required practical 1 Flashcards
how is a control set up in a practical measuring enzyme activity?
replace enzyme with boiled enzyme or distilled water
when calculating a mean
remove any anomolous results before calculating mean
fewer than 10 data points
not enough data points to accurately predict the patterns
when should you draw a curve/straight line of best fit
when you have enough data points to accurately predict the pattern.
what is the effect of temperature on enzyme activity?
as temperature increases, both the enzyme and substrate have more kinetic energy
increased frequency of collisions
more enzyme substrate complexes formed
beyond a certain temperature, the rate of reaction starts to decrease as the enzyme is denatured
its tertiary structure changes
hydrogen ionic and disulfide bonds break
enzyme no longer complimentary to substrate
fewer enzyme substrate complexes formed.
method limitations
not wide enough pH range as couldn’t identify ooint at which enzyme denatured
didn’t test enough intermediate values so cannot identify optimum pH
temperatuer of water bath not thermostatically controlled so decreases over investigation
end point is subjective so time measurements may be inaccurate
RP 2- what does hydrochloric acid do?
softens and loosens the root tissue
acetic orcein stain
turns chromosomes a purple red colour
mounted needle
to lower the coverslip onto the slide and prevent air bubbles under the coverslip
root tip of onion/garlic
growing region so cells here will be undergoing mitosis
why is filter paper placed on top of the slide? what must you make sure you do not do?
place filter paper on top of the slide and gently press down
ensure you do not slip and move the coverslip sideways
this is to spread the cells out to create a thin layer to allow light to pass through so it can be viewed using an optical microscope
why should you not slide the filter paper across?
some cells will be on top of the others which means there is not a single layer created so light cannot pass through
hazards
scalpel
risk of cutting yourself
precauation- cut against a white tile to prevent slipping
cut away from body
cut against flat surface
hydrochloric acid
irritant and corrosive (depends on concentration)
precaution- wash your hands with soap and water if any spills occur
wear safety goggles
when counting cells to calculate mitotic index, what should you do to ensure your count is accurate?
examine large number of fields of view/cells
to ensure sample is representative
what is osmosis?
the movement of water from a region of high to low water potential through a partially permeable membrane
