Practical 2 Micro
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50 Terms
what must you do in order to conduct the Kirby Bauer disc diffusion
spread the bacteria given on a TSB plate and then put the antibiotic disc down or a disc dipped into the disinfectant onto the plate to see if it inhibits the bacteria
what is zone of inhibition
clearing around antibiotic- impregnated disk
what does susceptible mean
a large clearing on the plate inhibiting bacteria growth
what does resistance mean
the ability of the bacteria to grow even if there is a disinfectant or antibiotic
what does hydrogen peroxide do
oxidinate stress
what does dimethyl ammonium chloride do
disrupt membrane
what does hydrochloric acid
denature proteins
what does chlorhexidine gluconate do
disrupt membrane and cell wall
what does lactic acid do
denature proteins
what does sodium hypochlorite do
denature proteins and cell wall
what does 65% ethanal do
denature membrane and coagulate proteins
what does penicillin do
inhibit some form of cell wall, inhibiting replication
what does streptomycin do
cause mRNA Condon to be misread
what does ciproflaxcin do
blocks replication of DNA other or transcription of RNA
what does amoxicillin CA do
inhibit bacterial cell wall synthesis
what does polymyxin B do
disrupt membranes
what does tetracycline do
cause mRNA Condon to be misread
what does erythromycin do
block polypeptide exit tunnel
what does vancomycin do
inhibit bacterial cell wall synthesis
what does Bactrim do
competitive inhibitor, prevent substrate from binding to folate synthesis
what is transformation
competent bacteria gets genetic material from it’s environment
why is CaCl2 used in pGlo transformation
makes membrane permeable which helps get plasmid across
describe the purpose of the genes on the pGlo plasmid
ori: origin of replication
araC: has arabinose as the activator for it’s inducible operon system
GFP: this is activated when araC operon is turned ON allowing the cell to glow
bla: ampicillin resistance gene
what does ampicillin tell us
it tell us what has the antibiotic resistance gene meaning it is pGlo+
that the bacteria can survive in the presence of ampicillin, indicating successful uptake of the pGlo plasmid since it is a selective.
what does arabinose tell us
arabinose turns on the inducible operon system on the arac gene and which then triggers GFP to make the cell glow
what will happen when the pGlo- on a LB plate
colony growth
what will happen to a pGlo- on a LB/Ampicillin plate
little to no colony growth
what will happen to a pGlo+ on a LB/Ampicillin plate
colony growth
what will happen to a pGlo+ on a LB/ampicillin/ arabinose plate
glow and colony growth
what will happen to a pGlo+ on a LB/arabinose plate
a lawn is formed
what was special about the E. coli that was used for this lab
E. coli is not naturally competent but E. coli HB 101 is a competent cell that allows highly efficient DNA transformation to occur
what is the constitutively expressed gene
the Bla gene (which is the ampicillin resistance gene) and the araC gene
what is the selection gene
the Bla gene
what is the conditionally expressed gene
the GFP gene which makes the cell glow
what is the screening gene
the GFP gene
why is serial dilution done in plaque assay
decrease the number of phages so we can calculate the concentration of phage which allows for a more precise and manageable count of organisms
what is FDF
the final dilution of the sample used in a serial dilution process to determine the concentration of a particular substance
what is phage titer
the plage forming unit over top of the FDF (pfu/mL)
what is a plaque
a single phage that can infect a host cell during absorption
what does the phage titer give you
it gives you the concentration of phages in a bacteria
why is soft agar used
to immobilize infected cells so the can not infect all the cells in the sample
what type of virus was used and why was E. coli used in the experiment
it was our host cell for this experiment and E. coli has many strains that share similar genomics while harboring drastic differences.
why is phage typing done
to allow us to identify a specific type go bacteria because bacteriophages can only infect specific strands of species of bacteria
what will subspecies of a species have the same and differ in
subspecies will have the same phenotypic classification but differ in symptoms and the phage that infect it (phage typing). they both share core genetic identity and fall under the same species name, they are cable of interbreeding (reproduce) or exchange genetic material. they differ in resistance pattern, pathogenic potential, surface structure.
how is phage typing performed
swab the surface of a grid TSB plate (reference library) which will create a lawn on it, then add the phages in the grid. let it incubate and then see which one develops a plaque which is a hole in the lawn.
why is serial dilution done in urinalysis
to decrease the number of bacteria in a urine sample since there is always going to be bacteria in your urine which allows us to achieve a reducible bacterial colonies
what is used to calculate the urinalysis
cfu/mL (colony forming unit/mL)
why do we use cfu instead of pfu
due to the urine forming colonies and not plaques since UTIs are based on quantitative urine culture
how do we know if our patient has a UTI
if the cfu/mL is above 105 because 105 is the threshold
why is there acceptable level of bacteria in urine
because urine has normal flora that is found in the external urethral meatus and genitals