# BIOLOGY 173 Study Guide - Quiz Guide: Antimicrobial Resistance, Plasmid, Sample Size Determination

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β Which variables make a t-score higher or lower?
β Higher difference in mean makes a higher t score
β  Results are significant
β Variance (more sig if its smaller)
β Same population (more sig if larger)
β Significant results
β Higher diff in means
β Smaller variance
β Larger sample
β High t score
β Low p value
β Figure out a hierarchy from data given.
β How antibiotic resistance works
β How did we do the transfer, dilutions etc?
β Biological fitness: relative reproductive success.
β Why do we have diff numbers of bacteria at different times of day?
β PLasmid loss: takes cells that are well adapted to one environment and put them in a new one.
β One without antibiotics
β The resistant plasmid slow the growth, development and reproduction of the bacteria compared to non
resistant bacteria.
β The cell gets rid of the plasmid
β Put the bacteria in a new flask repeatedly (after all of the nutrients are used up)
β Throughout the weeks, the cells begin to lose the plasmid
β  Initially all of them had resistant plasmid
β High copy number is a disadvantage
β Making unnecessary proteins
β Do dilution to decrease the amount of cells so that when theyβre plated on one plate w/ antibiotics and
one without, you can tell the difference (count)
β Aim for 30-300
β Canβt plate more than 1/10 of mL
β Plate for more than one tube so that the number isnβt too high or low
β Calculate cumulative dilution by multiplying all singular dilutions in the set
β Why does it not matter how much we diluted the cell?
β Plating equal volumes on both plates
β Why did we transfer only 0.1 mL to the plate
β Make sure there isnβt any liquid left on surface of plate.
β Using relative numbers to determine proportion resistant
β Dilution scheme
β Plate 0.1 mL from each tube until you get to countable number
β 30 - 300
β Plate the last three tubes
β  Ex. 500, 50, 5
β Things bacteria has that host cells don;t
β Cell wall (enzymes)
β DNA Gyrase
β Ribosomes (are diff)
β Why did we swab on EMB plates instead of L plates first?
β To select for E. coli against other species
β Why did we use a metal loop instead of a swab?
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## Document Summary

Higher difference in mean makes a higher t score. Figure out a hierarchy from data given. Plasmid loss: takes cells that are well adapted to one environment and put them in a new one. The resistant plasmid slow the growth, development and reproduction of the bacteria compared to non. The cell gets rid of the plasmid. Put the bacteria in a new flask repeatedly (after all of the nutrients are used up) Throughout the weeks, the cells begin to lose the plasmid. Do dilution to decrease the amount of cells so that when they"re plated on one plate w/ antibiotics and one without, you can tell the difference (count) Can"t plate more than 1/10 of ml. Plate for more than one tube so that the number isn"t too high or low. Calculate cumulative dilution by multiplying all singular dilutions in the set. Why did we transfer only 0. 1 ml to the plate.