

published article suggesting HIV not cause of AIDS, or other factors necessary in addition to HIV to develop AIDS

-attempt to instigate other research for possible causes of AIDS b/c global pop. was putting all $$ into HIV research

-couldn't do KP for diseases caused by viruses until learned how to cultivate viruses in 1930's/1940's

-if couldn't completely do KP:

- look for antibodies for organism in system

-molecular techniques - look for genes of organism

would be acceptable evidence of org as cause

GOLDEN AGE OF BACTERIOLOGY

(last 25 yrs of 1800's)

 - virtually all bacterial causes of diseases of that time discovered/confirmed

-developed different types of medium

before, used surface of sliced potato, broth cultures, etc.

used gelatin to solidify media BUT not good b/c:

1. liquifies @ 35 C - not good b/c incubate bacteria higher than 35C or higher, gelatin would break down

2. some bacteria breaks down gelatin

-very few orgs break it down

-heat to boiling or high temps so agar melts & then cool to solidify, can't melt again unless heat to ~45C

-ability to create solid media allows for greater research w/ pure cultures, can isolate/move cultures more easily

up until 1890's, did not know about viruses

"virus" referred to anything invisible & harmful

Tobacco Mosaic Disease

1890's

-plant disease: get discoloration pattern, kills plants

to try to stop disease: ground infected plants, filtered through special filter (tiny pore sizes)

collected filtered sap materials in flask, bacteria & other microorgs get caught on filter

put filtered sap on new plants, expecting no illness, BUT plants got sick

realized must be other microorg small enough to fit through filter

(viruses are) obligate intracellular parasites

must be inside cell, have cell's reproductive system to replicate them - can't grow on own b/c lack replicating systems

b/c of this, CAN'T GROW ON CULTURE (why never discovered before)

learned how to grow viruses on culture in 1930's

viruses need SPECIFIC host cells - can't use any cell

ex. needs animal, plant, bacteria or human cell;

w/in kingdom, need specific species of cell; w/in species, need specific type of cell

-> ex. human skin cells

bacteriocidal - kill bacteria

bcteriostatic - inhibit bacterial multiplication

-either interfere w/ structure of cells (i.e. cell wall) or w/ cellular processes (i.e. stop protein synthesis)

Fleming

1928/29

discovered Penicillin

accidental - was growing Staphylococcus on culture plates, set aside, came back & noticed contamination on plates - mold (fungi)

Staph. didn't grow on around mold - hypothesized mold was producing inhibitory substance stopping Staph. growth around mold

Penicillin first used in 1940's

affect narrower range of bacteria

advantage: not as many types of bacteria exposed to antibiotic, don't have chance to form resistance

possibility in near future - if no action, bacteria may be resistant to ALL antibiotics currently in use

HOW TO SLOW?

-don't prescribe/take antibiotics as often (don't take for viruses)

-take ALL of medicine - follow directions

-try to prescribe narrow spectrum drugs

-don't use antibiotics prescribed for other people

-buy organic/free range/antibiotic-free meat

-find new antibiotics

Protista - 3rd kingdom (in addition to plants & animals)

-unicellular & simple structured

R. H. Whittaker

1969

5 kingdoms

1. Animal

2. Plant

3. Fungi

4. Monera(bacteria)

5. Protista

2 EMPIRES/8 KINGDOMS

1. Bacteria

-Eubacteria

-Archaebacteria

2. Eukaryota

6 kingdoms

2 kingdoms

PLANT                                                ANIMAL

photosynthetic             non-photosynthetic

non-motile motile

bacteria & archaea

no nuclear membrane

no membrane-bound organelles

70s ribosomes

everything but bacteria & archaea

nuclear membrane

membrane-bound organelles

80s ribosomes

-1st cells - prokaryotes

-substances in beginning (gases, methane, etc) mixed w/ H2O & electric current => formation of molecules

oceans would have been too dilute for "primordial soup" to work

chemical rxns necessary to form molecules not possible in H2O

DNA: self-replicating but no enzyme functions

RNA:maybe (probs not) - self replicating but no enzyme function

proteins: not self-replicating = unlikely to be first

self-splicing RNA

(1981)

1st molecule = simple RNA

->

simple DNA

-> enclosed lipid vesicle

progenote (prodecessor to cell)

transfer/development from prokaryotic to eukaryotic cells

(series of event)

mitochondria & chloroplasts were bacteria, were engulfed by larger cells & kept

evidence: DNA present in these organelles

Lynn Margulis did a lot of work

16s rRNA 

PLAN: do sequences from orgs to study, compare, make evolutionary conclusions from comparisons

Carl Woese (2.0)

1970

(more practical way to sequence genomes, compare btwn orgs, but still could only do w/ small seg of DNA)

-realized specific requirements for types of molecules to study

-had to be relatively small but vital to all cells found in (b/c highly conserved through evolution)

-had to perform same function in all cells found in

1. bacteria (eubacteria)

2. archaebacteria -> now called archaea

strict anaerobes

methane is major metabolic endproduct

S may be reduced to H2S w/out yielding E production

Coenzyme M, factors 420 & 430, methanopterin

irregular gram - coccoid cells

H2S formed from thiosulfate & sulfate

Autotrophic growth w/ thiosulfate & H2

can grow heterotrophically

traces of methane formes

extremely thermophilic, obligate anaerobe

factor 420 & methanopterin, NOT factor 430 or coenzyme M

coccoid or irregular shaped rods (gram - or +)

aerobic chemoorganotrophs

require high [NaCl] for growth (>1.5M)

red colonies

neutrophilic OR alkalophilic

mesophilic or slightly thermophilic

SOME species contain bacteriorhodopsin & use light for ATP synth.

pleomorphic cells

no cell wall

Thermoacidophilic & chemoorganotrophic

facultatively anaerobic

plasma membrane contains mannose-rich glycoprotein & lipoglycan

gram - rods, cocci or filaments

obligately thermophilic (70-110C)

usually strict anaerobes but may be facultative or aerobic

acidophilic or neutrophilic

autotrophic or heterotrophic

most metabolize sulfur

S reduced to H2S anaerobically, H2S or S oxidized to H2SO4 aerobically

not much multiplication = very small increase in # cells/mL

cells "getting ready" to multiply - may have to synthesize ATP, make certain enzymes to utilize nutrients, make ribosomes to make enzymes to grow in media, etc.

older cells = longer lag phase

any conditions under which cells were not actively growing - will have lag phase

#cells increasing exponentially at a constant rate - "balanced growth"

culture growing at fastest possible rate given genetics & given conditions

varies between species

as close to synchrony as possible

cells in "best health" = study cells during log phase

time during log phase that it takes for # of cells in pop. to double

ex. E. coli - generation time = 15-20 min

Mycobacterium tuberculosis - generation time = 24 hrs

affects time necessary to get colonies on solid media

# cells remains about the same - some new cells, some dying

may last hrs, days, etc.

1. after period of time growing in log phase, cells use up most of vital nutrients in media (ex. glucose)

2. during log phase, bacteria give off end products - some are inhibitors = not much new cell growth

-depending on which nutrients available, cells, may enter stationary phase, then start second (slower) growth phase

decline in #cells (may not ever hit 0)

some cells not actually dead, but uncultivable (could come back if put under good conditions again)

cells which persist longer in death phase are more resistant to killing by chemicals/antibiotics than cells in log/lag/stationary phases

1. perform determinations at certain intervals of time after inoculation

DISADVANTAGE - colonies take time to grow, can't use to monitor growth

2. direct microscopic count - take small sample of culture at intervals, place on hemocytometer, count cells, calc # cells/ml

3. "particle counter" instrument - pass liquid sample through narrow channel - each particle which passes through is "counted" by electrodes

DISADVANTAGE (#2&3) - no way to distinguish btwn viable & non-viable cells

4. can quantitate amts of cell material (i.e. DNA, RNA, etc)

-if used w/ determinations initially, can establish correlation btwn amt of DNA/cell, use as standard curve to determine future # of cells based on amt of DNA

5. spectrophotometer - take sample from culture at certain intervals, set spec to λs to read turbidity of culture, read optical density of culture/sample. absorbancy incr. =  cells incr.

*don't typically see death phase unless dead cells lyse

can read gen time using OD if establish correlation btwn OD & cell count

rule of thumb: OD of 1.0 = 1x10⁹ cells/ml

amount of O2

*all orgs need some O2 to construct macromolecules

*don't tighten caps when growing in screw-top tubes

*incubate flask on shaker to make sure O2 available throughout

can't grow in presence of O₂

can't break down harmful ions made in presence of O₂ - H₂O₂, O₂^-

orgs that can grow on human body grow @ ~35C

dependent on niche/normal environ. temp

-all bacteria have range of temps in which they can grow

1. psychrophiles~ -5 to 15 C 

2. psychrotrophs ~-2 to 35C 

(1&2 = "refrigerator organisms")

3. mesophiles~ 15-45C

4. thermophiles 42-60C

5. hyperthermophiles (extremophiles) ~ 68-105C

have discovered bacteria that can exists in temps up to 250-300C

range of pH's over which each individual species can grow

as orgs grow, give off endproducts which change pH

*to fix = buffer

1. acidophile - like low pH environ.

2. alcalophile - like higher pH

3. neutrophiles - like neutral pH

8% saline sol'n

most bacteria can exist in this

concentration (low = dilute)

most bacteria can exist in very dilute environments b/c have rigid cell wall

oceans - 3.5% saline sol'n

Great Salt Lake - [6M] saline sol'n

attempt to find extreme halophiles here - create salty environ, see what grows

can inhibit bact. growth  by putting orgs in "salty" (or high sugar) environ. ex preserving meat, jam

orgs that exist in environment w/ higher [NaCl] than usual

moderate - ex. ocean orgs

extreme - ex. Great Salt Lake orgs

only photosynthetic orgs require sunlight

other orgs not harmed unless exposed to light that dried up media

UV light - damages org (nucleic acid)

won't get enough UV damage from sunlight to be issue - would have shine UV light on it

the series of processes by which an organism takes in & assimilates "food" for cell growth & maintenance & energy production

(keep in mind when trying to cultivate)

substances cells require for synthesis of cell material & production of energy

use nutrients to synthesize component macromolecules

*amazing diversity in nutritional needs of bacteria - comes from diversity of bacterial ability to make what they need

ex. E. coli needs only glucose & water & can make whatever it needs

have a lot of nutrient needs b/c can't make all on own

have diverse abilities to use dfft cpds

ex. some species can use 100s of diff cpds to get C & energy

CHONPS

most abundant elements in bacterial molecules = needed most

manganese, zinc, cobalt, nickel, copper, Mb

needed in minute amts

*present as contaminants in water, glassware - don't usually have to add

structure: genome is 1 circular chromosome (except for v. cholera = genome split in 2 chromosomes)

no introns, very little extra DNA

COMPACT

1st done w/ Haemophilus influenzae - 1.8 million bp

1. treat genome w/ restriction enzymes - get segments 1500-3000bp

2. ligate fragments into vector

make clones with overlapping segments - set of clones together make complete genome

3. sequence everything from set of clones

-look for transcription evidence (promoter, initiator, termination sequence, etc)

-more sophisticated algorithms - allow to see any gene transcribed/translated regardless of size

70 stretches of DNA coded for RNA=50-500bp

transcribed by RNA polymerase

can inhibit function @ target gene

ex. OmpF - E. coli gene

mRNA attaches to Shine-Delgarno sequence & farther downstream, stops transcription of gene

found thousands w/ telltale indicators

show translation by taking small protein, clone out of E. coli, @ end of protein attach GFP, put back in chromosome - if turns green, proves transcription/translation

if deleted, NO effect

possibly regulatory, redundant

contains end sequence for each gene/enzyme, intercistronic space btwn genes, trailer @ end

only exists for as long as necessary for transcription = easily & accurately regulated transcription

lac operon

(no lactose)

when no lactose, I regulator protein synthesizes repressor protein, which binds to O (operator regulatory protein)

interferes w/ polymeration = no gene expression

lac operon

(lots of lactose)

lactose binds to repressor protein, alters conformation so protein can't bind to operator

allows lactose to be broken down

CAP = cAMP binding protien

CRP - catabolite repression protein

CAP/CRP dimerizes, binds to CAP/CRP binding site (btwn I & P reg proteins), enhances transcription

too much glucose inhibits cAMP = stops enhancing promoter = limited lactose breakdown

Have accessory genetic elements ("baggage")

-plasmids

-transposons

circular extrachromosomal dsDNA molecules capable of independent replication

can sometimes enter bacterial chromosomes (episomes)

1. Resistance plasmids - offer drug resistance

2. co-plasmids - line of defense against other colonies

3. virulence plasmids

ex. anthrax - w/out virulence plasmids, is just soil bacteria

1st v.p. encodes substance - makes capsule around bacterium - immune to macrophages

2nd contains 3 proteins: lethal factor (LF), edema factor (EF) & protective antigen (PA)

LF + PA = lethal toxin

PA + EF = edema toxin

4. metabolic plasmids - contain genes which code for degradation enzymes

5. fertility factors - how bacteria have sex

organic cpds that some orgs require as precursors/constituents of its organic cell materials

*some orgs have no GF requirement

CATEGORIES:

1. vitamins - used in biochemical pathways

2. purines/pyrimidines - use to synthesize macromolecules

3. amino acids - used to synthesize proteins

1. photosynthetic - use light

2. use organic or inorganic cpds which are oxidized in cell energy production pathways (ex. glucose)

digest of a protein source

ex. casein (milk protein), beef extract, soy bean digest, yeast extract

contains all necessary nutrients, also contains inhibitory substance (only certain orgs grow)

-would use to isolate desired org from mix of orgs (ex. EMB plates)

often selective as well

ingredients in media will allow differentiation of colonies based on biochemical ability

-usually need pH indicator - indicates function of biochemical pathway by change in pH

-color change appears in colony or in media around colony

1. classification & definition

2. diagnosis

3. nomenclature

when read about org in classification system, provided w/ org's traits

definitions must be exhaustive (thorough) & exclusive (only fits one org group, clearly excludes orgs not in that group)

traits should be of significance

class schemes show properly accepted names of orgs w/ nmes done by universally accepted rules followed by everyone

*avoids confusion

binomial

started by Linnaeus

refer to org by Genus species 

names are descriptive

in charge of nomenclature rules

org. can be moved to new genus = new genus name BUT species stays same

1. all microorgs lumped together b/c simply microorgs

2. b/c of diversity of microorgs, criteria used in classifying 1 group diff. than crit. used to class. another group

ex. fungi - class. by spores

algae - class. by pigment color

protozoa - class. by motility

3. class. schemes are man-made - bias in deciding grouping

4. bacteriology is new (last 25 yrs of 1800s) = dynamic taxonomy

5. no official authority to say who's right

Bergey's Manual - doesn't claim authority

6. too much deference given to early researchers

ex. Haemophilus influenzae doesn't actually cause flu, but species name won't change to avoid confusion

7. study populations - not all orgs in pop identical

8. bacteria are haploid - mutations show up easily - can affect outcome of research

group of orgs that have a high degree of similarity but differ from other orgs

b/c of this def, orgs w/in species can have variation - causes controversy over allowable variation

lumpers vs. splitters

10. until 1970's, not good info about evolution/evolutionary ideas about bacteria - very few fossils, didnt give much info

as time went by - idea of molecular fossils

-study diff parts of molecules (sequence info), compare to infer evolutionary info

-at first studied proteins, then nucleic acids, now 16s RNA genes

look at individ. cells, colonial growth, staining behavior, flagella, mech. of motility, spore structure (non-reproductive), cellular inclusions, color

LIMITATIONS - not very many morphological traits to study vs. millions of bacteria to classify

ADVNTAGES - morph. traits determined by # of genes => bacteria in same morph. group may have related genetics

expressed in % GC

if orgs have very diff amts of %GC, CAN'T be related (if more than 10-15%GC, not in same genus)

REVERSE NOT NECESSARILY TRUE

orgs can have exact same %GC but not be related

bacteria as group have large range of %GC - can differentiate

to test: grow up culture, isolate DNA, take sol'n of DNA, put in spec (takes absorbance reading & heats sol'n slowly) - as heat, bonds break

GC bonds break more slowly than AT

Temperature at which 1/2 bonds are broken 

midpt of melting curve

statistical anaylsis (need comps.)

exhaustive study of all orgs using all diff types of traits (morph, biochem, genetic, molecular)

put data into program, calc similarity coefficient

ADVANTAGES: encourages exhaustive study, no biad b/c statistical analysis, can leave out traits that orgs lack (if could be more than 1 reason orgs lack trait)

tells if orgs have enough common props to appear to be related

can determine necessary s.c. to be in same species, genus, etc.

DNA-DNA

heat DNA strands, strands separate, get REANNEALING

if DNA is similar, can heat diff orgs DNA, will hybridize when cooled

more similar orgs = higher hybridization

can quantitate to compare orgs

need to do 2 things while growing orgs to be able to tell hybridization:

1. grow one org. w/ radioactive marker which will be included in DNA

2. have same org. grown using deuterium so DNA is heavier

use sucrose gradient to separate molecules by weight after hybridization - non-hybridized DNA from deut. org will be on bottom, hybridized will be in middle, reannealed DNA w/out deut. will be on top

pieces of DNA which change their location - discoevered in corn plants by Barbara McClintok

insertion elements & transposable elements

have insertion sequence at each end, w/ other genes (often drug resistance genes) btwn (larger)

-grouped into families based in genes btwn insertion sequences

transposase gene recognizes inverted repeats, cuts at each IR, "freeing" middle piece of sequence

transposase bound to IRs, takes to new site

NOT SEQUENCE SPECIFIC for new site (usually cuts 4-12 nucleotides apart)

inserts transposable element into cut target site, DNA polymerase/ligase fills gap, leaving IRs on either side AND repeats of target site sequence on either side of transposable sequence

element ends up replicated in new place AND still in original place

(see HANDOUT #5)

transposable elements can move to plasmids = can get plasmids w/ multiple drug resistance (R-plasmid) 

conjugation necessary - need physical contact

F+ donates genetic material

F- receives material (must be viable to make new viable cells)

plate separate = no growth

plate together = growth

proves contact btwn bacteria = conjugation

fertility! 100kb

NOT transfer of chromosomal DNA (fertility plasmid)

high frequency donor - hfr+

1000 fold

episomes that initiate transfer of chromosomal DNA from donor to recipient cell

in F+ cells there is occasionally an episomal anomaly w/ F+ plasmid integrated into chromosomal DNA

order & frequency are related to the position of the sex factor - determines frequency of transfer - further away = lower frequency

f-factor last to be replicated = rarely makes it into new genome

inserts in different places - determines order of conjugation/starting points

Laderburg did U tube experiment again, got no reduction in # of prototrophs - SO used diff sized filters

size in which prototrophs limited = size of virus gene P22

generalized transduction

P22 capable of lytic cycle

virus packaging doesnt care about sequence - cares about size

when bact. dies & chromosome breaks, virus heads package host DNA

genes close together will be more likely to be transduced together

bacteriophage λ - temperate phages

lytic infection vs lysogeny

cro required for lytic functions

if CI gains supremacy, blocks synthesis of cro, promotes lysogenic phase

when cro dominates, excisonase removes λ from chromosome, allows cells to enter lytic cycle

occurs at att sites, λ genome placed into plasmid using integrase

cell is superimmune to infection

plasmid w/ att λ = prophage, flanked by galactose & biotin

when cell under stress, cro dominates, silences CI, promotes lytic phase

protein reverses integration of λ

up to 2% of bacterial genome packaged into viral chromosome

*usually get correct excision - packaged, transferred, cell enters lytic phase

takes place @ att site BUT excision event can be erroneous

may leave part of λ gene in chromosome, or take pieces of bacterial DNA @ att sites

defective λ - contains part of bacterial DNA @ att site

may be λdgal - contains part of galactose operon

λdbio - contains part of biotin operon

can't promote new infection but can finish old one - package new viruses (w/ λd genes), kill & lyse cell, 

new λd phages able to begin infection in new cell (inject virus) but can't start lytic phase

defective λ chromosome (II)

stable transduction

If bacteria is gal- & not λ lysogenic & λdgal matches w/ gal on host chromosome, could be dbl crossover - bacterial genes switch, cell becomes gal+

stable - no viral DNA in new chromosome

if cell is λ lycogen (has resident integrated λ), instead of crossing over @ gal gene, switches @ att site = duplication - 2 copies of gal gene (- & +) & both pre-existing λ & new λ in chromosome

VERY UNSTABLE - can go into lytic cycle or throw out gal- or gal+ gene, etc

can map genes using generalized transduction b/c every piece of DNA is fair game for pathogen event

specialized transduction has limited practicality b/c only moves DNA near att sites

1st mode of genetic exchange to be discovered

1st demonstration - add virulent strep DNA to avirulent, rough strep - can convert rough strep to virulent, shiny strep

-stress response - transformation vs. sporulation

signalling transformation

(pg 3 of handout)

com genes (competence)

once DNA is in recipient cell, must be integrated

if active, blocks mecC & clpC (which prevent transcription factor comK)

stops genes involved in sporulation

allows genes that are required for transformation

recognizes concensus sequence in competency genes

suggests need of receptor @ some phase of transformation

HANDOUT PG 3

integration of new DNA into recipient cell - replaces same strand (watson replaces watson)

(hybrid) - could replicate, get mother & daughter cells (+ & -)

 or could get mismatch repair to either + or -

no muramic acid in cell walls

ether-linked, branched aliphatic chains as membrane lipid

initiator tRNA carries methionine

70s ribosomes

sensitive to anisomycin

several DNA dependent RNA polymerases

has polymerase II type promoters

methanogenesis