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139 Cards in this Set
- Front
- Back
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What are four phases of bacterial growth curve?
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Lag phase
Exponential (Log) phase Stationery phase Death phase |
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what is Lag phase of the bacterial growth curve?
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no growth, cells very metabolically active, preparing to divide
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What is the exponential or log phase of the bacterial growth curve?
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cell division at exponential rate
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What is the Stationary phase of the bacterial growth curve?
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cells stop growing due to depletion of nutrients, crowding, and toxic products. This stage is very useful for antibiotic research
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What is the Death phase of the bacterial growth curve?
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cells begin to die at exponential rate
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what is Optical density (turbidity)?
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measured using spectrophotometer to estimate number of bacterial cells
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What is an enzyme?
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Mediates all metabolic reactions of a cell
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What are exoenzymes?
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Extracellular enzyme that degrades large macromolecules
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What is a hydrolytic reaction?
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Exoenzymes degrade macromolecules by splitting chemical bonds between the polymeric subunits by adding water
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What is fermentation?
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oxidation of organic substrates to generate energy
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Simple test to detect fermentation?
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Inoculate sugar broths containing acid-base indicator.
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What is Durham tube?
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that collects gaseous end products within broth
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What does the TSIA Slant Combination K/K mean?
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all red
no sugars fermented |
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What does the TSIA Slant Combination K/A mean?
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red over yellow
glucose is fermented |
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What does the TSIA Slant Combination A/A mean?
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all yellow
glucose + sucrose or lactose is fermented |
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In the TSIA slant test, if you have a black precipitate, what does that mean?
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H2S is present
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All amino acids have these groups?
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Terminal amino (-NH2) and terminal carboxyl (-COOH).
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What does a deaminase reaction remove?
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Terminal amino end
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What does a decarboxylase reaction remove?
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Terminal carboxyl end
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Deamination reactions result in the release of this?
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Ammonia
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Decarboxylation reactions result in the release of this?
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CO2
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To test for phenylalanine deaminase activity you use this type of broth?
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Phenylalanine malonate
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What does IMViC stand for?
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Indole Production
Methyl red test Voges Proskauer test Citrate permease activity |
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IMViC tests are used to determine what?
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Gram negative, facultatively anaerobic rods
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What is indole test for?
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Ability of bacteria to produce indol from the amino acid tryptophan present in the broth
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What does methyl red and Voges-Proskauer tests(MR-VP) ferment?
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Glucose
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What does methyl red show?
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The ability to produce acid during glucose fermentation.
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What does Voges-Proskauer test show?
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The ability of bacteria to ferment glucose to the non-acid product butanediol.
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What does a Catalase test do?
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It catalyzes hydrogen peroxide (H2O2) into water and oxygen. (Which creates the bubbles)
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What is chemical equation for incomplete reduction?
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NO3- >>>NO2-
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What is chemical equation for denitrification?
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NO3->>>NO2->>>>>>N2O>>>N2
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What is denitrification?
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A loss of nitrogen to atmosphere.
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What is phenotype?
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Physical characteristics expressed under specific environmental conditions.
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What is a genotype?
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Total number of genes an organism contains.
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What are markers?
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Identifiable phenotypic characteristics
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What is a mutation?
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a heritable change in the DNA sequence of an organism
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What are mutagens?
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Increases rate of mutagenesis; examples: ultraviolet light, chemicals.
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What is a silent mutation?
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No change in protein product(gene).
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What is direct selection method?
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Directly selecting mutants from very large amount of cells.
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What is screening for mutations?
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Using a media where both mutants and non-mutants can grow, but the mutants look different.
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What is the equation to calculate spontaneous mutation frequency?
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Frequency= # of colonies/ # of organisms spread on the plate
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What is the average number for organisms spread on the plate?
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10^8
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What is the range of frequency?
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10^-8>>>1
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Can mutations occur as a result of a bacteriocide?
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NO!! Spontaneous mutations occur on their own.
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What are the three processes that result in genetic exchange?
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Transformation, Transduction, and Conjugation
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What is transformation?
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Taking up extracellular DNA from the environment. Can only be done by competent cells.
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What are competent cells?
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A physiological state where a cell can engage in transformation.
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What is transduction?
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Exchange of DNA between two bacteria mediated by a bacterial virus.
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What is a bacterial virus?
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A bacteriophage.
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What is conjugation?
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DNA exchange between two organisms by direct cell-cell contact.
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What is a plasmid?
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replicating circular extrachromosomal DNA
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What is the equation for conjugation frequency?
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Conjugation frequency= # of colonies/ total # plated
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What is a bacteriophage?
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Virus that infects bacteria.
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What does lytic mean?
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Infect and kill host by causing cell lysis.
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Name the steps of lytic cycle:
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Attachment
Penetration Replication Assembly Release |
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What is attachment of the lytic cycle?
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Attachment: The phage particle attaches to a specific receptor on the surface of host cell. Cell without specific receptor are immune.
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what is penetration of the lytic cycle?
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Penetration: Phage injects genetic material into host cell.
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what is replication in the lytic cycle?
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Replication: The phage nucleic acid codes for proteins that take over host cells biosynthetic machinery and directs it to make new phage genomes and the proteins required to make the phage capsid
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what is assembly in the lytic cycle
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Assembly: The phage genome and capsid proteins are assembled into intact phage particles.
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what is release in the lytic cycle
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Release: A phage encoded enzyme lyses the host cell and the newly assembled phage particles are released.
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What is lysogeny?
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Dormant virus inside bacterial cell. The bacterial cell is known as a lysogen. The phage capable of lysogeny is known as lysogenic or temperate phage.
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What is protein capsid?
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The head of bacteiophage that is not injected into cell
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What is phage typing?
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Known phage can be used to identify an unknown bacteria
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What is lysate?
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The clear liquid containing phage
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What are the clear areas called on a media plate?
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Plaques
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What are plaques?
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A formed by a single phage particle. Indicates lysis, and can be counted to determine the number of PFU in a lysate.
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What is PFU?
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Plaque forming unit.
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What is the equation for PFU?
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? #PFU/ml= # of plaques(PFU) on plate/plate dilution
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What is the equation for plate dilution?
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Plate dilution= (dilution of plate)(volume plated)
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Most bioluminescence bacteria are located where?
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Ocean
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Production of bioluminescence is carried out by this enzyme?
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Luciferase
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Bioluminescence requires what to take place?
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O2
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Why do bioluminescence bacteria gather in large groups?
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They need a large amount of autoinducer compound which would be to draining on a free living single bacterium
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What is the gathering of bioluminescence bacteria called?
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Quorum sensing
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In the starch hydrolysis test, what is your indicator to show that bacteria produce amylase?
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Gram's Iodine
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in the starch hydrolysis test, what are you testing for?
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breakdown of starch by amylase
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if you have a positive starch hydrolysis test, what does that mean?
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you have a clear zone around your inoculum
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in the casein hydrolysis test, what are you testing for?
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breakdown of casein into peptides and amino acids by Caseinase
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in the casein hydrolysis test, what does a positive test look like?
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zone of clearing around bacteria that produce caseinase
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in the dna hydrolysis test, what is the indicator?
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methyl green in media
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in the dna hydrolysis test, what happens?
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DNase breaks down agaar into nucleotides, phosphates, and bases
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what is the media used in the DNA hydrolysis test?
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DNase plate
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what does a positive test for DNA hydrolysis look like?
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color around bacteria fades to yellow.
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what is the enzyme in dna hydrolysis test?
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DNase
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what is the media used in starch hydrolysis test?
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starch agar plate
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what is the media used in casein hydrolysis plate?
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milk agar plate
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what is the media used in gelatin hydrolysis test?
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tubes of nutrient gelatin
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what happens in the gelatin hydrolysis test if positive?
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liquification.
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what is the tip for performing the gelatin hydrolysis test?
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put 3 loopfuls of culture in
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What is a mutant?
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strain that harbors a mutation
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what is screening?
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all cells grow to form colonies but the mutants are identifiable by some different characteristics
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what is selection?
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only the desired strain grows
preferred but not always possible |
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the TSIA test is used to identify fermentation of what?
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glucose
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the litmus milk test is used to identify fermentation of what?
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lactose
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what is the media used in a sugar fermentation test?
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phenol red lactose broth
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in the sugar fermentation test, describe the results that can be seen.
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G- Gas in Durham tube
A- Acid if acid is present turns phenol red to yellow color |
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what does TSIA stand for?
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Triple
Sugar Ion Agar |
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what is the media used in a TSIA test?
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TSI agar slant
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how do you read the results of a TSIA test?
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indicate the presence of acid or alkaline conditions in the slant and butt portion of the agar.
G- Gas A- acid (yellow) K- Alkaline (red) A/A, K/A, K/K |
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In a litmus milk test, what will happen to the litmus if it ferments lactose?
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it will turn pink
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what is the enzyme in the litmus milk test?
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casein
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how can you tell if casein is hydrolyzed in the litmus milk test?
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turns a yellowy/clear watery liquid.
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how can you tell if casein is peptonized in the litmus milk test?
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litmus turns lavender to blue, this means alkaline
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In the litmus milk test, what does it mean if the tube is colorless?
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Reduction of oxygen
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what broth do you use to test for phenylalanine deaminase activity?
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phenylalanine malonate broth
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what broth do you use to test for decarboxylase activity?
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decarboxylase broth
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when decarboxylated, what does lysine produce?
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CO2 and cadaverine
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what does a positive and negative malonate test look like?
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positive malonate broth turns from green to blue
negative malonate broth will be light green |
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how do you test for phenylalanine deaminase?
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add 3-5 drops of FeCl3 to malonate broth
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what does a positive phenylalanine deaminase test look like? a negative one?
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(after adding FeCl3)
positive= deep green color negative= yellow color |
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what does a positive lysine decarboxylase test look like? a negative one? what color is the control broth?
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positive= purple
negative=yellow control=purple |
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what color are urease positive organisms and what is the component they produce?
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they produce ammonia and the color is from orange to hot pink
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what is the enzyme in the urea test?
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urease
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what is important to remember in the decarboxylase tests?
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put oil on top
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the indole test shows bacteria's ability to produce what?
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indole
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what is the enzyme in the indole test?
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tryptophanase
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what are the methyl red and voges-proskauer testing for?
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fermentation of glucose
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what is the citrate test testing for?
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bacteria's ability to utilize citrate as their sole source of carbon and energy
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what does a positive indole test look like? a negative one? what is added to this test before determining that it is positive or negative?
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positive= cherry red color
negatvie= all other colors Kovac's reagent is added |
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what is added to the Voges-Proskauer Test to determine if it is positive or negative? what does a positive result look like?
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40%KOH followed by alpha-naphthol.
positive= red-orange color |
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what is added to the methyl red test to determine if it is positive or negative? what do positive and negative results look like?
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methyl red indicatior is added.
positive= red color negative= yellow |
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what is the IMViC test a key test for?
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gram negative rods
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what do positive and negative citrate tests look like?
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positive= blue slant/butt with visible growth on the slant
negative= absence of growth and no change of green color or broth |
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respiring organisms possess this in their membrans
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Electron transport chain
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what is one of the major components of the electron transport chain?
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iron containing proteins called cytochromes
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what is the enzyme in aerobic respiration?
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cytochrome oxidase
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what test is used to distinguish between respiring from non-respiring bacteria?
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catalase test
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in the nitrate reduction test, describe a positive and negative test
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positive=deep red within 2-3 minutes
if wasn't positive, add zinc powder positive=broth remains colorless after zinc is added negative=broth turns red after zinc is added |
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what are all the components added to the nitrate reduction test?
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nitrate reagent A and nitrate reagent B, then zinc is added
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describe a positive and negative reaction for the cytochrome oxidase test
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positive= blue color in the bacterial smear within10-30 seconds
negative= no reaction within bacterial smear |
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describe a positive and negative catalase test
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positive=bubbles
negative=no bubbles |
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what is added to the bacteria on a slide to prepare for the catalase test?
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3% H2O2
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what is the equation for number of cells plated?
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concentration x volume plated
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what is the equation for concentration of PFU
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PFU/plate dilution
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what is the equation for plate dilution?
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tube dilution x volume plated
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what is the equation for frequency
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number of colonies/total cells plated
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what is the equation for dilution?
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volume of substance/total volume
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what is the equation for final dilution
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dilution 1 x dilution 2
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what is the equation for final concentration
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concentration x dilution
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