microbiology exam 4
stringent response pathway
stalling inhibits translation and leads to production of the alarming pppGpp (guanosine tetraphosphate and guanosine pentaphosphate) by RelA and induction of this, leads to decreased rRNA and tRNA synthesis inhibiting protein synthesis and decreasing DNA replication and cell division, cells that have triggered become dormant, antibiotic treatments select and enrich for multi drug tolerant persisters
1-2 doublings/day
growth rate of bacteria in the intestinal tract
RNA polymerase, ribosome, mRNA, DNA gyrase, chromosome, cytoplasmic membrane, cell wall
growth targets of select antibiotics
bees
gut communities of ___ are surprisingly simple and consist of a core community of only 5 dominant and culturable bacterial species in adults
transfer of DNA between organisms of the same generation
hallmark of all horizontal gene transfers
DNA major groove
has possible toxicity when used in a clinical setting
Hfr strain
has the F plasmid integrated into the chromosome
F+ cell
has the ability to synthesize sex pili, presence of a fertility factor, and ability to mate with an F- cell
F+ bacteria
have a nonintegrated F plasmid
Hfr bacteria
have an F plasmid that is integrated into their main chromosome
human virome
healthy human is teeming with viruses, not just animal viruses but also bacteriophages and possibly even some plant viruses, some cause severe diseases such as hepatitis and severe acute respiratory syndrome, some cause milder acute infections such as influenza and viruses of the common cold, some are completely benign
attachment, colonization, development, active dispersal
steps of biofilm formation
recognition of partners, nod factor secretion, invasion, bacteroid formation, mature nodule
steps of root nodule formation (5)
daptomycin
specifically binds to phophatidylglycerol residues of bacterial cytoplasmic membrane, leading to pore formation, depolarization, and death
Wolbachia
sperm of infected males can sterilize uninfected females, parasitic symbiont
age
stability of the adult microbiome and transitions with:
acetogens and methanogens
strict anaerobes that use CO2 as an electron acceptor for energy conservation, H2 is the major electron donor for both, linked to ion pumps for energy conservation fueling ATP synthase in membrane
chlorosome
structure containing antenna bacteriochlorophyll, used by some photosynthetic gram negative bacteria like the green sulfur bacterium Chlorobaculum tepidum and the green non sulfur bacterium Chloroflexus
outer membrane
structure of chloroplast #1
inner membrane
structure of chloroplast #2
stroma
structure of chloroplast #3
thylakoid membrane
structure of chloroplast #4
stacked thylakoids forming grana
structure of chloroplast #5
energy flow
sunlight > photosynthesis > gas and glucose produced > cellular respiration > ATP and heat > gas we exhale and water
light independent reaction
sunlight is not directly needed to carry out the process; example: Calvin benson cycle
fecal transplant
treatment for someone suffering from Clostridium difficile infection, reintroduce sample to someone with bad gut microbiome
active dispersal
triggered by environmental factors such as nutrient availability in biofilm formation
false
true or false: conjugation results in the formation of new offspring
true
true or false: lower respiratory tract has no normal microbiota in healthy adults
true
true or false: rRNA is found in all organisms and is highly conserved over evolutionary time
viruses
turnover in seawater is relatively rapid, the populations are replaced within a few days or weeks, most are inactivated by hydrolytic enzymes or sunlight, most numerous biological entities in seawater
saquinavir and indinavir
two computer designed HIV protease inhibitors
transformation
type of horizontal gene transfer, transfer of free DNA, requires the recipient cell to be competent, naked DNA is transferred from donor to recipient, binding DNA, uptake of single stranded DNA, Rec-A mediated homologous recombination, bacterial cell with chromosomal mutation altering target of antibiotic resistant to antibiotic>bacterial cell not resistant to microbe, lysis of cell>previously susceptible cell is now resistant to antibiotic
carotenes and xanthophylls
types of carotenoids
conjugation, transduction, transformation
types of gene transfer
with or without cytochromes
types of methanogenesis
ectomycorrhizae and end-mycorrhizae
types of mycorrhizae
acetogenesis and methanogenesis
types of one carbon metabolism
anoxygenic and oxygenic
types of photosynthesis
chlorophylls/bacteriochlorophylls, carotenoids, phycobilins
types of photosynthetic pigments
toxic and antimicrobial chemicals
widespread defensive strategy used by insects to deter pathogens and predators is the production of this, most often the product of microorganisms symbiotically associated with the insect
microenvironment
place where the microorganism actually lives
crown gall
plant tumors induced by A. tumefaciens cells harboring a large plasmid (tumor induction plasmid), plasmid has been used in genetic engineering of plants such as Arabidopsis thaliana, model organism for studying cell differentiation and plant growth, circular plasmid
persistence
population of antibiotic sensitive bacteria produces rare cells that are transiently tolerant to multiple antibiotics
inosinic acid
precursor for purines (A,G) in biosynthesis of nucleotides
uridylate
precursor from pyrimidines (C,T,U) in biosynthesis of nucleotides
R plasmids
predate human use of antibiotics, allow bacteria to grow in the presence of other microorganisms that produce antibiotics like steptomyces and penicillium, resistance genes can be obtained through horizontal gene flow via:
Lactobacillus acidophilus
predominant bacteria between puberty and menopause that ferments glycogen to lactic acid
decreases
pregnant women's gut diversity _______, enrichment of Proteobacteria and Actinobacteria
transduction
process of acquiring antibiotic resistance by means of bacteriophage activity; transfers DNA from the chromosome of one cell to another
pederin
produced by Paederus beetle to deter predators, synthesized by an endosymbiotic pseudomonas species, cytotoxic chemical (inhibiting mitosis in eukaryotes) accumulates in the insects hemolyph and is deposited in its eggs, effectively deterring arthropod predation on the eggs
light energy
produces a proton gradient to make ATP in photosynthesis; converts weak donor into strong donor in anoxygenic photosynthesis
AHL synthase
produces homoserine lactone
gag-pol-env
progenitors of retroviruses
Synechocystis
prokaryotic cyanobacterium used to study oxygenic photosynthesis
conjugation pilus
pulls the F+ and F- cells together
DNA gyrase
quinolones and fluoroquinolones act against what bacterial target?
chromosomal
random _________ mutations can lead to resistance, spontaneous mutants resistant to rifampin can be obtained by exposing a large population and selection
illnesses caused by infectious agents
ranked among the most common causes of death worldwide at the beginning of the 20th century, now 3rd leading cause of death in the U.S. and 3rd worldwide
treat with the oldest effective antimicrobial
recommendation from the CDC to limit development of antibiotic resistance
Chlorochromatium Aggregatum
relationship of consortia, epibiont has been isolated and grown in pure culture
ectomycorrhizae
remain outside the plant roots, fungal cells form an extensive sheath around the outside of the root with only a little penetration into the root tissue, found primarily in forest trees, particularly boreal and temperate forests, type of mycorrhizae found associated with forest trees like pines
extreme piezophile
require high pressure for growth, ex: Moritella (700-800 atm)
F plasmid
required by an F- cell to become an F+ cell ; key difference between donor cells and recipient cells
membrane transport proteins
required for efflux pumps, beta-lactamases, and modification of porins all utilize membrane transport proteins
primary symbiont
required for the host to reproduce in heritable symbionts, restricted to bacterium, bacterial cells found in bacteriocytes, exhibit extreme gene reduction, genome of insect symbiont (160 to 800 kbp), genome of related free living bacteria (2 to 8 Mbp), retain only genes needed for host fitness, lose catabolic genes, pathogens normally lose anabolic genes
Staphylococcus, Streptococcus, Cornyebacterium, Neisseria
resident microflora for the upper respiratory tract
mobile
resistance genes can exist on _____ genetic elements and be transferred by horizontal gene flow, resistance genes encode enzymes that inactivate antibiotic (B-lactamase cleaves a ring structure; an acetylation enzyme adds acetyl groups to chloramphenicol)
modification of drug target, enzymatic inactivation, removal via efflux pumps, metabolic bypasses
resistance mechanisms genetically encoded in 4 classes:
carbon, nitrogen, macronutrients, micronutrients, O2 and other electron acceptors, inorganic electron donors
resources that govern microbial growth in nature
decreased iron
results in lack or corepressor binding to DtxR so DtxR will be unable to bind to the operator and repress transcription of the diphtheria toxin gene, leading to greater amount of toxin production as transcription is no longer being repressed
replicative transposition
results in the transposon being copied to a new location
pentose
ribose and deoxyribose, made by removing CO2 from hexose, uses the pentose phosphate pathway
inhibition of protein synthesis
ribosomes in bacteria are 70S; eukaryotic are 80S; puromycin binds to A site in 70S ribosome, inducing chain termination and inhibiting protein synthesis, aminoglycoside antibiotics target 16S rRNA of 30S ribosome, leading to error filled proteins that inhibit growth
target RNA synthesis
rifampin and actinomycin prevent RNA synthesis by blocking RNA polymerase active site or RNA elongation
terminal electron acceptors for anaerobic respiration
role of the inorganic compound that is reduced in dissimulative reductions
provides electrons and protons
role of water in cyclic photophosphorylation
oral cavity
saliva contains antimicrobial enzymes such as lysozyme, high concentrations of nutrients near surfaces in the mouth promote localized microbial growth, dental plaque
stomach
secretion of acid (HCl), digestion of macromolecules, pH 2 but food can alter
leghemoglobin
serves as an oxygen buffer to protect nitrogenases from free oxygen in legume root nodule symbiosis
cytoplasm
site of beginning of anoxygenic photosynthesis
periplasm
site of end of anoxygenic photosynthesis
transient microorganisms
skin flora: on skin due to daily activities, unable to multiply on dry acidic skin
resident microorganisms
skin flora: reside and multiply on skin, mostly bacteria, some fungi and yeast
rhizosphere
soil immediately surrounding the root of a plant
nutrients adhere to surface and surface itself could be nutritious
solid surfaces serve as microbial habitats because:
respiration with oxygen as a terminal electron acceptor generates more energy than respiration with other terminal electron acceptors
some organisms are capable of using aerobic respiration or anaerobic respiration but use aerobic respiration preferentially. why is aerobic respiration favored?
cyclic photophosphorylation
some oxygenic phototrophs have the ability to do anoxygenuc photosynthesis using only Photosystem I
NADPH
source of the electrons that reduce 1,3 bisphosphoglyceric acid and reduce the carbon compounds (reducing power) in the Calvin cycle
species abundance
species richness or species abundance: extreme environments
species richness
species richness or species abundance: undisturbed organic rich soils
yeast Ty element
2 long terminal repeats, TyA and TyB (encodes 2 proteins), 5900 bp
resistance mechanisms to neutralize or destroy antibiotics
- lack of structure - reduced permeability to antibiotic - antibiotic inactivation - alteration of target of antibiotic - development of resistant biochemical pathway - efflux pumping of antibiotic out of cell
steps in root nodule formation
- recognition and attachment of bacterium to root hairs - excretion of nod factors by the bacterium - bacterial invasion of the root hair - travel to the main root via the infection thread - formation of bacteroid state within plant cells - continued plant and bacterial division forming the mature root nodule
cross inoculation group of rhizobia
A farmer finds that his soybean plants do not look healthy. They appear stunted and the leaves are a yellowish color, indicating possible lack of nitrogen. To have a more successful crop next year, he should consider inoculating his fields with the appropriate:
species richness decreased and species abundance increased
A small farm pond containing many species of microorganisms (bacteria, cyanobacteria, algae, and protozoa) was perturbed when runoff from a manure pile entered the pond. The added nutrients soon turned the water green due to a bloom of cyanobacteria. How did this affect the microbial community's species richness and abundance in the pond?
methanogens without cytochromes
CO2 activated by methanofuran containing enzyme and reduced to formyl (CHO), formyl transferred to a methanopterin containing enzyme dehydrated and reduced using F420, methyl transferred from methanopterin to a CoM (coenzyme M), reduction of Methyl-S-CoM to methane involving F430 and CoB, regeneration of CoM and CoB through flavin based electron bifurcation of H2
various substituents on the tetrapyrrole ring alter the absorption properties of the pigments
Chlorophyll and bacteriochlorophyll pigment molecules absorb light energy for photosynthesis. Each specific version of these molecules absorbs a different range of wavelengths of light, allowing different species of phototrophs to coexist by partitioning their use of the light spectrum. What controls the absorption spectrum of each particular chlorophyll/bacteriochlorophyll?
slower
Compared with pure cultures grown in the lab, microbes in nature usually experience a wider range of environmental conditions, more variation in conditions over time, and more contact with other organisms. Therefore, the same organism in nature will typically grow _______ than in pure culture
presence of high amounts of highly reduced inorganic compounds and methane
Deep sea ocean ecosystems in the region of hydrothermal vents typically have much higher biomass with greater presence of larger eukaryotic organisms than other deep sea ecosystems. What is most responsible for this difference?
Rhodopsuedomona
Gram-negative purple sulfur Proteobacteria
insertion sequences (IS) elements
IS1,IS2, etc, 768bp-5000+bp in length, have inverted repeats at the ends, contains transposase gene that codes for the transposase enzyme that IS1 needs to move, simplest of all transposable elements, insertion of element into chromosomal DNA at target site, gaps filled by DNA polymerase and DNA ligase, duplicated target site sequence
fermentation
NADH produced during glycolysis donates an electron to an endogenous molecule (often organic) rather than to an electron transport chain
bacterial conjugation
R-plasmids are most likely acquired via:
antenna chlorophylls/bacteriochlorophylls
absorb light energy, transfer energy to reaction center
pigment
absorbs light energy, transfers light energy to photosynthetic reaction center, embedded in or associated with the photosynthetic membranes
reaction center
accumulate energy to initiate photosynthetic electron transport
ion motive force (Na+ or H+)
acetogens conserve energy by:
attachment
adhesion of a few motile cells to a suitable solid surface in biofilm formation
MecA
alternative penicillin binding protein that is not recognized by B-lactams
equal
amount of archaea and cyanobacteria become _____ in deep sea
methanogen
anaerobic Achaea, produces CH4, can use CO2, methyl compounds, or acetate as a substrate, can be autotrophs
Embden-Meyerhof-Parnas pathway
another name for glycolysis
carotenoid
antenna pigments, widespread, absorb blue light, give wide array of color to phototrophs, photo protective role to quench toxic oxygen species
alternatives to traditional antibiotics
anti-quorum sensing molecules, bacillus subtitles SDP and SKF short peptides used to kill other cells
penicillin
antibiotic overcome by beta-lactamase, first antibiotic to be mass produced, most frequently used antibiotic
metabolic bypasses
antibiotic target is no longer essential; example: methicillin resistant staphylococcus aureus (MRSA), methicillin is a B-lactam resistant to B-lactamase cleavage, MRSA strains contain a chromosomal island called Staphylococcus chromosomal cassette for methicillin resistance (SCCmec) that encodes MecA, MRSA synthesize MecA only in the presence of B-lactams due to repressor MecI and B-lactam sensor MecR1, island encodes multi drug resistance
antibiotic
antimicrobials naturally produced by microbes as secondary metabolites, kill or inhibit other bacteria, target essential molecular processes of the bacteria they inhibit or kill
HipB
antitoxin susceptible to Lon protease
no
are babies sterile prior to birth?
dissimilative
assimilative or dissimilation: reduction of sulfate by the sulfate reducing bacteria that have a symbiotic association with ANME
biosynthesis
assimilatory reduction
aging and frailty
associated with decreased microbial diversity
evidence of extended coevolution
association is present in paleo-records, symbiotic association is obligate, loss of genes for catabolic pathways in the host, bacterial DNA is found in the host nuclear genome (symbiotic association is not obligate); loss of genes for anabolic pathways in the host
formation of the complementary strand of the F factor
at what point does a recipient cell become an F+ cell?
temperature, water potential, pH, O2, light, osmotic conditions
conditions that govern microbial growth in nature
hypertonic
bacteria are generally _______ relative to their environment causing them to burst when their cell wall is weakened by the action of penicillin and other B-lactam antibiotics
upper respiratory tract
bacteria continually enter the ____ _______ ____ from the air during breathing
PABA
bacteria that are resistant to sulfonamide have enzymes that greater affinity for:
biofilm
bacterial assemblages that form on surfaces, formation and dispersal are regulated processes, form on virtually all submerged surfaces in nature, protect organisms from antibiotics, provide defense by number, allow cells to stay in favorable niche, allow cells to live in close association (metabolic cooperation between species); implicated in cystic fibrosis, periodontal disease, infections associated with implants, pipeline congestion and corrosion, and degradation of submerged objects like offshore oil rigs and boats, growth leads to increased antibiotic resistance, makes infections difficult to treat, AcrAB-TolC efflux pumps genes unregulated when cells enter growth mode
resistant
bacterium is neither killed nor inhibited by the antibiotic
cyanobacteria
bacterium that performs oxygenic photosynthesis, oxygenic
pyruvate
bacteroids are dependent on the plant to provide fuel in the form of ________ for nitrogen fixation in legume root nodule symbiosis
Bacteroide
basic enterotype of gut microbiota in meat eaters
Prevotella
basic enterotype of gut microbiota in plant eaters
biochemical oxygen demand (BOD)
because there is low oxygen availability of organic material or reduced inorganic energy sources, the _______ ___________ _____________ in deep sea ecosystems is low
nodulated plant
benefit is increased plant yield due to nitrogen fixation
Rhizobia
best known nitrogen fixing bacteria engaging in legume root nodule symbiosis, group of species of Alphaproteobacteria or Betaproteobacteria that can grow freely in soil or infect leguminous plants, different ones infect different species of legumes, rapidly divide in the root nodule after infection, change shape and are called bacteroids that form a symbiosome within the nodule
ergosterol synthesis
best target for selective toxicity when treating a fungal infection
substituted furanone
bind to bacterial cells at the sites normally used by other signals and block the signaling molecules from delivering biofilm promoting messages, prevent biofilm formation and help to break up existing films, ideal for medical use because they are nontoxic and relatively stable in the body
bacitracin
binds to bactoprenol and prevents new peptidoglycan precursors from reaching site of synthesis
vancomycin
binds to pentapeptide precursor and prevents interbridge formation
Psuedomonas aeruginosa
biofilm mushroom, encodes several multi drug efflux pumps that are more active when cells grow in an attached state, bacteria responsible for cystic fibrosis pneumonia, cellular activity and growth take place only where oxygen can penetrate
methanogenesis
biological production of methane, catalyzed by strictly anaerobic archaea (methanogens), present in freshwater sediments and wetlands, many animal guts, sewage sludge digesters, other bioreactors, CO2 reduction by H2 via acetogenesis, form of anaerobic respiration, use reductive acetyl-CoA pathway to assimilate CO2
quorum sensing
bioluminescence is controlled by this, when AHL concentrations are high AHL binds to LuxR which then activates transcription of luxCDABE allowing the cells to become luminous, intraspecific
bromhidrosis
body odor, stench, sweat, act of, due to bacterial species on the skin giving off smelly odors, when bacterial cells on the skin multiply in the sweat they break down proteins
ferrous iron oxidation
can be aerobic or anaerobic; only small amounts of energy can be produced in acidic environments even though many of the organisms using this are acidophilic
autonomous
can transpose by themselves
biosynthesis of nucleotides
carbon from several sources, nitrogen from amino acids, purines, pyrimidines
biosynthesis of amino acid
carbon skeletons from intermediates in glycolysis or citric acid cycle, amino group derived from inorganic nitrogen source (NH3)
sweat
carries excess heat from the body by evaporation
lechuguilla cave
cave studied in Carlsbad Caverns National Park because it was believed to have been isolated from surface water and human exposure for more than 4 million years
recombinant cell
cell that receives DNA from an outside source and incorporates it into its own
competent cells
cells that can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination
integrated Tn5 transposon
cells would show resistance to the antibiotic kanamycin
nucleic acid
cellular macromolecule that comprises the fertility factor
bacteriochlorophyll
central pigment of photosynthesis, used by anoxygenic phototrophs, embedded in photosynthetic membranes
chlorophyll
central pigment of photosynthesis, used by oxygenic phototrophs, embdedded in photosynthetic membranes, molecule used to capture light energy
selective toxicity
chemotherapeutic agents should act against the pathogen and not the host
complex transposon
codes for addition genetic elements such as antibiotic resistance genes; have 2 simple transposons with another DNA sequence between them, gene that confers a survival advantage to the host
TyA
codes for gag structural protein
TyB
codes for pol polyprotein
bacteria
common genus is Pelagibacter, some types found in the photic zone carry out aerobic photosynthesis, they are the predominant prokaryotes above 1000 m
toxin-antitoxin (TA) modules
components are toxin whose production inhibits cell growth and an antitoxin that counteracts the toxin, found in almost all bacteria and many archaea, roles in both normal physiology and pathogenicity, toxic activity thought to promote cellular adaptation by slowing cell growth to ensure survival during stress
simple and complex transposons
contain a gene for transposase
non composite transposon
contain antibiotic resistance genes, contain transposase gene, no IS elements, replicative transposition, copy is made and put elsewhere
composite transposon
contain antibiotic resistance genes, have IS element at each end that contain transposase genes needed for Tn to move, conservative transposition
green sulfur bacterial consortium
contains 13-69 epiboints and a flagellated bacillus
transducing phage
contains fragments of the host chromosome instead of the viral genome; when interacting with a new host cell the DNA from the previous host can recombine with the new host chromosome
legume
contains nitrogen fixing bacteria in nodules, plants with seeds in pods and nitrogen fixing bacteria, include soybeans clover alfalfa beans and peas
small intestine
continued digestion, absorption of monosaccharides, amino acids, fatty acids, water, pH 4-5
culture independent
culture dependent or independent: using 16S rRNA gene sequencing to determine species in green bacterial consortia, using meta genomic analyses to determine whether specific bacteria have the genes for nitrogenase, sequencing termite gut microbiota to study their diversity
culture dependent
culture independent or dependent: attempting to grow the honeybee microbiota in the lab outside of the gut, producing mycorrhizal spores in the lab to develop inoculants to improve plant growth
phycobilin
cyanobacteria thylakoid membranes and red algal chloroplasts, absorb yellow or red light, act as antenna pigments, found in groups attached to photosynthetic membranes, absorbance value in the 600s
pmf
cyclic electron flow generates:
polymyxin
cyclic peptides whose long hydrophobic tails target LPS layer disrupting membrane and causing leakage and death, can also damage living human cell membranes, but the drug is safely used on the skin, where the outer layers of cells are dead
1940s
date of the discovery and development of first antibiotics for clinical use
new antimicrobial compounds
deal with drug resistant pathogens, enhance our ability to treat infectious disease, lots of opportunities, analogs of existing drugs, computer drug design, new antibiotics from as yet undiscovered organisms, new targets of antibiotics as our knowledge of bacteria grows
termite
decompose cellulose and hemicellulose, classified as higher or lower based on phylogeny, gut consists of foregut midgut and hindgut, posterior alimentary tract of higher species consist of diverse community of anaerobes including celluloyti anaerobes capable of digesting cellulose, contain both acetate and other organic acids producers, lower species consist of anaerobic bacteria and cellulolytic protists
high pressure and low temperature
deep sea organisms live in habitats characterized by:
oligotrophic
deep sea sediments are typically __________, having very low nutrient availability
microbiota
describes all the microbes in a microhabitat
deodorant
designed to eliminate odor by turning the skin pH acidic making for a more hostile environment for bacterial growth
antiperspirant
designed to prevent odor and reduce sweat production by blocking the sweat pores
early experiences
determines gut microbiome
fluorescent in situ hybridization (FISH)
determines the phylogenetic diversity of an environmental sample, how many Salmonella typhimurium cells are present in a sample of pasteurized apple juice, whether a specific piece of mRNA is being produced
methanotrophic consortia
direct interspecies electron transfer, couple the activities of 2 anaerobic microbes effectively oxidizing methane to CO2 in anoxic marine sediments, specific methane oxidizing archaea form intimate associations with sulfate reducing bacteria
bacterial nod genes
direct the steps in nodule formation
innovation gap
discovery of new antibiotics has been slow
energy metabolism
dissimilative reduction
horizontal gene transfer
done by prokaryotes examples: transduction, conjugation, transformation
conjugation
donor and recipient cells must be of an opposite mating type, requires direct contact between bacterial cells which is typically mediated by a sex pilus, R plasmid or chromosome transfer - pilius retracts - cell pairs are stabilized, F plasmid nicked in one strand - transfer of one strand from F+ cell to F- cell; F plasmid simultaneously replicated in F+ cell - synthesis of the complementary strand begins in the recipient cell - completion of DNA transfer and synthesis, cells separate
proton gradient
drives the production go ATP in cyclic photophosphorylation
antibiotic
drug will kill or inhibit the growth of all of the sensitive bacterial cells
suboptimal growth
due to suboptimal resources or growth conditions, distribution of nutrients not uniform in habitat, microbes growing in mixed populations where competition exists (reason why soil particles arent slimy)
R strain
easily killed strain of Streptococcus pneumoniae; picked up the S strain DNA enabling it to produce a capsule in Griffiths experiments
genes would be constitutively expressed
effect of a mutation in the operator of a lac operon
cyclic
electron transport in anoxygenic photosynthesis is:
not cyclic
electron transport in oxygenic photosynthesis is:
N, P, C
elements exchanged between plants and arbuscular mycorrhizal fungi
laser scanning confocal microscopy
enables investigators to view slices at different depths within a living biofilm and to stack these planes together to create a 3D representation
hip A B genes
encode TA module that triggers persistence in E.coli, normally form a stable complex preventing HipA from exerting toxicity, if Lon is activated HipB is degraded translation is inhibited and growth arrested
nodABC gene
encodes proteins that produce oligosaccharides called Nod factors
chemoorganotroph
energy and electron source is organic compound, carbon source is CO2 or organic compound
anabolism
energy consumption
catabolism
energy generation
assimilative reduction
energy input is required and the products are used for biosynthesis
dissimulative reduction
energy is conserved and the products are waste that leaves the cell
sunlight
energy to excite the electrons in photosystem I
decreases
energy yield _______ as you get lower into the sediment community
cut and paste transposition
entire transposon moves to the new location
oxygenase
enzyme that incorporated oxygen into compounds
Chlamydomona
eukaryotic Chlorophyte (green alga)
Chlorella
eukaryotic green alga used to study oxygenic photosynthesis
mycorrhizae
evolution of plants that grow on dry land is thought to have depended in part on their development of symbiotic associations with which group of microorganisms?
leafcutter ants
example of an elaborate symbiotic association between multiple microbial species and insect, established an obligate mutualism with a fungus they cultivate using small leaf fragments to feed the fungus, symbiont Psuedonocardia covers much of the exoskeleton of workers
organism uses an electron transport chain with sulfur as the terminal electron acceptor.
example of anaerobic respiration
commensalism
example: E. coli bacteria use up the oxygen in the human colon allowing obligate anaerobes to survive
pathogenicity
example: Vibrio cholerae produces an enterotoxin that causes severe diarrhea in humans, Clostridium botulinum produces a neurotoxin, causing botulism in humans if consumed
cyanobacteria, rhodophytes, chlorophytes, dinoflagellates, and diatoms
examples of phototrophic symbionts
microbial mat
extremely thick biofilm, up to several cm, layers are made of species from different microbial guilds, most commonly found in hyper saline (high salt) or geothermal (high temp) habitats that have little grazing by animals and competition, changes depending on light intensity
weather, age, personal hygiene
factors that influence composition and density of skin flora
reduce NADP+ to NADPH
fate of electrons in noncyclic photophosphorylation
used in the Calvin benson cycle
fate of the NADPH molecules created during noncyclic photophosphorylation
stem nodule formation
few legume species, more common in tropical regions, where soil is nutrient depleted and nitrogen poor due to leaching and intense biological activity, ex: Azorhizobium
antibiotic resistance is ancient
findings of investigations of source of antibiotic resistance
sulfonamide
first antimicrobial in 1930s
staphylococcus aureus
first report of antibiotic resistance in 1940s
phylogenetic FISH stains
fluorescing oligonucleotides complementary in base sequence to sequences in rRNA, general to distinguish prokaryote from eukaryote, more specific to distinguish bacteria from archaea, even more specific to distinguish certain groups with bacteria or archaea, hybridize to rRNA in ribosomes
Agrobacterium tumefaciens
forms a parasitic symbiosis with plants causing crown gall disease, to initiate tumor formation must attach to the wound site on the plant, attached cells synthesize cellulose microfibrils and transfer a portion of the Ti plasmid to plant cells, DNA transfer is mediated by vir encoded proteins
1950s
golden era of antibiotic development and use was well underway and multiple new classes of antibiotics were introduced over the next 2 decades
phycobilisome
group of phycobilins
cross inoculation group
group of related legumes that can be infected by a particular species of rhizobia
piezophile
grow best under high pressure
microbiome
functional collection of different microbes in a particular environmental system, all sites on a human that contain microorganisms are part of this
endomycorrhizae
fungal mycelium becomes deeply embedded within the root tissue called arbuscular mycorrhizae, more common than ectomycorrhizae, found in more than 80% of terrestrial plant species, but cannot be cultured in pure culture
development of biomarkers for predicting predisposition to diseases, designing targeted therapies, personalized drug therapies and probiotics
future benefits of knowing the human microbiome
persister
genetically identical but dormant, dormancy prevents antibiotic from killing cell, when treatment is stopped cells emerge from dormancy and grow, believe to be cause of recurring Mycobacterium tuberculosis and Pseudomonas aerugingsa (cystic fibrosis) infections, toxin-antitoxin modules, stringent response, and phenotypic heterogeneity
efflux pumping, modification of the antibiotic target, enzymatic inactivation of the antibiotic
genetically inherited forms of antibiotic resistance
hexose
glucose and its derivatives, obtained from the growth medium or made by gluconeogenesis
lipids
glycerol, phosphate, and various sugars added to fatty acids
polysaccharide
glycogen, starch, peptidoglycan subunits, lipopolysaccharide, made from activated glucose (UDPG or ADPG)
ruminant
herbivorous mammals, possess a special digestive organ, cellulose and other plant polysaccharides are digested with the help of microbes, organ well studied because of implanted sampling port, contains 10^11 microbes per gram of rumen constituents, fermentation is mediated by cellulolytic microbes that hydrolyze cellulose to free glucose that is then fermented producing volatile fatty acids and CH4 and CO2, fatty acids pass through the rumen wall into the bloodstream and are utilized by the animal as its main energy source, microbes also synthesize amino acids and vitamins for their animal host, serve as a source of protein to their host when they are directly digested, anaerobic bacteria dominate the rumen, contains 300-400 bacterial species (mainly firmicutes, bacteroidetes, and euryarchaeota)
obligate
heritable symbionts of insects are: (lack a free living replicative stage)
adhesive matrix
holds biofilm together
acyl carrier protein
holds growing fatty acid as it is synthesized
produces nitric oxide in the mucus and light organ
how does the bobtail squid select only Aliiovibrio fischeri for colonization of the light organ?
1
how many of the 6 G3P's produced in one cycle are used to make one molecule of glucose?
available NAD+ would be converted to NADH and glycolysis would eventually stop due to the lack of NAD+
if an organism used glycolysis to break down glucose and produce ATP but was unable to subsequently use fermentation or an electron transport chain , what problem would develop?
lysozyme, lgG/lgA, lactoferrin, human defensins
immune defense mechanisms of the human vagina
new targets of action found only in bacteria
in the search for new antimicrobial drugs, to minimize resistance developing scientists should focus on:
propionibacteria
in the sebaceous glands break down amino acids into propionic acid, vinegar smell, main organism on sebaceous skin, acne causing mainly on face
methylotroph
includes the methanotrophs which catabolize methane, can be anaerobic or aerobic, includes the ANME
nod factors
induce root hair curling, trigger plant cell division, signal legumes to develop root nodules
Rickettsia
infected white flies produce twice the number of offspring compared to uninfected flies, parasitic symbiont
enterotype
influenced by what a person eats, influences the response to diet and drug therapy and may contribute to health of disease status in yet unknown ways
specialized transduction
initiated during the lysogenic cycle of a temperate bacteriophage; particular bacterial genes are transferred to the recipient
anoxygenic photosynthesis
inorganic molecules are electron donors, does not produce oxygen, light used to generate ATP, cyclic electron flow
CO2
input of Calvin cycle of photosynthesis
light and H2O
input of light reaction of photosynthesis
6 CO2, 12 NADPH, 18 ATP
inputs of Calvin cycle
entomopathogenic nematodes
insect killing, found nearly worldwide and infect a wide range of insect hosts, researchers are studying these as a mechanism for biological control of specific species of insects, species of gram negative bacteria photorhabdus and xenorhabdus are the primary bacterial symbionts, ribosomal studies have shown that the association is very specific
colonization
intercellular communication, growth, and polysaccharide formation in biofilm formation
target DNA replication
interfere with enzymes used in DNA replication, quinolones target DNA gyrase and topoisomerase IV by interfering with DNA unwinding and replication
insertional mutagenesis
into reading frame of gene results in loss of function mutation, after gene expression by affecting promoter access
anaerobic respiration
involves an electron transport chain with an exogenous terminal electron acceptor such as CO2, SO42, and S0, used in dissimilatory sulfate reduction
direct electron transfer through nanowires
involves the use of electrically conductive pili that connect cytochromes
viruses require host cells to replicate themselves
it is difficult to attain good selective toxicity with antiviral drugs because of the fact that:
carbon monoxide dehydrogenase
key enzyme in acetogenesis, catalyzing CO2 and H2 into CO and H2O
G3P
key product formed by the Calvin benson cycle
diphtheria toxin
kills eukaryotic cells by affecting translation by preventing movement of tRNAs from the A site to the P site of the ribosome; protein synthesis will be interrupted because the peptide chain is inhibited from growing and new tRNAS will not be able to enter the ribosome
nonautonomous
lack transposase gene, requires autonomous element to transpose
lichen
leafy or encrusting microbial symbioses, often found growing on bare rocks tree trunks house roots and the surfaces of bare soils, mutualistic relationship between a fungus and an alga, consists of algae or cyanobacteria and fungi, alga is photosynthetic and produces organic matter and nitrogen fixing, fungus provides a structure within which the phototrophic partner can grow protected from erosion and with dissolved inorganic nutrients, more complex than previously considered as they contain bacterial and archaeal microbiota
inversely
levels of organic carbon and oxygen are _______ related in a river
algal layer, fungal hyphae, rootlike connection to substrate
lichen structure
cilia
lining of the walls of the respiratory tract that beat upward pushing bacteria and particulates up to be expelled in saliva and nasal secretions
autotrophic chemolithotrophs
live near hydrothermal vents
aerobes and facultative aerobes
lives in the oxic zone
oxygenic phototrophs
lives in the photic zone
fermentative and other anaerobes
lives in the sedimentary anoxic zone
large intestine
location of archaea in the human body, absorption of bile acids, vitamin B12, pH 7 (same as mouth), more microbes than body cells
chromosomes, cytoplasmic membrane, thylakoid membranes
location of pigment in prokaryotes
coral bleaching
loss of color caused by lysis of symbiont, high temperature and high light impair the photosynthetic apparatus of dinoflagellate, nearly half of the great barrier reefs has experienced this in the past few years, different species of symbiodinium tolerate different temperatures, different stress tolerances
thylakoid space
lowest pH in cyclic photophosphorylation
Bacteroidetes
main microbial population in gastrointestinal tract
Streptococcus
main microbial population in saliva
Lactobacillus
main microbial population in urogenital tract
Propionibacterium
main microbial population on skin
betaproteobacteria
main organism on dry skin
corynebacteria
main organism on moist skin
firmicutes, bacteroidetes, proteobacteria
main organisms of saliva
glucose
main source of energy for fermenters
volatile fatty acids
main source of energy for ruminants
Wood-Ljungdahl pathway
major CO2 fixation pathway in obligate anaerobes, also known as reductive acetyl-CoA pathway, conservation, not a cycle, uses 2 linear pathways reducing CO2 to methyl group of acetate (methyl branch) and other to carbonyl of acetate (carbonyl branch),
H2
major electron donor for methanogensis
Proteobacteria, acidobacteria, bacteroides
major organisms growing in soil
halophiles, Proteobacteria
major organisms in deep sea
Proteobacteria, actinobacteria, bacteroidetes
major organisms in freshwater lakes
bacteria
make up 1/3 of feces, necessitates sanitation for clean drinking water
mycorrhizae
many plant species grow better with _________ associated with their roots
archaea
most of these living below 1000 m are thought to be ammonia oxidizers, below 1000 m the most common phylum is Thaumarchaerota, increase to near 50% of total prokaryotes below 1000 m
parasitism
microbe that benefits at the expense of its host without causing a disease
symbioses
microbes live with macroorganisms and other microorganisms in long term relationships, interactions where both organisms interact to the benefit of both, most mutualistic organisms evolved together (coevolution) over millions of years
protons entering the cell must be consumed to prevent the cytoplasm from becoming too acid; therefore electrons are required as H+ combined with O2 to form water
microbes that thrive in acid environments seem to have cost free ATP energy available to them due to the pre existing H+ gradient across the cytoplasmic membrane. this is not entirely true because:
ecosystem
microbial communities and their natural environment
guilds
microbial communities consist of _____ of metabolically related organisms
consortia
microbial mutualism of green sulfur bacteria (epibiont) and a flagellated rod shaped bacterium in freshwater, found in stratified sulfidic lakes, discovered over 100 years ago but details unknown until modern culture methods and molecular techniques allowed for more detailed studies
environmental reservoirs (horizontal transmission) or parents (vertical or heritable transmission)
microbial symbionts can be acquired from:
urogenital tract
microflora varies, bacteria and yeast present, urethra (urination regularly eliminates microbes), vagina (ethnicity and age), penis (circumcision lessens amount and composition)
elements (C, S, N, Fe)
microorganisms recycle _______ in the environment
transposable element
mobile genetic element, rearrangements within genome, DNA segment that can move from one position to another in the genome by non homologous recombination, cause mutation by insertional mutagenesis, found in prokaryotes and eukaryotes
development
more growth and polysaccharide in biofilm formation
bacteriophages
most abundance viruses in all body sites, likely play a protective role in human health, can be a first line of defense against certain pathogens especially within mucosal surfaces, 20 times more than bacteria exist in the mucosa of lungs and intestines, can be considered to have a symbiotic relationship with the human host and provide a form of host independent immunity
Prochlorococcus
most abundant photosynthetic microbe in oceans
mucus
most bacteria are trapped in the ____ of the nasal and oral passages and expelled with nasal secretions or swallowed then killed in the stomach
Calvin cycle
most common pathway for carbon fixation for biosynthesis
reef building corals
most ecologically significant between stony coral and dinoflagellate symbiodinium, harbors the dinoflagellates inside its cells in special vesicles called symbiosomes that are analogous to the nodule structures found in legumes, improves the light gathering capacity of dinoflagellates while the photosynthesis of the dinoflagellates provide organic nutrients, reproduce sexually by releasing gametes into the seawater, algal symbionts are found in the egg (vertical transmission), regulates cell division of the dinoflagellate with the newly formed dinoflagellate cells forming new symbiosomes within, developing can also ingest dinoflagellates
wavelengths
pigments absorb different _________ of light
cells must come into contact with each other
must occur for bacterial conjugation to take place
constitutive mutant
mutation that disables the repressor
silent mutation
mutation that doesn't result in antibiotic resistance
mycorrhizae
mutualistic associations of plant roots and fungi, fungus transfers inorganic nutrients from the soil to the plant while the plant donates carbohydrates to the fungus, improve nutrient absorption due to the greater surface area provided by the fungal mycelium, help to promote plant growth
legume root nodule symbiosis
mutualistic relationship between legumes is one of the most important symbioses known, infection of legume roots by nitrogen fixing bacteria leads to the formation of root nodules that fix nitrogen, leads to significant increases in combined nitrogen in soil, nodulated legumes grow well in areas where other plants would not, nitrogen fixing bacteria need O2 to generate energy from N2 fixation but the enzymes that fix nitrogen (nitrogenases) are inactivated by O2, in the nodule free oxygen is bound up by O2 binding protein leghemoglobin, characterized by oxygen sequestration, several metabolic reactions, and nutrient exchange
antimicrobial drug resistance
natural phenomenon, ability of a microorganism to resist the effects of a chemotherapeutic agent, accelerated by the careless use of antibiotics by humans
loss of 9
net total gain or less of ATP after one cycle of the Calvin benson cycle
both photosystem I and II
noncyclic photophosphorylation employs which photosystems?
secondary symbiont
not required for reproduction, not always present in every individual, can invade different cells and live extracellularly, must provide a benefit (nutritional, protection from environment, protection from pathogens)
1
number of ATP generated from conversion of acetyl-CoA to acetate by substrate level phosphorylation in acetogenesis
10^13
number of microbial cells in the human microbiome living in complex communities
3-4 million
number of sweat glands in a typical human
Archaea and Bacteriodetes
obese individuals have more methanogenic:
mutualism
obligate relationship in which both organisms benefit, example: mycorrhizae help plants absorb nutrients while receiving carbohydrates from the plants, honeybees have gut microbes that help them to digest sugars while the microbes gain a safe place to live and a supply of food, marine invertebrate/bacteria, riftia giant tube worm and sulfide reducing bacteria
HipA induced persistence
occurs in cells randomly producing higher amounts of PolyP signal molecule (phenotypic heterogeneity)
photosynthesis
occurs in the photosynthetic reaction center, series of electron transport reactions, creates proton motive force, ATPsynthase synthesis of ATP
aerobic H2 oxidation
often involves the hydrogenase enzyme, often occurs most efficiently in a microaerophilic environment
Staphylococcus epidermidis
on the skin, degrades amino acid leucine into isovaleric acid
simple transposon
only codes for the transposase gene essential for the transposon itself
10 um
only particles smaller than about __ in diameter reach the lungs; these include some pathogenic microbes, most notably certain bacteria and viruses that causes pneumonia
staphylococcus aureus and streptococcus pneumoniae
opportunistic pathogens of the upper respiratory tract
baby microflora
oral bacteria from mother are found in the placenta, amniotic fluid and fetal meconium have microbes, further colonized by microorganisms in the days after birth (air, food and water, people)
green sulfur bacteria
organism that has a chlorosome, obligate anaerobic phototrophs that make up nearly 70% of the bacterial biomass in lakes
syntroph
organisms that accomplish the catabolism and degradation of a substance through a cooperative effort with one or more other microorganisms
methyl
orginates from reduction of CO2 in reactions requiring tetrahydrofolate, corrinoid iron-sulfur protein, and acetyl-CoA synthase in acetogenesis
glucose
output of Calvin cycle of photosynthesis
O2
output of light reaction of photosynthesis
6 carbon molecule, 12 NADP+, 18 ADP, 17 P
outputs of Calvin cycle
decreases
oxygen ______ when going through fermentation vessel in large intestine
increases
pH of the vagina _______ with birth control, more prone to infection
2 gram negative Proteobacteria, 2 lactobacillus species, and a Bifidobacterium species
pack the lumen of the honeybee gut
photo
part of photosynthesis that describes the light driven electron transport to make ATP
synthesis
part of photosynthesis that describes using ATP to make cell material via the Calvin Benson cycle and other biosynthetic pathways
sebaceous gland and apocrine sweat gland
parts of skin layer that microorganisms most associate with (moist and warm)
growing
penicillin kills only ________ bacterial cells
B-lactam
penicillin, cephalosporin, derivatives, interfere with transpeptidation (formation of cross links) between muramic acid residues
autotroph
perform CO2 fixation and utilize CO2 as their sole carbon source
aerobic ammonia oxidation
performed by archaea and bacteria and produces nitrite; bacteria may oxidize the nitrite to nitrate
antibiotic exposure ends
persisters exit stringent response pathway and produce antitoxin returning protein synthesis to normal and allowing cells to grow, left with resistant population but will get susceptible population from environment
6CO2 + 6H2O + light > glucose + 6O2
photosynthesis equation
small subunit ribosomal RNA genes
phylogenetic diversity analysis of complex microbial communities often targets:
bioluminescence
symbiotic function of Allivibrio fischeri in the light organ of the Hawaiin bobtail squid, both species can be grown in lab, simple symbiotic relationship with a single microbial symbiont, squid harbors large populations of A. fischeri in a specialized light organ, bacteria emit light that resembles moonlight penetrating marine waters which camouflages the squid from predators, A. fischeri supplied with nutrients by the squid
biosynthesis of fatty acids
synthesized 2 carbons (acetyl unit) at a time, acyl carrier protein holds growing fatty acid as it is synthesized
platensimycin
target of action is lipid biosynthesis
insertion sequence
targets a sequence of nucleotides identical to the inverted repeat sequence found on itself; capable of effecting their own movement from one location to another on DNA, when transposase gene is mutated it would lose its ability to effect its own movement
symbiotic bacteria in their gut
termites are capable of digesting cellulose and hemicellulose due to the presence of:
generation times; growth rates
the conditions of nutrient availability, pressure, and temperature in deep sea ecosystems results in long __________ ____ and thus slow ______ ____
competition
those most fit for a microenvironment become resident flora
symbiotic gut bacteria
to help digest sugars, honeybees have:
piezotolerant
tolerate elevated pressure but grow best at low pressure
dental plaque
tooth serves as a surface for the formation of biofims
HipA
toxin that inhibits translation, targets glutamyl-tRNA synthetase (GltX), leading to ribosome stalling, inhibiting translation and protein synthesis
generalized transduction
transfer of any gene from one bacterium to another via a virus, initiated during lytic cycle of a virulent bacteriophage; phage infects the bacterial cell thereby transferring bacterial plasmid and/or viral DNA to the recipient, homologous recombination
bacterial plasmid
transferred during bacterial conjugation
NADPH and ATP
transferred from light reaction to Calvin cycle in photosynthesis
thermocline
transition between the warmer upper layers and the colder lower layers of water in freshwater
horizontal
transmission of bacterial cells in relationship between squid and A. fischeri, light organ is colonized by A. fischeri shortly after juvenile squid hatch, no other microbes are able to colonize due to nitric oxide a strong oxidant which A. fischeri can detoxify
bacterial insertion sequence elements and transposons
transposable elements that move as DNA
yeast Ty retrotransposons
transposable elements that move as RNA (convert to DNA for integration)
conservative transposition
transposon is cut from one location in genome and pasted into a new location
efflux pump
ubiquitous and transport various molecules including antibiotics out of the cell, lowers intracellular concentration allowing cell to survive at higher external concentrations, many act promiscuously and transport different antibiotic classes contributing to multi drug resistance, increase antibiotic resistance in bacteria by having more and less specific in resistant bacteria, example: AcrAB-TolC of E. coli (pumps out rifampicin, chloramphenicol, fluoroquinolones_
photosynthetic eukaryote
unique trait is the presence of chloroplasts
acetogenesis
use H2 and CO2 to produce acetate, other electron donors include methanol, methoxylated aromatics, other organics, some nitrogen bases, many can ferment or anaerobically respire nitrate or thiosulfate, reduce CO2 to acetate by reductive acetyl-CoA (Wood-Ljungdahl) pathway, some grow cdhemoorganotrophically by sugar fermentation or chemolithotrophically and autotrophically through reduction of CO2 with H2 to acetate, both iron pumps and substrate level phosphorylation are used to conserve energy,
mixotroph
use inorganic compounds for energy and organic compounds as a carbon source
chemolithotroph
use inorganic electron donors and CO2 as a carbon source
chemotroph
use inorganic or organic chemicals as energy sources
phototroph
use light as an energy source and CO2 as a carbon source
heterotroph
use organic carbon as their carbon source
water, sunlight, and carbon dioxide
used in photosynthesis by both plants and cyanobacteria
microautoradiography (MAR-FISH)
used to determine the ability of an organism to use a substrate
microsensor
used to determine the rate of production of carbon dioxide in a specific microbial habitat without growing the microorganisms in the lab
microelectrodes
used to make direct measurements of chemical conditions in biofilms, needle shaped, oxygen concentration varies radically between locations as close as 5/100 mm apart
agriculture
uses 64% of antibiotics
photoautotroph
uses carbon dioxide as their carbon source
D. pulchra
uses chemicals (substituted furanones) to keep free of biofilms
purple sulfur bacteria
uses hydrogen sulfide for reducing power, employ an oxygenic photosynthesis with hydrogen gas, sulfur compounds such as hydrogen sulfide, or sulfur as an electron donor (reducing power) in photosynthesis
photoheterotroph
uses organic compounds as their carbon source
coral skeleton
very efficient light gathering structure in reefs
Anabaena
water fern Azolla contains a species of heterocystous nitrogen fixing cyanobacteria known as:
oxygenic photosynthesis
water its the electron donor, produces oxygen, light used to generate ATP, Z scheme electron flow
beneficial genes
what benefit does the F- strain receive from mating with an Hfr strain?
alga produces organic compounds as nutrients for the fungus
what benefit does the final partner get from the lichen relationship?
cells have a capsule
what characteristic of the S strain allows it to evade the immune system of mice?
acylated homoserine lactone
when enough cells assemble in biofilm, the concentration of ________ ________ _______ increases which then changes the activity of many genes allowing the cells in a biofilm to recruit more cells, bioluminesce, make antibiotic, regulate virulence factors (release toxins)
mitochondria
where cellular respiration occurs
return to photosystem I
where do the electrons from photosystem I ultimately go after they are passed through the electron transport proteins?
surface of soil particles around plant roots in the rhizosphere
where does most terrestrial microbial growth occur?
chloroplast
where photosynthesis takes place, location of pigment in eukaryotes
humans and animals lack peptidoglycan cell walls
why are chemotherapeutic agents that work on the peptidoglycan cell wall of bacteria a good choice of drug?
expensive, FDA not approving, takes time, overprescribed
why are new antibiotics not being produced?
conjugation is disrupted before the fertility factor can be transferred
why does conjugation between an Hfr strain and an F- strain not result in 2 Hfr strains?
penicillin disrupts the cell wall, which is located outside of the cell membrane
why would an efflux pump for penicillin located on a bacterial cell membrane not be effective at providing resistance to the drug?