BioS 350 Micro Exam 3

halophiles

-"salt-loving" archaea that live in environments that have very high salt concentrations -require salt for growth -Found in marine environments where salt concentrations are around 3.5% -Increase potassium ion as internal osmolyte -Example: Aliivibrio fischeri

Transposons

-(transposable elements), or "jumping genes," are molecules of DNA that include special inverted repeat sequences at their ends and a gene encoding the enzyme transposase -Allows an entire sequence to independently excise from one location in a DNA molecule and integrate into the DNA elsewhere (transposition) -Discovered in corn -Not prokaryotic-specific -Non-replicative - cut and paste fashion or copy and paste -Have ability to introduce genetic diversity b/c they move within a DNA molecule from one DNA molecule to another or from one cell to another -May carry additional genes and move them from one location to another -can alter the DNA of prokaryotic and eukaryotic cells -may replicate while moving, resulting in more of these in the cell -can move onto plasmids which can then be transferred to another cell

Refrigeration

-1 of 2 cold control methods -0-7 C used in home kitchens or lab -Inhibits microbial metabolism and slowing microorganism growth (NOT sporicidal!) -Preserves food and medical supplies

freezing

-1 of 2 cold control methods -Below -2 C may stop microbial growth and kill susceptible organisms -Only safe ways that frozen foods can be thawed are in the fridge, immersed in cold water changed every 30 minutes, or in the microwave -Ultra-low freezing is at -70 C for bacterial cultures or medical specimens requiring long term storage -Can be achieved with dry ice in an ultra-low freezer or in special liquid nitrogen tanks with temps lower than -196 C -NOT sporicidal! -If bacteria are warmed up then they can grow again

transformation

-1 of the 3 HGT methods -Free DNA fragments taken into cell -naked DNA is taken up from the environment that is derived from lysed cells that release contents including genome into environment -The DNA may remain separate as a plasmid or be incorporated into the host genome. -New cell can acquire virulence factors (bacteria-associated molecules that are required for a bacterium to cause disease while infecting eukaryotic hosts such as humans) and antibiotic resistance genes -inefficient b/c environmental DNA levels are low due to activity of released nucleases during cellular lysis

Transduction

-1 of the 3 HGT methods -genes are transferred between cells in a virus -Bacteriophages move short pieces of chromosomal DNA from one bacterium to another -a bacteriophage injects DNA that is a hybrid of viral DNA and DNA from a previously infected bacterial cell. -the specialized version of this results from imprecise excision of a lysogenic prophage from the bacterial chromosome such that it carries with it a piece of the bacterial chromosome from either side of the phage's integration site to a new host cell -Bacteriophage is carrier of DNA from donor to recipient -Can cause Lysogenic conversion

typical conjugation

-1 of the 3 HGT methods -just F plasmid transferred to F- cell -F plasmid = fertility factor 1. Pilus of donor cell attaches to recipient cell, pilus contracts, drawing cells together to make contact w/ 1 another 2. 1 strand of F plasmid DNA transfers from donor cell to recipient cell 3. Donor synthesizes complementary strand to restore plasmid, recipient synthesizes complementary strand to become F+ cell w/ pilus -Donor bacteria (F+ cell) has gene for Conjugation Pilus -If gene for pilus carried on plasmid called F plasmid = fertility factor -If F plasmid contains gene or genes for antimicrobial resistance called R plasmid -F plasmid can also contain genes for toxins or metabolic enzymes -F+ cell builds Pilus → transfers DNA to Recipient (F- cell)

phenol coefficient

-1.0 means that the chemical agent has about the same level of effectiveness as phenol. -less than 1.0 is less effective than phenol. -greater than 1.0 is more effective than phenol -no longer commonly used b/c conditions and organisms used were arbitrarily chosen

Substitution (point mutation)

-A DNA mutation that changes 1 nucleotide -Most commonly occurs when 1 base is substituted or replaced by another -Its effect on proteins depends on the specific type of mutation this is

missense mutation

-A DNA mutation that results in a different amino acid being incorporated into resulting polypeptide -Effect depends on how chemically different the new amino acid is from the wild type amino acid -Location of changed amino acid within the protein is important -Many times, result in proteins that are still functional to some degree -substitute 1 amino acid for another -Effect is Unnoticeable to Severe

Sterilant

-A chemical mean that kills microbes and viruses and eventually endospores

(sex, conjugation, or F) pilus

-A hollow tube that transfers genes b/w cells during conjugation (think of a bridge connecting the 2 cells) -Donor bacteria (F+ cell) has gene for this during conjugation -If the gene for this is carried on plasmid called F plasmid = fertility factor (during conjugation) -F+ cell builds this → transfers DNA to Recipient (F- cell) (during conjugation)

Chemostat

-A machine that keeps a bacteria's population in the log phase so subculturing (taking some bacteria out and putting them into a new food source) it isn't required -It continues to add new nutrients (food source) at a steady rate while taking out some old media (waste products) from there -If the bacteria is aerobic then this machine can agitate the media and get more O2 into the media; a controlled amount of air is mixed in -Bacterial suspension is removed at the same rate as nutrients flow in to maintain an optimal growth environment. -Think of a lab's shaker table but this machine adds the extra functions listed above to that -AKA bacterial growth machine

autoclave

-A machine that relies on moist heat sterilization; physical control method -Used to raise temps above boiling point -Sterilizes items such as surgical equipment from vegetative cells, viruses, and endospores (sporicidal) -Most effective method of sterilization -Standard operating temp is 121℃ -Typically 20 minutes -Steam must directly contact liquids or dry materials so containers are left loosely closed -Heats heat-stable items (i.e. can't heat plastic Petri dishes or items that can't get wet) -Denatures proteins and alters membranes -Used in labs, clinical settings, and large industry retorts allow for moist-heat sterilization on a large scale

thioglycolate medium

-A medium that contains a low percentage of agar to allow motile bacteria to move throughout it -A test tube culture starts w/ this which is autoclaved -this type of medium has strong reducing properties and autoclaving flushes out most of the oxygen. -Over time, oxygen slowly diffuses throughout the media's tube culture from the top. -Bacterial density increases in the area where oxygen concentration is best suited for the growth of that particular organism. -Localizes growth and tells us what kind of metabolism a bacteria requires -obligate aerobes form around the surface of the test tube -obligate anaerobes form around the bottom -facultative anaerobes form around the surface mostly and throughout the rest of the tube -aerotolerant anaerobes form throughout the tube -microaerophiles form close to the surface

Cofactor

-A nonprotein component of an enzyme -An inorganic enzyme helper -Important for our diet -Inorganic ions, like trace metals, which are specific for the enzyme to take place by helping to stabilize the enzyme's conformation and function.

oxidation-reduction/redox reactions

-A pair of reactions that occur where one reaction removes electrons from donor molecules, leaving them oxidized while the other adds electrons to acceptor molecules, leaving them reduced, -the 2 reactions described above can occur in tandem because electrons can move from one molecule to another -Mnemonic: LEO the lion says GER -Loss of Electrons = Oxidation -Gain of Electrons = Reduction -can think adding protons is being reduced (i.e. NAD to NADH)

Oven

-A physical control method of dry heat sterilization -170 C for at least 2 hours -used as a last resort in lab if autoclave and everything else is broken

Peptidoglycan cell wall (synthesis and growth steps)

-A process where the divisome activates to produce this and build a septum that divides the two daughter cells. -The daughter cells are separated by the division septum, where all of the cells' outer layers (the cell wall and outer membranes, if present) must be remodeled to complete division. -For example, we know that specific enzymes break bonds between the monomers in peptidoglycans and allow the addition of new subunits along the division septum. -Autolysins: disconnect pept. polymers at their ends and various growth zones -Snip connections b/w NAG + NAM + opening up the wall and weakening it by opening up and cutting that polymer -Bactoprenal: "carrier" that inserts its hydrophobic region into this and rotate to put the new pept. piece into the vicinity where autolysin has been cutting -Transglycolases: help connect new NAM to old NAG + new NAG to old NAM and glue new pept. piece into position (connecting new pept. into polymer) -expands the polymer by 1 unit -connects the new pept. piece to existing wall -The new pept. piece that needs to be cross-linked into the wall has an extra amino acid at the end

Exergonic (reaction)

-A type of chemical reaction that's spontaneous and releases energy -Hint: Think energy EXits -A metabolic pathway that fits this reaction's criteria is the catabolic reaction -Is coupled with Endergonic reactions by providing energy to drive Endergonic reaction -ATP hydrolysis/breakdown (ATP → ADP + P) fits this type of reaction's criteria -Can also include energy lost/released as heat as a result of anabolism in the cell

Adenosine Triphosphate (ATP)

-A versatile compound which acts as an "energy currency" for cells; can be used to fill any energy need of the cell (i.e. anabolism) -Allows a living cell to handle the energy released during catabolism in a way that enables it to store energy safely and release it for use only as needed. -This compound is regenerated from the phosphorylation of ADP which requires solar or chemical energy -The bonds b/w phosphate groups are high-energy -When these bonds are broken, releasing a phosphate group(s) (dephosphorylation), energy is released to drive endergonic reactions

psychrotroph

-AKA psychrotolerant -optimal growth temperatures ranging from refrigeration temperature (4 degrees C) to 25 degrees C -important decomposer in cold climates

Decimal reduction time

-Amount of time it takes for a specific protocol to produce a "order-of-magnitude" decrease in the number of organisms or death of 90% of the population at a given temperature -a ten-fold decrease on a log scale -depends on amount of starting pop. -depends on temperature or concentration of chemicals -depends on organic matter present (i.e. you won't use same dish water all week) -depends on control agent you might use

lysozyme

-An antimicrobial enzyme, produced by a variety of cells, present in mucus, tears, and saliva -certain cells of the human immune system are able "recognize" bacterial pathogens by detecting peptidoglycan on the surface of a bacterial cell; these cells then engulf and destroy the bacterial cell, using enzymes such as this, which breaks down and digests the peptidoglycan in their cell walls -breaks down cell wall so bacteria can be inserted during the first stage of specialized transduction (viral attachment and penetration) -damages bacteria as a result

Photoautotroph

-An organism that gets its energy source from light and its carbon source from inorganic compounds -Gets carbon atoms from CO2 and energy light -Example organisms: All plants, algae, cyanobacteria, and green and purple sulfur bacteria

Chemoautotroph

-An organism whose energy source is chemical and whose carbon source is inorganic compounds -Example organisms: Hydrogen-, sulfur-, iron-, nitrogen-, and carbon monoxide-oxidizing bacteria

Chemoheterotroph

-An organism whose energy source is chemical and whose carbon source is organic compounds -Gets carbon atoms and energy from eating organisms -Example organisms: All animals, most fungi, protozoa, and bacteria

Photoheterotroph

-An organism whose energy source is light and whose carbon source is organic compounds -Example organisms: Green and purple nonsulfur bacteria, heliobacteria

antiseptic

-Antimicrobial chemical control agent safe to lower microbial counts on living tissues such as skin and mucus membranes -i.e. halogens -NOT sterile!

Capnophiles

-Bacteria that grow best in a higher concentration of CO2 and a lower concentration of oxygen present in the atmosphere

Microbial death curve

-Can measure the degree of microbial growth -Describes progress and effectiveness of a particular protocol -Fixed % of microbes die when exposed to a particular microbial control protocol -Rate of killing is constant so % killed is more useful -tracks decline (death) of a microbe pop. -not all cells die at the same time (tracking bacteriocide) -think of it as similar patterns and relationships we saw w/ the bacterial growth curve

Halogens: iodine, chlorine, and fluorine 2

-Chlorine gas is commonly used in municipal drinking water and wastewater treatment plants, with resulting hypochlorous acid producing actual antimicrobial effect; acts as an oxidizing agent -Chloramines and other chlorine compounds may be used for disinfection of drinking water, and chloramine tablets are used by military for this purpose. -May irritate skin, nose, or eyes and may not eliminate certain hardy organisms -fluorine is known to have antimicrobial properties that contribute to prevention of cavities -Common examples -betadine -bleach (chlorine) -various toothpastes, mouthwashes, and municipal waters

CFU

-Colony-forming unit -a living cell that can divide to give rise to a visible colony

aseptic technique

-Combination of protocols to maintain sterility -Common in labs and healthcare settings -When working w/ higher risk pathogens, when this is done poorly, it can cause sepsis

Sterilization

-Complete killing or removal of all vegetative cells, endospores, and viruses from targeted environment -Reserved for labs, medical, manufacturing, and food settings -Physical means: high heat, pressure, filtration -Chemical means: sterilants -includes dry heat or moist heat

Copper, nickel, and zinc

-Copper sulfate: common algicide used to control algal growth in swimming pools and fish tanks. -metallic copper to minimize microbial growth -Copper linings in incubators help reduce contamination of cell cultures -Copper coatings used on doorknobs reduces spread of microbes -Nickel and zinc coatings -Zinc chloride found in mouthwashes

Halogens: iodine, chlorine, and fluorine 1

-Disinfectants or antiseptics (NOT sporicidal)! -Iodine oxidizes cellular components and destabilizes macromolecules that contain these molecules; acts as an oxidizing agent -often used as a topical tincture, but may cause staining or skin irritation -iodophor: compound of iodine complexed with an organic molecule → increases iodine's stability and its efficacy. -Betadine is a brand of povidone-iodine

halotolerant organisms

-Do not need high concentrations of salt for growth -Will survive and divide in the presence of salt -important cause of food borne illnesses because they survive and multiply in salty foods -Increase internal osmolyte. Usually an amino acid -Example: Staphyloccocus aureus

Catabolism

-Exergonic metabolic pathways that break down complex molecules into simpler ones -this means they release energy -mnemonic: think EXergonic, energy EXits -degradative reactions -examples of these are the breakdown of glucose and ATP hydrolysis/breakdown (ATP → ADP + P) -substrates have more potential energy than the products

Hfr conjugation

-F plasmid integrates into the chromosomal DNA → high frequency of recombination -Refers to high frequency recombination when recipient F- cells receive genetic information from Hfr cells through conjugation -Hfr cell transfers (F' plasmid from) host chromosome to F- cell -2 types: -Hfr cell transfers F' plasmid w/ genes from host chromosome to F- cells -Hfr cell transfers part of host chromosome to F- cell -Cells may also treat bacterial chromosome like an enormous F plasmid and attempt to transfer a copy of it to a recipient F- cell -An F- cell is still an F- cell even if the complete plasmid isn't in it

planktonic cells

-Free-floating microbial cells that live in an aquatic environment -these cells become attached to a substrate and become sessile when forming a biofilm

ionizing radiation 2

-In labs, used to sterilize materials that cannot be autoclaved (plastic petri dishes and plastic inoculating loops) -Clinically used to sterilize gloves, intravenous tubes, and other latex items -used for the sterilization of other types of delicate, heat-sensitive materials (tissues for transplantation, pharmaceutical drugs, medical equipment) -gamma irradiation for food preservation (packaged dried spices -can be sporicidal over time

electron carrier molecule AKA electron carriers

-In living systems, these are a small mobile class of compounds -molecules that bind to and shuttle high-energy electrons between compounds in pathways. -carry an electron from the full molecules which are then used to make ATP -Example: nicotinamide adenine dinucleotide (NAD+/NADH), nicotine adenine dinucleotide phosphate (NADP+), and flavin adenine dinucleotide (FAD/FADH2) -NADH and FADH2 carry 2 electrons each and are coenzymes (organic vitamins that help enzymes) -NAD+ and FAD are empty or oxidized -NADH and FADH2 are full or reduced

horizontal gene transfer (HGT)

-In prokaryotes, introduction of genetic material from one organism to another within the same generation -is an important way to introduce genetic diversity and allows even distantly related species to share genes, influencing their phenotypes -DNA from 1 microbe to another (not its daughter cells) -More prevalent in prokaryotes but small fraction of genome may be transferred by this transfer at any time -This and mutation are significant sources of genetic variation in prokaryotes -asexual prokaryotes can achieve evolution w/ DNA changes from this method of gene transfer -more common among evolutionarily related organisms, it may occur between any two species that live together in a natural community -The 3 types of this: -Transformation -Transduction -Conjugation

fomite

-Inanimate (man-made) objects that can harbor microbes and aid in disease transmission -i.e. doorknobs, toys, or towels -disinfection uses heat or chemicals which kill many microbes on this thing's surface -sanitization cleans this so it's safe for the general public -nonionizing radiation is only good for a topical surface of this

Anabolism

-Involved in biosynthesis -Makes up metabolism (and hence is a metabolic pathway) -Small molecules are assembled into larger and more complex ones using cellular energy (meaning, it has endergonic pathways) -ENDERgonic, taking energy in -Puts energy in for a higher energy product -Can build macromolecules -i.e. ATP formation (ADP + P → ATP) -ATP powers this to make cell parts and for processes

autoinducer (molecule)

-Molecules that are made and released by the cell that can be released back into the cell to see how much of the microbe's population is present and what the pop. density is -Used for quorum sensing -When the cell population reaches a critical threshold (a quorum), this initiates a cascade of reactions that activate genes associated with cellular functions that are beneficial only when the population reaches a critical density. -Gram-negative: N-acetylated homoserine lactone -Gram-positive: Short peptides (a variety of different ones) -can activate the cell that secreted them. -may stimulate the production of virulence factors.

how a population count is calculated

-Nn = N0 x 2^n (Nn is number of cells at any generation n, N0 is initial population, and n is the number of generations) -AKA the fundamental growth equation which is only valid in optimal growth conditions (i.e. the log/exponential [increase] phase of a bacterial growth curve for a batch culture)

Heavy Metals: mercury, silver, copper, and zinc

-One of the first chemical disinfectants and antiseptics -Kill microbes by binding to proteins → inhibiting enzymatic activity -Oligodynamic: very small concentrations show significant antimicrobial activity -Ions bind to sulfur-containing amino acids strongly and bioaccumulate within cells → allows metals to reach high localized concentrations → proteins to denature. -not selectively toxic to microbial cells -may bioaccumulate in human or animal cells and excessive concentrations can have toxic effects on humans. -to reduce potential toxicity of heavy metals → carefully control duration of exposure and concentration of heavy metal -used early in history -mercury to treat syphilis -silver nitrate droplets protecting newborn eyes from gonorrhea + other STDs -copper prevents algae growth -nickel and zinc also have antimicrobial properties -work by binding to proteins and denaturing enzymes -Common examples: -mostly in clinical settings (mercuric chloride disinfectant) -silver in bandages -zinc oxide in diaper rash cream + dandruff shampoo -why lots of handles, railings, doorknobs, eating utensils, etc. are made of metal

Thermal death time (TDT)

-Parameter: length of time needed to kill all microorganisms in a sample at a given temp -often used to describe sterilization procedures that use high heat, such as autoclaving -Heat can kill microbes by altering their membranes and denaturing proteins.

-Thermal death point (TDP)

-Parameter: lowest temperature where microbes are killed in a 10-minute exposure/period (on the dot)! -Different microorganisms will respond differently to high temperatures, with some (e.g., endospore-formers such as C. botulinum) being more heat tolerant. -Heat can kill microbes by altering their membranes and denaturing proteins.

enzymes

-Protein catalysts for biochemical/metabolic reactions in living things by lowering activation energy -play an important role in controlling cellular metabolism.

how temperature affects cellular proteins and lipids

-Psychrophiles have antifreeze proteins in their cytoplasm and their membrane lipids are unsaturated to increase fluidity in very low temperatures -Thermophiles have a higher G + C ratio, special folding of proteins to help make them heat-stable, and more saturation of membrane lipids -At very low temperatures, proteins become too rigid to catalyze reactions and may undergo denaturation while heat denatures proteins

degerming

-Removing microbes from living tissues with the help of scrubbing -This physical action often goes w/ antiseptics, such as before you receive a shot from the doctor's office -i.e. act of handwashing where microbial numbers are reduced

The relationship b/w salinity, osmotic pressure, and food preservation

-Salinity - concentration of salt -Osmotic Pressure- pressure applied to keep one substance from flowing into or out of another -Most natural environments tend to have lower solute concentrations than the cytoplasm of most microorganisms. -Halotolerants have an increased internal osmolyte (low-molecular weight organic compounds that influence the properties of biological fluids). Usually an amino acid -Halophiles Increase potassium ion as internal osmolyte -Food preservation- salts and cold makes things last

-static physical and chemical methods of microbial control

-Suffix meaning growth is being inhibited -i.e. freezing a raw chicken from the grocery store slowing down foodborne illness but not preventing it i.e. preservatives, salt, sugar, drying, etc. -especially drying, salts, and sugars b/c they make things a hypertonic environment -Often less toxic to humans and other animals -Also better perverse integrity of the treated item -Sufficient to keep the microbial population of the item in check -Able to be impregnated safely into plastics to prevent growth of microbes -In healthy people, this type of treatment prevents multiplication of the pathogen allowing the immune system to clear the infection -If you remove this kind of agent, the microbe can grow again -Does NOT sterilize!

Surfactants: soaps, quaternary ammonium detergents (quats) 1

-Surface active agents -Group of chemical compounds that lower surface tension of water -Found in antimicrobial soaps and detergents -Soaps: salts of long-chain fatty acids and have polar and nonpolar regions allowing them to interact with polar and nonpolar regions in other molecules -can interact with nonpolar oils and grease to create emulsions in water, loosening and lifting away dirt and microbes from surfaces and skin -Do not kill or inhibit microbial growth (NOT sporicidal!) proper use of soaps mechanically carries away microorganisms, effectively degerming a surface -Soaps form films difficult to rinse away in hard way which contains concentrations of calcium and magnesium mineral salts

substrate

-The chemical reactant to which an enzyme binds in an enzyme-catalyzed reaction

Enzyme activity

-The factors which affect this type of activity include temperature, PH, and salt levels -The activation or inhibition of this based on these factors depend on the enzyme since they have different optimums to carry out their functions for the microbe's survival -Different microbes have different optimal growth conditions -Inhibition: proteins (enzymes) can denature by losing their 3D structure and function -pH affects R groups and how amino acids interact -Can be regulated by either competitive inhibitors, which bind to the active site, or noncompetitive inhibitors, which bind to an allosteric site. -substrate concentration: this type of activity is increased at higher concentrations of substrate until it reaches a saturation point at which the enzyme can bind no additional substrate. -binding of an allosteric activator increases this type of activity

maximum growth temperature

-The highest temperature at which growth can occur

minimum growth temperature

-The lowest temperature at which the organism can survive and replicate

quorum sensing

-The mechanism by which cells in a biofilm coordinate their activities in response to environmental stimuli -Sensed by autoinducer molecules (chemical messengers) -A certain number of microbes can activate genes and change their metabolic behavior -how microbes count to see if there is enough of them to complete a task; pathogens don't like to form till they know they'll win -determines the density of the microbe pop.

anaerobic jars/chambers

-The most common approach is obligate anaerobe bacterial culture in these types of jars -these types of jars include chemical packs that remove oxygen and release carbon dioxide (CO2) -these types of chambers are enclosed boxes from which all oxygen is removed -Gloves sealed to openings in the box allow handling of the cultures without exposing the culture to air

optimum growth temperature

-The temperature at which the growth rates are the highest for an organism

Metabolism

-The term used to describe all of the biochemical reactions inside a cell -made up of catabolism (degradative reactions) and anabolism (biosynthesis) -its goal is cell reproduction

Mercury

-Treats syphilis -Many are compounds bacteriostatic and have broad spectrum of activity -Bind to sulfur-containing amino acids within proteins, inhibiting functions -toxic to central nervous, digestive, and renal systems at high concentrations, and has negative environmental effects, including bioaccumulation in fish

Silver

-Used as antiseptic -Water stored in this type of jug -Often combined with antibiotics making them more effective -commonly incorporated into catheters and bandages, rendering them antimicrobial -heavy metals may also enhance selection for antibiotic resistance.

nonsense mutation

-a DNA mutation that changes 1 mRNA amino acid codon (a sense codon) to a STOP codon -result in the synthesis of proteins that are shorter than the wild type and typically not functional. -can lead to the alteration of how the protein folds -polypeptide is released

frameshift insertion mutation

-a DNA mutation that inserts 1 or more bases which shifts the reading frame -changes all amino acid codons after -Effect is Unnoticeable to Severe (functionally different or nonfunctional protein) -1-2 n.t. deletions are severe while 3 may be ok

Frameshift deletion mutation

-a DNA mutation that removes 1 or more bases which shifts the reading frame -changes all amino acid codons after -Effect is Unnoticeable to Severe (functionally different or nonfunctional protein) -1-2 n.t. deletions are severe while 3 may be ok -Example: THE CAT ATE THE RAT -->TH C|AT AT|E TH|E R|AT

silent mutation

-a DNA point mutation that results in same amino acid being incorporated into resulting polypeptide -Change would have no effect on protein's structure; doesn't change the protein

sepsis

-a body-wide infection -systemic inflammatory response to an infection that results in high fever and edema, causing organ damage and possibly leading to shock and death

membrane filtration (technique)

-a direct cell count modification of the plate count technique -In such cases, the original sample must be concentrated rather than diluted before plating. -Known volumes are vacuum-filtered aseptically through a membrane with a pore size small enough to trap microorganisms. -The membrane is transferred to a Petri plate containing an appropriate growth medium. -Colonies are counted after incubation. -Calculation of the cell density is made by dividing the cell count by the volume of filtered liquid.

Most Probable Number (MPN)

-a direct cell count statistical procedure for estimating the number of viable microorganisms in a sample. -often used for food samples; good for dilute bacterial samples especially in larger bodies of water -often used for coliform water testing (especially sewage water) -evaluates detectable growth by observing changes in turbidity or color due to metabolic activity. -must inoculate each set of tubes with 10, 1, and then 0.1 mL, respectively, for each dilution, and then incubate them at 37 degrees C (human body temperature) for 24 hrs

(the possible causes of) mutation

-a heritable change in the DNA sequence of an organism. -The resulting organism, called a mutant, may have a recognizable change in phenotype compared to the wild type, which is the phenotype most commonly observed in nature. -A change in the DNA sequence is conferred to mRNA through transcription, and may lead to an altered amino acid sequence in a protein on translation. -Because proteins carry out the vast majority of cellular functions, a change in amino acid sequence in a protein may lead to an altered phenotype for the cell and organism. -Asexual Prokaryotes can achieve genetic diversity and evolution with changes to its DNA by this -Mistakes in the process of DNA replication can cause these spontaneously -Exposure to mutagens causes induced versions of these which are various types of chemical agents or radiation

feedback inhibition

-a method of metabolic control/metabolism that involves the use of a metabolic pathway product to regulate its own further production -Example: Negative feedback, too much end product from a metabolic pathway shuts down the pathway through allosteric inhibition -Also occurs w/ hormones, microbes, and our cells -End product acts as an inhibitor early on -Analogy: can be described as a thermostat, we don't want our house's furnace to be too hot so it works w/ our house's temperature

competitive inhibitor

-a molecule/chemical similar enough to a substrate that it can compete with the substrate for binding to the active site by simply blocking the substrate from binding and thus blocking the enzyme's function during enzyme regulation -for this molecule to be effective, its concentration needs to be approximately equal to the substrate concentration -also an effector -AKA the substrate analog -the reaction doesn't occur and some of these are permanent where the reaction slows down to a stop -used in drugs to kill off pathogenic microbes -helpful to kill off infections or used in chemotherapy -Example: sulfa drugs which inhibit the bacterial folic acid synthesis pathway enzyme and thus its blocking of DNA, RNA, and protein synthesis kills the bacteria

allosteric (non-competitive) inhibitor

-a molecule/chemical that binds to an enzyme at an allosteric site, a location other than the active site, and still manages to block substrate binding to the active site by inducing a conformational change that reduces the affinity of the enzyme for its substrate -Because only one inhibitor molecule is needed per enzyme for effective inhibition, the concentration of inhibitors needed for noncompetitive inhibition is typically much lower than the substrate concentration. -also an effector

allosteric activatior

-a molecule/chemical that binds to locations on an enzyme away from the active site, inducing a conformational change of the enzyme that increases the affinity of the enzyme's active site(s) for its substrate(s). -turns on the enzyme -also an effector

logarithmic growth/exponential (increase) growth

-a phase in the bacterial growth curve in which the cells are actively dividing by binary fission and their number increases exponentially. -the relationship between time and number of cells is not linear but exponential

Evaporation

-a physical control desiccation method -Foods dried in the sun to achieve desiccation (i.e. sun-dried tomatoes) -may NOT be sporicidal b/c microbes and their endospores may regrow when conditions are more favorable and water is restored

Lyophilization

-a physical control desiccation method -Freeze drying -Rapidly frozen (freeze dried fruits) -Placed under vacuum to get rid of water through sublimation -Combines both exposure to cold temps and desiccation -Quite effective for controlling microbial growth -Causes less damage to an item compared to conventional desiccation -Preserves item better -May stay at room temp if packaged properly -may NOT be sporicidal b/c microbes and their endospores may regrow when conditions are more favorable and water is restored

Osmotic pressure

-a physical control desiccation method -Water activity can be lowered w/o physical drying by + solutes such as salts or sugar -At high concentrations salt or sugars, amount of available water in microbial cells is reduced bc water will be drawn from area of low solute concentration (inside cell) to high solute concentration (outside cell) -Many microorganisms do not survive these conditions -Some can tolerate conditions and can contaminate preserved foods -may NOT be sporicidal b/c microbes and their endospores may regrow when conditions are more favorable and water is restored

high-temperature short-time pasteurization (HTST)

-a physical control heat method exposing milk to a temperature of 72 °C for 15 seconds and then is refrigerated -lowers bacterial numbers while preserving the quality of the milk

ultra-high-temperature pasteurization (UHT)

-a physical control heat method in which milk is exposed for 2 or more seconds at 138 C -Milk can be stored in sealed containers without being refrigerated for long times -High temps alter proteins which causes changes in taste and smell

pasteurization

-a physical control heat method of microbial control for food -Kills pathogens and reduces number of spoilage causing microbes -Kills heat sensitive pathogens in milk and other foods at a certain amount of heat -commonly used for dairy products and eventually juices, too -NOT sterile/sporicidal! and will eventually spoil (why we see expiration dates)

boiling water

-a physical control heat method which is Less effective for killing endospores; endospores can survive up to 20 hours in this -Boiling point lower → time needed to kill microbes is longer -This at 100℃ (at sea level) does NOT kill endospores/sterilize (NOT sporicidal)! -Denatures proteins and alters membranes -Used for cooking, personal use, and preparing certain lab media -Becomes less useful at higher altitudes

air HEPA filtration

-a physical control method -Have pore sizes of 0.3 µm; captures bacterial cells, endospores, and viruses -Sterilizes air on other side of filter (sporicidal!) -Used in clinical settings, cars and airplanes, and homes -Found in vacuums, heat and AC systems, and air purifiers -Used for biological safety cabinets (BSC) -remove particulates in air by entering cabinet (air intake), leaving cabinet (air exhaust), or treating both intake and exhaust. -Used in hospitals to prevent airborne illnesses through ventilation

Sonication

-a physical control method -Use of high frequency ultrasound waves to disrupt cell structures -Application of ultrasound waves causes rapid changes in pressure within intracellular liquid → leads to cavitation (formation of bubbles in cell) → disrupts cell structure and causes cell to lyse -Useful in labs to lyse cells and use contents for research -Used to clean surgical instruments, lenses, and other objects -NOT sporicidal! -no heat or chemicals used -helps chemical control agent by lifting off organic material

liquid membrane filtration

-a physical control method -Used to remove microbes from liquid samples -Used to remove bacteria with pore size of 0.2 µm -Useful for removing bacteria from heat-sensitive solutions used in labs such as antibiotic and vitamin solutions -Large volumes of culture media are also filter-sterilized to protect heat-sensitive components (sporicidal) -Syringe used for filtering small volumes; vacuums used to filter large volumes -Selects for certain microbes for your culture -NOT for disinfection, antiseptic, or sanitization! -Filters must be changed regularly b/c of contamination from air -Can purify air and be used for public safety

Incineration

-a physical control method of dry heat sterilization that uses burning -destroys all microbes at very high temperatures (sporicidal) -doesn't penetrate the cells as well as moist heat sterilization does

nonionizing radiation

-a physical control radiation method -Commonly used for disinfection (NOT sporicidal)! -Uses less energy than ionizing radiation -Does not penetrate cells or packaging -Ex: UV light causes thymine dimers to form b/w adjacent thymines within a single strand of DNA; DNA polymerase encounters thymine dimers does not always incorporate appropriate nucleotide and leads to mutations that kill microorganisms -UV lights added to purify water -Germicidal lamps used in surgical suites, biological safety cabinets, and transfer hoods,

ionizing radiation 1

-a physical control radiation method -Includes x rays, gamma rays, and high energy electron beams -Strong enough to pass into cell → alters molecular structures and damages cell components -Ex: Introduces double strand breaks in DNA molecules → may directly cause DNA mutations or mutations may be introduced when cell attempts to repair DNA damage -X rays and gamma rays penetrate paper and plastic → can be used to sterilize packaged materials

Moist heat sterilization

-a physical control sterilization method involving steam under pressure in an autoclave which allows steam to reach temps higher than boiling water (121 degrees C) using increased pressure -can kill all vegetative cells, endospores, and destroy all viruses -Boiling water at 100℃ does NOT kill endospores! -More efficient than dry heat sterilization b/c it penetrates cells better

Dry heat sterilization

-a physical control sterilization method that involves direct application of high heat (i.e. burning or incineration) -Can be applied for at least 2 hours up to 170℃ by using a dry heat sterilizer such as an oven -less efficient than moist heat sterilization b/c it doesn't penetrate the cells as well

hyperbaric oxygen therapy (HBOT)

-a pressure control method -Sometimes used to treat infections -A patient breathes pure oxygen at a pressure higher than normal atmospheric pressure (1-3 atm) -Achieved by placing patient in hyperbaric chamber or supplying pressurized oxygen through a breathing tube -Helps increase oxygen saturation in hypoxic tissues due to infection and inflammation; increased oxygen -enhances body's immune response by increasing activities of neutrophils and macrophages -increases oxygen content in blood -increases immune activity -increases ROS which can damage strict anaerobes causing infection and hence this enhances the effectiveness of antibiotic treatments -can damage pathogens where it might not be easy to use antibiotics where they're growing -Rare risks include oxygen toxicity and effects on delicate tissues, such as the eyes, middle ear, and lungs, which may be damaged by the increased air pressure

binary fission

-a process which is the most common mechanism of cell replication in bacteria/prokaryotes -asexual reproduction -Before dividing, the cell grows and increases its number of cellular components. -Next, the replication of DNA starts at a location on the circular chromosome called the origin of replication, where the chromosome is attached to the inner cell membrane. -Replication continues in opposite directions along the chromosome until the terminus is reached. -The cell elongates -The center of the enlarged cell constricts from the formation of the division septum until two identical daughter cells are formed, each offspring separating from each other and receiving a complete copy of the parental genome and a division of the cytoplasm (cytokinesis).

ZipA

-a protein that's part of the divisome (a protein complex in bacteria/prokaryotes that is responsible for cell division in binary fission) -an anchor that connects the FtsZ ring to the plasma membrane (which is to the cell's center, specifically)

FtsA

-a protein that's part of the divisome (a protein complex in bacteria/prokaryotes that is responsible for cell division in binary fission) -an anchor that connects the FtsZ ring to the plasma membrane AND recruits other divisome proteins by becoming its own attachment part -divisome proteins are near this and become associated with this

FtsZ

-a protein that's part of the divisome (a protein complex in bacteria/prokaryotes that is responsible for cell division in binary fission) -directs the process of cytokinesis and cell division in binary fission -polymerizes to form a Z ring on the cytoplasmic membrane which determines the location of the septum and where it forms (where the cell divides in 2)

FtsI

-a protein that's part of the divisome (a protein complex in bacteria/prokaryotes that is responsible for cell division in binary fission) -helps determine the placement of the cell wall b/c when dividing, prokaryotic cells need a new cell wall to split into 2

FtsK

-a protein that's part of the divisome (a protein complex in bacteria/prokaryotes that is responsible for cell division in binary fission) -the attachment point for the bacterial chromosome -chromosomes duplicate before division and this ensures these chromosomes are segregated into their daughter cells -rod-shaped cells elongate before division so duplicated chromosomes attached to this are pulled away from the center so each daughter cell will have 1 when division is complete

antisepsis

-a protocol that removes potential pathogens from living tissue

Asepsis

-a sterile state resulting from proper use of microbial control protocols

Extracellular Polymeric Substances (EPS)

-a substance that is a part of the extracellular matrix (ECM) that's secreted by the organisms in the biofilm. -the properties of this vary according to the resident organisms and environmental conditions. -a hydrated gel composed primarily of polysaccharides and containing other macromolecules such as proteins, nucleic acids, and lipids. -plays a key role in maintaining the integrity and function of the biofilm. -can form a surface which allows more microbes to attach and restrict access to nutrients reaching certain parts of the biofilm -channels in this allow for the movement of nutrients, waste, and gases throughout the biofilm which keeps the cells hydrated, preventing desiccation -also shelters organisms in the biofilm from predation by other microbes or cells (e.g., protozoans, white blood cells in the human body).

catalyst

-a substance that speeds up the rate of a chemical reaction

in-use test

-a test that can determine whether an actively used solution of disinfectant in a clinical setting is microbially contaminated -AKA disinfectant-use test -using control agents out in the real world and seeing if they actually killed off the microbes or not -A 1-mL sample of the used disinfectant is diluted into 9 mL of sterile broth medium that also contains a compound to inactivate the disinfectant. -Ten drops, totaling approximately 0.2 mL of this mixture, are then inoculated onto each of two agar plates; agar solidifies the source -One plate is incubated at 37 °C for 3 days and the other is incubated at room temperature for 7 days to give them enough time for growth. -The plates are monitored for growth of microbial colonies. -Growth of five or more colonies on either plate suggests that viable microbial cells existed in the disinfectant solution and thus it is contaminated (meaning, the disinfectant solution is ineffective).

Endergonic (reaction)

-a type of chemical reaction that requires energy to proceed -Hint: Think of taking energy in -A metabolic pathway that fits this reaction's criteria is the anabolic reaction -Is coupled with Exergonic reactions since it is driven by receiving energy from them -ATP formation (ADP + P → ATP) fits this type of reaction's criteria

complex media

-a type of culture media that contains extracts and digests of yeasts, meats, or plants -Precise chemical composition of the medium is not known -At least one ingredient is not chemically defined -Amounts of individual components are undetermined and variable -Examples include: nutrient broth, tryptic soy broth, and brain heart infusion

enriched media

-a type of culture media that contains growth factors, vitamins, and other essential nutrients to promote the growth of fastidious organisms, which have complex or particular nutritional requirements for growth i.e. chocolate/blood agar

differential media

-a type of culture media that makes it easy to distinguish colonies of different bacteria by a change in the color of colonies or medium -Color changes are a result of end products created by interaction of bacterial enzymes with differential substrates in the medium or the lysis of red blood cells in the medium -Colonies of bacteria or area around colonies looks different to help you tell organisms apart

selective media

-a type of culture media that prevents growth of unwanted microorganisms and supports growth of organism of interest by supplying nutrients and reducing competition -Contains ingredients to inhibit growth of certain bacteria to allow others to grow -Example is MacConkey agar which contains bile salts and crystal violet → interferes with growth of many gram positive bacteria and favors growth of gram negative bacteria such as Enterobacteriaceae

all-purpose media

-a type of culture media that supports the growth of a large variety of organisms -Example: tryptic soy broth (TSB)

(chemically) defined media

-a type of culture media where the complete chemical composition of a medium is known -Example: in the EZ medium, all individual chemical components are identified and exact amounts are known

Acidophiles

-acid-loving bacteria -produce acidic metabolic products and release from cell -display a number of adaptations to survive in strong acidic environments. -its membrane proteins adapted to properly fold in low pH -proteins show increased negative surface charge that stabilizes them at low pH. -grow optimally at pH less than 5.55 -Pumps actively eject H+ ions out of the cells.

Alkaliphiles

-alkaline-loving or base-loving bacteria -microorganisms that grow best at pH between 8.0 and 10.5. -use sodium motive force instead of proton motive force -its membrane proteins adapted to properly fold in high pH

Holoenzyme

-an active enzyme with the necessary associated cofactor or coenzyme (helper) -Mnemonic: think of "whole" (entire) (enzyme)

Prionzyme

-an antimicrobial enzyme that can remove prions, especially on medical instruments

turbidity (spectrophotometer)

-an indirect cell count method that measures the cloudiness of a bacterial sample in a liquid suspension by using a spectrophotometer -a light beam is transmitted through a bacterial suspension, the light passing through the suspension is measured by a detector, and the amount of light passing through the sample and reaching the detector is converted to either percent transmission or a logarithmic value called absorbance (optical density). -Electrode detects and provides transmission or optical density data (i.e. optical density v. transmission) -As the numbers of bacteria in a suspension increase, this also increases and causes less light to reach the detector. -The decrease in light passing through the sample and reaching the detector is associated with a decrease in percent transmission and increase in absorbance measured by the spectrophotometer. -Measuring this is a fast method to estimate cell density as long as there are enough cells in a sample to produce this. -No growth = 100% transmission (growth and transmission are inversely proportional) -won't give us total cell number but will let us know if there's more or less bacterial growth in a particular tube -Pros: can be done pretty quickly, spectrophotometer is pretty accurate -Cons: Doesn't count total cell number or total number of living cells, sometimes dead cell debris blocks light, some cells grow in clumps which throws off the reading's accuracy

Coenzyme

-an organic vitamin that helps enzymes AKA an organic enzyme helper or an organic helper molecule -required for enzyme action -Like enzymes, they are not consumed and, hence, are reusable -most common sources of these are dietary vitamins

BSL-4

-biosafety level (BSL) where microbes are dangerous and exotic -Pose a high risk of aerosol transmitted infections which are fatal without treatment or vaccines -In addition to personal protective equipment (PPE, i.e. gloves, etc.), a hazmat suit is also worn to work w/ these kinds of microbes in the lab -Ex: ebola and marburg viruses

BSL-3

-biosafety level (BSL) where microbes are indigenous or exotic -cause serious or potentially fatal diseases through respiratory transmission -requires personal protective equipment (PPE, i.e. gloves, etc.) to work w/ in the lab -Ex: Mycobacterium tuberculosis

BSL-1

-biosafety level (BSL) where microbes are not known to cause disease in healthy hosts -requires the fewest precautions because it applies to situations with the lowest risk for microbial infection. -Pose minimal threat to workers and environment -Doesn't require personal protective equipment (PPE, i.e. gloves, etc.) but usually worn in the lab anyway -Ex: non pathogenic strain of E. coli

BSL-2

-biosafety level (BSL) where microbes are typically indigenous and associated with diseases of varying severity -Pose moderate risk -requires personal protective equipment (PPE, i.e. gloves, etc.) to work w/ in the lab -Ex: Staphylococcus aureus

Peracetic acid

-can be used as a liquid or plasma sterilant insofar as it readily kills endospores -more effective than hydrogen peroxide even at low concentrations -immune to inactivation by catalases and peroxidases -breaks down to environmentally innocuous compounds; in this case, acetic acid and oxygen.

Bis Biguanides: chlorhexidine and alexidine

-cationic (positively charged) molecules known for antiseptic properties ◦ How they work: ◦ Disrupts cell membrane ◦ Causes congealing of cytoplasmic contents ◦ Common examples: ◦ Chlorhexidine in surgical soaps, topical antiseptics, antimicrobial soaps, and oral rinses

sessile cells

-cells attached to a surface -helps w/ the formation of biofilms

critical items

-certain medical equipment that must be sterile because they will be used inside the body, often penetrating sterile tissues or the bloodstream

Phenolics: bisphenol hexachlorophene and triclosan

-chemical compounds found in antiseptic mouthwashes and throat lozenges -Chemically consist of benzene ring w/ -OH groups and phenolics are compounds with this group -Thymol and eucalyptol naturally in plants -Others derived from creosote (coal tar) -Stable -Persistent on surfaces -Less toxic and odorous than phenol -Inhibit microbial growth by denaturing proteins and disrupting membranes (NOT sporicidal!) -Can lower microbial counts on surfaces and tissues -disinfectants or antiseptics -Lister first to use clinical (carbolic acid) Common examples: ◦ Lysol ◦ Triclosan (antimicrobial soaps + hand sanitizers) ◦ pHisoHex

disinfectant

-chemical control agent -should be fast acting, stable, easy to prepare, inexpensive, and easy to use. -Examples include vinegar and chemical versions of these like chlorine bleach -i.e. halogens, peroxygens, alkylating agents, and alcohols

-cidal physical and chemical methods of microbial control

-cide means to kill -suffix building off this -can sterilize

Sanitization

-cleansing of fomites to remove enough microbes to achieve levels deemed safe for public health/the general public/public use

psychrophile

-cold-loving bacteria -microorganisms that can grow at 0 °C and below -optimum growth temperature close to 15 °C -usually do not survive at temperatures above 20 °C -found in permanently cold environments such as the deep waters of the oceans. -important decomposer in cold climates

formaldehyde (methylates enzymes and nucleic acids) & formalin (CH2OH, solution w/ 37% concentration)

-commonly used in solution at concentration of 37% (known as 1 of these) or as gaseous disinfectant and biocide. -strong, broad-spectrum disinfectant and biocide that kills bacteria, viruses, fungi, and endospores → leads to sterilization at low temperatures → is sometimes a convenient alternative to more labor-intensive heat sterilization methods -cross-links proteins and used as chemical fixatives. -Therefore used for storage of tissue specimens and as embalming fluid. -used to inactivate infectious agents in vaccine preparation -very irritating to living tissues and is toxic and carcinogenic → not used as antiseptic. -1 of these methylates enzymes and nucleic acids

culture density

-defined as the number of cells per unit volume. -In a closed environment, this is also a measure of the number of cells in the population.

use-dilution test

-determines chemical's disinfection effectiveness on inanimate surface -cylinder of stainless steel dipped in culture of targeted microorganism and then dried -cylinder then dipped in solutions of disinfectant at various concentrations for specified amount of time. -cylinder is transferred to new test tube containing fresh sterile medium that does not contain disinfectant, and this test tube is incubated. -Bacterial survival is demonstrated by presence of turbidity in medium which means less effective disinfectant -killing of the target organism on the cylinder by the disinfectant will produce no turbidity, more effective disinfectant

Coulter counter

-direct cell count done electronically, cells move through system and electronic sensor, fast and accurate as long as concentration of cells are not too high -differs from the chemostat b/c it's actually counting the number of cells growing in the system -Cons: doesn't differentiate b/w live and dead cells, more expensive -Pros: Less error (no human error) and hence more accurate

microscopic cell count/Petroff-Hausser Chamber/Counting chamber

-directly counts cells with microscope, known volume added to counter and cells are tallied in a given area of squares, calculations help determine cell number -Cons: error rate high b/c of miscounting, includes environmental debris, doesn't differentiate b/w live and dead cells -Pros: Cheap, quick and easy to use and easy to train someone to do it

Alcohols: ethyl alcohol and isopropyl alcohol 2

-ethyl alcohol (ethanol) and isopropyl alcohol (isopropanol, rubbing alcohol) are most common disinfectants -tend to be bactericidal and fungicidal, but may also be virucidal for enveloped viruses only -NOT SPORICIDAL; inhibits processes of sporulation and germination. -Volatile and dry quickly -used to make tinctures with other antiseptics (iodine) -high volatility limits effectiveness to immediately after application

benzoic acid

-exhibit increased efficacy as the pH decreases. -found naturally in many types of fruits and berries, spices, and fermented products. -decreases intracellular pH, interfering with mechanisms (oxidative phosphorylation) and uptake of molecules (amino acids) into cells. -lower pH, affecting activity of proteins and enzymes, can interfere w/ pathways

sorbic acid

-exhibit increased efficacy as the pH decreases. -inhibits various cellular enzymes, including those in the citric acid cycle, and catalases and peroxidases -added as a preservative in a wide variety of foods, including dairy, bread, fruit, and vegetable products. -lower pH, affecting activity of proteins and enzymes, can interfere w/ pathways

Hyperthermophiles

-extreme thermophiles -characterized by growth ranges from 80 °C to a maximum of 110 °C, some above 121 degrees C -The hydrothermal vents at the bottom of the ocean -Pyrobolus and Pyrodictium archea

o-phthalaldehyde (OPA)

-found in newer formulations of Cidex and similar products, replacing glutaraldehyde -has two reactive aldehyde groups, but are linked by an aromatic bridge -work similarly to glutaraldehyde and formaldehyde -less irritating to skin and nasal passages -produces minimal odor -does not require processing before use -more effective against mycobacteria.

Alkylating agents: formaldehyde & formalin; Glutaraldehyde, o-phthalaldehyde (OPA), and ethylene oxide

-group of strong disinfecting chemicals that act by replacing hydrogen atom within molecule with alkyl group -inactivates enzymes and nucleic acids and cross-link proteins to prevent decay -sporicidal

Chlorhexidine

-has broad-spectrum activity against yeasts, gram-positive bacteria, and gram-negative bacteria (exception of Pseudomonas aeruginosa, which may develop resistance on repeated exposure) -disrupts cell membranes and is bacteriostatic at lower concentrations; bactericidal at higher concentrations, in which it causes cells' cytoplasmic contents to congea (solidify). -has activity against enveloped viruses poorly effective against Mycobacterium tuberculosis and nonenveloped viruses -Not sporicidal -clinical setting: surgical scrub, handwashing needs for medical, and topical antisepsis for patients before surgery or needle injection. -more persistent than iodophors, providing long-lasting antimicrobial activity -Oral rinses

Glutaraldehyde

-has two reactive aldehyde groups → allows to act more quickly than formaldehyde -commonly used as a 2% solution for sterilization → brand name Cidex. -Disinfects surfaces and surgical and medical equipment. -irritates skin and not used as antiseptic.

Thermophiles

-heat loving microbes -grow at optimum temperatures of 50 °C to a maximum of 80 °C -do not multiply at room temperature. -widely distributed in hot springs, geothermal soils, and manmade environments such as garden compost piles where the microbes break down kitchen scraps and vegetal material. -Thermus aquaticus and Geobacillus spp.

generation time

-in eukaryotic organisms, this is the time between the same points of the life cycle in two successive generations. -more than just the time to physically divide, includes time to elongate/grow/split -varies depending on species and growth conditions/environment (i.e. access to nutrients, pH, and temperature) -in prokaryotes, this is also called the doubling time which is defined as the time it takes for the population to double through one round of binary fission.

disinfection

-inactivates most microbes on the surface of a fomite by using antimicrobial chemicals or heat. -Does not lead to sterilization b/c endospores survive even if vegetative cells are killed -can be reduced to sanitization if directions aren't followed (i.e. not leaving surface alone for a certain amount of time after wiping it w/ a Lysol wipe, AKA contact time)

propionic acid

-inhibit enzymes and decrease intracellular pH -more effective preservative at higher pH than sorbic or benzoic -naturally produced by some cheeses during their ripening and is added to other types of cheese and baked goods to prevent mold contamination. -added to raw dough to prevent contamination by the bacterium Bacillus mesentericus, which causes bread to become ropy. -lower pH, affecting activity of proteins and enzymes, can interfere w/ pathways

disk-diffusion method

-involves applying different chemicals to separate, sterile filter paper disks -disks then placed on agar plate → inoculated with targeted bacterium and chemicals diffuse out of disks into agar where the bacteria have been inoculated. -"lawn" of bacteria grows, zones of inhibition of microbial growth are observed as clear areas around the disks. -larger zones typically correlate to increased inhibition effectiveness of the chemical agent -Diameter across each zone measured millimeters. -more commonly practiced test than phenol coefficient -NOT looking for isolated colonies!

semicritical items

-items that must be highly disinfected but don't necessarily need to be sterile (i.e. certain medical equipment) -don't penetrate tissues

noncritical items

-items that need to be cleaned but not highly disinfected (i.e. pillowcases, towels, sheets, etc., especially in hospitals) -don't penetrate tissues

factors that influence the action of antimicrobial agents.

-length of exposure is particularly important, with longer exposure increasing efficacy. -concentration of the chemical agent is also important, with higher concentrations being more effective than lower ones. -Temperature, pH, and other factors can also affect the potency of a disinfecting agent. -swabbing surfaces before and after use to confirm whether a sterile field was maintained during use.

biofilm

-little complex and dynamic ecosystems that form on a variety of environmental surfaces -a layer of microbes living together on some type of surface -not restricted to solid substrates -environmental conditions influence the overall structure -Sticky blanket that covers and protects microbes -Pathogens embedded within this exhibit a higher resistance to antibiotics than their free-floating counterparts. -Cells in the deep layers of a biofilm are metabolically inactive and may be less susceptible to the action of antibiotics that disrupt metabolic activities. -The EPS may also slow the diffusion of antibiotics and antiseptics, preventing them from reaching cells in the deeper layers of the this -Phenotypic changes may also contribute to the increased resistance exhibited by bacterial cells in this -provide an ideal environment for the exchange of extrachromosomal DNA, which often includes genes that confer antibiotic resistance.

Mesophiles

-moderate temperature or middle-loving microbes -optimal growth temperatures ranging from room temperature (about 20 °C) to about 45 °C. -normal human microbiota and pathogens are these -E. coli, Salmonella spp., and Lactobacillus spp.

neutrophiles

-most bacteria are these -grow optimally at a pH within one or two pH units of the neutral pH of 7

facultative anaerobes

-organisms that can live and grow with or without O2 (oxygen)

non-halophiles

-organisms that can only grow in isotonic conditions and cannot tolerate high salt for their growth -even a small amount of salt can hurt it -Example: E. coli

obligate anaerobes

-organisms that cannot live where molecular O2 oxygen is present

aerotolerant anaerobes

-organisms that do not utilize oxygen but can survive and grow in its presence

obligate aerobes

-organisms that require O2 (oxygen) for cellular respiration

microaerophiles

-organisms that require O2 oxygen concentration lower than air

Supercritical Carbon dioxide (scCO2)

-penetrate surfaces. -Materials put into a chamber in which carbon dioxide is pressurized -Penetrates cells and forms carbonic acid → lowers cell pH -effective against vegetative cells -used in combination with peracetic acid to kill endospores. -efficacy augmented with increased temp or by rapid cycles of pressurization and depressurization → more likely produce cell lysis. -Benefits: non reactive, nontoxic, and nonflammable properties of carbon dioxide, and effective at low temperatures. -preserves the object's integrity -commonly used for treating foods (including spices and juices) and medical devices such as endoscopes. disinfects tissues such as skin, bones, tendons, and ligaments prior to transplantation scCO2 -used for pest control bc kills insect eggs and larvae within products

Ozone gas

-peroxygen with disinfectant qualities -used to clean air or water supplies.

Pascalization

-pressure control method -High pressure processing -Used to kill bacteria, yeast, molds, parasites, and viruses in foods while maintaining food quality -Pressure between 100-800 MPa Sufficient to kill vegetative cells -Used in human and pet food industries (especially for contamination, like meat products) -NOT sporicidal!

How biofilms can positively and negatively impact human health

-pros and cons of this regarding how it impacts human health -Pros: good in digestive tract to protect us -Cons: catheters (increased UTIs), joint replacements, dental plaque, contact lenses

Min proteins

-proteins in binary fission that determine the placement of the FtsZ ring and thus the septum (where the cell divides in 2) -sweeps from ends of the cell to the middle of the cell to ends to middle to push Z ring towards the middle -where these proteins are located, the FtsZ proteins won't be able to polymerize so after they're swept/forced into the middle they'll polymerize into the Z ring -this allows for separation in the middle and 2 equally-sized identical daughter cells to form so we should have a main copy of the chromosome in there

Surfactants: soaps, quaternary ammonium detergents (quats) 2

-quaternary ammonium salts (quats): have properties similar to phospholipids, having hydrophilic and hydrophobic ends. -have ability to insert into bacterial phospholipid bilayer and disrupt membrane integrity. -stable, nontoxic, inexpensive, colorless, odorless, and tasteless. -They tend to be bactericidal by disrupting membranes. active against fungi, protozoans, and enveloped viruses, but endospores are unaffected. -Antiseptics

plasmid

-small, circular, double-stranded DNA molecule in the cytoplasm of a bacterium or a protozoan -typically independent from the bacterial chromosome (can replicate independently) -Often code for genes involved in virulence (the severity or harmfulness of a disease or poison) -Genes required for production of toxins and molecules important for colonization during infection may be found encoded on these -bacterial genes that encode metabolic enzymes needed to degrade specialized atypical compounds like polycyclic aromatic hydrocarbons (PAHs) are also frequently encoded on these -transferred b/w cells during typical conjugation -in its complete form, it can be part of an F- cell during Hfr conjugation but it doesn't have to be -Ability to move from bacterial cells to other cells (plant and animal) through mechanisms distinct from conjugation

the role of agar in culture media

-solidifies the source -MacConkey agar- an example of a selective medium which contains bile salts and crystal violet, which interfere with the growth of many gram-positive bacteria and favor the growth of gram-negative bacteria, particularly the Enterobacteriaceae.

Peroxygens: hydrogen peroxide, peracetic acid, benzoyl peroxide, ozone gas

-strong oxidizing agents used as disinfectants or antiseptics, and in high concentration as gaseous sterilizing agents -Produces free radicals that damage organic molecules (ROS)

Alexidine

-surgical scrub and an oral rinse -Acts faster than chlorhexidine

serial dilution & viable plate count

-the goal of this direct cell count method is to to obtain plates with CFUs in the range of 30-300, and the process usually involves several dilutions in multiples of 10 to simplify calculation -Amount can be put into equate to determine living number of cells -N = C / DV (N = number of viable cells, C = number of colonies, D = dilution factor, and V = volume plated) -Colony-forming unit (CFU): living cell that can divide to give rise to a visible colony -Sample must be diluted first -Keep track of dilution, volume plated, and number of colonies

Apoenzyme

-the inactive protein portion of an enzyme/an inactive enzyme, which lacks a helper (coenzyme or cofactor) which is required for activation

active site

-the location within the enzyme where the substrate binds to make a product in an enzyme-catalyzed reaction

vertical gene transfer

-the transmission of genetic information from generation to generation. -Main mode of transmission of genetic information in all cells -When prokaryotes and eukaryotes reproduce asexually, they transfer a nearly identical copy of their genetic material to their offspring through this

ethylene oxide

-type of alkylating agent used for gaseous sterilization highly penetrating and sterilize items within plastic bags (catheters, disposable items in labs and clinical settings (packaged Petri dishes), etc. -exposure is a form of cold sterilization → useful for sterilization of heat-sensitive items. -Carcinogenic and highly explosive -Highly effective with proper aeration -toxic

Benzoyl peroxide

-used in acne medication solutions. -kills Propionibacterium acnes

Hydrogen peroxide

-used in solution to disinfect surfaces and may be used as gaseous agent. -inexpensive skin antiseptics that break down into water and oxygen gas -decomposition is accelerated in the presence of light, so typically sold in brown or opaque bottles. -Disadvantage: causes damage to skin that may delay healing or lead to scarring. -Used in contact lens solution -produces free radicals that damage cellular macromolecules -broad-spectrum activity, working against gram-positive and gram-negative bacteria (with slightly greater efficacy against gram-positive bacteria), fungi, viruses, and endospores. -bacteria that produce oxygen-detoxifying enzymes catalase or peroxidase may have inherent tolerance -To kill endospores length of exposure or concentration must be increased -Gaseous version of this: greater efficacy and used as sterilant for rooms or equipment. -May be introduced as a plasma -Besides sterilization, may also be used as a disinfectant or antiseptic

the product(s)

-what the substrate turns into after the reaction/enzymatic fit in an enzyme-catalyzed reaction

Alcohols: ethyl alcohol and isopropyl alcohol 1

-work by rapidly denaturing proteins → inhibits cell metabolism, and by disrupting membranes → leads to cell lysis. -Once denatured, proteins may potentially refold if enough water is present in solution. -typically used at concentrations of 70% aqueous solution and work better in aqueous solutions than 100% alcohol solutions bc they coagulate proteins -In higher alcohol concentrations, rapid coagulation of surface proteins prevents effective penetration of cells -70% isopropyl and 70% ethanol can be combined w/ halogens to be antimicrobial -denature proteins, disrupt cell membranes, lead to cell lysis -Common examples -alcohol-based hand sanitizer -alcohol pads

the 4 phases of a bacterial growth curve in a closed (batch) culture

1. Lag phase: no increase in the number of living bacterial cells; cells are preparing for the next phase of growth -cells grow larger and are metabolically active, synthesizing proteins needed to grow within the medium. -If any cells were damaged or shocked during the transfer to the new medium, repair takes place -duration determined by many factors (i.e. species and genetic make-up of the cells, the composition of the medium, and the size of the original inoculum. 2. Log/exponential (increase) phase: exponential increase in the number of living bacterial cells in a very short period of time (where fundamental growth equation is valid, Nn = N0 x 2^n) -cells actively dividing by binary fission 3. Stationary phase: a plateau in the number of living bacterial cells; the rate of cell division and death are roughly equal; growth rate is considered 0 -cells switch to survival mode (i.e. sporulation, metabolite/antibiotic synthesis, etc.) 4. Death/decline phase: exponential decrease in the number of living bacterial cells over time (slowly) -toxic waste is accumulated and nutrients are exhausted -Not everything is dying off at once b/c dying cells could lyse and release nutrients keeping other members of the pop. alive and surviving -persister cells have a slow metabolic rate -Eventually, all the cells will die

c. two phosphate groups.

A "high-energy" bond in an ATP molecule is located between a. adenine and the first phosphate group. b. adenine and ribose. c. two phosphate groups. d. ribose and the first phosphate group.

deletion mutation (KC Week 8 #2)

A DNA base sequence was GGCATAT before a mutation and is now GGATAT. This type of mutation would be an example of a(n): point mutation. silent mutation. insertion mutation. deletion mutation.

halophile (KC Week 7 #10)

A bacterium that can survive in high salt is known as a(n): acidophile osmophile halophile mesophile

c. hydrogen peroxide

A common antimicrobial chemical (or chemicals) used as both an antiseptic and a general disinfectant and is also capable of sterilizing: a. hydrogen peroxide AND 70% ethanol b. 70% ethanol c. hydrogen peroxide d. ethylene oxide e. hydrogen peroxide, ethylene oxide, AND 70% ethanol

may be beneficial (KC Week 8 #3)

A gene mutation: has no effect on the base sequence of the gene. is always harmful. may be beneficial destroys the DNA molecule.

a. oxygenated / low salt

A halotolerant obligate aerobe would grow FASTEST in which of the following environments? a. oxygenated / low salt b. oxygen depleted / low salt c. oxygen depleted / high salt d. oxygenated / high salt

nonsense mutation (Practice Exam #8)

A mutation that changes a normal codon to a stop codon is called a: silent mutation frameshift mutation nonsense mutation missense mutation

transposon (KC Week 8 #9)

A small DNA molecule that has the ability to independently excise from one location in a larger DNA molecule and integrate into the DNA elsewhere is called a ________.

psychrotrophs (Ch 9 #19)

A soup container was forgotten in the refrigerator and shows contamination. The contaminants are probably which of the following? thermophiles acidophiles mesophiles psychrotrophs

DNA to RNA to protein (Ch 11 #2)

According to the central dogma, which of the following represents the flow of genetic information in cells? protein to DNA to RNA DNA to RNA to protein RNA to DNA to protein DNA to protein to RNA

d. a thermophile

According to the table below, the bacterium would be categorized as: (I don't have Quizlet premium so I can't insert the table here but as a hint, it has the shortest generation time at the highest temperature) a. a neutrophile b. a halophile c. a mesophile d. a thermophile e. a microaerophile

d. sensitive

An antimicrobial disk on a plate that shows a large zone of inhibition indicates that the microbe being tested is most likely __________ to the drug. a. immune b. intermediate c. resistant d. sensitive

The organisms are obligate anaerobes. (Ch 9 #12)

An inoculated thioglycolate medium culture tube is clear throughout the tube except for dense growth at the bottom of the tube. What is your conclusion? The organisms are obligate anaerobes. The organisms are facultative anaerobes. The organisms are aerotolerant. The organisms are obligate aerobes.

The organisms are facultative anaerobes. (Ch 9 #11)

An inoculated thioglycolate medium culture tube shows dense growth at the surface and turbidity throughout the rest of the tube. What is your conclusion? The organisms die in the presence of oxygen The organisms are facultative anaerobes. The organisms should be grown in an anaerobic chamber. The organisms are obligate aerobes.

alkaliphiles (Ch 9 #17)

Bacteria isolated from Lake Natron, where the water pH is close to 10, are which of the following? alkaliphiles facultative anaerobes neutrophiles obligate anaerobes

mesophiles (Ch 9 #20)

Bacteria isolated from a hot tub at 39 °C are probably which of the following? thermophiles psychrotrophs mesophiles hyperthermophiles

halotolerant (Ch 9 #24)

Bacteria living in salt marshes are most likely which of the following? acidophiles barophiles halotolerant thermophiles

acidophiles (Ch 9 #16)

Bacteria that grow in mine drainage at pH 1-2 are probably which of the following? alkaliphiles acidophiles neutrophiles obligate anaerobes

a. Log phase

Binary fission is occurring at maximum rate. a. Log phase b. Death phase c. Stationary phase d. Lag phase

halogens (ch 13 #12)

Bleach is an example of which group of chemicals used for disinfection? heavy metals halogens quats bisbiguanides

halogens (KC Week 9 #10)

Bleach is an example of which group of chemicals used for disinfection? quats halogens heavy metals bisbiguanides

is read by ribosomes during the process of translation (Ch 11 #1)

DNA does all but which of the following? serves as the genetic material passed from parent to offspring remains constant despite changes in environmental conditions provides the instructions for the synthesis of messenger RNA is read by ribosomes during the process of translation

log phase (Ch 9 #3)

During which phase would penicillin, an antibiotic that inhibits cell-wall synthesis, be most effective? death phase lag phase log phase stationary phase

selective complex differential (KC Week 8 #7)

EMB agar is a medium used in the identification and isolation of pathogenic bacteria. It contains digested meat proteins as a source of organic nutrients. Two indicator dyes, eosin and methylene blue, inhibit the growth of Gram-positive bacteria and distinguish between lactose fermenting and nonlactose fermenting organisms. Lactose fermenters form metallic green or deep purple colonies, whereas the nonlactose fermenters form completely colorless colonies. EMB agar is an example of which of the following? Select all that apply. selective complex defined differential

differential only (KC Week 8 #8)

EMB agar is a medium used in the identification and isolation of pathogenic bacteria. It contains digested meat proteins as a source of organic nutrients. Two indicator dyes, eosin and methylene blue, inhibit the growth of Gram-positive bacteria and distinguish between lactose fermenting and nonlactose fermenting organisms. Lactose fermenters form metallic green or deep purple colonies, whereas the nonlactose fermenters form completely colorless colonies. You inoculate two types of microbes on the EMB plate. Both grow and one forms metallic green colonies and the other forms colorless colonizes. In this case EMB is uses as which type of media? both selective and differential enriched only differential only selective only

a selective medium, a differential medium, and a complex medium (Ch 9 #25)

EMB agar is a medium used in the identification and isolation of pathogenic bacteria. It contains digested meat proteins as a source of organic nutrients. Two indicator dyes, eosin and methylene blue, inhibit the growth of gram-positive bacteria and distinguish between lactose fermenting and nonlactose fermenting organisms. Lactose fermenters form metallic green or deep purple colonies, whereas the nonlactose fermenters form completely colorless colonies. EMB agar is an example of which of the following? a selective medium only a differential medium only a selective medium and a chemically defined medium a selective medium, a differential medium, and a complex medium

lower the activation energy needed for the reaction to proceed (KC Week 7 #3).

Enzymes can speed up chemical reactions because they are able to: lower the activation energy needed for the reaction to proceed. create more energy needed for the reaction to happen. increase the temperature causing the reaction to proceed. raise the activation energy needed for the reaction to proceed.

reducing the activation energy (Ch 8 #3)

Enzymes work by which of the following? increasing the activation energy reducing the activation energy making exergonic reactions endergonic making endergonic reactions exergonic

b. At high concentrations of substrate, all of the enzyme active sites are being occupied by substrate molecules.

For many enzymes, the rate of product formation increases as the concentration of the substrate increases. Eventually the rate of the reaction reaches a maximum at which further increases in the concentration of the substrate have no effect. Why? a. At high concentrations of substrate, the activation energy of the reaction decreases. b. At high concentrations of substrate, all of the enzyme active sites are being occupied by substrate molecules. c. At high concentrations of substrate, the reaction is endergonic. d. At high concentrations of substrate, the activation energy of the reaction increases. e. The enzyme is no longer specific for the substrate.

fastidious (Ch 9 #26)

Haemophilus influenzae must be grown on chocolate agar, which is blood agar treated with heat to release growth factors in the medium. H. influenzae is described as ________. an acidophile a thermophile an obligate anaerobe fastidious

c. Mesophilic neutrophile

Helicobacter pylori is a bacterial pathogen known to cause duodenal and gastric ulcers in humans. It survives by releasing the enzyme which produces ammonia to neutralize the stomach acid. Which of the following terms best describes H. pylori? a. Mesophile acidophile b. Psychrophilic acidophile c. Mesophilic neutrophile d. Extreme thermophilic neutralophile e. Mesophilic alkaliphile

aerotolerant anaerobe (KC Week 7 #9)

How would you describe a microbe that was found growing equally as well throughout a fluid thioglycollate tube? microaerophile facultative anaerobe aerotolerant anaerobe obligate aeorobe

Photoheterotroph (KC Week 7 #4)

I am a bacterium that uses light as my energy source. I will break down organic molecules to obtain my carbon source. How would you describe my metabolism? Photoautotroph Chemoautotroph Chemoheterotroph Photoheterotroph

c. cell ; colony

In a viable plate count, each isolated ______________ forms a ______________ in the sample population growing on the plate. a. hour ; generation b. cell ; generation c. cell ; colony d. colony ; cell

b. BSL-2 (Practice Exam #14)

In the UIC microbiology lab you are required to wear a lab coat, gloves, and goggles while working with many of the bacteria due to the moderate risk they may pose. This would be considered which biological safety level? a. BSL 1 b. BSL 2 c. BSL 3 d. BSL 4

a bacteriophage

In transduction, the DNA taken into the cell comes from: cell to cell contact sexual reproduction a bacteriophage free DNA in the environment

hydrothermal vent at the bottom of the ocean (Ch 9 #21)

In which environment are you most likely to encounter a hyperthermophile? hot tub warm ocean water in Florida hydrothermal vent at the bottom of the ocean human body

a hot vent at pH 1.5 (Ch 9 #18)

In which environment are you most likely to encounter an acidophile? human blood at pH 7.2 a hot vent at pH 1.5 human intestine at pH 8.5 milk at pH 6.5

death phase (Ch 9 #2)

In which phase would you expect to observe the most endospores in a Bacillus cell culture? death phase lag phase log phase log, lag, and death phases would all have roughly the same number of endospores.

A. Exergonic reactions that break large molecules into smaller ones. B. The loss of electrons from a molecule. C. The name for reactants going into an enzyme catalyzed reaction. D. Reaction, such as photosynthesis, that requires an input of energy. (KC Week 7 #1)

Match the following terms with their correct definition. Exergonic reactions that break large molecules into smaller ones. The loss of electrons from a molecule. The name for reactants going into an enzyme catalyzed reaction. Reaction, such as photosynthesis, that requires an input of energy. A. Catabolism B. Oxidation C. Substrate D. Endergonic E. reduction F. exergonic

A. The location where the substrate binds to an enzyme. B. A molecule can block a chemical reaction by binding to the enzyme at the same location as the substrate. C. The pH where the enzymes is properly folded and the reaction can proceed is know as the: D. The type of regulation where a molecule binds to an enzyme to either turn it on or shut it down. (KC Week 7 #2)

Match the following to test your understanding of enzymes. The location where the substrate binds to an enzyme. A molecule can block a chemical reaction by binding to the enzyme at the same location as the substrate. The pH where the enzymes is properly folded and the reaction can proceed is know as the: The type of regulation where a molecule binds to an enzyme to either turn it on or shut it down. A. Active site B. Competitive inhibitor C. Optimum D. Allosteric E. Maximum F. Non-competitive inhibitor

a. Critical items.

Medical items that require sterilization. a. Critical items. b. Household items. c. Non-critical items. d. Semi-critical items.

BSL-1 (KC Week 9 #1)

Microbes found in this biological safety level pose the least threat? BSL-4 BSL-1 BSL-2 BSL-3

conjugation (KC Week 8 #5)

Plasmids are transferred between cells during the horizontal gene transfer process known as: transduction conjugation replication transformation

are circular molecules of DNA found in the cytoplasm of bacteria (KC Week 8 #4)

Plasmids: are carried to the ribosome during translation. are part of the main bacterial chromosome. are circular molecules of DNA found in the cytoplasm of bacteria. contain regulatory RNA molecules.

an obligate aerobe (Ch 9 #13)

Pseudomonas aeruginosa is a common pathogen that infects the airways of patients with cystic fibrosis. It does not grow in the absence of oxygen. The bacterium is probably which of the following? an aerotolerant anaerobe an obligate aerobe an obligate anaerobe a facultative anaerobe

the density of the population (Ch 9 #9)

Quorum sensing is used by bacterial cells to determine which of the following? the size of the population the availability of nutrients the speed of water flow the density of the population

an aerotolerant anaerobe (Ch 9 #14)

Streptococcus mutans is a major cause of cavities. It resides in the gum pockets, does not have catalase activity, and can be grown outside of an anaerobic chamber. The bacterium is probably which of the following? a facultative anaerobe an obligate aerobe an obligate anaerobe an aerotolerant anaerobe

conjugation (ch 11 #23)

The F plasmid is involved in which of the following processes? conjugation transduction transposition transformation

reduce a microbial population by 90% (ch 13 #5)

The decimal reduction time refers to the amount of time it takes to which of the following? reduce a microbial population by 10% reduce a microbial population by 0.1% reduce a microbial population by 90% completely eliminate a microbial population

phenol

The effectiveness of chemical disinfectants has historically been compared to that of which of the following? phenol ethyl alcohol bleach formaldehyde

exposure to ultraviolet radiation (Ch 11 #17)

The formation of pyrimidine dimers results from which of the following? spontaneous errors by DNA polymerase exposure to gamma radiation exposure to ultraviolet radiation exposure to intercalating agents

A disinfectant is used to decontaminate lifeless objects, while an antiseptic is applied to living tissue (KC Week 9 #2)

The primary difference between a disinfectant and an antiseptic is that: Disinfectants are low-level germicides, whereas antiseptics are high-level germicides A disinfectant is used to decontaminate lifeless objects, while an antiseptic is applied to living tissue A disinfectant is used to decontaminate critical equipment, whereas an antiseptic is used to decontaminate semicritical equipment. A disinfectant is microbiocidal whereas an antiseptic is microbiostatic.

transduction (KC Week 8 #6)

The process by which a virus delivers a new gene to a bacterium is known as: transcriptional control mutation conjugation transduction

the substrate (Ch 8 #4)

To which of the following does a competitive inhibitor most structurally resemble? the active site the allosteric site the substrate a coenzyme

b. EMB is both a differential and a selective medium.

Urinary tract infections are commonly caused by Staphylococcus saprophyticus and Escherichia coli, and are less commonly caused by Proteus mirabilis You have a mixed culture of these pathogens which you inoculate onto both Eosin Methylene Blue agar and nutrient agar and then incubate the plates at optimal growth conditions. On the EMB agar, E. coli appears pink, P. mirabilis appears colorless, and S. saprophyticus does not grow. All three microorganisms appear cream on the nutrient agar plate. The best explanation for this data is that: a. Nutrient agar is both a selective and differential medium. b. EMB is both a differential and a selective medium. c. EMB agar is a selective medium whereas nutrient agar is a differential medium. d. EMB agar is a differential medium whereas nutrient agar is a selective medium.

A, C, D, E (KC Week 8 #1)

Use the following choices: A) Lactose 4g B) Peptone digest of casein 5g C) (NH4)2SO4 1g D) methylene blue 0.5g E) K2HPO46g Which combination of the above ingredients could you use if you were making a defined medium that selected for Gram negative bacteria? A, B, E A, B, C, D A, C, E A, C, D, E

iodine and chlorine (example Q Gibbons had in lecture)

What acts as oxidizing agents?

It forms a contractile ring at the septum (Ch 9 #5)

What is the function of the Z ring in binary fission? It controls the replication of DNA. It forms a contractile ring at the septum. It separates the newly synthesized DNA molecules. It mediates the addition of new peptidoglycan subunits.

a psychrophile (example Q Gibbons had in lecture)

What would always be in the alpine or arctic conditions and wouldn't survive in a typical room temperature?

the polypeptide is released (Ch 11 #15)

When the ribosome reaches a nonsense codon, which of the following occurs? a methionine is incorporated the polypeptide is released a peptide bond forms the A site binds to a charged tRNA

BSL-2 (ch 13 #3)

Which biosafety level is appropriate for research with microbes or infectious agents that pose moderate risk to laboratory workers and the community, and are typically indigenous? BSL-1 BSL-2 BSL-3 BSL-4

formaldehyde (ch 13 #13)

Which chemical disinfectant works by methylating enzymes and nucleic acids and is known for being toxic and carcinogenic? sorbic acid triclosan formaldehyde hexaclorophene

d. A, B, C

Which combination of the below ingredients could you use if you were making a defined medium that selected for Gram positive bacteria? A) Lactose 4g B) (NH_4)_2SO_4 1g C) K_2HPO_4 0.6g D) Peptone digest of casein 5g E) methylene blue 0.5g a. A, B, D b. A, B, C, E c. B, C, D d. A, B, C

Cells are metabolically inactive at the base of a biofilm (Ch 9 #8)

Which is a reason for antimicrobial resistance being higher in a biofilm than in free-floating bacterial cells? The EPS allows faster diffusion of chemicals in the biofilm. Cells are more metabolically active at the base of a biofilm. Cells are metabolically inactive at the base of a biofilm. The structure of a biofilm favors the survival of antibiotic resistant cells.

specialized transduction (Ch 11 #21)

Which is the mechanism by which improper excision of a prophage from a bacterial chromosome results in packaging of bacterial genes near the integration site into a phage head? conjugation generalized transduction specialized transduction transformation

autoclaving (KC Week 9 #5)

Which of the following IS a method of moist heat sterilization? incineration autoclaving pasteurization heating in a dry oven

coenzymes (Ch 8 #5)

Which of the following are organic molecules that help enzymes work correctly? cofactors coenzymes holoenzymes apoenzymes

fungistatic (ch 13 #4)

Which of the following best describes a microbial control protocol that inhibits the growth of molds and yeast? bacteriostatic fungicidal bactericidal fungistatic

fungistatic (KC Week 9 #8)

Which of the following best describes a microbial control protocol that inhibits the growth of molds and yeast? bacteriocidal fungicidal fungistatic bacteriostatic

surfactant (KC Week 9 #6)

Which of the following cannot sterilize? aldehyde surfactant ethylene oxide hydrogen peroxide

sulfites (ch 13 #11)

Which of the following chemical food preservatives is used in the wine industry but may cause asthmatic reactions in some individuals? nitrites sulfites propionic acid benzoic acid

promoter (Ch 11 #8)

Which of the following components is involved in the initiation of transcription? primer origin promoter start codon

mountain lake with a water temperature of 12 °C (Ch 9 #22)

Which of the following environments would harbor psychrophiles? mountain lake with a water temperature of 12 °C contaminated plates left in a 35 °C incubator yogurt cultured at room temperature salt pond in the desert with a daytime temperature of 34 °C

both pascalization and freezing are correct (KC Week 9 #3)

Which of the following is NOT a method of sterilization? both pascalization and freezing are correct freezing pascalization autoclaving

deletion of one nucleotide (Ch 11 # 18)

Which of the following is an example of a frameshift mutation? a deletion of a codon missense mutation silent mutation deletion of one nucleotide

chemoautotroph (Ch 8 #1)

Which of the following is an organism that obtains its energy from the transfer of electrons originating from chemical compounds and its carbon from an inorganic source? chemoautotroph chemoheterotroph photoheterotroph photoautotroph

antiseptic (Ch 13 #2)

Which of the following is suitable for use on tissues for microbial control to prevent infection? disinfectant antiseptic sterilant water

the length of time it takes for a population of cells to double (Ch 9 #4)

Which of the following is the best definition of generation time in a bacterium? the length of time it takes to reach the log phase the length of time it takes for a population of cells to double the time it takes to reach stationary phase the length of time of the exponential phase

low water activity (Ch 9 #23)

Which of the following is the reason jams and dried meats often do not require refrigeration to prevent spoilage? low pH toxic alkaline chemicals naturally occurring antibiotics low water activity

sonication (ch 13 #6)

Which of the following methods brings about cell lysis due to cavitation induced by rapid localized pressure changes? microwaving gamma irradiation ultraviolet radiation sonication

total plate count (Ch 9 #1)

Which of the following methods would be used to measure the concentration of bacterial contamination in processed peanut butter? turbidity measurement total plate count dry weight measurement direct counting of bacteria on a calibrated slide under the microscope

filtration (ch 13 #8)

Which of the following microbial control methods does not actually kill microbes or inhibit their growth but instead removes them physically from samples? filtration desiccation lyophilization nonionizing radiation

Thermophile - inner ear canal of a Labrador (KC Week 7 #8)

Which of the following microbial temperature classifications is improperly matched with its potential growth environment? Extreme thermophile - Hydrothermal vent Mesophile - Upper respiratory tract Thermophile - inner ear canal of a Labrador Psychrophile - Arctic lake sediment

NADPH (Ch 8 #2)

Which of the following molecules is reduced? NAD+ FAD O2 NADPH

hydrogen peroxide (ch 13 #10)

Which of the following peroxygens is widely used as a household disinfectant, is inexpensive, and breaks down into water and oxygen gas? hydrogen peroxide peracetic acid benzoyl peroxide ozone

tincture (ch 13 #9)

Which of the following refers to a disinfecting chemical dissolved in alcohol? iodophor tincture phenolic peroxygen

conjugation (KC Week 8 #10)

Which of the following refers to the mechanism of horizontal gene transfer naturally responsible for the spread of antibiotic resistance genes within a bacterial population? mutation transformation transfecting conjugation

transformation (Ch 11 #22)

Which of the following refers to the uptake of naked DNA from the surrounding environment? conjugation generalized transduction specialized transduction transformation

They bind directly to DNA to activate transcription.(Ch 9 #10)

Which of the following statements about autoinducers is incorrect? They bind directly to DNA to activate transcription. They can activate the cell that secreted them. N-acylated homoserine lactones are autoinducers in gram-negative cells. Autoinducers may stimulate the production of virulence factors.

thermal death time (ch 13 #7)

Which of the following terms is used to describe the time required to kill all of the microbes within a sample at a given temperature? D-value thermal death point thermal death time decimal reduction time

needles (Ch 13 #1)

Which of the following types of medical items requires sterilization? needles bed linens respiratory masks blood pressure cuffs

catheters (KC Week 9 #7)

Which of the following types of medical items requires sterilization? respiratory masks thermometers pillows catheters

stationary (KC Week 7 #5)

Which phase of the bacterial growth curve is defined by zero net growth due to a lack of nutrients and excessive waste products being present? log lag stationary decline

in-use test (KC Week 9 #9)

Which type of test is used to determine whether disinfectant solutions actively used in a clinical setting are being used correctly? in-use test use-dilution test phenol coefficient test disk diffusion assay

It is a capnophile. (Ch 9 #15)

Why do the instructions for the growth of Neisseria gonorrhoeae recommend a CO2-enriched atmosphere? It uses CO2 as a final electron acceptor in respiration. It is an obligate anaerobe. It is a capnophile. It fixes CO2 through photosynthesis.

ethylene oxide (KC Week 9 #4)

You are a manufacturer of polypropylene hypodermic syringes. Which of the following methods would be best for ensuring sterility of this heat-sensitive material? pasteurization non-ionizing radiation ethylene oxide autoclave

Gram positive bacteria would have difficulty forming a biofilm (KC Week 7 #6)

You have developed a drug that blocks the action of short peptide chemical communication signals. The end result would be: Gram positive bacteria would have difficulty forming a biofilm. Gram positive bacteria would have difficulty dividing. Gram negative bacteria would have difficulty dividing. Gram negative bacteria would have difficulty forming a biofilm.

a spectrophotometer (KC week 7 #7)

You need to quickly determine if any bacteria are growing in your new broth media. The fastest way to check for growth would be to use: the MPN technique. direct counting chamber. a chemostat. a spectrophotometer.