Microbiology exam 2

How long does it take an E.coli cell to multiply

essential nutrients

6 microorganisms needed macronutrients

macronutrients are needed and in large amounts while micro nutrients are needed but in very small amounts

6 micronutrients all cells need

why are the micronutrients needed

breaking down molecules for energy

using E to rebuild cell components, reduces entropy

central biochemical pathways used for the balance between catabolism and anabolism

3 examples of metabolism

all life requires are these 3

drives ins into/out of cells and is used to create ATP

materials to make cell parts example is nutrients

predominant E source in microbial metabolism is

How is the E source of microbial metabolism electricity

electron flow requires these 2

2 sources of electrons for electron flow needs

inorganic molecules are electron donors for this source of electrons

organic molecules are electron donors for this source of electrons

inorganic molecules that act as ultimate electron acceptors are these 2

organic molecules that act as ultimate electron acceptors is

ultimate electron acceptors are these 2 kinds of molecules

2 sources of E for microbial metabolism

excited molecules are electron donors in this source of energy obtaining microbes

chemicals are electron donors in this source of E obtaining microbes

carbon source for biomass

CO2 assemble into organic molecules

acquired organic molecules as carbon source

a chemotroph that obtains its electrons and carbon from organic molecules (organotroph)

a chemotroph that obtains its electrons from inorganic molecules and its carbon from CO2 (lithotroph)

a phototroph that obtains electrons from water (oxygenic) and carbon from organic molecules

a phototroph that obtains electrons from sulfuric acid (anoxygenic) and its carbon from CO2

most organotrophs are also heterotrophs

must be supplied from the environment

4 ions necessary for protein function

different microbes require different additional nutrients

contains only the compounds needed for an organism to grow

N2 makes up 79% of earth's atmosphere but is unavailable for use by most organisms

oxidize ammonia to nitrate

convert nitrate to N2

N2>nitrogen fixers>NH4>nitrifiers>NO3>denitrifiers>N2

nitrogen fixing bacteria may b free living in soil or water, or they form symbiotic association with plants

3 functions of symport and antiport active transports

electron transport creates PMF which transports other molecules

ATP binding cassette (ABC transporters) are the superfamily of transporters

ABC transport functions

3 functions of siderophores (nutrient uptake)

active transport of nutrient uptake

3 characteristics to PTS

PTS explained: glucose enters cell and s phosphorylated. As a result, gradient of G pushes more G inside while the phosphorylated ones cannot leave

has all materials necessary for growth

what are the 4 components of a culture media

the culturing media varies for different bacterial species.

A culturing media needs an energy source if its

A culturing media needs a carbon source if its

A culturing media needs a nitrogen source if its

6 different types of culture media

2 functions of MacConkey medium

are nutrient rich and poorly defined

are precisely defined

are complex media to which specific blood components are added

favor the growth of one organism over another

exploit differences between two species that grow equally well

all cells in a colony derive from a single cell

the single cell makes a colony that contains cells that are genetically identical (clone of that original cell)

2 dilution streaking characters

dilution in liquid culture does what when it comes to obtaining pure cultures

what does dilution in liquid culture determine

in dilution in liquid culture you spread liquid on plate to see single colonies

disadvantage of petroff hausser chamber when looking at cells

counts cells directly using microscope and gives accurate numbers

in the petroff hausser chamber directly in the middle, there are 25 groups of 16 small squares

measures optical density and gives rapid measurement

disadvantage of spectrophotometer

in spectrophotometer the solution must be 10^7-10^10 cells/ml

3 viable counts characteristics

cells are synthesizing materials and are not dividing

exponential growth, doubling of growth

log phase increases linearly

cells are no longer growing

4 phases of the growth cycle in a liquid batch culture

g=t/n generation time

cells secrete material to hold to a surface

4 characteristics of biofilms

when cells act together in biofilms they could be from multiple or single species

when cells signal to each other in biofilms

when bacteria are faced with environmental stress, they undergo molecular reprogramming such as changes in cell structure

these two spores can produce dormant spores that are heat resistant

when starvation initiates, an 8 hour genetic program occurs that involves

sporulation can be divided into discrete stages based primarily on morphological appearance

2 ways cells respond to a changing environment

in heterocysts, the different cells produce different nutrients

What heterocyst cells produce energy

what heterocyst cells fix nitrogen

in response to the environment, these kind of cells form inside fruiting bodies

the fruiting body formed by myxospores is a multicellular structure

actinomycetes respond to the changing environments by

when do actinomycetes form spores

3 functions of the spores created by actinomycetes

micronutrients are required by cells because they are components of cofactors, what are cofactors

how were microbes found

the critical process of the carbon cycle involves these 2 metabolic groups of organisms

is a cell molecule critical to energy metabolism

build biomass by fixing CO2 into complex organic molecules

autotrophs gain energy through 2 metabolic routes

produces E from oxidizing inorganic molecules such as iron. E is used to fix CO2 into biomass

a type of photosynthetic microorganism produced most of the oxygen we breathe and form the base of the food chain

nitrifying bacteria gain E by oxidizing ammonia to produce nitrate

E stored by an electrical potential across the membrane is known as

chemical energy in a cell

2 types of E useful to the cell

how is membrane potential generated?

capable of utilizing photosynthesis or heterotrophic respiration depending on environmental conditions

3 ways selective permeability is achieved

nutrients that aren't permeable to the mem, microbes secrete digestive enzymes that breakdown the molecule into smaller compounds

facilitated transport cannot move a molecule against its gradient

most important facilitated diffusion transporters are those of the aquaporin family that transport water and glucose

most common chemical gradient used are those of ions, specifically +

electron neutral coupled transport in which there is no transfer of charge antiporter

a healthy cell maintains proper charge balance using the electron transport chain to move protons in and out of cell, nonbalanced mem, it cannot carry out simple transport that it needs to sustain life

major function of proton transport is to create the PMF that powers ATP synthesis

ABC transporters are used as multidrug efflux pumps that allow microbes to survive exposures to hazardous chemicals

microbes have the fastest and slowest growth rates of known organisms

the environmental habitat that a species inhabits is based on one main criterion

4 environmental limits of microbial growth

growth rates increase with temp but if too high proteins denature

type of microbe that can withstand 0-20 C

type of microbe that can withstand 12-45 C

type of microbe that can withstand 40-80 C

type of microbe that can withstand 65-113 C

what is a microbes response to high temp

2 occurrences to heat shock response

2 kinds of emergency proteins produced in heat shock response

what 3 cause heat shock response

are adapted to high pressures

they can grow at high but not too high of pressure

they die at high pressure

measure of how much water is available for use

the measure of the # of solute moleules in a solution

this is inversely related to water activity

these help protect the cell from osmotic stress

solutes raise osmolarity

these organisms require high conc of NaCl and live in salt seas

ph levels alter the conc of protons

bacteria regulate internal ph

these organisms grow at a pH of 5-8 and have bacteria in their gut

these organisms grow at pH of 0-5

grow at a pH of 9-11

can only grow in O2

grow only at lower O2 levels

die in the presence of O2

grow in oxygen while retaining a fermentation based metabolism

anaerobes pass electrons to different ultimate electron acceptors

have inorganic electron acceptors

have substrate level phosphorylation as electron acceptors

two enzymes exist to neutralize the toxic forms of oxy formed as byproducts of reduction of oxygen

4 types of toxic oxygen

4 ways to control measures of microbes

killing of all living organism

killing or removal of pathogens from inanimate objects

killing/removal of pathogens from the surface of living tissues

reducing the microbial pop to safe levels

D-value

2D-values

antimicrobial agents decrease D-value

moist heat is more effective than dry heat

boiling water kills most cells

killing spores and thermophiles usually requires a combo of high pressure and temp (autoclave)

steam autoclave

diff time and temp combos can be used for this

in pasteurization low temp=long time high temp=short time

this slows growth and does not kill all bacteria

viruses are not removed in this method of physical agents

2 functions of disinfectants

this chemical agent is benchmark comparison to phenol and examples of it are chlorine and iodine

this chemical agent is less toxic for living tissues and has conc

3 chemicals that damage proteins, lipids, and DNA

commercial disinfectants and antiseptics are used to reduce or eliminate microbial content from objects

this chemical agent selectively kills microbes and may not work on all species

3 characteristics of antibiotics

slow growing bacteria take longer to die

this blocks cell wall synthesis

good bacteria that displace disease organisms from tissues

bacteria can undergo cell diff in response to environmental stress

a medium containing bile salts and crystal violet selects for growth against

if 1 ml of a 10^-4 dilution of a cell culture yields 98 colonies on an agar plate, how many colony forming units/ml are there in the original culture?

endospores are resistant to many stresses that would kill vegetative cells

endospores are durable and can remain viable for years

if an enzyme of the PTS system was nonfunctional, the import of all substrates dependent on the PTS system would eventually stop

these help move iron into bacteria

if a bacterium can divide once an hour, after 5 hours, 1 bacterium will yield

how is a continuous culture different from a batch culture

biofilms may cause health problems for humans

complex media are easier to prepare than synthetic media and bacteria grow faster on complex

cyanobacteria is an example of

cells are more negative inside, so when couple transport moves nutrients into the cell against their conc gradient is most likely to occur along

these kind of transporters bind ATP on the intracellular side of the cell mem

a permease that moves an uncharged sugar into the cell along with a protein, this is classified as

these organisms need to ingest reduced carbon

autotrophs are self feeding
lithotrophs generate ATP from reduced inorganic compounds
phototrophs generate ATP through light E

of cells in batch culture, they will not remain at a constant mass

a bacterial pathogen that can cause an infection in the blood is most likely a

barophiles are also psychrophilic because that are usually found in cold ocean depths

organisms with high rate of growth at low nutrient conc

organisms that must use O2 as a final electron acceptor in ETC are

piezophiles are also known as

aerobes may tolerate the presence of O2 because they have the enzyme

is the addition of nutrients to an ecosystem

eutrophication may lead to decreased microbial diversity

many alkalphiles have a sodium motive force because it will be hard to maintain a PMF in an alkaline environment

phage therapy refers to

bacteria cannot regulate their temp

chemotrophs whether they be auto or hetero oxidize and reduce compounds to get E

in chemotrophy, the amnt of E gained from Ox a compound if related to the compounds red state. The more red the compound is, the more e- it has to give up and the high the PE yield.

chemoautotrophy is the same as

fungi require complex organic molecules for their growth; some of their lifestyles involve these 3

obligate intracellular bacteria lose metabolic pathways provided by their host and develop requirements for growth factors supplied by their host

autotrophs male complex organic molecules that are consumed by

eukaryotes carry out only a limited range of heterotrophic and photo rxns

how do symports and antiports function

the inside of the cell has to be kept negative while the outside is to remain positive

ABC transporter consists of 2 hydrophobic proteins, that form a membrane channel and two peripheral cytoplasmic proteins that contain a highly conserved amino acid motif involved with binding ATP

amino acid sequence found in a family of proteins

the uptake systems of ABC transporters possess an additional extracytoplasmic protein called

SBP have a high affinity for their matched solutes, their use increases the efficiency of transport when conc of solutes are low

SBP binds to the face of the protein to open the channel after a structural change is made to open

once the signal is received from the opened channel with the SBP, the nucleotide binding proteins start to hydrolize ATP and signal the channel to open the cytoplasmic side to allow the entrance of solutes

Fe scavenger molecules secreted from siderophores occurs when intracellular iron conc is low

PTS is a well characterized group trabslocation system present in many bacteria

eukaryotes undergo exocytosis to and endocytosis to bring in and take things across the cell membrane, they also have pumps as well

lysosomes bind with phagosomes to creat phaglysosomes which help the digestive enzymes breakdown the endocytosed material

this medium is useful when

this kind of media is useful when trying to separate mixtures of diff organisms as they are found in the natural environment

spread plate starts from a liquid batch of bacteria, a series of tenfold dilutions is made and a small amount od each dilution is placed directly on the surface of the agar plates

an organism that successfully replicates to form a colony

CFU are chains of cells that have not split and look like a group of cells

straightforward approach to monitoring pop growth is the measure the dry weight of a culture from cells collected by centrifuge, washed and dried in an oven then weighed.

optical density of light scattered by bacteria is a very useful tool for estimating pop size

if a cell produces 2 cells per generation then it will be 2^n

bacteria divide at a constant interval called

generation time varies with respect to the species, type of medium, temp, and ph

no fresh media is added during the incubation of this kind of culture

simplest way to model the effects of changing conditions is to culture the bacteria in a liquid medium within a closed system called

batch media illustrate the remarkable ability of a bacteria to adapt to their environment

a chemostat in which a photoelectric cell constantly monitors the optical densityof the culture

biofilms can be cued by different environmental signals such as ph, Fe conc, temp, etc.

starvation triggers a developmental cycle in which 100,000 of more individuals aggregate rising into a mound called a fruiting body

are bacteria that form mycelia and sporangi analogous to a filamentous structures of eukaryotic fungi

this allows us to study the biology of organisms that we cannot culture

this reveals whether or organism under study may possess specific metabolic pathways and regulatory responses

every organism has an optimal that in which they perform their best at, while they also have a minimal and a maximum which limits them to what they can handle

log k=C/T

2 reason as to why psychrophiles like cold

psychrophile enzymes are of commercial interest because of their ability to carry out reactions at low temps, this could help with food processing

thermophiles proteins do not unfold as easily so they can hold their shape at higher temps

like all microbes thermophiles have chaperone proteins that help refold other proteins as they undergo thermal denaturation. Their genomes are packed with DNA binding proteins hat stabilize DNA and make it less likely to denature

the membranes of the thermophiles glue together parts of the 2 hydrocarbon layers making them more stables

chaperones function in heat shock response

increased hydrostatic pressure and cold temps similarly reduce membrane fluidity

most bacteria require how much water activity in order for them to grow

2 other mechanisms microbes have to help minimize osmotic stress across membranes

are small molecules hat do no disrupt normal cell metabolism even when present at high intracellular concentrations

function of pressure sensitive channels in microbes as a minimizer to osmotic stress

% and M of NaCl do halophiles need in order to grow
% and M of NaCl do most bacteria need to grow

how can halophiles live in high salt conc environments?

high conc of hydronium or hydroxyl ions in a solution will limit the growth of microbes

Altering the PH can alter changes of various amino or carboxyl groups within a protein which can change the proteins structure and activity

the Ph and the osmolarity of a microbe is not dictated by its outside environment

the cell can become acidic when weak uncharged permeable acids can cross the cell and then dissociate which releases a proton that acidifies the internal pH

these organisms can oxidize reduced metals and generate strong acids such as sulfuric acid. They are also known as chemoautotrophs

these organisms are commonly found in saline soda lakes which have high salt conc and pH values

most alkaliphiles use a Na motive force in addition to PMF because external protons are in such short supply at the alkaline pH

when cells are placed in pH conditions below their optimum, protons can enter the cell and lower the internal pH to lethal levels.

Microbes can prevent the unwanted influx of protons by exchanging extracellular potassium for intracellular protons when internal pH gets too low

Under extreme alkaline conditions, the cells can use the Na/H antiporters to recruit protons into the cell in exchange for expelling Na

bacterial physiology undergoes a major molecular reprogramming in response to hydrogen ion stress. some of the physiological responses are these 2

acid and alkaline stress responses occur when

the use of O2 as the terminal electron acceptor is called

electrons are pulled from various E sources. They do this by extracting the E in stages and using it to move protons out of the cell. This unequal distribution of H+ across the mem produces a transmembrane electrochemical gradient called PMF

this enzyme removes oxide in anaerobes

these 2 enzymes remove hydrogen peroxide in anaerobes

aerobes have resourceful enzyme systems that detect and repair macromolecules damaged by oxidation

facultative anaerobes

these can only use fermentation as E but contain superoxide dismutase and catalase to protect them from reactive oxygen species

anaerobic respiration

fermentation depends on these two factors

3 techniques for culturing anaerobes

this kind of technique, enzyme systems can eliminate dissolved oxy so that it can be added to ordinary liquid media

this technique has the organisms streaked and placed into a sealed jar with a foil packet that releases H2 and CO2 gases

this technique has the atmosphere removed by a vacuum and replaced with a mix of N2 and CO2 gases

in result of a starvation response, the metabolic slowdown generates increased conc of critically important small signal molecules such as _____ and _____ which transforms gene expression

when the environment continues to get worse, the organism has stress survival genes that become active, these genes protect against stressors such as reactive oxy rad or temp and pH extremes

what happens when eutrophication occurs amongst microbes

what causes eutrophication

antimicrobials can either inhibit growth or kill the cells completely

the ability of an antimicrobial agent to kill microbes influence the D-value

it takes all cell in a population a while to die because not all proteins and genes in a X are damaged by an agent at the same time

assume all cells in a pop are identical

vegetative cells

boiling water at 100 C can kill most vegetative cells

the bombardment of foods with high E electromagnetic radiation

3 sources of irradiation

the amount of E transferred to food, microbes, or other substance being irradiated

parasites that have a large amount of DNA are killed rapidly by

it takes more radiation to kill bacteria because they have less DNA/cell unit
.3-.7 kGy

viral pathogens have the smallest amount of nucleic acid making them resistant to irradiation doses

irradiation is effective in eliminating parasites and bacteria but not viruses or prions

those that don't contain nucleic acid are only inactivated by irradiation at extremely high doses

Deinococcus radiodurans  is known as conan the bacterium because

a chemical on a dirty surface will bind to the inert organic matter and lower the agents effectiveness against microbes

4 factors that influence the efficiency of a given chemical agent

the chemical agent should be effective against a broad range of pathogens

the disinfectant should not corrode the surface ex skin

the chemical should be stable upon storage, possess a neutral or pleasant odor or have low surface tension so it can penetrate cracks and crevices

3 reasons why phenolics are useful disinfectants

detergents can also be antimicrobial agents, the hydrophob and phil ends of detergent molecules will emulsify fat into water

+ are useful as disinfectants because they contain + charges that can gain access to the negatively charged bacterial cell and disrupt membrane

very effective sterilization it destroys cell proteins and penetrates packing material

chemical disinfectants are compared to one another based on the phenol coefficient

are compounds produced by one living microorganism that kill other microorganisms

the measure of how much more heat is needed to reduce D-value to 1/10 its original value