L9 Flashcards
(30 cards)
what are the ways of determining bacteria numbers (3)
absorbance
plating
counting chamber
what can determine which antibiotic can be used and its concentration
sensitivity testing
disk diffusion assay
epsilomete test
will a bacteria eventually become resistant to any antibiotic?
yes
what accelerates the development of antibiotic resistance in bacteria
misuse of antibiotics
can antibiotics be used for viruses
no
what was the very first antibiotic used
Salvarsany
what are the 5 modes of resistance
drug modification/destruction
pathway protection
target alterations
rapid efflux
alternative pathways
what is drug modification for bacterias mode of resistance
b lactamase for penicillin
what is pathway protection for bacterias mode of resistance
bacteria created false target for antibiotic and it can bind to something else (diversion of true target)
what is target alterations for bacterias mode of resistance
a single ribosome alters the protein on the target site
what is rapid efflux for bacterias mode of resistance
bacteria actively pimping out the antibiotic so the concentration isn’t high enough to inhibit
what are alternative pathways for bacterias mode of resistance
if the target becomes a non essential target
what does a b lactamase inhibitor do to antibiotics
breaks down the antibiotic using an enzyme
what greatly decreases the chance of developing drug resistance
using a combination of drugs
what do enzymes do
lower activation energy
they act as a catalyst for a chemical reaction
are enzymes proteins
yes
what is enzymatic specificity a result of
having the right shape to hold the substrate and catalytic centre to facilitate the reaction
whats the equation for reaction rate
v = -delta [S] / delta t
what are the units of enzymatic reaction rate/velocity
(umol/L)/s or (mg/ml)/s
concentration over time
when is initial velocity of an enzyme usually measured
right off the bat and short time (before 10% of reactant is used up)
where should initial velocity be measure from on a graph
the linear portion at the beginning
whats the Michaelis menton equation
vo = [S] Vmax / [S] + Km
what is Km defined as
the concentration of the substrate when initial velocity is at 1/2 Vmax
what is the Km of hexokinase?
30 um
