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?